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Premium Member
2,997 Posts
Discussion Starter #21 (Edited)
So after I got back from Lincoln, I was pretty Jazzed. I got a chance to really see where I and the car stacked up and was very encouraged with the performance of the car (the driver needs work....but isnt that always the case ;) ). I needed to make the next step up in the cars development.

I had a lot of ideas going, but one dominated in my mind....I needed a new chassis.

I wanted this for three reasons..(1)The sunroof plug is not 100% kosher. Its gets the effect of the rules, but its really not legal as written. The rules say you can convert the car to whatever trim package was available from the factory. Since there was such a thing as a non-sunroof GT, I can convert my car to non-sunroof status....but the thing is it has to match exactly as was available from the factory. That means the plug wont do, it has to be a complete reskin.

Id either have to find a non-sunroof GT (BWahahahahahahahha!!!!) or get a DX, cut the roof off, then get the glass out of my car, cut its roof off (or a large section), trim, weld, sand, primer and paint......for about $2000 for a shop to do that. Yeah, thats what I was thinking too. OR!! since I have to source a DX anyway, why not just swap the chassis? DXs are cheap, $500 for a non-roller (or a drivable car) isnt out of the question. Yes, I would have to swap over EVERYTHING (no seriously, everything) that made a GT a GT, but it would be more time than money. Awesome, Thats the plan. I figured Id get a car and taking my time, a month would get me a no sunroof GT.

2nd reason was, I wanted to see if there was any sheet metal changes (In terms of weight) between the A and B cars. I know in other manufacturers who had cars that ran before and after 1990, they had to change the cars slightly to conform to the post 1990 requirement of adding an airbag or having some sort of passive restraint system (autobelts FTL). Going to autobelts or moving the seatbelt mounts to the doors meant that the chassis had to be reinforced to deal with the possible forces exerted on it. As a consequence, the weight of the chassis was usually higher in those later cars. I know that all of the 626s used the autobelts from inception so there may be no difference in reinforced chassis points, but I wanted to test it out anyway...just for curiositys sake.

3rd reason I wanted a new chassis was, I didnt want to do 2x the work with the remaining projects. Id put them on one chassis, then take them off and then have to lay them out on a new chassis...again. Best to wait for the new canvas....And then something happened....or rather, didnt happen.

I could never find a decent DX. They were either clapped out or...REALLY clapped out. Since I wasnt working on the other projects until the new chassis was procured, I basically did nothing. The car sat and then....I started to enjoy having weekends again. I didnt have to chase the next event. Didnt have to do prep the day/night before. I could go out to clubs, to movies, hang out with friends.....go out with a girl on a date. It wasnt bad. As time went on, I pretty much lost motivation for working on the car and so it sat..........since last September.

Early march or so something happened. I came to the conclusion that I could no longer hold on to the 1984 Rabbit GTi that I had gotten with SVTfrush and some other folks for the 24hrs of Lemons race. It was sitting for two years and I had to come to grips with the fact wasnt going to happen again. There just wasnt enough money to spread between two project cars. I would part it out.......hmm, you know, I had amassed a fair amount of racy parts for the VW (konis, rally bilstiens, it had a roll cage, struts bars, springs...a lot of desireable items). Those could catch a pretty penny on the market. Hmm......Im ahead of my bills for the first know, my tax returns are coming soon......!!!

All of a sudden, it dawned on me that there was a narrow window where I could have a fair amount of cash to get the final money intensive projects off the ground and completed!

You know what? Enough of this waiting for the perfect DX chassis. I can get to that another time....Ladies and gentlemen...My motivation is BACK :)


Premium Member
2,997 Posts
Discussion Starter #22 (Edited)

Ancilliary parts for the TEC3r. Map sensor, DFU, sensors, mag pickup, trigger wheel.

I sent the trigger wheel and the aluminum crank pulley to the machine shop get turned down. Both are perfectly round and make an interface fit with each other. I have to figure out where the mag pickup is going to be mounted soon (I think the front near main coolant return)

I decided to make my own plug and play adaptor harness, but the flying loom for the TEC3r is $200. Im not buying a $200 wiring harness just to cut them down to 12". Thats just dumb. Took me a while to figure out the plugs that the TEC3 uses and where to get them, but I have them now...oh yeah, the plugs are $9.50 each (not including the crimp connectors which is another $5 for 50)....I rule.

Gotta figure out what goes to what between the TEC3 wiring schematic and the MX6s wiring schematic (um...the leg bone connects to the...???).

I apologize in advance. I had said that I would like to have done a couple before and after dynos to see what did what and how much..but I am feeling the urge to just get things going. Basically, Ill be adding a lot of components at the same time. Yes, that muddies the water a bit and am a bit sad at that myself. I did want to see how things performed individually, but I feel that I should just keep working while my motivation is on High and not delay things any longer.

To that end, the ECU makes adding the new sheet metal intake manifold and ridding the car of all the emissions hardware a possibility. Lots of weight savings there.. speaking of weight savings

Im pressing on my welder dude to start work on the tubular turbo manifold. I gave him a box of stainless Els, pictures of manifold designs and an extra cylinder head to use as a jig about a year ago. At the time I wasnt that eager to get it done, so things just drifted on. My motivation is back up so I am turning up the heat a little on welder dude (hey, he owes me..its been a year of him slacking as well )

No, its not an Aeromotive, just a simple and effective B&M fuel pressure regulator and thats all Ill need. The autometer bolt is an M16 to 1/8th NPT. Perfect size for the end cap of the fuel rail. A 90deg elbow and I have most everything to add the pressure fitting from the SPA gauges. I want to remote mount the sensor on the firewall so I still need to have a hose made for that.

Got the supra 440cc injectors back from witchhunter performance. Cleaned and balanced. Two are pushing slightly higher than 440ccs. Ill keep those as spares for the time being.

Pulled this out of the car. It needs to be replaced by something, but what?

Yeah, I think thatll work.

Thats 5ft of 3"diameter 18ga straight pipe, two 16ga 90deg 3" elbows, burns stainless lightweight racing muffler (3"in/out), a 14ga 2.5" 180deg bend, a 1.5" 180deg bend, 2.5">3" reducer, 2.5" v-band clamp and a flange for the VJ-11.

The piping is from Colombia river mandrel bends, the clamp and reducer are from vibrant, the muffler..well thats easy, The flange is from BMCrace. Aside from the flange, everything is 304 stainless. I plan to make my own O2 housing with the 180deg bends. I got those in heavier gauge because I wanted a bit more strength and resistance to heat since it will be right next to the turbo. Should be a nice and simple and quiet exhaust system. There is a new sound policy in place for the National Tour events. Indeed, as I mentioned, lots of local clubs have to adopt some sound ordinances to keep happy neighbors as urban sprawl finds its way out to previously far away places. I will do my part to comply. Besides, nowadays, loud no longer equals power. There are solutions on the market that are free flowing, dont hurt power and are quiet.

Oh yeah, if I do this right, the new exhaust setup will probably weigh about half of what I removed (that removed section is 30lbs). :)

After 2 years I finally made the trip to Sears Point in Sonoma county, california to go to PSI (Koni, Ohlins, Moton, Penske, Hypercoils, Your Racing Shocks Shop!) to have them rework the "penske" triple adjustable shocks I built out of some ex-porsche racecar struts. I think I may have mentioned this already, but I say "penske" because after a lot of talking with PSI, it turns out they arent 100% penske items. They were off a 993 Porsche 911RSR, but penske didnt really start making struts until the 996 came out.....and those were inverted struts. Best guess anyone has is that they are a custom build using Anze strut bodies, penske internals and external canister, with maybe 22mm JRZ or Moton shock shafts, er......or something :shrug:. Luckily, PSI is familiar with the individual parts, but will have to do some research on them to confirm what they think they revalving [email protected]$1000....ugh.

Oh yeah a local fellow was selling this so I picked it up. Never used, just fitted to the car (too shallow, they got deeply dished momo instead). Its fuzzy :)


Premium Member
2,997 Posts
Discussion Starter #23 (Edited)

Much like everything else...some assembly is required.

Turns out the unit I got doesnt fit the MX6 FPR as it is too small (I want to say the internal diameter is 36mm). A quick trip the the machinist to punch it out to 38mm fixed that issue. The top "cap" of the B+M uses an o-ring to seal against the top of the stock FPR. I thought the stock item was a bit too thin and got a thicker o-ring (and a bit of hylomar gasket sealant) to have it seal a bit better to the stock housing.

out with the old

And in with the new

Finally started dressing the intake manifold. New fuel lines, injectors, sorting out coolant lines, pulsation damper needed juuuust a little more clearance to the main plenum (precision hammering ensues), etc.

One thing that I did add was an extra nipple for the coolant (on the flange in the 2nd picture). I still needed a feed source for the oil cooler since that was eliminated in the making of the new manifold. I was thinking of making a "T" fitting from the inlet hose that feeds the heater core, but then I realized that the 2nd coolant port in the head (that I had originally had welded shut) was the perfect place to have the coolant feed.

So heres something that amuses me when looking at this manifold....
-flange and runners: Mazda
-Sheet metal body: VW
-injectors : Toyota
-Fuel pressure regulator: Honda
-throttle body: Ford

What a mutt :)

Heres some comparison shots of the two manifolds together..

Stock intake manifold is 25lbs with accessories. The new manifold is 10lbs fully dressed. I like that :)

The manifold is actually in the car now. There was a lot of detail work that needed to be done. Clearance to other parts, fitment of throttle cables, routing of hoses....pretty much the things you would have to expect with a custom fitment.

Here is another project tie in that involved the manifold...

Pressure sensors for the SPA gauges

So I have two pressure sensors (fuel and oil) that I wanted to install while the stock intake manifold was out. The back of the engine block would be easy to get to and I also needed to tap into the fuel rail to get readings as well.

Ive been doing a bit of reading about pressure sensors and what I gather is there is concern about excessive vibration. Whether the fears are well founded or just internet rumormill, I decided to remote mount the sensors to the firewall.

I also added a couple of 90deg couplers to sort things out.

I needed a couple other things to make this all work. I needed tubing of some sort to feed the sensors and fittings to tap to the sources.

A friend of mine has a SPEC Miata and donated a spare remote oil pressure line and mount. The line was a long length of stainless braided line with pre-assembled ends and assorted swivel couplers/male/female NPT ends.

After a bit of measuring, There was plenty of length to make two hoses out of one. I quick run down to the local hose/hydraulic line shop and I picked up some reusable hose fittings and male/female adaptors and made these items....

Since the lines had to be cut, I also got some clear electrical shrink wrap to cover the braid of the lines and add an extra layer of protection should they rub on something (and they do). The shrink wrap also helped in another unexpected way as well. I had to do some trimming of the lengths of line and the shrink wrap supported the braid and prevented it from fraying and making a royal mess.

The fuel fitment went together pretty well. As mentioned above, I had purchased an M16>1/8" NPT adaptor from Autometer for the end of the fuel rail. I added a simple "T" that had female ends to the adaptor. One end would feed the pressure sensor, the other will feed to a small 1.5" fuel pressure gauge for quick under-the-hood reference.

You can see the assembled bits on the rail. Ill have some better pictures of the whole thing together. Its actually nice and tidy.

The oil pressure fitment was a bit more puzzling....My idea was to tap off of the stock oil pressure sensor. Just use an in line adaptor with a "T" off of it and you have a tap for the line and the stock sensor can also be reattached.....well, sort of.

Thats the stock oil pressure sensor from my car. Nothing odd about it right?

How about now? No? Here.....let me help you out a bit...

This should be pretty apparent as this is a japanese car, but the threads for the oil pressure sensor are BSP (british standard pipe thread) and not NPT. BSP is a slightly different thread pitch than NPT (27teeth per inch vs 28teeth per inch(?)). The thread pitch isnt too much of an issue since you only use about 1/4" of pipe thread anyway, but as the pictures show, the issue is the difference in tapers. BSP is a thinner taper than NPT. You can get away with using the smaller BSP(male) in NPT(female), but NPT>BSP isnt going to work out too well.

Id done plenty of reading and people (MX6-ers and probesters) had reported that they simply used NPT fittings without, ok then. Dunno, how that worked for them, but it wasnt going to happen for me.

I have a tap and could simply ream out the hole in the engine block, but theres no provision for that modification in the rules (yes, this would count as a modified it and inch or a mile, so go the rules). What I needed was a BSP>NPT adaptor. As it turns out, I already had one. The Miata guys also run into this issue. The braided hose that was given to me also came with an adaptor for that very reason.

BSP adaptor, NPT M/F Tee and stock oil pressure sender all bundled together.

And installed.

Funny story about the reusable braided line fittings. I actually wanted to have the new ends of the line fitted with crimped connectors. So I went to the hose shop and....nope. Cant do it. I am curious....why? Liability (of course). To protect themselves from liability the shop (and I assume this is getting to be the standard now) aligns itself with a manufacturer or two (say, russell, or earls). They then get certified as per the manufacturers guidelines on their line of fittings and hoses and how to install/assemble them. Should the assembled piece fail...the burden falls to the manufacturer and not the shops as they were adhering to the manufacturers guidelines. This means no mixing of parts (earls fittings on earls lines only), so they would not work on my lines as they were of another marque that they were not certified with....What a world we have created for ourselves :)

The quick around was reusable fittings. If the part fails, its my fault and not theirs (pfft...whats the worst that could happen? :p )


Premium Member
2,997 Posts
Discussion Starter #24 (Edited)

Remember this? As mentioned, I was too busy actually racing the car to be concerned with the timeline on when this was going to be done so a year or so breezed by. Now that Im back on the modification kick, I wanted this project moving again.

When it comes down to it, theres basically 2 types of turbo manifold designs, logs and....everything else (generally "tubular" style manifolds).

Logs are simple to design, do not require a multitude of parts (and therefore generally lighter than a tubular manifold) and deliver reasonable performance for a given HP level. From what I gather, logs start showing their inefficiencies at about the 375-ish level. At that point, a tubular style manifold with nice radiused runners is the next step up. The extra material to make those nice curves will make the overall unit heavier than a log manifold (possibly even heavier than the stock cast piece if you get really fancy), but the extra percentages of efficiency at delivering the exhaust gasses to the turbine is worth the effort(provided you are making big HP).

And besides....lets face it. They look PimP-tastic!!

I had a notion to do a tubular manifold (hence all the elbows in the box), but..for 200-ish hp? It didnt seem practical to go through all that effort to add extra weight to a manifold that I really dont think Id be maximizing its potential. A log seemed a more senseable idea if only for weights sake......but I did have all those elbows already. How about a log with a twist? :)

After looking at tons of designs for turbo manifolds, I saw a really neat design that was for the stock turbo in a 2nd gen toyota MR2. Apparently the stock manifold pinches one of the runners and hurts efficiency(even in stock form), so one of the owners had a custom piece made. It was a sort of log-ular setup. It used elbows instead of "T" fittings so the runners were somewhat profiled from the head to turbo, but not all of the runners terminated at the turbo flange (like a log).

I liked it, so I adopted the design :)

I had some old parts (busted head/turbo) that I used for a jig. According to the rulebook, I can do whatever I want between the exhaust ports of the cylinder head and the intake port of the turbo. The one thing I dont see though is a provision for relocating the turbo (IE: moving it beyond where it would be with the stock manifold). Using the "if it doesnt say you can, you cant" understanding of the rules, I took a conservative approach and had the jig set up so the turbo would be in its stock orientation (hey, I get to still use the stock turbo brace :) ).


And compared to the stock manifold...

If you look close at the middle runners, youll see that they dont terminate in the outer runners at a straight shot. They cup under and inward to blend in gradually and take advantage of the curved profile created by the outer runners. The outer runners pretty much fell into place, hardly any work there really. The inner runners were a little bit of work to to get that blended curve.....but I wanted to do it because it was neat :)

(I wont lie, I giggled like a schoolgirl when I saw the finished product :) )

PS: stock manifold is about 16lbs. The new manifold.....7lbs.

I still have to do a little cleanup inside the manifold, after that......maybe get it thermal coated? Swaintech makes pretty awesome coatings. Looks to be about $125-150 for a turbo manifold.

OR........maybe I should work on the O2 housing, downpipe and exhaust. Yeah....thats an idea.


Premium Member
2,997 Posts
Discussion Starter #25 (Edited)
Intake manifold installed

And heres the rest of the intake manifold

There was a bit of adjustment that had to be made for things to fit. New inlet and return fuel lines, a little adjustment to the throttle cable (I will be looking into an extra return spring just in case), The vacuum hose to the brake booster had to be lengthened. I had to get a new coupler to mate the HKS intake elbow and the ford throttle body. I guessed at where things would be oriented and it turned out pretty well, all Ill need is a 3">2.75" 90deg silicone coupler.

One nice thing with all of this is...No more emissions hardware. The maze of vacuum lines are all gone to be replaced by whatever needs to be tapped into the 3 ports on the manifold.

And here is a picture of the routing of the hoses for the oil and fuel pressure readings...

That line from the fuel rail is actually touching the manifold on that raised block. That block was built up for a vacuum port for the fuel pressure regulator. Even though I think the stainless braid is tougher than the aluminum, Ill be sanding down that sharp edge just in case.

The braided line for the oil pressure makes a tight curve under the intake manifold and into the sensor. It also rubs against something (coolant line feeding the oil cooler). As mentioned, I covered the braids with clear heat shrink to add another layer of protection should the braids rub against something and start chafing. In this case, it also protects things that would be abraded by the braid.....Matter of fact, thats pretty much the case for all the hoses under the manifold. If they touch something or look like they could touch something, they get a sleeve or something to protect them from getting chafed/abraded.

Ok, next up....... o2 housing and the remainder of the exhaust


Premium Member
2,997 Posts
Discussion Starter #26 (Edited)
15min per day.....eventually it WILL get finished.

Ive been lazy, especially in light of working on the wiring for the TEC3r. What seemed like a simple idea has mushroomed to a colossus that threatens to kill me if Im not careful.

See, I had this idea.....I saw all these unused connectors from the stock harness and thought "hmm, why dont I just use those instead of overlaying everything....make use of whats there". Yeah, that seems simple enough. Weeks and weeks later after tracing wires and wiring diagrams, trying to sort out what connectors would be appropriate for what I even have enough plugs?....why the hell am I doing this again? Then theres translating from Electromotive-speak to Mazda-speak (wait, when they say the tec3 needs this, is this that in the wiring diagram? :confused: ).

Amazingly though, I am making good headway and I am almost done with the wiring between the two manufacturers. Its been a learning experience for sure. Heck, I am even delusional enough to think it may all actually work. (definetly NOT tuning this thing after all this headache :p )

In the meanwhile though, Ive managed to sort out the intercooler piping for the new intake manifold. This actually required a bit of modification......thats right, I chopped up the incredibly rare HKS intercooler pipes (dont kill me)

Before and a bit after. The issue was that the stock manifold had the throttle body much higher and further forward than the new setup. It almost looks like the pipes can reach, but the angles were not making it easy.

After looking at things and thinking about it a bit, the pipes simply needed to be modified.

first thing, the aluminum elbow has the inlet and outlets slightly offset (maybe 160deg angle) from each other so it can make a slight left turn into the throttle body. The elbow needed to be cut in half and reclocked so the inlet and outlet were straight in/out (180deg )from each other.

Next, the small elbow needed to be less angled to the left as it normally was. I cut out a small pie wedge (1/2" on the wide side of the wedge) out of its curve to get the new angle I wanted. This had the net effect of pointing the assembly more to the right.

Lastly, since I will not be using the stock airbox or VAF, I simply needed a small bit of tubing to extend from the turbo inlet to some fresh air. The HKS tubing that fits in that position would be ideal...but for a few things.

-That tubing extends from the turbo and curves inward to the firewall, I needed it to point downwards to the ground.
-If i simply turned it downwards, the nipple for the bypass valve no longer would line up
-The extra port for the stock boost regulator was no longer needed.
- the piping was actually a bit too short to adequately clear the transmission.

I needed new tubing.

I think that bottom right 45deg elbow was from a volvo (940?), it was just the right length and was the same diameter as the HKS pipes.

I didnt add a bead to the end of the tubing as that end will not be subject to pressure. It will just hold a filter under vacuum.

Heres the end result of all of this.

(pointing at cool air)

Next up...finishing the TEC3r wiring.


Premium Member
2,997 Posts
Discussion Starter #27 (Edited)
Madness?? This is not madness..this_is_SPARTAAAAAA

Wiring the TEC3r. (Or, how to make something really simple…really complicated for no apparent reason :shrug:)

15min per day.....eventually it WILL get finished.

Ive been lazy, especially in light of working on the wiring for the TEC3r. What seemed like a simple idea has mushroomed to a colossus that threatens to kill me if Im not careful.

See, I had this idea.....I saw all these unused connectors from the stock harness and thought "hmm, why dont I just use those instead of overlaying everything....make use of whats there". Yeah, that seems simple enough. Weeks and weeks later after tracing wires and wiring diagrams, trying to sort out what connectors would be appropriate for what I even have enough plugs?....why the hell am I doing this again? Then theres translating from Electromotive-speak to Mazda-speak (wait, when they say the tec3 needs this, is this that in the wiring diagram? :confused: ).

Amazingly though, I am making good headway and I am almost done with the wiring between the two manufacturers. Its been a learning experience for sure. Heck, I am even delusional enough to think it may all actually work. (definitely NOT tuning this thing after all this headache :p )

Ever do something really stupid? No, I mean REALLLLY stupid? Well heres my version of “no srsly..WTF was he thinking? :confused:

As per the above plan, I was thinking to make the connection of the TEC3 plug and play. If there was an issue with the unit, I could always fall back to the stock ECU. Makes sense right?…Um, not so much.

If one thinks about this and the components of my build for say…2sec, this is a ridiculous notion. I have a custom intake manifold that uses non stock sensors, the VAF and associated hardware will be removed, boost control is gone, a ton of stock connectors are being retasked for other purposes, etc, etc

Why on Gods green earth I thought rewiring things through the stock harness was a good Idea… Ill never be able to explain (temporary insanity? Swamp gas sickness? smokeable “Herbal” products?…ugh :( ). At that point I should have stopped and simply done the smart thing and overlayed the stock harness with a new harness…..but that’s NOT what I did. I kept going…..cuz Im dumb :eek:

Heres the tale of my decent into madness.

Not having done anything like this before I looked at what others had done in the past here and on other sites. Surprisingly (despite a lot of usage in high performance vehicles for decades), there is little information about the installation of the TEC3 unit.

If I were to integrate the wiring of the TEC3 into the mazda wiring harness I needed to know what went where(and how). This is the first issue…language. You see, what Mazda calls a thingamabob, electromotive calls that a doohickey. Not being fluent in either Mazda-speak or electromotive-ese I had to translate both to English. Oy vey!

I needed help.


Premium Member
2,997 Posts
Discussion Starter #28 (Edited)
First and foremost to embark on something of this magnitude, one needs the factory service manual. (Much thanks to Wilba who has the 90-92 manual uploaded).

The engine control wiring diagram is on pages 96-99
The complete ECU wiring pinout at the connector is on pages 100-102.

As said, reading Mazda-speak can be a bit difficult. Sure would be nice if it was all in English….well, that’s available also thanks to the folks at Performance Probe.

Performance Probe

I am somewhat of a “visual”/spatially oriented type. It helps me to see how things connect as a whole instead of abstract concepts. I wanted to see how the stock wiring harness layed out.

Thanks to Larken, this was also possible…

While I had a fair amount of info to help me I saw still a bit lost on the particulars, so I invested in some more help. What had others done to have their plug and play systems work?

d0zxmustang has a fairly comprehensive writeup of his PnP megasquirt setup for the 88-89 cars.

It also has wiring diagrams

Now granted this is for the megaquirt DB9 pinout and the 89 ECU, but armed with performance probes ECU pinout guide for the 88-89s… Performance Probe

I could then do a traceback to see what was used in the megaquirt,
- then what that corresponded to on PPs 89 ECU pinout sheet
- then translate that to the PP 90+ ECU pinout sheet
- then FINALLY..use that to correspond with what was called for in the TEC3 instructions
- and of course I had the official Mazda FSM to confirm wiring and official pinouts.

So basically I was speaking four languages….reading in Megaquirt then translating to English, back to electromotive-ese then confirming in mazda-speak. Wait, wat?

This is what I eventually would up with, in terms of paperwork.

Ignore the blatant fire hazard :p


Premium Member
2,997 Posts
Discussion Starter #29 (Edited)
Ok, I got this :) …..wait, no I don’t :(

First issue to arise was trying to understand what was done with the megasquirt…I couldn’t get it. Doing a tracedown using the above diagram lead me nowhere. Every time I got to a sensor or input, I would double check with the pinout sheets from mazda and PP and they wouldn’t match. NONE of them matched. Was I doing something wrong? Maybe this is way beyond my understanding. It didn’t make sense….but it had to, d0zxmustang had gotten his car working, as had others.

It took a lot of attempts and trying different permutations but eventually I found that d0zxmustangs in/output sheets were inadvertently wrong.

After transposing d0zxmustangs numbering convention for the factory plug back to mazdas convention (mazda has the connectors separated into connectors1,2 and3), I found that if everything was charted out, d0zxmustang had accidentally flipped the connectors creating a mirror image of the pinouts within each individual plug.

In other words...1E>1S, 2P>2D, 3I>3A, etc, etc.


PS: despite the difficulty I had, I do thank d0zxmustang for having his writeup present. It was the springboard that I needed to move forward with the project. Again, I need to “see” how systems fit together to work so I can apply that understanding to what I need.

Ok, I got this :cool: ……..wait, no I don’t. WTF? :mad:

Now that I had sorted out how things went from d0zxmustangs megaquirt and had all those outputs/inputs converted to PPs 88-89 pinout sheet, I simply needed to find the corresponding component on the PP 90+ pinout sheet. No problem there…..except when I tried to confirm that with the official Mazda wiring diagram and pinout sheet. Nothing matched (OFNA!).

PPs 88-89 pinout sheet says that injectors 1 and 3 are on pin 3E…ok
PPs 90+ pinout sheet says that injectors 1 and 3 are on pin 1U…ok
Mazda 90+ pinout sheet says that pin 1U is a ground…wait wat?

Even better, Mazda says that injectors 1 and 3 are on pin 3U……hey, wait a second.

1U?, 3U?…lemmie check into this a bit. Sunofabitch…its backwards.

Performance Probe

While the pinout image on PPs site for the 90+ GT is correct, the descriptions for all of the components of connector 1 and connector 3 are swapped. So everything labeled as "1x" is actually "3x" and vice versa.

I haven’t even soldered anything together yet and this is killing me already, ugh…is that a grey hair? I feel ill :(

After a LONG time of checking and rechecking and checking again…and again, to ensure that I have all of the wiring right, I finally was confident that I understand how things connect together as a system and I started getting things assembled…What are those things?

- 60-2 trigger wheel
- magnetic pickup
- air temp sensor
- 3 bar MAP sensor
- Direct Fire unit

And a couple things not seen here

- Coolant temp sensor
- Throttle position sensor
- Exhaust gas sensor
- Knock sensor (optional, but I wired it up anyway)
- Tachometer signal

Also, I had to build harnesses for all of these items so that I could connect them to the stock wiring harness (remember, I was building this mythical plug and play setup :rolleyes: ).

15.9.E. Wiring harnesses may not be removed in whole or in part. Wiring connectors for emissions control devices are considered part of the harness, not part of the emissions control system, and may not be removed.
The stock harness simply cannot be modified, so I cant simply splice into the wires. This is why adaptors were needed.

One at a time then…..


Premium Member
2,997 Posts
Discussion Starter #30 (Edited)
60-2 trigger wheel.

Not only am I allowed any crank/accessory pulley….

Any crankshaft damper or pulley may be used. SFI-rated dampers are recommended. Supercharged cars may not change the effective diameter of any pulley which drives the supercharger.
But also I am allowed to modify that or the stock pulley for the expressed purpose of using a crank fire ignition system…

Appendix F

For the purposes of triggering a crank fire ignition system, which is an allowed modification in the Street Prepared category, a trigger ring may be added to the crankshaft, or a crankshaft pulley may be modified to serve the purpose of the trigger ring. Mounting of the trigger ring, or modification to the crankshaft pulley may serve no purpose other than to provide a means of triggering the ignition system. The original distributor may be removed and the distributor mounting hole covered with a plate. The location of electronic ignition control modules is unrestricted.
Next the the fellow who does all of my welding projects is a machinist. I enlisted his help in doing some modifications to the Performance Probe aluminum pulley and the trigger wheel so I would have both bolted together perfectly true.

The trigger wheel was starting to rust a bit and I didn’t like that, so I had it plated along with some camber plates that had been cut for me a long while ago by Ed Vandermolen (he has the black and green FE-DOHC racecar in the Netherlands)

Assembled and finished off with stainless steel button head screws. (marvel at its bling-tasticness ;) )

Magnetic pickup

The TEC3 likes to use the 11th tooth of the trigger wheel (from the missing teeth while the engine is at TDC) to start its count. I had to create a mount for the magnetic pickup so that it could be oriented properly to the trigger wheel tooth in question and also firmly affixed to the engine.

There are a couple bolts to the left of the crank pulley that seemed to be mounted on the same plane. That would allow me to build a mount that would orient the mag pickup in the 10-o-clock ish area of the trigger wheel. This is what I came up with.

The bracket was a fairly simple thing. I built it so I could have adjustment for tilt, height and distance away from the block (you can see the slots on the “L” bracket). Once I finalized the correct orientation I wanted, I drilled and tapped screws to pin everything into place.

I reused the existing screws as the added thickness of the mount was thin enough to still have ample thread engagement….at least on the bottom of the mount. The top had the additional thickness of the “L” bracket and I preferred to have a bit more cushion in terms of thread engagement there. I found a longer screw from a disassembled transmission and used that for the top of the mount. Heres how it all looks assembled.

The mag pickup had to be wired up. The inputs from the distributor go straight to the mazda ECU. Since the path is direct and no other component uses those circuits, they are pretty much “unassigned” pathways, so I used the distributor plug to send the necessary signals from the mag pickup to the TEC3. There are four wires in the distributor plug, I only used three since the TEC3 needed pos, neg and a shielding ground. I used the red, blue and yellow wires of the distributor and created an adaptor.

so basically….(tec3 requirement : mazda wire color : mazda pinout)

Positive + : red : pin 3H
Negative - : blue : pin 3E
Shield : yellow: pin 3F


Premium Member
2,997 Posts
Discussion Starter #31 (Edited)
Throttle Position Sensor

I am using a Ford 4.6l throttle body and TPS for my car. The Ford TPS is a three wire unit as is the stock Mazda TPS. Wiring them up should be a simple matter of figuring out what outputs correspond to which wires on the Ford TPS and make a harness that ties into the Mazda wiring that did the same thing for the Mazda TPS.

The Ford TPS wiring diagram (for the one I used) is as follows:

BRN/WHT – Voltage reference (+5v)
GRY/WHT – TP sensor input
GRY/RED – Signal return (ground)

Both Mazda and the TEC3 use the same inputs, and more or less call them the same thing(+5v,signal,ground), so wiring was straightforward.

+5v : lt green/red : pin 2I
Signal : lt green/black : pin 2F
Ground : lt green/yellow : pin 3D

Unlike the distributor wiring that goes directly to the ECU unshared with any other component, some of the wires (+5v, ground) for the TPS are used by another component…the EGR. Unless I could find another item the TEC3 uses, that also uses those signals, I would have to leave the EGR plug dangling. Luckily there is another item that uses those signals…..The MAP sensor.

MAP sensor

Since I am ditching the VAF, some other method of metering air has to be used. In this case, I am using a manifold air pressure (MAP) sensor. It’s a 3-bar unit, which should have me covered for 28psi positive manifold pressure (not that Ill be getting anywhere close to that).

Since I am not using the EGR with the new intake manifold, I reused the plug for the MAP sensor, creating this adaptor for the two.

As mentioned, the TEC needs a ground, signal and +5v for the MAP. Since Mazdas wiring was set up for two components to use some of the same wiring (TPS/EGR), the EGR plug was used for the MAP sensor.

+5v : lt green/red : pin 2I
Signal : yellow/blue : pin 2J
Ground : lt green/yellow : pin 3D

Air temp sensor

With the stock airbox and VAF gone, the stock air temperature sensor is also gone. Need to add another one. If you look at the picture above that has all the accessories for the TEC3, youll see a GM air temp sensor. The new intake manifold was built with a bung for the air temp sensor on the plenum. The only thing left is to wire it up.

The air temp sensor just needs a signal and a ground. Tracing back on the Mazda schematics I found the stock temp sensor leads in the VAF plug and wired it into the corresponding sig/gnd leads.

Temp Signal : red : pin 2K
Ground : lt green/yellow : pin 3D

In case you are wondering..from top to bottom, thats vacuum for Brake booster, boost gauge, bypass valve, MAP sensor and finally...air temp sensor.

Coolant temp sensor

I am going to be reusing the stock coolant sensor. From a bit of reading, I gather that the temp sensor is the same/similar to the sensor used in 2nd and 3rd gen RX7s. Those who have used TEC3 products on RX7s say there is a default setting for that sensor (or if not, there is plenty adjustment so that it can be used….I havent checked this for myself though). To that end, the coolant sensor needs the same as air temp sensor…leads for signal and ground.

Coolant Sig : yellow/black : pin 2E
Ground : lt green/yellow : pin 3D

If you noticed that a lot of the grounds are going to the same mazda pin (3D), that’s the primary ground used for a lot of the stock sensors. The stock wiring is already branched to those components. Since the TEC3 also uses shared grounds for sensors, I just used the wiring in the same manner.


The injectors will be 440cc/min from a 3rd gen turbo Supra. These are low impedance injectors. While I am only planning for moderate increases in HP and I probably could push the stock injectors to what I needed, I really didn’t see a need to do that with decent injector controls. The 440s should meet my goals while not being maxed out…and if I do want more in the future, there should be ample headroom available.

While I have an option to fire the injectors sequentially or in pairs(batch fire), for the time being I will be wiring the injectors to “batch fire” (keeping it simple for this stupid).

Just like the coolant temp sensor, I would be using the stock wiring for the injectors. There was a curiosity however. As said, the injectors are wired in pair. Reading the stock diagrams they are paired as odd/even (1/3, 2/4). The Tec3 however asked for the injectors to be paired 1/4, 2/3 (much like their ignition firing order). Checking diagrams and tracing wiring seemed to confirm that mazda has the injectors paired in this manner. Both mazda and the TEC3 have the same ignition pattern (1-3-4-2). This would have an injector firing pattern of 1-2-1-2 for the TEC3 and 1-1-2-2 for Mazda (if I have that right). Odd, and since Im no expert on this, I just made an extension for the #3 injector so I could swap the plugs for the #3 and #4 injectors. This satisfied the TEC3 instructions.

The injectors are on 2 signal channels and also need 12v power. The power comes straight from the main power relay and not the ECU, so there is no specific pinout there.

Channel 1(injector 1/4) : yellow (old 1/3) : pin 3U
Channel 2(injector 2/3) : yellow/black (old 2/4) : pin 3V
+12v : white/red : main power relay

EDIT: better pic of the air temp sensor.


Premium Member
2,997 Posts
Discussion Starter #32 (Edited)
Direct Fire Unit(DFU)

The coil and distributor are no longer in the car.

Any ignition setting, adjustment, or system may be used, subject to the requirements of 15.10.D. This does not prohibit the use of “twostep” rev limiters used when the car is stationary.
Appendix F

SR, Section 15.9.A. For the purposes of triggering a crank fire ignition system, which is an allowed modification in the Street Prepared category, a trigger ring may be added to the crankshaft, or a crankshaft pulley may be modified to serve the purpose of the trigger ring.
Mounting of the trigger ring, or modification to the crankshaft pulley may serve no purpose other than to provide a means of triggering the ignition system. The original distributor may be removed and the distributor mounting hole covered with a plate. The location of electronic ignition control modules is unrestricted.

With the distributor gone, the hole it left needed to be covered. Thanks to RbluEMx6 for finding the appropriate part number for the seal cap.

The part number for the distributor seal cap is KLG4-12-603.

With the seal plate installed I fabbed a mount for the DFU to fit in the space left by the distributor.

Then I made a harness for it using the wiring that went to the plug of the igniter coil.

Like the injectors there are two channels for each coil (A and B) and +12v power coming from the main relay.

Channel 1(coil A) : blue/red : pin 1V
Channel 2(Coil B) : yellow/black : pin 1G
+12v : white/red : main power rela

This setup will be “wasted spark” as one coil will fire two plugs at the same time. Coil A will fire spark plugs 1/4 and coil B will fire 2/3. The firing order will still be the same as Mazdas, 1-3-4-2

Lastly the DFU was dressed up with a set of Magnacor 8.5mm wires for a 99 Cavalier.

I might flip the DFU around so the wires aren’t crossed over the coils. Itll add a bit more slack to the wires. There is a bolt in the way that prevents that so I may build a new mount. For right now though, this is adequate.

Coolant fan

There are “general purpose” outputs on the TEC3 to control whatever extra accessories you may want to run (electronic boost control, nitrous, water injection, etc)I used one of those outputs to control the coolant fans. This is a simple switch so only a single on/off output is needed.

GP01 (coolant fan switch) : black/green : 2D

Tachometer signal

This was a bit difficult to wire up. The stock tack gets its signal from the ignition coil every time it fires. The first issue is that there is no stock coil to produce such a signal. The other issue is that the signal is sent upstream to the tach via the 4-pin plug on the coil. That plug is NOT part of the ECU wiring harness. Its actually part of the chassis harness.

So something has to generate a tach signal and somehow it has to make it up the chassis harness to the tach.

The Tec3 ECU will produce a 12v square wave signal for each time the coil fires. This signal is whats used for the tach to work. That signal would be sent through an unused wire coming from the ECU (pin 2A) to the VAF plug. From the VAF plug, I bridged the two harnesses with a bit of wire and another plug that would connect to the 4-pin plug that lead from the coil.

Here you can see the adaptors on the igniter plug (DFU), VAF plug (air temp sensor) and the little pigtail going from the VAF to the 4-pin coil plug (distributor signal)

Tach signal : yellow/blue (coil plug) >>>> red/white (VAF plug) : 2A

The only other issue here is that the 12v square wave probably isn’t suitable for the stock tach to make sense of it. Here is electromotives manual…

Electromotive said:
F.2. Tachometer Output The tachometer output on the Tec3-r is a +12 Volt square wave. Each time a coil fires, a “tach pulse” is generated. Therefore, the output from the tachometer signal is ground, then +12 Volts for 30 degrees of crankshaft rotation starting at each TDC/spark event. A 4-cylinder will output 2 tach pulses per revolution, a 6-cylinder will output 3 tach pulses per revolution, an 8-cylinder will output 4 tach pulses per revolution, and a 12-cylinder will output 6 tach pulses per revolution. For applications that have a tachometer configured for a different number of cylinders than the engine (i.e. a 6-cylinder car that was converted to an 8-cylinder), there is the option of changing the tach output type in the software. This type of signal is compatible with most new-style tachometers. However, some older tachometers trigger off the high-voltage signal from the ignition coil (C-). These types of tachometers require the use of a tachometer amplifier, since they are designed to trigger off of a 120 Volt signal. Tachometer amplifiers (PN: 150-15210) are available from Electromotive to suit these applications.
Much the same issue like using MSD ignition boxes on our cars. In that case, MSD PN 8910 should solve that issue. I have extra plugs to wire an MSD tach adaptor inline just in case this is the case (and likely is).

Main Harness

And this is where it all comes together, the (lol-not-really) plug and play harness adaptor that bridges the connections at the end of the stock Mazda ECU harness and then ties that to the connectors at the TEC3.

Using the information gathered above while tracing out what wires go to what connection, I created this harness..

I had a couple extra stock ECUs on hand. As it turns out the connector on the 90-92 N/A and Turbo ECUs are the same. Just as d0zxmustang had charted out in his Megasquirt writeup ( ) I removed the connector from the ECU and used that to make the new harness.

That’s one end of things, the other end involved the plugs for the TEC3r. I could have bought the flying loom that is sold for it…but at $200!! (and the fact that I was going to chop it up), er…..hell no.

It took a bit of searching, but I figured out who made the connectors/plugs for the TEC3. AMP connectors is the manufacturer. Seems they are somewhat popular nowadays.

TEC3 ECU plugs: AMP 770680-4 and AMP 770680-2

PS: the AMP connectors were $6 apiece.

Interestingly enough, while looking through AMPs catalog, I found this part number… AMP 174518-7. That’s the part number for the Mazda 90-92 ECU connector. If you are looking for a brand new Mazda ECU connector (for some bizarre reason), there it is. (I didn’t check for the P/N for the 88-89 ECUs..sorry :( ).

ECU mounted....(hope it all works).

So.....after doing all of this insanity, what have I learned? “Don’t do that”.

Seriously, this could have been done much simpler and with much less headaches, but I had some harebrained notion that lead me down this path. I did learn a lot, and maybe that’s why I stubbornly continued. One bit of confusion lead to a revelation, another obstacle lead to a resolution….I just kept going. Madness, I tell you….sheer madness.

Completely unrelated to nothing…

Did a bit of heat shielding to some of the parts and lines that were right next to the headers. Also….

I had removed the A/C system including the evaporator(you can see it still in the first pic). That left an empty evap box. I tracked down a car that did not have air conditioning and got the correct non-A/C vent (bottom pic, left). Its half the weight of the injection molded box, so I lose…1lb? :shrug:

Anyway, more to come….mounting the TEC3, installing and wiring the gauges, exhaust.

Merry Christmas!


Premium Member
2,997 Posts
Discussion Starter #33 (Edited)
SPA gauges

Um, they do...stuff.

Well it certainly took a while, but they are installed. As mentioned before....

The oil temp sensor was tapped to the oil pan, the fuel pressure was tapped to a "T" off the fuel rail and oil pressure was tapped off the stock oil pressure sender...the only thing left was, where to get the coolant temperature reading from?

Well as it turns out, since I have removed the air conditioning system...including the fan, I no longer have a use for the stock thermo-switch (in the thermostat housing) that controls the A/C fan at higher temperatures. Excellent, I have a perfect place to tap the SPA temp probe.

Problem....the SPA thermo sensor is 1/8th NPT. The stock thermo-switch for the A/C is 3/4th NPT (actually, it seems like its not even a tapered thread, just straight 3/4th? 10/24 pitch?). In any case, I needed to make an adaptor....(like just about everything else in this build :( )

I came up with this....

I found an old thermo-switch and cut it down to size so that the SPA temp probe could be immersed fully in coolant to get the best reading. After it was cut down to size, I drilled it out and threaded it with a 1/8 NPT tap. End result is...

Wait..."why not use the stock temp sensors spot, since its also 1/8th NPT?"...good question. Even though the 90-92 temp gauge is basically a 3-step switch (cold/up to temp/boom) vs, the 88-89 full sweep rheostat, it still works somewhat. That and I wanted a backup should something go wrong with the SPA gauges.

Wait, whats next again?


Premium Member
2,997 Posts
Discussion Starter #34 (Edited)

Pulled this out of the car. It needs to be replaced by something, but what?

Thats 5ft of 3"diameter 18ga straight pipe, two 16ga 90deg 3" elbows, burns stainless lightweight racing muffler (3"in/out), a 14ga 2.5" 180deg bend, a 1.5" 180deg bend, 2.5">3" reducer, 2.5" v-band clamp and a flange for the VJ-11.

The piping is from Colombia river mandrel bends, the clamp and reducer are from vibrant, the muffler..well yeah, The flange is from BMCrace. Aside from the flange, everything is 304 stainless. I plan to make my own O2 housing with the 180deg bends. I got those in heavier gauge because I wanted a bit more strength and resistance to heat since it will be right next to the turbo. Should be a nice and simple and quiet exhaust system.

So...I had been wondering about something for a while, namely the strength and longevity of the stock turbo. Most believe the limits of the stock turbos' production to be @200-220hp/16-18psi, then issues with failure are likely. Whenever a discussion of the merits of the stock turbo comes up, what you tend to get is a steady chorus of.."get rid of it", "the stock turbo sucks", "weak", "get a T3(4/5/9?/whatever)", etc. Even when the subject of the hybrid VJ-17 ("t-bird") comes up, the same advice is offered.

But why?

See, I like to know how and why things work...and also why they dont. For me, "it sucks", or "doesnt make power" doesnt tell me why/under what circumstances it sux or doesnt make power. For example...if someone were to say ,hypothetically, that "the stock brakes suck". Id want to know why they think so or what issues they have encountered to come to that conclusion. that could lead to a conversation where I find out that.....

-one has to pump up the brakes before a corner or else youll get a long pedal
-ok, so that could be air in the lines, bad pads, fluid or pad knockback
-The pads check out. The lines are well bled and free of air, etc, etc, you just have to keep pumping the pedal to get a firm pedal.
-eliminating everything else it could be pad knockback...maybe bad wheel bearings or a spindle thats flexing under heavy load
-find out that the hub and hub bearings are, it must be a flexing spindle. EUREKA!
-so the issue isnt so much the "brakes" that are bad...its a spindle flexing under heavy cornering load thats allowing the hub and rotor to press the caliper pistons back in their bore.

Something like the above hypothetical would not only give me an understanding of what and why, BUT more importantly, it would give me a path to work with if I wanted to combat those issues...(maybe spindle reinforcements, maybe custom spindle sets, maybe...yadda yadda yadda).

That, drilling down to the root cause of the issue, is something that I really have never seen with regards to why people believe the stock turbocharger to be so full of faults. Its taken for granted that it just is...and while it well may be, it would be nice to know why. Anyway.......

A while ago I was involved in an interesting thread over on performanceprobe...Stock or t3 turbo for endurance racecar? - Performance Probe Forum. This fellow was having a spate of turbo failures, one after the other during sustained runs at full boost. I thought it odd, but I was interested in what happened to make his turbo fail. Theres a bit of "stock turbo sux/dont even bother/waste of time" talk and a couple of (in my opinion) red herrings like "turbo spins too fast", etc. While interesting, I tried to steer things back to a..."how/under what circumstances did the turbo fail?". I would be doing something similar as he had using the stock turbo and there could be something valuable learned from his experiences.....and I think I did get that.

Thats one of the old team Highball cars from the old IMSA Luk Cluch challenge. It was a fast car in its day. Made good power with mostly stock hardware. These were cars that ran 45min-1hr sprints and 3-6hr enduros. Its been a while and information is scarce, but I was lead to understand that the cars ran a lot(?) of boost and ran very lean(?) to make their power. Because of the lean running, the big maintenance items were the valves and pistons every season. Again, info is sparse, but I didnt hear much about the turbo. Now, It certainly could have been that the turbos blew up after 1 hr and were simply replaced after every race by factory sponsor Mazda Motorsports...but that seems unlikely. These cars are now in the hands of average club racers who simply wouldnt have the time, effort and resource$$$, to campaign a car that you need to replace turbos every hour or so.

Now, I believe this fellow in the PP thread when he says his turbos were built with highest care, but clearly something is amiss. With the same stock turbo..what are these old racecars doing to ensure longevity, where he was not able to achieve the same results?

The MX6 racecars ran in a series where the use of stock components was mandatory, and efforts were taken to ensure equity in performance between different why would you give a car an allowance to change a part that could potentially give a large performance gain and an unfair advantage? (You a custom O2 housing). You wouldnt....not unless there is a damned good reason.

The exit of the hot side turbine is about 46mm but flares out to about 48mm (1810mm sq). The narrowest part of the stock O2 housing is about 40mm x 44mm (1760mm sq).

So Im thinking to myself...while that could probably work ok for daily driving and maybe a little beyond, could that be an issue at much higher boost levels? I form a loose hypothesis (Please feel free to pick it apart as you wish). Is it possible....that such a restriction could cause high levels of backpressure to build up on the exhaust wheel causing sluggish performance or even damage (like a form of compressor surge, but sustained and on the hot side)? Consider also that most who switch to alternate not use the stock O2 housing. It gets discarded for some other O2 housing thats less compromised or completely custom. In other words, while the stock turbo has its performance limitations, its possibly even MORE limited by being used in conjunction with the stock O2 housing. At increased or prolonged boost levels, the stock O2 housing is restrictive enough to cause enough backpressure within itself to cause undue strain to the turbo and possibly shorten its life.

Its a theory, probably imperfect, and I have no way of empirically testing this theory out. I do think that somewhere in there is an answer and am confident enough in it that I decided to move towards a "solution" anyway....a custom, free flowing O2 housing (besides, the stock one is heavy...and ugly ;) )

Jake had already done quite a bit of legwork on creating a very nice O2 housing with a separate wastegate routing here

I used this as a template to make my own. While Jakes was made with the idea that people may have their A/C, I did not and made mine to utilize the space from the missing A/C compressor to be a bit more flowing. this was the result.

The 180deg tubing I had was a 3.75" radius. It was smooth, but not as tight a radius as I would have liked. To make the angles work I would have had to cut the tubing at a very shallow angle. I didnt like that and wanted a less abrupt transition. I decided to section the piping and do pie cuts. This turned out to be a good thing because the tube had to snake a bit to the left and then right to give clearance the power steering lines while still pointing in the right angle to the downpipe. In the end, I think a 2.5" donut would have been easier to sort out...but you do the best with what you have.


I had things lined up initially in terms of angles, but when I had the O2 housing welded and refitted to check on things, the angles were a little off. Lots of pie cuts will do that I suppose. Since I was using v-band clamps, I needed things to be right on, so I fixed the mismatch in angles with a small wedge.

and all together now....

I still have to get the muffler, tubing and some hangers welded on, but thats what itll look like in the end. Oh yeah, the turndown tip is aluminum... gotta save weight you know ;).

With the stock O2 housing the stock exhaust above was 36lbs, the new setup is 17lbs, maybe 18lbs when the welding is done, half as much as stock which is what my goal was for making this exhaust. Im happy with that :)


Premium Member
2,997 Posts
Discussion Starter #35 (Edited)
I decided that I didnt need the adjustability of sliders on the passenger seat.



Since there are no passengers on competition runs, the passenger seat is really just there to fill a rules requirement.

15.2.F. The driver and front passenger seats may be replaced, with the following restrictions: Seats must be securely mounted per 3.3.3.B.2. The seating surface must be fully upholstered. Any replacement seat must be a full back, bucket-type automobile seat incorporating a functional headrest. Kart seats, low-back dune buggy seats, and other similar types of seat are expressly prohibited. Cars may have no fewer than the standard number of seats. The seat tracks are considered part of the seat and may be substituted. Alternate seat tracks may serve no other purpose. The standard seat belts may be removed to facilitate the installation of alternate restraints complying with safety requirements. An alternate seat which replaces an airbag-equipped seat is not required to have an airbag. I redid the seat bracket removing the slider mechanism and made a fixed mount. That saved about 5lbs.

Now if a person wanted to be "clever" and took that allowance to its ultimate ends...they could save even more weight by using aluminum flat stock...or zip ties...or velcro...clever, right ;)? Sure, racers being racers, they will try to get the most performance out of a rule without hard and fast borders(weight/dimensions/material, etc), but for me, I do grant ridealongs to passengers at local meets and Im simply not going to make someone sit in a seat held down by velcro or something else that I feel isnt safe (for a couple lbs of weight saved? thats just rude). But, aside from my own personal ethos, theres another mechanism designed to curb the desire to sacrifice safety for performance in the above rules..."Seats must be securely mounted per 3.3.3.B.2". Which states...

3.3.3.B.2 Passenger’s seat back and all cushions, bolsters, headrests, etc. must be secured. All allowed aftermarket replacement seats (i.e. driver and passenger) must be securely and safely mounted. Special care should be taken when using other than OE mounting points and/or fabricated bracketry.
Its a safety rule for tech scrutineers, written with very loose and generous language(intentionally so). It gives a lot of leeway to the scrutineers to apply the "sniff test" to make sure things are really safe instead of simply meeting the letter of the law. Also knowing there is a "common sense" rule out there that determines compliance of seat mounting keeps people in check with their cleverness. For me, steel was used to make a sturdy and safe mount thats still relatively lightweight.


Premium Member
2,997 Posts
Discussion Starter #36 (Edited)

Mounted the Housing and downpipe...

I didnt have a super amount of clearance for that most forward bolt..whoops. A standard 17mm hex M10 x 1.5 was not going to fit in there. I found a 15mm Hex M10 X 1.5 that juuuust cleared under.

Clearances with the PS hoses, dipstick and subframe are close. I heat wrapped the PS lines with reflective fiberglass backed tape and I may have the hot bits coated at some point...maybe wrapped?

Getting the remainder welded tomorrow I think.


Premium Member
2,997 Posts
Discussion Starter #37 (Edited)

Probably another $15-20 for the downpipe>exhaust tubing>muffler, hangers and an extra O2 sensor bung for future wideband if needed.
$15 actually. And thats with a slight revision. The downpipe and main tube were butt welded. I didnt check if the ends were actually ground flat and were perfectly 90deg. Turned out there was a bit of flashing and this made a slight kink downwards from the downpipe (which I had set in place with a bubble level). Normally, not a big deal, but that slight angle turned into a large mismatch at the other end where the furthest hanger was 3" off. A quick cut, square up and reweld and all is better.

-installed the fuzzy Momo steering wheel
-installed the radiator
-drained the fuel tank of gasoline (it might have been good for diesel fuel at that point :( )
-re.did some rewiring of the TEC3...funny thing, when you are soldering, reading wiring diagrams and are really tired, lower cased "q"s sometimes look like lower case "g"s....who knew? :shrug:
-redid the gauge wiring so they went on with power/acc instead of on all the time.

Did a test of the revised wiring..key/on, the fuel pump cycles and all necessary blinky lights are on....getting there :)


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