Comments On: Gavins 1st gen MX6 DSP autocross build

[eraezer]

Sticky Thread contents: http://www.mx6.com/forums/1g-mx6-oth...oss-build.html (Gavins 1st gen MX6 DSP autocross build)

[compnut21]

Originally Posted by eraezer

A++++++

+1 45678

[Keeloh]

Like a good story... I can't wait

[SixSick6]

You win +5 internets for this thread.

[SABBAi]

as always Gavin, nice work.

[A Simple MX6]

You make me miss my DX, even if it wasn't turbocharged. =(

Very nice write-up.

[chief tool]

Nice work Gavin, it'll be really interesting to see what you can do with the stock turbo and "unlimited" boost.

Although the ford sierra (I think you called a merkur) will wipe the floor with unlimited boost

I dont know what you can do with intake piping etc but maybe there are ways to extract a bit more efficiency.
Its too bad you cant toss the intercooler and replace it with water injection, that'd decrease some of the lag by reducing the post turbo pipe volume.

[Stevoh]

Gavin, I forgot to ask you at the Duel. Is there a reason the rear wheels are a little narrower, especially the tires that accompany them. Does this allow the car to rotate better? Or is because if there is too much grip in the rear, the car will be dive happy?

I have seen Gavin and this car at an autocross in person, it is a very impressive and very inspiring to see. The red M3, the Merkur, and the white ITR he speaks of are actual competitors he raced against that I have seen. He was within 1 second from the well prepped red M3(and a TT 911!) give or take a couple points of a second. So his goals are well within reach I feel. With a tad more boost and a lighter car I feel the potential is definitely there. Gavin what did Ben get again? He also did fairly well.

Gavin, if you were to remove more weight from the front end such as a lighter hood(yes I know they do not make it- shame) and the delete of the bumber support do you think that would aid in the balance of your car? If I remember correctly you said you corner weighed the white car. Do the rule books even allow such weight reduction?

I removed the bumper support in my 2g Probe and the ABS plastic support has a substantial weight to it(25 lbs if I remember correctly). The bumper support in my 1g Probe is all metal so it should be of similar to, if not more weight, than the 2g support. The Mx6 bumper support I would assume is not that much different tham the Probe's.

You could probably lose an added 50-60 lbs from just the front end alone I would assume.

I will be following this thread.

[gavin]

chief tool... Im looking to see what can be done with the turbo as well. It will be a matter of making things more efficient around it, lessen the amount of work it has to do in other words. Ill get to that in a bit though.

The Sierra (or merkur as they labeled them here in the states) is very much a concern. A light(ish), turbocharged RWD car thats well driven is something to keep an eye on. A couple of things have been holding the car back however. Ben has been having a spate of reliability issues (wheelbrarings, distributor, bent rod, etc, etc) If that car holds together itll be a terror. The other thing thats holding the car back is the small front tires compared to the rear. The BMWs and subaru run 285/30/18s up front. The Sierra has to make do with 245s up front because of the small wheel arch(and theres a lot of rubbing with that size already). Thats a lot of lost front end grip. Ben thinks he can make that setup work, but I think he needs to find a way to get more rubber on the front end.

Intercoolers are free in size/configuration. However the intercooler must be cooled by the atmosphere(you can have a water jacket but the water has to go through a radiator and not an ice chest...Bens Sierra has this setup currently). Also, no external cooling methods while on course unless available on the stock car (water/alcohol injection, etc)

Heres the passages if you are interested.

15.10.C.2. Except for standard parts as defined in these rules, the external use while on course of liquids, ice, dry ice, refrigeration systems, vaporized compressed gases, etc. to reduce the temperature of the intake air charge is prohibited. Wrapping of intakes with liquid-soaked fabric is not permitted.

15.10.C.3. As utilized only on engines originally equipped with forced induction, induction charge heat exchangers (known as “intercoolers” or “charge air coolers (CACs)”) are unrestricted in size and configuration. Air-to-air CACs and radiators for air to-liquid CACs must be cooled only by the atmosphere, except for standard parts. Body panels, fascias, or structural members may not be cut or altered to facilitate CAC installation.

Stevoh....The wheel stagger was on purpose. Ill get into that a bit later though.

Funny you mention a lighter hood. Not 10min from my house is a brand new 15lb fiberglass hood made for the 1st gen MX6. Too bad its not legal for the class . Pulling the bumper supports isnt legal either as theres no allowance for it and "if it doesnt say you can, then you cant".

I didnt realize the bumper supports in the 1st gen Probe was all metal. No wonder its a porker compared to the MX6(always wondered where ford hid that extra 250lbs). The bumper in the mx6 is fiberglass and styrofoam. Its not light, but its not all metal either.

Gavin

[defiler]

-Boost controls have been released on turbocharged cars. With the advent of ECU controlled boost on newer cars and an existing rule that allowed for aftermarket ECUs, it became problematic to verify stock boost levels. Instead of fruitlessly chasing electrons the rule was changed to allow open boost controls in the STOCK turbocharger(stock turbo can be easily verified by something as simple as a set of calipers). Its become known as the “unlimited boost” rule.

Just curious here... how would they verify the stock turbo size? Like on the MErkur, I'm pretty sure it came with a .63 exhaust housing, but if he switched it for a readily-available .48 one (Which would help him in spooling a bunch) how would the "rules people" verify it? Or to say, if you upgraded to a T-bird (Not that it wouldhelp)

[gavin]

Either by documentation or by protest.

Its a competitor policed sport. Its pretty hard to know everything about every particular car(and their various configurations). In general most people mind their manners. If theres a question about this or that, the car owner generally has information/documentation to back up whatever modification was done. If theres still a question about legality a competitor can choose to protest a specific part in a vehicle.

There have been protests in the past for things to check compression ratios, piston size, valve grinds, etc. Anything you can think of, its probably been checked/protested to verify legality.

The protestee fronts the cash for the teardown bond. The protestor would have to provide documentation that the protested item is in fact legal. The factory service manual(if necessary the turbo manufacturers documentation), another sample of the item in question would go to the protest committee. That documentation then gets tested against the turbo in question. At that point its down to a set of calipers.

Its really hard to hide physical changes because those can be compared to spec sheets. Turbos are pretty easy to check actually. Boost is(was) another story.

PS: the merkur was protested at the nationals for an illegal intercooler setup. Ben read the rules incorrectly and wound up with a setup that wasnt legal. It got protested and his times were disallowed.

PPS: I am lead to believe that the merkur can in fact run the smaller A/R turbine. Apparently the automatics were specced with the smaller turbine. The rules dont make a differentiation between the auto and manual cars so swapping turbos in this case is allowed. (Has to be the whole turbo though, cant make a franken-T3).

Gavin

[SABBAi]

how have you been setting up camber/castor/height/toe? On a laser rack or string and tape with a protractor?

I'm guessing you've been log booking heights, damping rates, spring rates, etc and making small adjustments as you go? Monitoring tyre pressures, and inside/outside/central temps of the tyres?

[Stevoh]

Wow, you sure know a lot about suspension and the geometry that goes with it Gavin. I am gonna have to read some more on castor and your post again. I knew castor was a good tuning tool, but it seems it is a very strong tool to use on a McPherson strut front suspension.

Those Penske's look sweet. Is Penske gonna be the one who revalves them?

Good deal on that trailer too! Damn, I thought I got a good deal with my truck. That trailer is insane for 850. How frequently do trailers go for that price on the autox boards? I would assume this is probably the first time.

Also I have been wondering how the derlin/UHMW bushings faired. Do they provide ample give to retain the characterstics designed into the factory arms/bushings? No one makes aftermarket bushings for lateral arms for either generation Mx6 so eventually I will have to more than likely provide the lateral arms(in the 2nd gen) with alternative bushings. Does it matter which side of the arm has the softer bushing? I will have to review that thread.

[gavin]

Originally Posted by SABBAi

how have you been setting up camber/castor/height/toe? On a laser rack or string and tape with a protractor?

I'm guessing you've been log booking heights, damping rates, spring rates, etc and making small adjustments as you go? Monitoring tyre pressures, and inside/outside/central temps of the tyres?

I havent done my own alignments yet. My friend with the MX5 racecar is thinking of getting his own set of strings. If he does I may be doing my own alignments in short order. Currently I have the car aligned on a laser alignment rack and corner weighted on scales to get as close to 50/50 diagonal crossweight on the car.

Yes. I have been tracking data points on the car. Its been a bit disjointed though. I am in the process of modifying an excel spreadsheet used by miata(mx-5) folk for my purposes. Its pretty comprehensive and contains information on wheel/laden/unsprung weight, swaybar stiffness/springrate/motion ratios, bounce frequency, and all other pertinent info on the car and suspension pieces. I am also modifying a setup sheet that will have a place for all the information I gather between runs. Itll be better than jotting numbers down on random scraps of paper.

Currently I am using an IR surface pyrometer for the tires. Its useful, but surface readings are somewhat incomplete. It would be best to get a probe type pyrometer and get the readings from inside the carcass, but they are somewhat pricey. The surface readings have been useful so Ill continue with that as it does give me quick feedback on tire pressures.

Gavin

[gavin]

Originally Posted by Stevoh

Wow, you sure know a lot about suspension and the geometry that goes with it Gavin. I am gonna have to read some more on castor and your post again. I knew castor was a good tuning tool, but it seems it is a very strong tool to use on a McPherson strut front suspension.

Those Penske's look sweet. Is Penske gonna be the one who revalves them?

Good deal on that trailer too! Damn, I thought I got a good deal with my truck. That trailer is insane for 850. How frequently do trailers go for that price on the autox boards? I would assume this is probably the first time.

Also I have been wondering how the derlin/UHMW bushings faired. Do they provide ample give to retain the characterstics designed into the factory arms/bushings? No one makes aftermarket bushings for lateral arms for either generation Mx6 so eventually I will have to more than likely provide the lateral arms(in the 2nd gen) with alternative bushings. Does it matter which side of the arm has the softer bushing? I will have to review that thread.

What I dont know about suspension makes what I do know look insignificant in comparison

The Penskes will be sent to Guy Ankeny (Formerly of Ankeny Racing Enterprises and now with Tri-Point Engineering). Guy has built penske racing shocks for many national championship autocross and roadracing cars. Its pretty convenient that he is working at tri-point since thats the shop that did the work on my Konis. He will have the dyno plots for my struts available to him when he needs a reference point for how my car is currently set up.

The trailer was an unreal deal. Its pretty common to see 16ft trailers on the west coast going for $1400-1800. If you find something for less than $1000 its usually some beat, rusted out frame with dry rot wood on top. On the east coast short track racing is a way of life. There are just so many tracks that, consequently, theres a lot of trailers that go for sale. Its easy to find deals like mine there day-in day-out. But in the west, its nigh impossible. Check Craigslist often for prices, you may get lucky.

Actually there are two companies that make aftermarket bushings for the 1st lateral/trailing links. Noltec and Superpro (both australian companies). Ive actually used both products in the past. The derin/UHMW combo seems to be working excellently. The arms move freely (with just "enough" resistance) without binding. There has to be movement/compliance in the rear lateral/trailing links or things get messy fast. I actually took an educated guess as to where the "softer" of the two bushings would go because theres very good arguments for either placement. I may one day have to revise the whole setup, but so far, so good.

Gavin