Proper antilag, thoughts, comments, suggestions?

[fredio54]

Originally Posted by rodhog

I know in Aus there is on the Rx-7 S2 and S3 a air pump.

but THe main thing to look at might be early model Commodores about 83 or so. they had the air pump up untill about 86. All the carby ones.

thank you very much.

but I think over all with your ute not weighing that much anyway. Your better off with a more responseive turbo. It really depends how unresponsive your current one is.
With limited weight to move and well obvious lack of traction you should be able to keep it on boost with ease. I know few turbo Hilux utes that can't get on the throttle because the rear just kicks out.

there isnt that much lack of traction. in the dry, only first has issues and second is geared how first should be... so when i sort out the gear ratios it will be fine to drive, its just the sliding aspect that i want to be controllable. and it just cant be without a much smaller unit (and less power) or antilag, so i'll try to make it work as it is. the goal is 500 - 550crank hp (ie, max the holset out) and drivable in all ways. that kind of rules out the small turbo option. though, if i have to, i'll drop back to the 300hp region just for skids :-)

Most of the winding roads don't have long straights in them. So top end would not be a problem.

i want both :-) or i'll throw a tanty ;-) and most of the roads i play on do have straights... they come between the corners. thing is that if i go small, i'll be able to boost high (25psi) in the mid range, but not till redline, so the torque curve will fall off bad as i back off the boost to avoid death of the turbo as the rpms rise. i'd rather run less boost than have a midrangy engine, the usa built v8 guys can keep them!

[RbluEMx6]

I got it while back from the guys at LancerRegister.com.

It doesn't look like an egr setup because its appears to be feeding into the exhaust. Plus I have never seen an egr feed directly into the throttle body or take exhaust gases from more than one feed.

[fredio54]

good call. silly me.

[rodhog]

nah that evo5 onwar engine - it's not anti lag it's mix of both air injection and egr. it's bit to comply with euro 3 or Jap 19 ? or similar emission came in in 1997 in Japan.

it's bit of both. goes both ways. unlike EGR goes one way and air injection goes there other, it's does both.

[gavin]

Antilag? Go to the source..... The Umluft

Audi made a very ingenious and effective antilag system for their quattros on the groupB era.

Effectively they ran 2 sets of wastgates on their exhaust manifold. One was a standard wastegate controlling boost pressure by bleeding exhaust gasses. The other wastegate was acting as a relocated bypass valve directing boosted air that would have normally have to be bled off to the atmosphere back into the exhaust manifold.

Add a second set of injectors(or a layered injection pattern) to take advantage of the extra air being injected in the exhaust manifold...presto, antilag.

They do say though that this was on the extreme side of things in the antilag genre requiring frequent rebuilds(exhaust valves only last for 1hr?...yikes!). But its interesting as a look at how it was done.

Gavin

[moebius]

Okay, another thought on Anti-lag options -- what about a variable nozzle turbo - ala the VW/Garrett VNT Turbos??

It isn't a anti-lag system, but in theory, you get full reliability but with better spooling characteristics --
Turbotech - Australia's specialist in turbochargers - Garrett Turbochargers



But really, what you want fred, is a supercharged, variable-nozzle turbo, with dual wastegate/bypass setup, along with nitrous, and CO2 spray on your intercoolers --- then you'd get instant boost - all the time, and massive power...

and a very very light wallet, a weight reduction which will undoubtable help.



Seriously, I like that dual waste gate idea. It would seem to me, that you should be able to store the waste exhaust gasses somehow, and re-use them to keep the turbo spooled. It would require that you start the car up, and have it running for a little while, to buildup pressure, but then once the "bypass storage" container is full, then you'll get your anti-lag effect, via the second valve....

I don't know how practical. You'd want to keep the exhaust gases hot.... and the timing on the valves will be rough... you'd almost want to set things up so that it is always overboosting, so that you'd have something to go into the "bypass storage" container...

I'm imagining some crazy U-shaped pipe, with a bulge in the middle, and two check valves, one on each end. On one side it is connected to the main waste-gate, that would be the input to the "bypass storage", and the other end goes to the exhaust manifold before the turbo - almost like a fifth cylinder.... definitely custom manifold time. When the pressure is too low in your exhaust, it would open - and you'd get the contents of the "bypass storage" into your turbo...

Somehow, I don't think it would work very well.


I'm still voting for a Supercharger added to the system.

[evo626]

Browser Warning

Read this:

"When switched on, a random cylinder ignition cut was employed using a simple circuit consisting of a 555 timer and a power tranny shorting the coil (heavily heat-sinked!). The passed mixture was ignited using a spark plug that was tapped into the exhaust manifold, and was driven by an EHT circuit (I think it was the Jacobs Ladder power supply from memory). But we had pretty severe cracking problems that occurred due to the thermal stresses incurred by dissimilar metals placed together. I think that the spark plug expanded more. The carby was jetted so that it ran pretty rich too. The circuit switched itself off after the engine RPM hit 2500 (using the shift light circuit), and was switched off after the car reached third gear (micro-switch).
Once switched on, the combustion WAS controlled, and sounded like a bloody great V8 with only 6 cylinders firing. The exhaust manifold glows a pretty colour after about 30 seconds though (as did the turbo)! On launch, the car spat a 2-3 foot yellow-blue flame that was only really visible at night. For the best launch, the car was revved up to 2000rpm at the lights (keeping an eye on the boost, letting it build up to 7psi, and letting the wastegate do the work) then either a slip or a dump of the clutch. There were problems though. Once, on take off, the spark plug lead fell off and the car was pumping raw fuel into the manifold. It ignited, and blew burning fuel out the tailpipe all over the front grille of the car behind us. OOPS!
The engine ran like [shizzle] when the system was running - really lumpy - so the revs had to be kept up or it would stall. Mind you, the mixture wasn't exactly stoichiometric!
We were also experimenting with propane injection into the manifold. We actually had more success with this method - the explosions were more powerful thus making it more effective - but as the exhaust manifold finally blew itself to bits, we decided that it really wasn't worth the effort. But the main disadvantage of this ignition-cut only system was that the fuel charge would cool the manifold (we believed) causing thermal stress = cracking manifold. Air injection would still be a wise thing to try, we also tried pure oxygen injected into the manifold with limited success..."

evo

[fredio54]

Originally Posted by moebius

Okay, another thought on Anti-lag options -- what about a variable nozzle turbo - ala the VW/Garrett VNT Turbos??

It isn't a anti-lag system, but in theory, you get full reliability but with better spooling characteristics --
Turbotech - Australia's specialist in turbochargers - Garrett Turbochargers

I'm still voting for a Supercharger added to the system.

for the same reason a supercharger is no good, so is a vnt no good : budget :-)

including shipping the holset (530hp turbo) came to 750nz thats 1/4 of what a brand new garret of equal potential would have cost. i went to the expensive end of holsets offerings because i'm fussy and i wanted it pretty new and therefore A reliable, and B efficient. i got what i wanted. my turbo was supposed to have done about 2500miles or so, and its like brand new. literally.

evo : that ign cut system is less sophisticated and worse than the heavy retard system thats easy to get happening with ms and no further mods.

but, i dont like what it will do to the exhaust valves on the way out...

gavin, thanks for posting that link, very interesting indeed. i hadnt considered the idea of "blowing off" straight out the exhaust :-) a pretty clever idea, but i dont think it would work for me on the street. if you welded in a 5th runner to the collector such that it aimed straight for the turbine, and didnt use the air to ignite fuel in the exhaust, but just to blow the turbine around, it would work nicely during shifts. off idle though, it couldnt build boost like i want.

i'm not concerned about spool between shifts, thats not too bad as it is even with the sucky ratios. what i want is for the turbo to not unspool when i lift to control a slide or prevent a slide when cornering hard. the latter, i'm sure you know what i mean.

i mean, i've slid cars all my life, i live sideways, but i took the ute round a largish roundabout on the way home after tuning it for boost in the wet, and i tried to slide it smoothly all the way around... i couldnt. i could lean on it and it would build boost and skid out, but when i lifted, the turbo would more or less stall, and upon reapplying, there was no torque to keep the skid happening, result : lots of skid angle, no skid angle, lots of skid angle, no skid angle. i couldnt slide it smoothly.

i'm sure with practice i could get it better, but i'm good at that [shizzle], and i couldnt do it off the bat. i found that frustrating, cause its one of my favourite things, that and sex. its a hard call which i like more.

hence "proper antilag". perhaps i'll just have to wait and try it myself :-)

i could use a control strategy to take the vac feed away from the bovs and thereby create pressure at the same time releasing a controlled amount of air into the exhaust (rather than all of it as audi seemed to do) and without the boost pushing the valves closed, the would bleed off any excess pressure that exceeded their spring pressure. i could log a second map sensor for tuning it. to see what sorts of pressures were found. i'd need to replumb the wastegate feed to pre throttle to ensure that it vented exhaust gasses if there was a need also. that ought to keep it from over spooling, and yet make sure that there was pressure in the intake ready to pass the throttle after i stop lifting. i'm not too worried if the system cant start it spooling, so long as it can keep it spooled when i'm doing skids/cornering hard at part throttle...

i hope you lot all see where i'm coming from now :-)

[rodhog]

variable vane geometry turbo Cost bugger all in comparisson to a full anti lag setup..

Your claiming oyu can't afford one - how can oyu afford a probler anti-lag.
I know of two engine Managment systems built to run such things and both cost more then a VGT

[fredio54]

you dont know of ms, and that i am a software developer by trade, and can implement any control strategy i like in the open and freely available code, that my friend is as free as laying the beads onto the air injection tubes...

no need to post around to cause trouble just because you got your tits in a tangle.

[rodhog]

Not here to cause trouble I just don't see the point.

It's your project and your free to do as you wish. If I had a homiligated GT-4 I would proberly want to fit up myself as well.

MS to me is an average system. Nothing special if it was decent I'd proberly see more use of it but I don't.

Anti-lag it's great for this for that but it's not great soloution, there is always a compromise. I know people say the new 911 Turbo has not lag etc but it's BS it has lag yes very very very minor but you notice it regardless.
Lag will always be an issue in turbo car using Boost to create power to compenstate for both lack of capacity and excessive weight.

[fredio54]

MS to me is an average system. Nothing special if it was decent I'd proberly see more use of it but I don't.

if you dont open your eyes, you do not see. there are at least 4 fe3s running it. hell, there are probably only 20 or so fe3ts around (at least online) at all. there are 15000ms registered users, maybe more like 20000, and there are countless others out there that use it and have never got a login because its easy enough to not need one.

its the best value most versatile customisable solution there is. it can do whatever you want to make it do. code exists (good code, NOT built to a budget) to do most anything you want anyway. and if it doesnt, you can A ask, and B just do it yourself.

thats immensely powerful.

as for antilag having lag... properly setup antilag has no such issue. thats the whole point of antilag, the turbo is artificially spooled all the time, when you lift, you feed flames at it to make it keep spinning enough to push the boost you need, and the airflow you want to keep throttle response linear with respect to opening and time.

ps, we dont use small displacement engines because we cant afford bigger ones, we use them because they are light for their output when turboed. vehicle weight irrespective. rpm and boost easily make up for capacity. antilag can make up for a bigger turbo to some extent, and i'll be finding out just how much it can do for me at some stage.

some stats i calculated for you :

rodhogs percentage of posts with karma : 3.5 - 5.3%
mine : 19%
sleepcounter (hes still a member to me) : 18.5 - 24.6%
gavin : 53.8 - 80.7% (thats how you do it!!) (i love quoting that figure)
sick : 7.8% +++ (2000+ ? whats the real number? this is too low)
carcenomy : 20.7 - 31.1

etc etc

these numbers directly related to credibility and how much you contribute per post. ie, you are not credible, and have little respect from your peers. perhaps its better that you quit now while you arent too far behind?

to put that post there with that timing with regards the other thread was only for that purpose, and nothing else. dont try to pass it off as something constructive.

once again, and just to be sure, holset 750nz including shipping near new, vnt turbo which STILL HAS LAG at least 3 - 4 times that, probably more (for same power potential) not a good option.

[moebius]

Getting back on topic.

Thinking about things, going back to first principles - you can't get something for nothing.

I think the idea that has the most merit is directly injecting fuel into the manifold that feeds the turbo -- making a little jet engine effectively.

Basically, you'd need to add a fifth injector, which has very different firing profile from your other injectors.

To make this effective, and to keep your turbo alive for a long time, you'd have to make some changes -- effectively increase the heat capacity/tolerance of your system. I think the easiest way to do this, would be to put some special high temperature ceramic coating on the *inside* of your manifold and on the hot side of your turbo, and on the downpipe, all the way up to the catalytic converter (wait, you still have one of those, right? )

Why? -- keep the darn turbo spooled all the time - make it a fricking JET engine.

You'll need the fuel injector from a diesel, that's the only thing that can take the temperature/pressure in the manifold, and a high pressure injector pump - again, from a diesel. You should be able to run high octane gas, straight in to the manifold.

If you've got your manifold/turbo properly coated (the most expensive thing), then you'll be able to take the extra high temperature which will result from running the turbo as a jet engine.

Once the turbo is spooled - you don't need to inject any more fuel.
You probably don't want to inject any extra fuel when coasting.


I was trying to think about this, while in the shower, in the following terms:
1) You can't get something for nothing.
2) Heat drives the turbo. Increase the heat to spool the turbo, keep the heat constant.
3) How do you increase heat? Dump fuel into the exhaust manifold !
4) How do you do that safely??? Just a little, at the right time, take proper precautions
5) Weld, Coat, Take pictures, Enjoy!



In other words, I think before I was wrong, and that the bang-bang systems are the right idea. Really, the only way to do it well. Don't bother with the wasted spark and extra injectors, just shove some more fuel directly into a prepared exhaust manifold and enjoy!

[SixSick6]

Not to mention that the variable geometry Garrett turbos are dinky and pale in comparison to the Holset he is using. Even if you put the compressor housing on a lathe and machined it to accept say a TO4E 60 trim wheel, the turbine wheel is still very small compared to the standard T3 turbine. And with the VGT exhaust housing, there isn't much that you can do for machining. So, you'd be left with an oversized ill suited compressor wheel (when sized according to increase in surface area IE size % increase vs the turbine wheel) and a turbine with a tendency to overspool when the boost is raised.

+1 for Fred. (I'm out of Karma this round)

[fredio54]

dumping fuel into the manifold is no good unless you dump air in at the same time.

i'm not sure that i'd be happy with injecting fuel into the exhaust even if it was legal in nz. dont know if it is?

you can over fuel the engine (even if its round robin style) to supply fuel safely through the cylinders while introducing air safely through the exhaust and thus creating the heat/bangs needed for spool.

the difference in operation of the turbo normally and when using any of these antilag setups is that the internally combusted gasses come as a bunch of fast hot air. the antilag comes as a single wall of impacting hot burning air. i witnessed the effectiveness of that when i wired my coils incorrectly shortly before successfully starting the engine for the first time.

it went something like this :

splutter splutter bang whiiiiirrrrrrrrrrrrrrrrrrrrrr

;-)

ie, you dont need the volume of gasses to keep it spooled because the sheer velocity and pressure of the explosive ones from antilag is enough in lesser quantities.

i'd like ceramics, but thats more $$ that i dont need to spend. although i know the benefits are real, that manifold comes within an inch of the bonnet, and the paint was unaffected in my shortish but hardish use of it thus far, hence i think that heat lost at the moment is not significant.

i think its wrong to say that heat drives the turbo. i think its velocity and mass that drive it. as the temperature falls, the velocity falls, hence the "keep the manifold hot" beliefs that are around.

in this case what you exchange for constant boost is reliability. how much of it i dont know. but i'm willing to find out. it will be a dash switched system, so it will only be on when i wanna play, not all the time. if the turbo would last 3000km with it on constantly, then it should last much more if its on only 10% of the time.

lastly i guess, dumping in fuel without air wont produce any heat anyway, not unless the engine is running uber lean at the time.

so, sick, how many karma points do you have? i wanna make that little chart accurate...