Air Injection / Antilag....

[GT4 20]

Here's a poser for ya...

As you may recall, my GT4 is a WRC version and as such carries the homologation extras required in those days. Along with cold start water injection and chargecooler spray bar, it also has a form of anti-lag. Now, speaking to Warwick (Mr Revhead) who a Toyota, he says that the system is listed as an 'Air Injection System' - we'll call it AIS from now on.
Having pulled the engine apart, it is possible to have a closer look at the parts.

This is the exhaust manifold -


Here are what I suspect are control solenoids for the water injection (1 set of hoses run to a seperate pump on the washer bottle) and another connects to the AIS -


Between the manifold and solendoid is a valve which connects to the chargecooler on the top of the engine and when opened, looks like this -

- this is the top half. Note the pipe at 10 o'clock wihich plumbs into the chargecooler. There are two hoses attached to the top which go to the solenoid.

The bottom half -

has two holes at the bottom with two hoses which connect to the pipework on the manifold.

So we've come up with this theory...
When the throttle is shut, the solenoid allows the unit on the chargecooler to open which in turn, allows boost pressure from the intake system to be 'injected' into the exhaust manifold. This extra pressure in turn helps keep the turbo spinning. There are no connections from the fuel system which obviously makes this different to a conventional anti-lag system. If this theory is correct, then it would be an option to connect up somehow as it wouldn't damage the exhaust/turbo as antilag usually does.

Perhaps one way of making this work would be to treat the unit on the chargecooler as a dump valve. Just using vacuum to allow the valve to open so the pressurised boost is then 'injected' into the manifold. Thoughts?
Gary

[Mr Revhead]

another possibility is that the fuel is fed from the injectors.. and as the throttle is closed the air injection supplies air to burn.... so the combustion takes place in the manifold not the combustion chamber.....

however that poses questions of bore wash etc.....

[pidge]

There is actually a connection to the fuel system - through the engine...

The anti-lag system may have injected excess fuel into the engine, the excess being combusted in the turbine housing with the air provided by the engine bypass.

Doesn't make for a very long lived turbo though...

[Mr Revhead]

isnt that what i just said?

[pidge]

OK, that's 2 for 2 so far, anybody else want to agree?

I first viewed the message before you submitted your reply... I then submitted my own reply...

Then realised that you had sumbitted a reply.

Now I notice that you've replied to my reply.

Wanna go another round

[Mr Revhead]

*ding ding*

anyone else got more intimate knowledge of this?

i do wonder if bleeding air alone back through will help....

[Malcolm]

the way I understood it was that the air lines on the exhaust manifold were there to assist with the functioning of the antilag, by supplying fresh air which would assist combustion in the exhaust manifold, rather than as the sole part of the system. If the electronic side of the antilag system was supplying extra fuel, along with lots of ignition retard, then the fresh air would assist the air/fuel mixture to continue burning as it made its way through the exhaust manifold.

there's a bit of info on Richard Doig's site:
http://gtfour.supras.org.nz/homologation.htm

I don't think that simply plumbing the bypass valve to direct air through the turbo would give any noticable gain, as the pressure and volume of air is nothing like what is needed to spin the turbo and produce boost. Also it would only work when changing gear, having already been on boost, rather than making boost while stationary (but it still wouldn't work IMO ).

[CozmoNz]

bah, to much theory... go figure out how to turn it on, and take a video .

very very cool though..... are the factory ecu's hooked up to be able to control / compensate for this, or did the rally chaps just swap them over when they were gonna go have a play?

[Malcolm]

bah, to much theory... go figure out how to turn it on, and take a video .

very very cool though..... are the factory ecu's hooked up to be able to control / compensate for this, or did the rally chaps just swap them over when they were gonna go have a play?

if you look at the URL i posted, the fittings in the lines aren't drilled and the bypass valve appears to be locked shut (unless Richard's was seized).

chances are the ECU isn't programmed for it, my guess would be that TTE had an ECU that plugged in to the factory loom (hence why some things are wired to it but don't work), that was fully programmable and such

[Ako]

Looks to me like the same as on the evo 4 onwards.

They all come with the HARDWARE for anti-lag, but you can't just flick a switch to get it going.



One thing which is funny is homemade antilag though.. Retarding timing so much (on 0 throttle) that you start building boost. Seen it done on a VR4, its funny as hell. Also gets MASSIVELY hot. Go figure.

[CozmoNz]

just had a look yeh....

oh well thats a shame... so its all just more bling to show your mates haha .

[Dirtbag]

Is this the same kinda stuff that rally cars use nowadays how they retard the timing so misfire when the throttles off so that the turbo doesnt lag?

p.s. if ya read this revhead have u received ma email? Im not to sure if my emails are working, good old orcon :\

[Ako]

In a nutshell -

Antilag as retarding the timing so severely that the combustion happens INSIDE the exhaust manifold, or at the very end of the power stroke. This does 2 things - keeps the turbo spinning, and generates HUGE amounts of heat, which damages both manifolds and turbos. Fuel is still injected into the cylinders as normal - like mentioned before, the turbo still has to make boost somehow.

The air injection is just to assist this process, they have it on the road cars for homologation purposes.

[Stu-]

Antilag is awesome. I used it when launching at meremere. Its fairly tricky to launch without it in my car as the turbo is fairly laggy so its a on or off affair ie bog and slow roll off the line or mad wheel spin.

[GT4 20]

i do wonder if bleeding air alone back through will help....

Warwick
Exactly what I was trying to find out. Seems that everyone (including you and I) knows what antilag is and how it generally works - but no one knows for sure if a burst of pressurized air into the manifold will make any difference.
Gary

[MrOizo]

Warwick
Exactly what I was trying to find out. Seems that everyone (including you and I) knows what antilag is and how it generally works - but no one knows for sure if a burst of pressurized air into the manifold will make any difference.
Gary

I know this might be pointless buuuuut....

When the flexi on the supra shat itself, i could rev the engine and let off the throttle and there would be wickedly massive flames and bangs out the back. i guess this was from the unburnt fuel meeting with fresh air and burning again due to heat and nice fresh air that would have been drawn in from the hole.

This would be the same as whats going on inside the manifold wouldnt it?

Some fresh air enough to combust unburnt fuel from the combustion cycle and giving enough oomf to get that turbo spinning?

[Mr Revhead]

gee. supra drivers arnt all think then!

yeah thats pretty much it.... i think on the rally cars they keep the injectors open to increase the fuel in that process

[Mr Revhead]

i think that for an air type system to work.. its need better designed nozzles in the manifold... looking at those its not exactly a good flow onto the turbo

[Malcolm]

i do wonder if bleeding air alone back through will help....

Warwick
Exactly what I was trying to find out. Seems that everyone (including you and I) knows what antilag is and how it generally works - but no one knows for sure if a burst of pressurized air into the manifold will make any difference.
Gary

but if you read what I said...

I don't think that simply plumbing the bypass valve to direct air through the turbo would give any noticable gain, as the pressure and volume of air is nothing like what is needed to spin the turbo and produce boost. Also it would only work when changing gear, having already been on boost, rather than making boost while stationary (but it still wouldn't work IMO ).

get an air compressor and blow 15psi of air out of an airgun into the exhaust side of the turbo and see if it pressurises the inlet tract. Bet it wont.

[GT4 20]

The pipework is patent and the banjo bolts are functional -


As Richard says though, the bypass valve does appear to be locked in the closed position. Unfirtunately it is a sealed unit making further investigation difficult

When running over 20psi, I wonder if the extra shot of compressed air into the exhaust manifold would make any difference?
Not sure what you mean by pressurizing the inlet tract?
Gary