slcsubaru.com

I have a vague understanding of how it works. What do you have to do to your car to get an anti-lag set up? I would also think this would put your turbo under huge stress. I'm (obviously) not going to be doing this anytime in the foreseeable future, but I just thought some anti-lag discussion would be interesting and informative.

you need a tune that has it
IIRC, 02-05 cars cant have anti-lag via a cobb OTS map/custom tune

you can get it through an open source tune/3rd party tune, though

can't remember the site I read a topic on Anti-lag but I read that the vf22 and vf30 were the best IHI series turbos for AL. I'll try and find it and post it up.

ya don't get it unless you are competing and need it. Or unless you have tons of money to spare and can have fun showing it off and replacing things constantly

The Cobb Accessport cannot do anti lag and im pretty sure the OS stuff cant either, they can do launch control and full throttle shifting. Youll need stand alone engine management (AEM, Hydra, etc....) to do ALS.

How ALS works taken from www.rallycars.com

When the driver lifts his foot from the gas pedal the ignition timing is altered with sometimes 40° or more of delay (retard) and the intake air and fuel supply mixture is made richer. The inlet butterfly is kept slightly open or an air injector, bypassing the inlet butterfly, is used to maintain air supply to the engine. This results in air/fuel mixture that keeps getting in the combustion chambers when the driver no longer accelerates. The ignition being severely delayed, the air/fuel mixture reaches the exhaust tubes mostly unburned. When the spark plug fires, the exhaust valve is starting to open due to the ignition delay mentioned above. Additionally, the exhaust temperature being extremely high, the unburned fuel explodes at the contact of the exhaust tubes. Luckily the turbo sits right there and the explosion keeps it turning (otherwise it would slow down since its intake, the exhaust gases, is cut-off). The effect is vastly lower response times with some downsides:

* A quick rise of the turbocharger's temperature (which jumps from ~800°C to the 1100°C+ region) whenever the system is activated
* A huge stress on the exhaust manifold and pipes (mounted on a street car a bang-bang system would destroy the exhaust system within 50-100 km)
* The turbo produces significant boost even at engine idle speeds
* The explosions which occur in the exhaust tubes generate important flames which can, sometimes, be seen at the end of the exhaust tube
* Reduced engine brake

The ALS effect is mostly dependent on the quantity of air allowed into the engine, the more air supplied the more the ALS effect will be noticeable. Consequently ALS systems can be more or less aggressive. A mild ALS will maintain a 0 to 0.3 bar pressure in the inlet manifold when activated whereas, when inactive, the pressure in the inlet manifold with the throttle closed would be in the region of -1 bar (absolute vacuum). Racing ALS versions can maintain a pressure of up to 1.5 bar in the inlet manifold with the throttle closed.
While the systems mounted in Toyota and Mitsubishi racing cars are relatively smooth and noiseless those fitted in Ford and Subaru cars are much more noisy and aggressive.
The bang-bang system owns its name to the loud explosion noises one hears whenever the driver lifts off. Most racing implementations have user selectable anti-lag settings depending on the terrain, usually three settings can be selected by the driver going from mild to very aggressive.

Note that some regional or national European events prohibit the use of ALS systems while more and more WRC events regulate the noise levels allowed by competition cars effectively disabling ALS.

Starting in 2002 new anti-lag techniques, such as Exhaust Gas Recirculation (EGR), are slowly overtaking the method described above as they are kinder on the engine's mechanical parts.

Nice write up bh!

if I ever have enough money to never worry about having to spend lots of it I'm doing it. It is freaking sweet.

^ +1 (adding: if i rally the car and "....") i don't think it's really necessary on a road course. but still. it'd be so sick!

I've always been curious how destroyed the WRC car turbos are after a hard couple of stages.

ya anti lag would be awesome lol.. you can break boost your car its tough to do though. by giving your car gas and pressing the break a little. I have heard of people doin this. But I think it can also reset your knock sensor settings. So I guess your KS could pull a bunch of timing from doing it and ruin your tune lol. especially if the sensor got reset or messed up, not sure how true this knock sensor thing is but I do know that break boosting works.

Brake boosting makes absolutely no sense to me. You're holding the brake slightly to go faster? The ONLY time it would make sense to brake boost would be during a street race and that is gay in the first place. Unless I'm mistaken, this is worthless in any other situation no?

lol pretty much pointless in any other situation yes. works in street racing lol

i think he's referring to launching. like if you have an automatic.. stand on the brake as hard as you can, then press the gas as much as you can without moving the car.. let off brake+mash gas more=faster launch. i don't think that really applies to manuals tho... unless it's an anti lag thing?

idk

no. you do it while your on a roll. 2nd gear or third. try to maintain the same speed while pushing the break and the gas and give it more and more throttle until your boost starts climbing up then release the brake. I know some guy who use to do it with great success i wouldnt recommend it im just saying lol its ghetto anti lag