Anti-lag for turbocharged cars..., just thought everybody should know what it is.. Options

[RUNNIN-LOW]

ANTI-LAG
Anti-lag, (often incorrectly called a Misfiring System), is a system used on WRC rally cars to completely eliminate turbo lag. It is a feature of the engine management system. WRC cars are fitted with a class mandated restrictor on the turbocharger inlet and this increases turbo lag significantly. Because of the pressure drop across the restriction, the pressure ratio for a given boost level is much higher and the turbocharger must spin a lot faster to produce the same boost as before.

Anti-lag effectively increases the mass of exhaust fed to the turbocharger. This is typically done by retarding spark timing to a point where most of the combustion happens in the exhaust manifold, typically around 40° ATDC. At the same time more air must be added, this can either be done by the use of a throttle bypass valve or a throttle stop solenoid. When anti-lag is switched on it is typically active when the throttle is closed, and when the throttle is opened the spark timing is resumed to normal.

Exhaust temperatures produced by this system are phenomenal but they can be controlled by varying the amount of fuel injected while anti lag is active; a richer mixture lowers the temperature. Anti-lag is typically only used on race cars because it can shorten the turbocharger service life down to impractical periods for street use. The turbine blade life is drastically reduced, and the entire exhaust system is put into shock, which can lead to explosion or fire. Rally cars generally change turbochargers every chance they get to do so.

As a note, all Subaru Impreza WRX STi (and STI) and Misubishi Lancer Evolutions are equipped with a Anti Lag System because FIA rules require complete homogulation with street cars ( only until 1998, newer "WRC" class cars do not have true street going versions. By way of example the roadgoing STI has 2.5L engine which is 25% larger then the engine used by Subaru to rally). These cars, however, do not carry the computer or software necessary to activate the system, ( the computer software is the chief component of any anti-lag system).


This was in the gt4 meet video that driveby posted in general discussion it sweet if you watch the video...
just thought everybody wanted to know what it was...

[bigal004321]

seems too dangerous to run on our cars though. I dont want to have to go out and buy a new turbo every six months. Cool idea though if it wasnt so hard on the car.

Bigal

[Hanyo]

good post, very helpfull.

[Supersprynt]

ST205 WRC's came with anti-lag, but its not hooked up. It basically cuts ur engine life by 75%.

[jgreening]

ST205 WRC's came with anti-lag, but its not hooked up. It basically cuts ur engine life by 75%.

Other than the turbocharger, what other portions of the engine experience high wear due to anti-lag?

[CilverSeliST205]

ST205 WRC's came with anti-lag, but its not hooked up. It basically cuts ur engine life by 75%.

You ment turbo life? I just do not see how retarding the timing and soaking exhaust in gas can reduce engine life by 75%

But the coolest thing about antilag is those tailpipe fireballs

[Bitter]

you can also fit a TINY (100CC) injector into the manifold before the turbo and put it on a low duty cycle and set to turn off when manifold pressure reaches a certain point. of course you'd need a standalone or possibly a piggy back with auxillary injector control. and not to mention it would **** with your AF readings so you'd have to run your tune open loop all the time.

[97sccelica]

ST205 WRC's came with anti-lag, but its not hooked up. It basically cuts ur engine life by 75%.

You ment turbo life? I just do not see how retarding the timing and soaking exhaust in gas can reduce engine life by 75%

But the coolest thing about antilag is those tailpipe fireballs

i dont know about 75% reduction, but it will reduce engine life

the car is always in boost and very high EGT's, so its like the driver is beating the crap out of the car non stop

i have a type of anti-lag system on my wrx(launch control)

[CilverSeliST205]

ST205 WRC's came with anti-lag, but its not hooked up. It basically cuts ur engine life by 75%.

You ment turbo life? I just do not see how retarding the timing and soaking exhaust in gas can reduce engine life by 75%

But the coolest thing about antilag is those tailpipe fireballs

i dont know about 75% reduction, but it will reduce engine life

the car is always in boost and very high EGT's, so its like the driver is beating the crap out of the car non stop

i have a type of anti-lag system on my wrx(launch control)

First of all car is not always in boost like you said because it does not need to be for ALS to work (different principle), second of all launch controll and ALS are two different things (also a different principle).

High EGT in use of ALS occurs mostly past exhaust ports of the engine damaging mostly turbocharger, manifold, cats, and the rest of exhaust system

It might reduce engine life but i doubt that it would be anywhere past 10%

Something to read: http://www.rallycars.com/Cars/bangbang.html - how does ALS work

This post has been edited by CilverSeliST205: Mar 21, 2006 - 12:13 PM

[presure2]

the biggest thing anti-lag will do on your typical street car is make it basicly eat turbos.
the reason WRC can afford to do it is because theyre basicly changing turbos every race.

[playr158]

that and have you considered wat a WRC turbo is constructed of?

The Compressionhousing is out of magnesium, the Compression propeller is out of Titanium and the on the tubine side it is out of steel. The Turbo is oil-cooled and -lubricated

about 12000$ USD new from TTE so they are highly more durable then the average garrett

This post has been edited by playr158: Mar 21, 2006 - 12:32 PM

[CilverSeliST205]

the biggest thing anti-lag will do on your typical street car is make it basicly eat turbos.
the reason WRC can afford to do it is because theyre basicly changing turbos every race.

Yeah ALS in a street application is a VERY bad idea. UNLESS it is a STEAM powered Anti-lag system, some guy came up with an idea that you can use engine heat to steam up the water and shoot the highly pressurized steam at a secondary turbine to produce the same effect as ALS (but without the bangbang noise and damage ) i think that this is a damn good idea, what do you guys think?

and plyr, wow serious $$$! I wonder how much $ goes into their manifold or DP?

[phattyduck]

seems too dangerous to run on our cars though. I dont want to have to go out and buy a new turbo every six months. Cool idea though if it wasnt so hard on the car.

Bigal

How about a new turbo every few hundred miles or so... A normal street turbo would wear out even faster.

Anti-lag and/or launch control is very cool - but very expensive. Its race-car only type stuff.

-Charlie

[97sccelica]

ST205 WRC's came with anti-lag, but its not hooked up. It basically cuts ur engine life by 75%.

You ment turbo life? I just do not see how retarding the timing and soaking exhaust in gas can reduce engine life by 75%

But the coolest thing about antilag is those tailpipe fireballs

i dont know about 75% reduction, but it will reduce engine life

the car is always in boost and very high EGT's, so its like the driver is beating the crap out of the car non stop

i have a type of anti-lag system on my wrx(launch control)

First of all car is not always in boost like you said because it does not need to be for ALS to work (different principle), second of all launch controll and ALS are two different things (also a different principle).

High EGT in use of ALS occurs mostly past exhaust ports of the engine damaging mostly turbocharger, manifold, cats, and the rest of exhaust system

It might reduce engine life but i doubt that it would be anywhere past 10%

Something to read: http://www.rallycars.com/Cars/bangbang.html - how does ALS work

ok, so at idle its not in boost, but i know that subrarus with ALS make about 4psi just by giving the car a little cas to pull into a parking space

basically any time you touch the gas pedal, it would be making boost. thats a lot more time in boost than with out the ALS. also, i already said i wasnt sure about 75% reduction in engine life, just that for sure there would be a reduction in engine life. i didnt put a value to it.

high EGT's are bad no matter what. how far away is the exhaust manifold from the exhaust port on the engine? they are bolted together. well, the turbo is atleast a few inches from the ports, but that distance doesnt mean too much since the heat is throughout the whole exhaust system from head to down pipe. thats a lot of heat and pressure on the head.

ALS and LC are very similar. both make use of timing manipulation to put a load on the engine

ALS requires opening of the throttle body with a solenoid to something like 30%, then it messes with the timing so that the engine is still at idle speeds, but it is sucking in the air it would when at 30% throttle. this loads up the motor and results in very low vacuum and the car is ready to make boost at the touch of the throttle

with LC timing manipulation takes place at a preset rpm, on my wrx, 5500rpm. it is activated when i press my clutch pedal. then i floor it. same effect as a solenoid opening the throttle 30% for the ALS, but my throttle is at 100%. when it reaches 5500rpm, the timing manipulation begins. the rpm's are held steady and load is placed on the engine, just like ALS, but with 100% of the air going in, and with the much higher load at 5500rpm than idle speeds, it makes about 10psi of boost instead of low vacuum that the ALS system makes

both shoot fire, and both make bang bang noises. both put load on the engine with timing manipulation, and both require the throttle to be more open than what's required to idle. like i said, they are very similar

[CilverSeliST205]

From personal experience, ALS and LC are VERY different. Im not talking about banbang and flames to compare, I am talking about the purpose and feel of both systems. Viscous ALS can make a big turbo 4cyl make feel like a big n/a engine, although it won't affect straight drag run noticeably. Most LC (as a piggyback feature) I have seen are just some form of rev limiters, although I am not so familliar with WRX LC as you are, so I might be wrong. But don't you hate when people drive around bangbanging on their piggyback LC and then trying to say that they have a functional ALS too bad i do not notice any difference with it on or off

[97sccelica]

From personal experience, ALS and LC are VERY different. Im not talking about banbang and flames to compare, I am talking about the purpose and feel of both systems. Viscous ALS can make a big turbo 4cyl make feel like a big n/a engine, although it won't affect straight drag run noticeably. Most LC (as a piggyback feature) I have seen are just some form of rev limiters, although I am not so familliar with WRX LC as you are, so I might be wrong. But don't you hate when people drive around bangbanging on their piggyback LC and then trying to say that they have a functional ALS too bad i do not notice any difference with it on or off

only one other person in my city has launch control that i know of

and its my buddy with a 9 second turbo mustang. we are currently working on getting 8's out of it.

launch control is more than just a simple rev limiter. a simple rev limiter cuts ignition till rpms fall a couple hundred rpm then turns it back on. launch control keeps the rpm constant by alternately retarding ignition on the cylinders. the result is a good amount of load on the engine and a good bit of unburt fuel entering the exhaust manifold and exploding.

since my launch control is activated by pressing the clutch pedal, i never have to let off the gas when i want to go fast. the result is that the car is always in boost, 12psi+(even during shifts) which again i would say is very similar to the feel of an ALS, the feel being 0 lag.

from the moment i launch my car till when i let off the gas to slow down, the only thing that lets you know its a turbo car is the sound of the turbo sucking in air.

care to elaborate on Viscous ALS? i have heard of a Viscous LSD, but not viscous ALS. the only EM's i have seen that offer ALS are timing based which like i said is the way that LC is controlled.