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...

[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.