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  #1  
Old 05-03-2007, 01:33 PM
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Default Anti Lag

Hi guys, I was curious as to what is involved in getting anti lag setup on a wrx? And what parts are recommended. I'm under the impression that anti lag works by igniting in the manifold as opposed to the cylinders, thus putting a lot of stress on the manifold (i'm only speculating here). Any help or information would be helpful.

Alex
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Old 05-03-2007, 01:34 PM
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aftermarket ecu with anti lag enabled (motec, autronic, link etc etc) and the workshop does the rest
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Old 05-03-2007, 01:36 PM
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be prepared to pay for a new turbo eventually tho, and as one member of this forum recently found out, a new engine aswell...

Antilag is in no way good for your car... but its still awesome!!!
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Old 05-03-2007, 01:37 PM
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http://www.perth-wrx.com/vb/showthre...otational+idle
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Old 05-03-2007, 01:41 PM
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thanks guys. i'm not all that interested in getting it for the street car. just curious to it's workings. my wrx is fairly quiet and i intent to keep it that way. just something to look at for the project car.
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Old 05-03-2007, 03:00 PM
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Anti-Lag System, ALS, and sometimes also called a Misfiring System or "Bang-Bang", is a system used on mainly turbocharged racing and rally engines to eliminate turbo lag. It was used in the early days of turbo charging in F1 until fuel restrictions made its use unsuitable. Later it became a common feature in rally cars due to the mandated restrictors on the turbocharger inlet. 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. This increases turbo lag significantly compared to unrestricted turbochargers.

An ALS system requires an air bypass, and generally this is done in one of two ways. The first method is to use a throttle air bypass; this may be an external bypass valve or a solenoid valve which open up the throttle 12-20 degrees. This allows air to bypass the closed throttle and to reach the engine. The second method is to use a bypass valve which feed charge air directly to the exhaust manifold.

The throttle bypass/throttle solenoid system is combined with ignition retardation and slight fuel enrichment (mainly to provide cooling), typically ignition occur at 35-45° ATDC. This late ignition causes very little expansion of the gas in the cylinder; hence the pressure and temperature will still be very high when the exhaust valve opens. At the same time, the amount of torque delivered to the crankshaft will be very small (just enough to keep the engine running). The higher exhaust pressure and temperature combined with the increased mass flow is enough to keep the turbocharger spinning at high speed thus reducing lag. When the throttle is opened up again the ignition and fuel injection goes back to normal operation. Since many engine components are exposed to very high temperatures during ALS operation and also high pressure pulses, this kind of system is very hard on the engine and turbocharger. For the latter not only the high temperatures are a problem but also the uncontrolled turbo speeds which fast can destroy a turbocharger. In most applications the ALS is automatically shut down when the coolant reaches a temperature of 110-115°C, this to prevent overheating the engine.

An ALS system working with a bypass valve which feeds air directly to the exhaust system can be made more refined than the system described above. Some early systems used by Ferrari in F1 followed this approach, so does the anti-lag systems used in WRC today, which are even more refined with advanced computer control. Today this kind of system has reached such a refinement that it’s even possible to use the system in a road car, which was tested by for example Prodrive with their P2 prototype. The system works by bypassing charge air directly to the exhaust manifold which will act as a combustor when fuel rich exhaust from the engine meets up with the fresh air from the bypass. This will provide a continuous combustion limited to the exhaust manifold which significantly reduces the heat and pressure loads on the engine and turbocharger. With the latest anti-lag systems the bypass valve can not only be opened or closed but it can actually control the flow of air to the exhaust manifold very accurately. The turbocharger is fitted with a turbo speed sensor and the engine management system has a map based on throttle position and car speed which is used to find a suitable turbocharger speed and boost pressure for every condition. When the engine alone can’t provide enough exhaust energy to reach the turbo speed/boost demanded by the management system, the combustion in the exhaust manifold combustor kicks in. This does not only remove turbo lag, but it also allow boost to be produced at very low engine speed earlier limited by compressor surge or exhaust energy. With a high boost at low speeds, this makes the low end torque superior even to large naturally aspirated engines. The system also operates very quietly.

from Wiki.
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Old 05-03-2007, 06:39 PM
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Heh, Who want's quiet anti-lag? =)
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Old 05-03-2007, 11:11 PM
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Yes one person did, Minus one 2.2 Jun stroker

Quote:
Originally Posted by ImPreSiV
be prepared to pay for a new turbo eventually tho, and as one member of this forum recently found out, a new engine aswell...

Antilag is in no way good for your car... but its still awesome!!!
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Old 30-03-2007, 11:35 AM
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Hi guys. Thought I would hijack this thread instead of starting a new one.

A mate has just bought an MY00 with M800 fitted to it. My question is what is needed/involved to run antilag on this ECU as it's not fitted to his car.

Cheers

Scott.
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Old 30-03-2007, 11:41 AM
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is the ecu unlocked to perform antilag? That would be ur first hurdle, i hink its an extra 400 and u get LC enabled also.

Now for it to work, the tuner has to setup activation through the ecu. Im not sure if Motec require a solinoid to increase RPM levels at the throttle cable, but i know that the old autronics used this method.
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