Explanation of the Anti-Lag Tune for n00bs
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7thgen Power Maker
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Explanation of the Anti-Lag Tune for n00bs
Originally Posted by Innovative Turbo
ALS, or Anti-Lag System, also known as bang-bang, is an engine management technique that minimizes turbo-lag.
Turbo systems can exhibit what is known as turbo-lag, which is the time needed for the turbocharger to gain enough speed for the compressor wheel to pressurize the intercooler, tubing and intake-system of an engine.
The amount of turbo-lag or time, depends on many factors such as rotating-group inertia, how well the componenets in the system work together, back-pressure before and after the turbo, engine (volumetric) efficiency, camshaft spec, etc. . In race cars it is common to fit relatively large turbochargers in order to produce enough airflow to provide desired engine output. Big turbochargers can display significant amounts of lag (on small displacement engines) due to their increased rotational inertia. The lag-issue, is partly dealt with by fitting a turbo with a Dual, Ceramic Ball Bearing System in the center section, such as the system produced by Innovative Turbo Systems. Another helpful addition is the bypass valve or dump valve, which operates during part-throttle or when the driver lifts. These valves will help reduce the load on the turbo and allows it to free-wheel, keeping the rotational speed higher – thus reducing turbo-lag. In race cars where immediate torque and engine response are critical factors, most applications can benefit from the use of anti-lag systems.
How ALS works:
The ignition timing is retarded with 25-30° or more and the air/fuel mixture is made richer at low throttle opening and low load. With the ignition timing delayed, the air/fuel mixture reaches the exhaust tubes mostly unburned and because the exhaust system’s temperature is higher than the flash point of the air/fuel mix, the unburned fuel explodes in the exhaust tubes. The turbo is accelerated by the increased temperature/pressure and the rotational speed of the turbo is kept high. While ALS is engaged, full boost is available the moment the throttle is opened.
Some downsides:
An immediate increase in exhaust gas temperature (800°C to 1100°C+) whenever the system is activated puts greater demand on all turbo-system components - reliability becomes a major concern; the turbocharger and exhaust-manifold tubing must be made with the best available materials, driving the cost higher. ALS is prohibited from use in certain racing series.
Turbo systems can exhibit what is known as turbo-lag, which is the time needed for the turbocharger to gain enough speed for the compressor wheel to pressurize the intercooler, tubing and intake-system of an engine.
The amount of turbo-lag or time, depends on many factors such as rotating-group inertia, how well the componenets in the system work together, back-pressure before and after the turbo, engine (volumetric) efficiency, camshaft spec, etc. . In race cars it is common to fit relatively large turbochargers in order to produce enough airflow to provide desired engine output. Big turbochargers can display significant amounts of lag (on small displacement engines) due to their increased rotational inertia. The lag-issue, is partly dealt with by fitting a turbo with a Dual, Ceramic Ball Bearing System in the center section, such as the system produced by Innovative Turbo Systems. Another helpful addition is the bypass valve or dump valve, which operates during part-throttle or when the driver lifts. These valves will help reduce the load on the turbo and allows it to free-wheel, keeping the rotational speed higher – thus reducing turbo-lag. In race cars where immediate torque and engine response are critical factors, most applications can benefit from the use of anti-lag systems.
How ALS works:
The ignition timing is retarded with 25-30° or more and the air/fuel mixture is made richer at low throttle opening and low load. With the ignition timing delayed, the air/fuel mixture reaches the exhaust tubes mostly unburned and because the exhaust system’s temperature is higher than the flash point of the air/fuel mix, the unburned fuel explodes in the exhaust tubes. The turbo is accelerated by the increased temperature/pressure and the rotational speed of the turbo is kept high. While ALS is engaged, full boost is available the moment the throttle is opened.
Some downsides:
An immediate increase in exhaust gas temperature (800°C to 1100°C+) whenever the system is activated puts greater demand on all turbo-system components - reliability becomes a major concern; the turbocharger and exhaust-manifold tubing must be made with the best available materials, driving the cost higher. ALS is prohibited from use in certain racing series.
Last time I had this much fun some furniture got broken!
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From: PA
Rep Power: 360 Good to know for people who want to use it, but generally this is not the best system to use on the road, correct?
Didn't they do this in rally a little while back, till it was prohibited by new regulations, too?
Didn't they do this in rally a little while back, till it was prohibited by new regulations, too?
Joined: Aug 2001
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From: Jacksonville, Fl
Rep Power: 374 is there a way to control it for just when you want ALS and then be able to turn it off? btw good info once again paul.
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From: edwardsville, illinois (near stl.)
Rep Power: 295 yeah, think what kind of cylinder pressures there are with a turbo motor, ok now apply a good portion of that pressure to the exhaust mani/ and piping, doesnt sound smart for a street car unless you absolutely need it.
Dezod could you elaborate on the milder version? what are the differences?
Dezod could you elaborate on the milder version? what are the differences?
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Originally Posted by auto84
yeah, think what kind of cylinder pressures there are with a turbo motor, ok now apply a good portion of that pressure to the exhaust mani/ and piping, doesnt sound smart for a street car unless you absolutely need it.
Dezod could you elaborate on the milder version? what are the differences?
Dezod could you elaborate on the milder version? what are the differences?
DONT PANIC
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From: California, Palmdale
Rep Power: 285 You can pull around 5-7* of timing in 0 vaccum and the first few psi, along with a/f ratios in the mid 10's. This can increase the spoolup time by 500 rpm or so and still be relatively reliable on the street.
Worst thing I've heard of happening is a cracked head from too much heat. Only system you'll find this on for the 7th gen is the AEM. You can switch it on and off with a laptop.
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