anti-lag system
01-13-2003 | 10:27 PM
#2
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They use a combination of the IAC valve and some moderately complex programming to acomplish this.
What happens is that when the throttle is closed rapidly under heavy load conditoins, the IAC is opened up very wide to allow extra air into the engine, then the software adds a bunch of extra fuel and simultaneously removes nearly all ignition advance. This causes the combustion event to happen very late in the cylce, and transfers a huge amount of heat energy into the exhaust. It is this heat energy that spools the turbo and builds boost.
When the throttle is re-opened, all functions return to normal and boost is maintained.
-Ben
What happens is that when the throttle is closed rapidly under heavy load conditoins, the IAC is opened up very wide to allow extra air into the engine, then the software adds a bunch of extra fuel and simultaneously removes nearly all ignition advance. This causes the combustion event to happen very late in the cylce, and transfers a huge amount of heat energy into the exhaust. It is this heat energy that spools the turbo and builds boost.
When the throttle is re-opened, all functions return to normal and boost is maintained.
-Ben
01-13-2003 | 10:36 PM
#3
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thnx for your healp, I also foudn this web site that gives a great deal of insight on it in case anyone else is interested as well
http://www.rallycars.com/Cars/bangbang.html
http://www.rallycars.com/Cars/bangbang.html
01-15-2003 | 07:51 PM
#4
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Not all anti-lag systems use Idle Air Control (IAC) solenoid. Autronic Anti-Lag also lets you run with a fixed open throttle ie at 'closed' throttle the throttle is still open 5 to 15%. Using IAC to feed air does have it's draw backs as it robs the car of vacuum pressure and brakes can feel a little weak as they're vacuum assisted. Other option is to run a throttle 'kicker' solenoid.
When AL is activated on my MY99 WRX road car EGTs sky rocket to 700c and it's quite easy to build up 0.5bar of boost standing still. And in the rally car I navigate in (Ver6 STi) we achieve nearly 1.0bar at the start line which makes for a rather noisy and violent take off.
Good little document to explain anti-lag is available here
http://www.autronic.com/software/antilag.pdf
Just a little tip for you Americans, just wait till Autronic finally release a PnP ECU for the MY02 WRX, this ECU will blow away everything out there except for maybe the top of the range Motecs.
When AL is activated on my MY99 WRX road car EGTs sky rocket to 700c and it's quite easy to build up 0.5bar of boost standing still. And in the rally car I navigate in (Ver6 STi) we achieve nearly 1.0bar at the start line which makes for a rather noisy and violent take off.
Good little document to explain anti-lag is available here
http://www.autronic.com/software/antilag.pdf
Just a little tip for you Americans, just wait till Autronic finally release a PnP ECU for the MY02 WRX, this ECU will blow away everything out there except for maybe the top of the range Motecs.
Last edited by Jonno; 01-15-2003 at 08:01 PM.
01-15-2003 | 08:16 PM
#5
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thnx bro
you say you run it on a street car, how is that, any undue wear on teh exhaust system and turbo (I would imagine there would be) any extra maitnence or I should say preventative maintnence needed to run such system on a street car? Also what is the pump octain down there? (102??)
you say you run it on a street car, how is that, any undue wear on teh exhaust system and turbo (I would imagine there would be) any extra maitnence or I should say preventative maintnence needed to run such system on a street car? Also what is the pump octain down there? (102??)
01-15-2003 | 08:48 PM
#6
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Have been running it now for about 6 months. I change my engine oil every 7500km with Mobil 1 and as yet (touchwood) haven't had any problems. Exhaust system has a 3" Cat so if anything is going to fail I'd that would be it. Must remember though that the explosions happen between the engine and turbo so it's not like the Cat is copping it on the chin. I only run AL selectively so it's not like it's on all the time, just when I play 
Great when a fully stickered Honda rice boy racer pulls up to you at the lights and wants a race. Flick my 'fog light' switch and my car transforms into a rough idling, fire breathing, popping, barking biarch.
In oz we have 98 RON fuel, I believe US uses a MON rating, slightly different. In Japan the fuel is 100RON.
Great when a fully stickered Honda rice boy racer pulls up to you at the lights and wants a race. Flick my 'fog light' switch and my car transforms into a rough idling, fire breathing, popping, barking biarch.In oz we have 98 RON fuel, I believe US uses a MON rating, slightly different. In Japan the fuel is 100RON.
Last edited by Jonno; 01-15-2003 at 08:51 PM.
01-15-2003 | 09:17 PM
#7
Registered User
Joined: Dec 2002
Posts: 242
From: Good ol oregon
Car Info: 02' WRX
Subarus dont use a IAC/retard system like you described. The anti-lag that subaru uses dramiticly richens the mixture and uses a late spark, so that when the exhaust valve opens a large amount of unburned fuel goes out the cylinder, which hits the hot headers and ignites, which is why you get the loud pops and backfire sounds when you hear subbies in anti lag. There are of course drawbacks to this, as if too much anti lag is used like this the headers will crack.
01-16-2003 | 04:24 AM
#8
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iTrader: (7)
Joined: Dec 2002
Posts: 10,029
From: Sacramento CA
Car Info: 02 Impreza WRX sedan
Originally posted by Jonno
In oz we have 98 RON fuel, I believe US uses a MON rating, slightly different. In Japan the fuel is 100RON.
In oz we have 98 RON fuel, I believe US uses a MON rating, slightly different. In Japan the fuel is 100RON.
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