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Tuning strategies for anti-lag setup


Guest |722|

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Guest |722|

I've got a blank slate I'm starting with on an anti-lag setup for my rally car. The car has a stable map for all regular operations, but I'm adding ALS.

Assuming a standard GrpN setup with the throttle cracked at 10%, always-on cyclic idle and a separate ALS activation switch, what steps would people use to start tuning ALS?

I've entered the base tables as shown in the documentation, but am looking to refine? Is it best to zero out the fuel and then add it back and adjust timing, or...?

I can't seem to find any good methods on how to attack tuning ALS.

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Guest |526|

Ray, any updates with the AC idle up problem I'm having when ALS is enabled?

Just want to know if I'll have to wait for an update or buy an external solenoid.

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Guest |722|

Ray,

I've got a base map to start with. My question is what's the process for tuning up anti-lag?

Do you change the timing values first? fueling? ign cut? What's the process for getting the "right" setup?

There has to be some method to tweak out the settings...

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Guest |208|

Aside from the obvious affects of anti lag there are a few things to consider when tuning the anti lag system. Firstly and most improtantly is to make sure the manifold and turbocharger limitations. WRC cars run specially deveoped turbochargers to allow very high levels of stored boost on idle. Factroy style turbochargers re simply not equiped to handle this work load. So temperature is one major concern and therefore an EGT sensor is a very useful tool to monitor what is going on. Does the car have a brake booster? If so then you are very limited as you need vacuum to ensure the boost has vacuum available. Most rally cars would have a pedal box. In this case this is not an issue. essentially burning more fuel in the exhaust will increase turbine speed and therefore available response. The air flow based on the thottle crack or air bleed with govern how much anti lag air supply and therefore determine how much fuel you can burn. Start with low retard figures, low air bleed. The cut percentage will help help stabilise the exhaust temperature and allow more air in the exahust as opposed to retard and fuel only systems which cause very high exhaust temperatures. Monitor exhaust temperature. A good clue to where you tuning is going is also the sound. You will find very loud banging will result in a highly unstable burn whic his good at wrecking turbos and manifold gaskets, etc. The way the anti lag transistions off and on will be determined by the dirver and the desired handling effect. My personal EVO rally car has a very mild anti lag system as opposed to other cars which run very aggressive antilag systems. This is a driver based thing and its transition affects the way the car handles. i hope this helps. Remember, anti lag increases wear and will always eventually lead to turbocharger failure. Please consider a turbochrger service routine. I hope this helps.

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Guest |737|

I've been wondering about this too, I have a base ALS map which we have used, but noticied when running the ALS on an increase in engine coolant temp, (usual during a stage is about 40%, with the ALS on it was up to more like 60%+) We've used it at one test day and also at a State Championship round.

What is it exactly that increases EGTs? is it more air, or more fuel or more retard? As i understand it the cut figure helps cooling as non ignighted fuel will help cool? is that correct? Off the back of that question, what is the man factor that increases the agressiveness of the ALS, air, Fuel or retard

I found the ALS was not very loud when operating, I will try and post up an image of our ALS maps.

cheers

Lewis

p.s sorry to thread hijack Eric

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What is it exactly that increases EGTs? is it more air, or more fuel or more retard?

Ignition retard. The more you retard the timing, the more of the air and fuel burns outside the engine (in the manifold an turbocharger). So rather then all the heat energy pushing the piston down the bore, the more it cooks your turbocharger. Adding extra fuel as well, just fuels the fire, making the turbocharger die quicker.

Ray.

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Guest |737|

Thanks Ray, that was what i was thinking.. what about more fuel in conjunction with more ign cut? does that help with cooling, or when the fuel detonates in the hot manifold does it pretty well just do the same thing?

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Guest |722|

So, I was planning on using a 10% throttle position for my fixed air bleed.

The recommendation would be then to put in a small amount of retard and a small amount of fuel and a small amount of cut and just keep bumping it up until I get the desired effect?

Or is it better to start with a bunch of fuel and slowly add in ignition retard?

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  • 1 month later...
Guest |722|

Bumping this up. Ray, any recomendations on strategies?

I've heard a lot of circumstantial stuff - like "you want it to be a smooth rumble".

What's the best way to go about a logical tuning method? Currently, I've got about 90kpa off-throttle and it's still pretty explosive.

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Guest |208|

I've heard a lot of circumstantial stuff - like "you want it to be a smooth rumble".

Based on you having a constant throttle and usng cooldown mode to keep the engine idling, what is the RPM the engine produces if you turned the cooldown off? This RPM usually gives me a good guide to how agressive someone has the anti lag set. The smooth rumble you are advised to chase indicates more stability in the burn within the exhaust. The explosive bangs you are referring to can smash turbines. Get yourself an EGT and fit it to the manifold as well to monitor your system. If you run a pedal box then you will be able to run more air as opposed to running a standard braking system which relies on vacuum. If you run too much throttle crack with a boosted braking system the pedal will go hard. Remember turbochargers which most production rally cars run are not designed to run antilag systems so be conservative unless you want to run a strict regime of replacment turbochargers. Running less crack will require less retard and cut in order order to brake the engine(allow the engine to decel) and this will require little or no fuel additon. This will be a very mild system and will not yield much exhaust energy to the turbine. You can run a system like this with say running 3000rpm base idle (cooldown off) and transition some retard as you throttle the engine out of antilag to yield addional turbo spool. You will find this type of system quite easy to drive in the rally stages (especially when running secret rallies) and still get good turbo response. Much higher air flow systems require a lot more cut, retard and fueling which therefore generate much more heat. Some systems feed air directly in the exhaust to increase the anti lag as this allows for less throttle crack. This helps improve the engines braking ability as well. So put simply - high air flow systems require more fueling, cut and retard and low air flow system requires less cut retard and fueling (and therefore provide less anti lag effect).

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