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Bypass valve antilag tuning

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Hi guys,

I curious to know if anyone has had much to do with bypass antilag valve tuning on a Motec M1.

Hoping to get some insight into the tuning strategy.

I have fitted a turbosmart antilag valve to a Fiesta ST rally car, direct injection.

I presume the bypass valve will be tuned a little differently than the traditional antilag. Other than throttle aim of course.

Thanks so much.

Just in case you missed it. There was a very early webinar on Antilag that used the MoTeC M1..


Unfortunately Andre does not discuss tuning strategies for a wrc style external bypass into the exhaust manifold. I assume most applies for the external bypass, but there may be some slightly different strategies for getting the most out of it.

Absolutely fantastic webinar none the less!

Hi Adrian,

The control strategy you would implement would vary based on the firmware package you are using.

The GPR-DI will have different options to the Ford Fiesta ST 2013 Ecoboost package for instance.

Hi Nathan, thanks for that.

Antilag tab in my Fiesta package is basically the same as the above webinar.

I am using the antilag status as a trigger on my C125, using a output from C125 to control the solenoid for the antilag valve.

Hope this helps.

Ok, so you already have the solenoid under control, which is one issue sorted.

Funnily enough, I have another HPA video for you to refer to, more for conceptualising how the strategy will change for you:


Unfortunately there isn't a trim that can be applied to the fuel timing limit or an alternate fuel timing that can be applied when anti lag is active in the fiesta package.

What you will be able to do however, is have a lower value in the anti lag throttle aim table, as you won't need the throttle to be open to divert air in. So where you probably have 15-20%, you may get away with 5%, which means the car won't push as much on throttle lift off.

I would suspect you will need spend some time adjusting the ant lag fuel volume trim, and possibly set it up as a table instead of a single value. As the fiesta is direct injection, and you don't have the luxury of a timing trim, you will quite likely need more fuel as you will be bypassing more air, and you will be trying to mix the atomised fuel with the air introduced in the exhaust, instead of the mixing in the cylinder.

Thanks Nathan,

Watching that video was one of the things that made up my mind to switch to the bypass style valve. Because mine is fwd, the push makes it awful to drive.

OK great, so it looks like it'll take a bit of time getting it right, but it should be better in the end.

I was worried about having excessive exhaust manifold temperature with the extra air bypassing. From what I can tell, it may actually be better if done correctly.

Car is being tuned next week, then I'll take it out and do some antilag tuning over the next few weeks before the first rally.

I will start at 5% throttle aim, 10% fuel and leave the timing maps as they were and go from there.

Thanks so much for your help.

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