MoTeC Global Forum

Hello
I'm wondering how mild a anti lag setup can you have?

I'm looking at maybe a few psi just to help get the turbo started out of slow corners, without putting too much stress on the Turbo & engine and not too much effect on engine braking.

I'd have to open the throttle for extra air as I have no means of air bypass.

How much extra throttle % opening would i need for a small amount of boost?

Can someone help with the settings to start> ie retard & Cut amount.

It's a single gt35R on a 3.0ltr V6 running 11psi
appreciate any advice.

I’m not sure whether there was any progress on this since the post itself, but I wanted to bring a couple to your attention about how an anti-lag strategy works.

You noted that there was no means of facilitating air bypass on command, you might want to address this to give the best response possible. If you’re using a mechanical throttle then you are best off employing an actuator so that the strategy can regulate the amount of air bypass necessary. If you’re using an electronic throttle then the strategy can move the throttle blade to facilitate the air bypass.

The truth is that every power unit and turbocharger combination will respond differently to various anti-lag strategy setting. Essentially, you’re allowing some air to pass through the PU while the driver is off the throttle but instead of the spark event happening at the end of compression stroke, the spark event is triggered quite a few crank angle degrees into the power stroke. In this sense, there’s very little cylinder pressure being generated in comparison to a normal MBT combustion event, but rather a concentration of thermal energy which is then focused towards the turbine inlet; this is what drives the shaft speed up for the turbocharger during a lifted throttle scenario where the anti-lag strategy is working.

There’s a balance of fueling that’s needed, you’ll have to go based on the air bypass achieved. Similarly, the effectiveness of the ignition advance used depends upon the air bypass achieved once the throttle lift starts. Maybe it would be beneficial to keep an eye on the EGT at the turbine inlet, while shaft speed is your objective you certainly don’t want it at the expense of decreased turbocharger life. Also, something to be mindful of is whether your valve train employs a shim under bucket valve actuation strategy. While your cylinder pressure isn’t the same as normal combustion, there can be pressure spikes that can push against the valve causing the shims to pop out of place. These described pressure spikes can also spell trouble for hydraulic lifters. Please note this is only something to be mindful of and it’s not guaranteed problem that you will see.

If possible, let us know how you progress.