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060 | Effect of AFR on engine torque

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I have been waiting for this webinar to be put in the archive and as soon as I saw it was uploaded I watched it. I must say it is very interesting to see that there is very little change in output for what could be considered a wide AF range.

I have 1 question for you, at what point do you deem it worthwhile to set each individual load areas AFR at max torque (of course taking exhaust temps into account)? Do customers ever ask for this? If you have done it how much extra time and effort is required (on average) to set this up?

I remember back in the early V8 Supercar days Gibson Motorsport (who Mark Skaife started his Touring Car career with) used to be able to do the entire Bathurst 1000 with 1 fuel stop less than all the other competitors. They used to run their cars leaner than the other teams yet were still at race pace and won many races (both sprint and endurance) through using this combination.

In my own experience it's basically irrelevant. As per the webinar, under WOT conditions you're typically going to be using an AFR that produces maximum torque unless you have a very good reason to tune richer or leaner than this. At part throttle you can often see a small improvement in torque by tuning a little richer, but this gives up obviously some fuel economy and the reality is that if you're at part throttle then you're not asking for maximum torque anyway - That's always been my philosophy when tuning mid range/part throttle AFR targets.

There's an entire module in the EFI Fundamentals course that covers the topic of lean tuning and how this can be used to advantage (particularly for endurance racing). It's all about understanding the implications of your chosen AFR and managing the thermal considerations.

Thanks Andre.

I would of liked to see a full rpm run at stoichmetric, esp wtih the EGT sensors attached

I'll do exactly that on the engine dyno as soon as I can get time to get the Haltech TC4 connected :)

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