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Discussion and questions related to the course Understanding AFR
Interested to see what others feel would be a good AFR target strategy at WOT for a centrifugal supercharger.
In my situation I have a 6.2L V8 (LS3) feed via a Vortech V1 Ti trim. Currently I run a transition AFR target at 0psi of 0.89 Lambda dropping to 0.79 Lambda by 2psi, holding 0.79 Lambda all the way through to full boost approx 14psi.
Just wondering if I should hold my transition target on a bit longer ie 0.89 until 3.5psi before dropping to 0.79 or inverse my target AFR with reference to boost ie 0.89 @ 0psi then 0.86 @ 3.5psi then 0.84 @ 7psi then 0.82 @ 10.5psi then 0.79 @ 14psi. A linear decline in Lambda number inverse of the linear increase in boost.
Or apply the above tactic but be full rich by 7psi. ie 0.89 @ 0psi then 0.84 @ 3.5psi then 0.79 @ 7psi holding 0.79 all the way through to full boost.
My current AFR target are a little rich but would like to dial in my AFR strategy before starting to lean on it.
Personally, I think you're overthinking it. Different engines will make their best torque/power with different fuel ratios (lamddas) and timing, and you can't say xyz is going to be 'the' ratio to use.
If you can find one, you're going to be best served having the engine properly tuned, on a dyno', so you're giving it what IT actually needs. I would expect this to be around lambda 0.9 throughout, for MBT, but could certainly be wrong - it's going to be down to your particular set up.
That's pretty spicy for a bar of boost on a port injection engine isn't it?
Unfortunately I don't have access to a dyno at the moment. I understand finding MBT would be best practice although a bit of a pain when doing reflash changes vs live with aftermarket ecu's. For the time being it will continue to be road tuned just looking for opinions on best AFR target strategy.