Lt4 afr

[tbrtuning]

Sorry to mimic my LT1 question but I'm tuning more Gen V stuff now so just coming across these things...

Are you guys running LT4 at similar AFR to factory or richer? About to tune a bolt in and cammed CTS-V and wasn't sure what kind of AFR and timing people are considering reasonable. I know timing will very based on AFR and modifiers but was just looking for a ballpark.

[Mustang5.0]

Actually the AFR is rich from the factory. About 12.2 - 12.5 is good place to be.

[tbrtuning]

That's right around where I ended up with it. Leaner side of that until high RPM then tapering to richer end but I suspect it would be fine on the leaner side. Funny you mentioned the area I ended up in. Thanks for the input

[TriPinTaZ]

Technically the most power is made by being richer up to peak torque RPM and then leaning it out a bit to redline.

[obd2]

Technically the most power is made by being richer up to peak torque RPM and then leaning it out a bit to redline.

totally agree. I have been tuning several cars on a dyno most like it richer to 5200. speaking of afr would be 12.2 then upper rpm lean to 12.5 as a general rule. doing so really carries the torque curve nicely. I mostly focus on carrying a good torque curve more than peek hp

[tbrtuning]

Thanks guys

[paulsmithsr]

Leaner then stock

[lt1z350]

also depends on fuel being used. I am finding out on my own when supplementing the fuel system using meth it doesn't like the leaner 12.4-12.0 range at all verified it on 2 cars now as thought it was a fluke or bad wideband reading on the one. On full bolt ons knowing the fuel system is not enough e50-e40 spraying around 16gpm of meth if I try to run anything less then .80 its breaking up even with a 5.5 ms. Im using all lambda and seems like .77 is about where it is running well. I m not sure why yet but everytime I have tried to lean it back out its going back to running like it was when was seeing low fuel rail pressures and 7.0-11ms. Where it gets tricky is I wasn't showing lean as I assume it was just spraying extra fuel out the exhaust valve and skewing wideband readings. It will just on its own continue to advance the soi no matter what your settings are as its trying to make the car run more rich. That then starts it spraying into an open exhaust valve making what your spraying totally useless and making rail pressures even worse. I have logs with it in the 380s when I was trying to command even lower then stock trying to force it to keep rail pressure higher. My point being you cannot just trust the wideband need to log soi and all other injector timing to make sure its not trying to over compensate on its own. I hope that car with the cam has the bigger fuel lobe or its going to need meth if doesn't have it already. I almost cant even run on 93 alone any more with out fuel pressure issues with a stock cam and a lot of bolt ons and ported blower nose W/ 95mm zr1 tb. Looking at low side upgrade first to see how much it will help. I don't like the idea of how everyone is doing it now and rather upgrade the in tank pumps if possible rather then tying into the tank with a separate line and pump that uses its own method to control it like all these upgrade kits do.

[tbrtuning]

No problem with 38% enhanced fuel lobe. I am guessing you would run out of octane to be safe before out of fuel on 93 with stock blower and that fuel lobe right?