New Project - Tuning my 3.4L for POWER

[insite]

certainly there are lots of different variables. one thing is for certain: the stock ECU map for a 996 contains no fuel ratios near 10:1. it's a losing proposition: less power, more emissions, worse mileage. the only cars that need to run in the 10's are augmented (turbo, supercharger). the extra intake heat & cylinder pressures raise the probability of knock. the extra fuel is used to cool the charge (latent heat required to vaporize fuel is around 300kJ/kg) & stabilize the flame front.

the accuracy of MAF readings in a given system is largely irrelevant so long as it is PRECISE. the ECU is tuned to the specifics of that vehicle. if the MAF reads 20% low compared to reality because of flow idiosyncrosies, it doesn't matter, because they program the ECU with maps that take that into account. that means that with a completely different intake, the stock 996 maps on my car may be irrelevant even though the engine is from a 996.

most NA cars will make good power between 12.3 and 13.5 AFR. i will be generating maps at WOT that model lambda from around .83 to .92 in 1% increments across the RPM band. i will plot HP vs. RPM vs. AFR, chosing the power path & programming the computer accordingly. i will also monitor knock to make sure things are safe. one thing i need to learn more about is ethanol in fuel. does RON+MON/2 account for the anti-knock properties of ethanol? i.e. does ethylated 93 octane fuel have a higher EFFECTIVE octane rating?

i digress. at any rate, as i do all of this, i will have many pretty charts, graphs and tables to spell it all out. it will be cool. my guess: 50HP (crank). quote me on that.

[BYprodriver]

most NA cars will make good power between 12.3 and 13.5 AFR. i will be generating maps at WOT that model lambda from around .83 to .92 in 1% increments across the RPM band. i will plot HP vs. RPM vs. AFR, chosing the power path & programming the computer accordingly. i will also monitor knock to make sure things are safe. one thing i need to learn more about is ethanol in fuel. does RON+MON/2 account for the anti-knock properties of ethanol? i.e. does ethylated 93 octane fuel have a higher EFFECTIVE octane rating?

I have wondered this too. I'm guessing that it is unregulated other than to insure it has the posted octane as a minimum. Consumer reports a 15% reduction in MPG when using "Gasohol"

[jaykay]

Originally Posted by insite

certainly there are lots of different variables. one thing is for certain: the stock ECU map for a 996 contains no fuel ratios near 10:1. it's a losing proposition: less power, more emissions, worse mileage. the only cars that need to run in the 10's are augmented (turbo, supercharger). the extra intake heat & cylinder pressures raise the probability of knock. the extra fuel is used to cool the charge (latent heat required to vaporize fuel is around 300kJ/kg) & stabilize the flame front.

the accuracy of MAF readings in a given system is largely irrelevant so long as it is PRECISE. the ECU is tuned to the specifics of that vehicle. if the MAF reads 20% low compared to reality because of flow idiosyncrosies, it doesn't matter, because they program the ECU with maps that take that into account. that means that with a completely different intake, the stock 996 maps on my car may be irrelevant even though the engine is from a 996.

most NA cars will make good power between 12.3 and 13.5 AFR. i will be generating maps at WOT that model lambda from around .83 to .92 in 1% increments across the RPM band. i will plot HP vs. RPM vs. AFR, chosing the power path & programming the computer accordingly. i will also monitor knock to make sure things are safe. one thing i need to learn more about is ethanol in fuel. does RON+MON/2 account for the anti-knock properties of ethanol? i.e. does ethylated 93 octane fuel have a higher EFFECTIVE octane rating?

i digress. at any rate, as i do all of this, i will have many pretty charts, graphs and tables to spell it all out. it will be cool. my guess: 50HP (crank). quote me on that.

Sounds like a very methodical way to accomplish it. Are cylinder temperatures at WOT a concern to you?

How are you going to create an AFR altered map from all your data and then code it, test it, upload it to the ECU? I am talking hardware and software ....coding language etc. Are we simply talking about manipulating the MAF signal as a means of correction?

I ask as it seems difficult to get any custom tune work done and I would like to do this for my 3.2

Sounds great let us know how it works for you

[insite]

jaykay -

cylinder temps are a concern, but only insofar as they induce knock. i will be pulling a knock signal & also checking spark to see if the car starts to pull timing. if that happens, i will richen up a little.

to make the actual fuel corrections, i'm using a piggyback computer that will modify the MAF signal. i'm then checking the actual AFR's with wideband to verify / tweak the result. i will be able to measure rough spark & fuel maps by monitoring the OBD II port and a wideband sensor. i will drive several test points to gather data at 10% TPS intervals from 30 to 100.

when i change AFR, the car will likely change spark as well. i will try to monitor that. over a certain RPM, the spark advance should be fairly constant. we shall see.

BTW, there is a product called MAF Translator that i almost bought. i couldn't verify at the time whether it would work w/ my car. i have since come to the conclusion that it would. it has the capability to run closed loop wideband setup. basically, it hooks up to your wideband & adjusts the MAF signal to achieve the desired AFR's in the map you load to it. pretty cool.

Originally Posted by jaykay

Sounds like a very methodical way to accomplish it. Are cylinder temperatures at WOT a concern to you?

How are you going to create an AFR altered map from all your data and then code it, test it, upload it to the ECU? I am talking hardware and software ....coding language etc. Are we simply talking about manipulating the MAF signal as a means of correction?

I ask as it seems difficult to get any custom tune work done and I would like to do this for my 3.2

Sounds great let us know how it works for you