mjw

iTrader: (1)

Just curious where you guys with experience begin in adjusting your fuel maps after going with a larger turbo. For example, I've gone from a TO4E to a TO4S..
seeing that the TO4E flows 53lbs/min. max and the TO4S is at 60 - 61lbs/min max. I'm looking at about a 15% increase in airflow, this seems to hold true when comparing dynos as well.

I thought that I would spread that 15% increase out between 0psi/low rpm (where spool would start) and about 15psi/5500 rpm (peak torque), does this seem to make safe tuning sense? Adding 15% across the entire boost map seems heavy handed and overkill.

Thanks for any help.

mwatson184

You shouldn't need to adjust even close to 15%. The flow of the turbo is limited by the RPM/port style of the motor. The turbo may be capable of flowing more, but it won't do so unless the boost, RPM, or VE is increased. The different efficiency at a given boost level may cause a slight difference in the amount of total airflow, thus needing some sort of fuel adjustment. Increasing the fuel across the board is a good safe way to start, then lean out until the desired AFR is reached.

-Marques