larger injector scaling
Moderators: robertisaar, dex
larger injector scaling
Hi GOT BMW E30 325 WITH TURBO AND 325CC INJECTORS AND AM LOOKING TO SCALE THEM IN.I was going to go with the constants just so I can get it to idle and not over fuel.But was wondering if it is better to lower the fuel maps to compensate for extra fuel but cold start is crazy rich.Can somebody help.
i have tuned a couple and sell a turbo chip for 315cc (30lb) injectors so i can offer sound advice here because i went through all this myself before. trying to do it via the constants is iffy at best and after a point it stops having an effect on AFR plus some other random gremlins. your best to leave the constants at stock values and drop fuelling via fuel maps instead. you will need to be able to tune cranking fuel (not sure how many XDF's have cranking fuel, but my 173 XDF does and its on the tunerpro site in downloads section, 2nd from bottom submitted in 2011).
since your injectors are nearly the same size as what i used i can give you some ballpark fueling numbers to get you started.
cranking fuel:
160rpm - 127
360rpm - 77
800rpm - 57
idle fuel:
around 43
low part throttle fuel:
starting at 49 in lowest rev/lowest load corner up to around 80 in highest rpm/highest load cell.
high part throttle fuel:
starting around 60 in lowest rev/lowest load corner.
WOT fuel:
starting around 70 working up with boost to around 105 give or take.
this was at 8psi of boost. ofcourse depending on your boost pressure, personal preference when tuning AFR's and whatnot you may find you will want to tweak it a bit but that should be enough to get you in the right ballpark.
once finished the car had no cold/hot start problems and ran a decent AFR both on and off boost.
since your injectors are nearly the same size as what i used i can give you some ballpark fueling numbers to get you started.
cranking fuel:
160rpm - 127
360rpm - 77
800rpm - 57
idle fuel:
around 43
low part throttle fuel:
starting at 49 in lowest rev/lowest load corner up to around 80 in highest rpm/highest load cell.
high part throttle fuel:
starting around 60 in lowest rev/lowest load corner.
WOT fuel:
starting around 70 working up with boost to around 105 give or take.
this was at 8psi of boost. ofcourse depending on your boost pressure, personal preference when tuning AFR's and whatnot you may find you will want to tweak it a bit but that should be enough to get you in the right ballpark.
once finished the car had no cold/hot start problems and ran a decent AFR both on and off boost.
EthosMotorsports