how much mainscale would be a good amount to start my tuning from when I'm upgrading from 440cc injectors to 720cc injectors
question for maftpro guys
- Thread starter djordan97
- Start date
thanks bob that is exactly what I'm loking for. now all I gotta do is get my injectors to seal properly to my fuel rail.
get the those injectors correctly on the fuel rail first!
Then if you are using an adjustable fuel pressure regulator (which you should at this point) follow this formula to see what fuel pressure to use and based on that, how much of the maincale you should reduce...:
The formula to get your new injector flow rate at a specific fuel pressure goes as follows.
Firsts:
Divide the new fuel pressure by the old Fuel pressure and then get the square root of that.
Second:
Multiply that square root (results from the first step) by the injector size that you have, and that will give you the new injector flow for that size injector at the new fuel pressure.
Here is an example:
28psi/43.5psi = 0.64367
now get the squareroot of 0.64367 which is = 0.802290
now multiply that result by the injector size
0.802290 x 720cc = 577cc
So at your new fuel pressure of 28psi the 720cc injectors are flowing at 577cc
This means that at that fuel pressure of 28psi the 577cc are flowing about 31% more than the stockers which would allow you bring the maincale some where in the area of -30%.
hope this helps.
Then if you are using an adjustable fuel pressure regulator (which you should at this point) follow this formula to see what fuel pressure to use and based on that, how much of the maincale you should reduce...:
The formula to get your new injector flow rate at a specific fuel pressure goes as follows.
Firsts:
Divide the new fuel pressure by the old Fuel pressure and then get the square root of that.
Second:
Multiply that square root (results from the first step) by the injector size that you have, and that will give you the new injector flow for that size injector at the new fuel pressure.
Here is an example:
28psi/43.5psi = 0.64367
now get the squareroot of 0.64367 which is = 0.802290
now multiply that result by the injector size
0.802290 x 720cc = 577cc
So at your new fuel pressure of 28psi the 720cc injectors are flowing at 577cc
This means that at that fuel pressure of 28psi the 577cc are flowing about 31% more than the stockers which would allow you bring the maincale some where in the area of -30%.
hope this helps.
Last edited:
very helpfull if I knew how to do that kind of math but I got my dad that can figure out the equations for me and help me figure out where to start at. that post right there should be a sticky for the maft pro guys going with BIG injectors.