ok..i got stumped on a question asked by a friend...so help me out here guys....

what's the max boost you can run with these injector setups:

injectors: my guess

1. 4x550 (12 psi)
2. 2x550, 2x680 (15 psi)
3. 2x550, 2x720 (16 psi)
4. 2x680, 2x720 (18 psi)
5. 4x680 (16 psi)
6. 4x720 (19 psi)
7. 2x550, 2x1600 (20+ psi)

thanks in advanced...

 

Boost and fuel injector size don't have a direct correlation - remember, boost is just *quanity*, but *quality* of boost is as important if not more important. A full turbo setup will make the system breathe better on the exhaust side and heat the intake charge less, requiring dramatically different fuelling.

Dale

 

What turbo will you be boosting to 20psi? Or even 18?

 

Yes, the density ratio is what matters, not the pressure ratio.

Besides the thermal efficiency of the turbocharger & intercooler, other things which will change fuel injector requirements are:
Ambient temperature and pressure
Fuel Rail Pressure
Fuel Type (unleaded pump gas, leaded pump gas, race gas, etc.)
Air/Fuel Ratio
Engine RPM
Engine Volumetric Efficiency
... and probably some other things that I can't think of right now.

Here is a worksheet that you can play with:
http://www.rceng.com/technical.htm

 

well, he's got a turbonetics to4 (i don't know what trim) with a greddy fmic and wants to know what the max boost he can run safely with 720s all around...
i'm currently running 550s in p and 680s in s and i'm running pretty safely at 12psi with stock turbo, ic and 2.5 exhaust all the way back, so i told him that with his setup he should only run about 15 or so...but again, i'm not an "expert" when it comes to boost and fuel...didn't even know that amt of fuel will change with "quality" of boost as dcfc3s stated (you learn something new everyday )...that's why i'm in here asking away...cause i don't wanna give him some "i think..." advice and have him blow something up...remember, we're friends here...