v8killer

This is a car I use DE. Are my 55# injectors too small for 340-350rwhp @ 18lbs of boost?

Ski

If you have the right combo, you can get 350 rwhp out of 17psi. So yes, but all components have to be in good order to get your air fuel right.

gt37vgt

so 98 octane fuel 4+bar of fuel pressure and all the planets correctly positioned probably not able to happen on e 85 as its to thirsty

v8killer

This is my current combo on 93 oct. Until I go E-85 I want to make sure I am good to go with my set up. Maybe its just another way to rationalize going to E-85.

gt37vgt

well your not realy ..if you make 350 hp with the injectors near maxed out on 93oct they are likely to make only 300 on e85

beentherebaby

55 lb. injectors are just enough for 350 SAE flywheel HP @ 80% duty cycle, @ 43.5 PSI system pressure, with conventional gas in a 4 cyl. application with a .5 BSFC, which is borderline lean for a boosted app. Increasing the fuel pressure with boost will accommodate the increased flow required for a safer AFR. See the link below for easy calculation of injector sizing. For E85 you will need much larger injectors and ECU recalibration for the larger injectors.

http://www.rceng.com/technical.aspx

Ski

LR II MAF, VR race chip, 104 unleaded, 55# inj, piggyback, FP set at 36# static, made 351/344 rwhp/torque @17psi. I own the car with Jim Lankford, thus lankford on the dyno sheet.

beentherebaby

Be careful with chassis dyno data as it's rarely ever accurate due to all of the uncontrolled variables that result in bogus correction factors. Car makers use engine dynos run in accordance to SAE standards to obtain accurate, repeatable engine power data that anyone using the same test controls on a properly calibrated dyno can obtain. Chassis dynos are an exercise in frustration.

Chris White

Its also quite likely that it was running over 80% duty cycle....

beentherebaby

An 80% duty cycle is essential wide-open because of the opening and closing time required for an EFI injector. Longer duty cycle does not produce any more appreciable fuel flow. Increasing the fuel pressure via boost control will provide the necessary increased flow - up to a point based on the injectors flow characteristics and the fuel pumps flow/pressure capacity. You can change the FP in the calculator at the link to see the change in fuel flow with increased pressure.

http://www.rceng.com/technical.aspx

Ski

yeah well some of us only have access to a local dyno SAE, API or BFD by the HMFIC which is me. FYI, the duty cycle was at 74% or so the uncorrected, factors unbeknown and the ways the clouds aligned said it was on the software.

v8killer

I probably need to to step up the size of my injectors. Sounds like a good time to step up to 95lb. injectors (fuel pump and other supporting equip.) and E-85.