After 3 hours of using the vaunted search function, I have come to the conclusion that asking a new question may be warranted. In my upcoming intake upgrade, I was told something that calls my fuel injector selection into question. I was told that running an injector that is too big will produce overheating of the injectors at PT. I trust the source of the information (you would too) but now I wonder, are 30lb injectors too much?

The changes will be the usual; Edel manifold, ASM runners, port matching, AFPR set to 48psi, 52 mm TB (air box already an open element) and initially 30 lb injectors. I have tried to find an explination of BSFC but I cannot seem to figure it out. I have a reman 355 w/ the features in my sig. It was tested w/ an Edelbrock Performer Intake and 750 carb. and produced an approxamate 350HP and 385TQ.

First question is: .40, .45, .50 what BSFC estimate would be accurate for this engine?

Secons question is: (I found no real specific answer through my search) with my mods or in general, how far can my TPI rig go as far as HP number?

Overall I would have no idea how much HP my engine CAN produce. Initially I was thinking my rig could crank out 385-400 HP. Don't laugh, it was a guestimate. Any idea what I could REALISTICALLY expect to produce with my mods? Lastly, I will try and calculate my injector needs if someone can inform me about BSFC..that said if anyone has any suggestions I'd appreciate it. I am currently thinking that 28lb injectors may work correctly.

Thanks to all who reply, and I cannot wait to start on this project.
Eric

 

The 30 LB injectors will work fine, they will not overheat, you will need a custom prom to use those injectors.

The BSFC means that for every HP your engine makes at WOT it will use .5 LBS of fuel per hour if your BSFC is .5. The .5 BSFC number is a typical estimate, it may be .45 it may be .55 so use .5 for your caculations.

In your case if the engine makes 350HP the LBS of fuel per hour at .5 BSFC will be 175LBS. Take the 175/8 = 21.875/.8 injector duty cycle = 27.34 injector size needed (The 30 LB injectors will be fine). These are rough numbers, I am sure the engine would run fine on injectors sizes from 24 LBs to 36 lbs per hour by tuning the chip correctly.

I am currently running my Firebird with more then 400 HP on 24LB injectors and my drag racing partner is running his 350 HP corvette with 36 LB injectors.

If the current engine you have made 350 HP with a carb I would guess you are going to loss 25 HP with the TPI set-up but pivk up some torque.

 

Thank you bj....