454 injector sizing question

**kevinvinv** · 08-25-2014

OK I have a 94 454 (TBI) with CR about 9.5:1 and a bit of a cam. Sim's say the motor will max out somewhere just over 300HP.

I have read that the stock TBI Injectors / fuel pressure are good for only about 250HP or so.

Do you guys agree?

If so- what do I do? - Raise the pressure (already at 30 PSI)… perhaps I could go back to my 5.7L injectors and run them at high pressure?

Thanks for any advice.

**dave w** · 08-25-2014

If I were going to use 5.7 liter injectors on a 454, I would use a pressure of about 22 PSI as a starting point.

dave w

**kevinvinv** · 08-25-2014

hi dave, do you agree then that something like this is going to be necessary to support 300HP (as opposed to using the stock 454 injectors at stock pressure?)

Thanks!!

**Fast355** · 08-25-2014

Originally Posted by kevinvinv

hi dave, do you agree then that something like this is going to be necessary to support 300HP (as opposed to using the stock 454 injectors at stock pressure?)

Thanks!!

I have a marine TBI unit from a 405 HP 502 and the setup was high pressure 61# injectors and 30.5 psi fuel pressure.

**dave w** · 08-25-2014

Originally Posted by kevinvinv

hi dave, do you agree then that something like this is going to be necessary to support 300HP (as opposed to using the stock 454 injectors at stock pressure?)

Thanks!!

I often see challenges when tuning the VE table with a performance 454 engine like yours. Depending on the the injectors and fuel pressure there could be trade off in the VE tuning. Usually it's a good plan to keep the upper RPM's and upper Kpa's in the VE table with values not greater than 94 yet keep the lower RPM's and lower Kpa's in the VE table with values not less than 40.

Most all performance 454's I've tuned needed more fuel, usually achieved with more fuel pressure. I agree, your performance 454 will need more fuel. Not everyone will agree on the parts combination you could / should use to achieve more fuel flow. I have a personal preference for keeping TBI fuel pressures below 30 PSI. Base on my personal experience either, 305 injectors or 350 injectors with a fuel pressure below 30 PSI will provide the necessary fuel flow your performance 454 will require. The challenge is "Trail & Error" on which combination "fuel pressure vs. injector flow" will successfully work for your performance 454.

dave w