I'm building a 383 cid TBI motor. My engine guy has built several with the same components I'm using. These engines dyno-ed at or near 356 hp and 447 ft/lbs of trq.

I use a Holley 104 mm (52x2) 670 cfm Throttle Body, the injectors flow 65 lb/hr. @ 11.5 psi and 85 lb/hr. @ 21 psi. I intend to run at 85# on this motor. Holley's Tech says this set up will only support 300 hp. Other tuners and people in the know say from 320-411 hp.

So wtf, I'm more confused than ever, does anyone really know the formula and can you tell me how much power I can make with this TBI. If I can make more than 350 I'm gonna boost the 383 to 385-400 hp.

 

I'm running 60# injectors on a blown 370 that shud generate more than 500rwhp. Its as much a function of ur pump and total system IMO. There's a few others running 402's that have 85# injectors. Talk with MoreGrip and check his thread as its covers pretty much everything. U might also talk with Richard @ WCCH ->. Lastly, ur heads and compression are determining factors as well...good luck. R/

 

To calculate the horsepower capacity of injectors based
on their flow rating @85% Duty Cycle:
Injector flow rate x Number of injectors x 0.85 divided by .4 (BSFC) =
Fuel Support for max HP
60lb/hr x 2 x .85 / .4 = 255HP
80lb/hr x 2 x .85 / .4 = 340HP
125lb/hr x 2 x .85 / .4 = 531HP
or for a rough guess on TBI four time the single injector

airdeano

 

OK, my TBI has 2 injectors and if I raise the psi to 21 where they will flow 80-85 lb/hr. then I can safely make 340 hp without lean issues as long as I have a fuel pump and heads to support that flow, is this correct?

 

and have the adaquate hardware also to support like cam, compression and tuning.
jacking the pressure doesnt automatically make the power.

airdeano

 

Read the post at the beginning of the thread. All the mods, the added "hardware" is why I need to know the TBI ceiling on power production.

I'm adding 30 cubic inches, (1.5 liters), 115 hp and 125 ft/lbs. of trq.

I'm afraid my current TBI flowing 670 cfm and 85 lb/hr. psi may not be adequate to fuel the larger engine.