TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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I have a 450 hp 383 with 500ftlb of torque carbed. I want to make it a tbi so i can put it into my 91 rs. Will the tb,injectors, fuel pump provide enough fuel to support that engine here are the specs on the engine -cam 510 lift 1:5 rocker duration is .50 240. pistons are 12cc dish. it is a 350 over 30 with 3057 stroke with a 4" stroker rods. Egde 3000 stall converter. the compression is 9:1. Please help i can provide more info if needed.
Use .5 lbs/hr/HP as a conservative baseline for BSFC.
So: 450 HP x .5 lbs/hr/HP = 225 lbs/hr
Divide by the # of injectors, and divide by the duty cycle.
225 lbs/hr /2 total = 112.5 lbs/hr per injector; divide that by .85 (85% DC) and you get about 132 lbs/hr.
If your injectors will flow that, then they'll support 450 HP.
Since the 454 injectors are designed and sized to support around 300 - 325 or so, I kind of doubt they will do it.
On the other hand, 450 HP from the specs you gave for your motor, is HIGHLY optimistic. With such super-low compression, I don't see even 1 HP per CI, much less almost 1.2 HP per CI. So with a more realistic HP guess, it may turn out that they would be enough, at a higher fuel pressure.
__________________ Numquam ponenda est pluralitas sine necessitate. — William of Ockham, from Quaestiones et decisiones in quattuor libros Sententiarum Petri Lombardi
Roughly paraphrased into modern English, and applied to figuring out what's wrong with your car:
The simplest explanation that fits all the facts is probably the right one.
Couple of Q's first.
Whats is your idle vacuum - cam overlap?
A BBC 2.0" TBI can flow around 650 CFM. There were several flavours of 454's that had 300+ hp factory rating. They also had puny cams. In your case fuel delivery system will have to be enlarged to deliver enough fuel. Stock TBI runs at 13 psi, later version of 454 TBI run at much higher fuel pressure levels (do not recall of hand). You'll have to run 90 lb injectors and up the pressure.
I believe that Fast355 had marine 454 TBI unit on his very capable 350 with outstanding results. To get high level of performance you'll have to modify ECM calibration tables. There are other things as well....
I believe 1 and 2 barrel carb and TBI are flowed at 3 inch HG and Carb at 1 inch so I understand they cannot be compared heads up. I further believe a carb at 670 CFM flow more than same size TBI unit. I am uncertain if a conversion factor can be found. I am sure something is on this site. Member KDROLT comes to mind.
idle vaccuum 10.5-11 i am not sure the over lap but here it the info i do know it is comp extreme energy hydro Basic Operating RPM Range:2,300-6,500Intake Duration at 050 inch Lift:240Exhaust Duration at 050 inch Lift:246Duration at 050 inch Lift:240 int./246 exh.Advertised Intake Duration:284Advertised Exhaust Duration:296Advertised Duration:284 int./296 exh.Intake Valve Lift with Factory Rocker Arm Ratio:0.507 in.Exhaust Valve Lift with Factory Rocker Arm Ratio:0.510 in.Valve Lift with Factory Rocker Arm Ratio:0.507 int./0.510 exh. liftLobe Separation (degrees):110Intake Valve Lash:0.000 in.Exhaust Valve Lash:0.000 in.I have 1:5 rocker but also have a pair of 1:6 if neccesary
