I have a fully forged 383 stroker with AFR 195 Heads that have been ported and polished with decent flow numbers. I have a pretty big custom grind cam and a blower with 15 lb pulley. The injectors that i have are lucas 42lb/h. The reason i'm asking is there seems to be a mystery rev limiter around 4500 RPM and the car won't accelerate past it. I have a walbro 255 lph in tank pump with procharger in line pump. If any more info is needed to offer some ideas just let me know. Thans

 

Have you logged the car to see what the duty cycle is? Or, had it on a dyno with a wideband hooked up? It's really kind of hard to say what injectors you'd need, but those should be close. Have you tried bumping the fuel pressure up?

 

I was having same problem with same injectors. we put my svo 30's back in and it corrected the problem. Did you get yours from a ebay dealer? I would advise trying a different set of injectors that you know are working..

 

I doubt they are even close to what you need. What do you estimate the flywheel HP at?

The 383 you describe should be capable of at least 500 flywheel HP without the blower. That would require at least a 35# injector. Add 15# of boost, and you need a much higher brake specific fuel consumption. Double the air pressure and you double the mass of air in the cylinders, which required twice as much fuel. You should either be running at least 65-75 #/Hr injectors at stock pressure, or have the fuel pressure jacked up to at least 58psi to allow you to run something in the 56-64#/Hr range.

Moving to "Fuel and Ignition".......

 

I haven't logged the car yet cause i can;t figure it out..lol..but that's another story. I wanted to get it running decent and get the engine broken in before i went to the dyno.

 

Some more info, I just went out and with the car idling the fuel pressure guage is at 42psi. When i unhook the vacuum line from the FPR, the guage automatically jumps to 50psi. So i figure the FPR is working the way it should. I went for a ride and had a passenger watch the fuel pressure guage so i could keep an eye on the road..lol...when i got into the car in second gear, right about the time the mystery rev limiter started to cut in he said the guage had dropped back to about 25psi...Soon as i let off a little the fuel pressure went back up to 42psi and the mystery limiter was gone. Think it is the injectors or pumps? any suggestions?

 

First, the fuel pressure shouldn't shoot up to 50 psi with the vacuum line off (should be somewhere around 43.5 psi). Second, that sounds like your pump can't keep up.

 

I was at the car last night and found one problem....the inline pump wasn't working because of a wire off the relay....so the car was idling fine and low RPM was fine but when i step on it the intank pump was trying to push through the inline pump causing a restriction and then fuel pressure drop....I fixed the wiring and the inline pump is working now along with the intank....I took it for a drive and stepped on it and the car went to 5500 with out a mystery rev limiter..but its running lean at about 3/4 throttle and the fuel pressure only drops to about 38-40 PSI..any ideas, maybe o2 sensors or maybe i should change the fuel filter again?

 

there is alot smaller mystery limiter at 5500-6000 now but fine right up to 5500.