SC'd Fuel Systems (650rwhp+)
 

I have 60lbs injectors, 255 intake fuel pump and everything else is stock in the fuel system. It was running fine when i was making 550rwhp, but today after increasing the boost from 7.5-8psi to 11-12psi we couldnt even get it past 4500RPM because it goes from low 12's AF to 18's in a matter of 100 RPM's. We know that the MAF is maxed out and we dumped as much fuel as we can, but still no change. The injectors Duty Cycle was 75% before with 550rwhp around 6700RPM seeing 60-62psi, but now its 96% at 4400RPM with a pressure drop of 3-5psi bouncing to 60 and going down again. It was almost impossible to tune the car with this fuel system on the dyno today. I know for sure that the 60lbs injectors should be enough for 650-700rwhp SuperCharged setup so what could be the problem? Fuel Rails or not enough pump or just small stock fuel lines?

My question is.... What should i change to improve my fuel setup while retaining the stock plastic tank and if possible have a return system with a boost refrenced regulator to make life easier on the dyno?

Get some new fuel rails and a BAP (MSD or KB). And a boost reference regulator would be a great upgrade.

BAP? U think thats enough for my problems? How about the fuel lines coming from the tank to the front or the Fuel pump?

Well your best bet would be to go with a dual intank setup. And just use the discharge you have now for a return line. A BAP might get yout there. :D

i would start with the regulator and go from there.
if that doesnt cut it then a dual pump setup or a BAP
really dont think you need the lines or rails unless you actually do surpass the 650 mark

I figured since he said 650 + he would need them :)

What is BAP? Do u mean Boost-A-Pump the one from MSD IIRC?
Well the car made 555rwhp with 7.5-8psi around 6400RPM. Now its seeing 7psi around 4500RPM and already saw 480rwhp with 12 degrees when we did shut down instead of 19 degrees before. So im thinking its going to see over 600rwhp if not close to 650rwhp around 6400RPM and maybe 11-12psi. If the stock bottom end go boom im going forged so most likely im going to need a good fuel setup now so i can use it later with 15-16psi.
So two intank Walboro 255's, Boost refrenced regulator, return line, and still keep the stock fuel rails?
What could cause the fuel pressure to bounce up and down like that?

I'm running over 650RWHP with the stock fuel rails... You need 2 pumps .. That's basicly it..

Good luck.

Clint

off topic question, what are the specs on that cam and how does it idle etc?

Its 224/230 .578 .593 114LSA. It idles like a TR224 114LSA which is not bad at all. I used to drive the car everyday for almost a year before i got me a daily driver and going all out with this car. Search for FM7 and u will find bunch of info about this cam. I have wrote a review for this cam million times lol.

Do i need a return line to run BAP or a boost refrenced FPR with the extra intank pump?

After researching i found out that the BAP cant support two intank fuel pumps. So is it better to use two 255 intank pumps instead of one 255 intank pump and BAP?

A single 255 and a MSD BAP wasnt enough for me, had to move the regulator up front and its enough with 57lb injectors for now after moving the regulator. I will eventually do a dual 255 in the tank.

The BAP doesnt need a return line, moving the regulator up front does. Boost referencing on this single pump does no good for me, 57-58psi is all it will do at WOT even with the 1:1 hooked up.

So you are saying i should get another 255 intank pump with boost refrenced Regulator in the front and a return line? How can i do a return line with the stock plastic tank i have? Also what size fuel lines should i use (8 or 10 to engine and 6 return)?
Sorry for all these questions, but I have little experince with fuel systems so i really need the help here :)
I want to finish the fuel system so i can break 650rwhp :devil: if the motor last ofcourse lol.

VERY nice... I wonder if it would work on a C5???

Ive had some problems with that CAS regulator. Im leanign towards a) a hotwire kit and boost a pump or b) the regulator all the way in the back of the tank may have something to do with the surge

at 4800-5000 rpm on the nose it goes off the chart lean. injector pulsewidth raised from 18 ms to 23 ms on the 60s and while it did go PIG rich before then, soon as 4800 came it went off the charts lean again

Feher, think about going to a 2 bar setup at all?

Look in my Sig.. I did a setup of Dual In tank for 99 and newer plastic fuel tanks..

Clint

I think adding another intank pump would be the easiest and cheapest solution for me. Im thinking to do a boost refrenced FPR, Speed inc rails, Fuel Filter, -8 feed and -6 return while im at it. This should be enough to feed my car fuel later on when i go forged and 16-18psi, right?

I never saw anyone running a 2-3 bar tune just yet. I would like to see a car running a 2-3 bar tune before i go with one.

I made 649 rwhp so I'm about as close as you can get to the mark. But I've got 72 lb hr injectors and a 2000 hp billet series aeromotive fuel pump. I know its a bit much for now but I have bigger plans for the future and it still works great for me now.