Sprayed92

Decided to dyno the car last weekend. Any way here's a quick run down

383 12.8/1 compression
profiler 210cc heads 64cc 2.08/1.60 valves
hyd roller 248/256 584/584 110lsa cam with 1.6 pro mags
hsr 58mm tb
55lb injectors
255 walbro intank pump
eagle 4340 crank
eagle 6in hbeams
700r4 3200 stall
9inch 3.89s

only able to pull the motor to 5600 since fuel pressure was dropping like a rock it still ended up making 385/360 once i get a fuel system in the car should make 410 ish with ease id think but we"ll see

Orr89RocZ

iTrader: (20)

Well it aint bad for 5600. Cam will go to 6600+. there could be 50 more hp there. Why is pressure dropping? Figure that out and spin it up you will see numbers

Sprayed92

Yeah i guess its not bad for 5600 but its just plain out of fuel pump gonna weld a bung in the tank put a holley pump at the tank run some an line and should solve this issue and retune it.Then see what happens, i was thinking there was atleast 40hp left on the table but we'll see.What you do for the fuel system on your car....

abray1

If you have a stealth ram it will be the stock regulator. Did mine at Ed Wrights a few years ago and I have a gauge installed on my fuel rail block and my pressure was dropping from 46 to around 30 at WOT. The car still made 401RWHP and over 500RWT. I got a Kirban installed now but need to get the chip re-done. It is drowned in gas now. Ed and I thought it was the factory pump not cutting it so I installed a walbro but it didn't help anything. Later I learned the factory regulator was junk so got a Kirban but haven't messed with it since.

Sprayed92

Car has a kirban regulator on it sorry didn't mention it

Orr89RocZ

iTrader: (20)

Stock walbro type 255 lph pump will feed 600hp with high voltage line from alternator feeding it so it sees 13-14 volts at all times. You should not run out of fuel with that assuming 43 or so psi base pressure and injectors sized right for the application. Mine made 400whp on a single pump and wire kit from racetronix. I've seen a few other cars make some good numbers on 255 pumps. twin pumps are generally good to near if not at 1000whp

TTOP350

iTrader: (8)

Where did you dyno the car at???? A loong time ago i used to work in Edwardsville..

Sprayed92

Yeah it's weird my old 355 on a 100 shot made almost 440 on a 255 walbro which I did replace and put a new walbro back in it. Tony I dynoed the car at Redline. my buddy that built the motor and has always tuned it said it needed more fuel than a lone 255 could handle since I plan on spraying it too

TTOP350

iTrader: (8)

Redline, nice, I haven't been there but hear its a good place.
What happened to Tim ?? He still there or?? Who does your tunning?

Sprayed92

Not sure what happened to Tim but my buddy Steve does all of Redlines tuning now for Tpi,Lt1 and Ls stuff

cuisinartvette

Sometimes a higher stall will eat up some rwhp #s on a dyno.
Get it tuned good as you can then see what your time slip says

Dynos can be humbling sometimes yet the car can still run hard at the track.

Putting mine on the rollers next week for some baseline #s

hard not to get your hopes up. lol

Sprayed92

Yeah it's not the dyno numbers so much that had me upset now do I think it should have made more power absolutely but the key factor is its not making the power it should because it's not getting all the fuel it needs. So if I took it to the track and leaned it out on the big end and hurt the motor then that doesn't accomplish anything either so I'll just wait until I solve the fueling issue then run it at the track, just saying but yeah I get your point a dyno is just a tool

1gary

See this post??. Want to solve your fueling problem??. Listen to what he is telling you. He knows what he is taking about.

Sprayed92

The issue is the size of the fuel line not being large enough and the pump not being able to push all the fuel thru a 5/16 fuel line

gcpoland

iTrader: (18)

Minimum you need -6 feed and -8 return with a -8 crossover feed. Also buy a high quality regulator (I use Aeromotive) on the return side of the fuel rail.

Orr89RocZ

iTrader: (20)

Stock hardline should be 3/8 i believe and 5/16 return. 3/8 is same as -6 an. It should be plenty. Lsx guys on stock 3/8 line make 450+ with single walbros and they run 58 psi pressure! More pressure has less hp potential as pump flow drops but still a single pump should turn 500 whp at our pressures

gcpoland

iTrader: (18)

Just relaying real life info. -6 is not stock feed from tank (3/8) also -8 is needed on return for regulator to run right. Pressure is different than flow.

Orr89RocZ

iTrader: (20)

-6 is 6/16" which is 3/8. Stock line is very close to that. I am also stating from real life experience. -6 return on my car with no issues. Had no fuel pressure issues that i noticed with stock 5/16 hardline at 400whp on my 383. Even ran a wet 150 shot kit on top of that on single pump but thats different. Turbo car has 2 pumps but only 1 is on til ~5 psi. Its close to 450-500whp id guess on 5 psi and its not having any difficulty in fueling. I havent monitored pressure to see but have no reason to at this time. It has good air fuel ratio and responds to ve table changes so i have adequate supply.

Now when my second pump kicks on i get a rich condition and have to really lean out my ve table and pe table. This leads me to believe the pressure is spiking since i dont need the fuel for only 5-6 psi boost and the return is smaller at -6. But once i get over the limit of a single pump around 8 psi things should be working well.

I rarely see return sizes bigger than supply. That doesnt seem to make sense.

Street Lethal

iTrader: (16)

Although you mentioned it was new, it might very well be the pump itself, just crapping out on you at higher RPM's. I went through so many Walbro's awhile back, then I just decided on the deatschwerks pump. Like Orr said, your fuel lines should be fine...

Orr89RocZ

iTrader: (20)

Nothing wrong with going bigger line if you feel its restricting. Imo and experience its not the issue and larger lines are lot more money. Good point about the pump being bad that could happen. Bunch of guys reported problems with pumps losing pressure after gettin hot. Could be an issue. Once fuel pressure is resumed and you pull another 1000 rpm i dont think you will be dissappointed....