I've posted this topic before but as spring gets closer to being here I want to make sure I'm driving this spring and not tuning all spring/summer. I brought my car into the dyno before winter and was let down on my results with what my motor has. My engine was professionally built by an engine shop for my procharger 600b. As well as getting a new carb hat and sending the carb to CSU for a new build. Bringing it to the dyno it didnt even make 300 RWHP. From there reading the car was running extremely on the lean side and I am very confused by this. I have upgraded my fuel pump and regulator. But I have not upgraded fuel line size because I was told that I would have to drop the fuel tank. I'm getting a steady fuel pressure with no drop during boost. According to there a/f during WOT the mixture leaned out but talking to others they said that at that a/f mixture it should have blown the carb off. Without taking the engine out and starting from scratch can anyone help me out? I'm frustrated because I was told the car should make 650-700 RWHP with my combo no problem. Especially since I'll be adding a 100 shot of N02 wet kit this summer I want to make sure I'm covering all angles.

 

what fuel pump and fuel pressure regulator are you using?

what size carburetor are you using?

what was done to the carburetor when you had it sent out?

what size fuel lines are you running for the main line and return line?

how many lbs of boost are you running?

what was the a/f reading when you had it dynoed?

 

what fuel pump and fuel pressure regulator are you using?

Race Pumps FPR with boost reference and Pump


what size carburetor are you using?

Holley 4150

what was done to the carburetor when you had it sent out?

Full Blow through build cost me around $600 by sending my carb

what size fuel lines are you running for the main line and return line?

-8 lines to the regulator

how many lbs of boost are you running?

About 9-10lbs on standard pulley

what was the a/f reading when you had it dynoed?

The #'s ran over a/f 17-18

 

the size of the carb not the series....

also need more info on the pump like max psi, whats the gallons per hour

no return line from the regulator to the tank?

boost reference regulator
?????

 

that a/f reading is kinda high.....should be in the 10-11.0 range at wot and 13.5-15.0 at idle.........whats your cruising a/f ratio as well


your definitely running lean.sounds like a fuel delivery issue

one other thing is whats your timing set to?

 

Timing is locked out at 36 degrees. But my fuel gauge reads a steady fuel pressure during the run

 

what fuel pressure are you running ? is your fuel pressure regulater one that rises with boost ?

 

what fuel pressure are you running ? is your fuel pressure regulater one that rises with boost ?


Fuel pressure at idle is around 4-5 lbs. My regulator pressure rises under wot

 

your not answering my question about the specifications on the pump and the fuel pressure regulator.

and what type of fuel pressure regulator your running

boost referenced or not???

return style as well???

whats the fuel pressure at ?

how are we supposed to help if you cant answer the questions??????

 

You asked me in the first post what pump and regulator I am running. It's Race pumps FPR with boost reference. Yes it has a return line running to the fuel pump. return line is -8 Fuel pressure maxes out 2-3 lbs per 1 lbs of boost. So at 9-10 lbs max boost fuel pressure is 17lbs

 

yesh i was wondering wht the gallons per hours was of your fuel pump.

what jets did thay use.....als what size squirters did they use.

50cc accelerator pumps on both carb bowls?


you def have a fuel issue..... you may have the psi but what about the volume output of the fuel pump?

what size carburetor as well? im assuming 650?

is it this style pump http://www.racepumps.com/Fuel%20Pumps.html

 

I forgot the volume per hour on the pump but this pump is more than I'll ever need I think it's in the ballpark of 150lbs per hour, jets were 68 front and 76 rears but I'm going to up the jets. Not sure what accelerator pumps will have to ask Kevin. Carb is a holly 650, moving the jets to 76 second and 88 mains

 

ok get the specifications on the carb.......whats your a/f ratio at idle and cruise? 150 gph is def not enough to feed that...your going to have to change to an electric fuel pump......something like a aeromotive a1000 which is capable to handle up to 1000 hp forced induction

 

The fuel pump that I have is more than plenty believe me did a lot of research the pump Im using has a max flow of 450lbs per hour. This is a modified efi pump for blowthrough apps up to 2500hp. Don't know the cruising a/f I dont have a gauge for that yet

 

get yourself a nice wideband air/fuel ratio guage......aRE YOU USING THE STOCK LINE FROM THE TANK TO THE FUEL PUMP????? oops sorry about the caps

 

i was runnina a modified 700 holley draw thru supercharger carb with no issuse with my turbo setup pushing 14 psi of boost anything more it would drain the fuel bowls and then i would notice a drop in fuel pressure.............im upping to a C&S 800 blow thru and a a100 pump with a new regulator so i can go to 20 psi of boost with no fuel delivery issues

 

Yeah it's the stock line, I didnt have the $6.00 a foot for -10 line right off

 

To run new fuel lines on the 3rd gen I was told I would have to drop my fuel tank, I'm thinking about installing a fuel cell

 

thats another issue.stock line = nono you need to run a -8an line right from the tank to the fuel pump also id recommend not using the stock return line either that will also have to be -8an.

you should consider -10an for the main line from the tank to the pump though. your starving your carb of fuel.sure you may see the psi being all good an dandy but there again.not enough volume.......... i see this with efi vehicles all the time at work(GM automotive technician) plenty of pressure.no volume

 

He recommends -10 line for main fuel and -4 for return/bleed. That might explain a lot of time when my fuel bowls empty out during some driving situations, I've had to pull the hat off countless times and squirt gas back in the carb to fill the bowls. Don't they call that vapor lock?

http://racepumps.com/New%20Plumbing/Plumbing%20122.swf

 

ok most of us run -8an for the return but if he suggests -4an which i think is a lil small might want to run -6an at least......definitely change the main feed line.........your hurting yourself there by runnin the stock line.

 

The fuel line size is not the problem, at least not now. A stock 3/8" line is good for ~600hp and he's not even getting half of that. I would look at the other components. A wideband O2 gauge would definitely be my first purchase.

 

well he said he was going lean on the dyno which would lead me to beleive he has a fuel volume issue

 

Yeah stock fuel lines, defiantly lean according to the dyno but and I say But everyone I've talked to said at those lean numbers I would have had blown the carb off or had massive problems. I'm going to a. rejet the carb and see what that does. Did I mention I can't even spin the tires at take off?

 

i blew a motor at 13.9 a/f running on a crazy tune .i would think 17-18 would of blown that motor . get you a aem wideband .i think theres the most accurate plus yoou get 6 different faces to choose from . . ideal a/f at wot depends on your timing an knock . where are you running your timing at? how are you controlling it under boost ?

 

I have a D1SC on my 383.

My fuel system is:
Stock tank with a -10AN bung welded into the lowest point on the rear of the tank, -10AN from the tank to the A1000 pump, -10AN to my Aeromotive boost referenced regulator, dual -8AN to my Carb Shop 750, and then a -8AN return to a -8AN bung welded to the top corner on the drivers side of my tank. All of my hose is pushlock style.

I did some A/F runs on the street last week for the first time. I have my idle f/p at 8psi. At full throttle my boost was 7 lbs and my A/F reading was 10.1-10.5 all the way up to to 6300 RPM's, which i know is rich.

My fuel pressure increases just fine as the boost comes on. I changed my secondary jets down to 83's, it did have 85's

I'm not sure where you got the 600HP number from, i didnt think a 600P could support 600HP.