Fuel system design

[Pyrotechnic]

I did a search for this info and I found this link here: http://www.centuryperformance.com/fu...e-spg-140.html

I have a 450-500HP 383 being fed by a Holley 750 DP.

My fuel system right now (temporary just to get me down the road):
Holley Blue pump hooked to stock sending unit pickup tube, feeding the stock steel fuel line to the engine. The regulator is a Holley 12-803 deadhead style.

Based on the info on that page with those stock steel lines, my fuel system at this point is only good for 250HP ?

Future fuel system:
Holley 12-803BP return style regulator
-8AN supply and return line
This filter after the pump:
http://www.summitracing.com/parts/PFS-10100/
This filter before the pump:
http://www.summitracing.com/parts/PFS-10214/
I'm going to weld a sump to the stock tank and that will feed the pump.

Based on that info, this setup should be good for 700HP and it should make that pump last a lot longer because of the return line.

Is this the route I need to take or is this overkill ? I'm asking because this is going to be a pretty expensive project to complete.

The biggest cost is going to be running the -8AN line for the supply and return. I have a square body and I chose to make the drivers side tank the primary tank. If I run the lines on the passenger side like factory, they have to cross over between frame rails. If I run the lines on the drivers side, those lines end up shorter but the supply line from the regulator to the carb will have to be slightly longer since the carb is passenger side inlet. I am leaning towards doing the lines on the drivers side. What do you all think ?

[djracer]

What are you gonna do with the truck?

[Pyrotechnic]

The truck serves two purposes. It's my daily driver and only vehicle, but it will also see some track time.

[Marv D]

One, you are mistaken on the an-8 line being the expensive part,, those damn fittings!!! Hose is cheap compared to all the fittings and nipples you need. Especially with 2 filters, return,,, sit down when you total up that shopping list.

Sam is always overkill on his tech articles. I don't mean that in a bad way. Sam and I go way back and one thing I can assure you.... If you follow the tech recommendations over at Century,, you will NOT have ANY issues with delivery or reliability. 'OVERKILL' it may be, but when your talking fuel delivery,, 'marginal' will get you in BIG trouble in a hurry.

And as a BTW, with Mallory just down the road from his shop he could walk and talk anything in the Mallory line. He still knows it well, but appears to be shying away from the Mallory line. (as are a lot of people) Still the best Mallory tech help EVER IMO. And GOOD people to boot!

I have ran a 580HP smalblock on an-6 line (about 5/16")with a deadhead regulator and Malloy 140 pump. It didn't burn holes in the pistons. Never displayed any indication of going lean on the top end,, nothing. So the only question is do you want to pay now or pay later??? That faster faster faster thing will always jump up and bite us in the butt,, and have us building 'just a little quicker' and test the limits of every system we put on these things.

just my 2¢

[djracer]

I'm with Marv if you aren't going Fuel injected in the future or all out race I would just put a 16 gallon cell with sender and a nice filter/pump in the rear with a dead head regulator up front you should be fine.

I had a dual pump setup on my truck with a return line on the motor side and a dead head on the nitrous pump. I am switching to a magnafuel pump/filter with a return from the pump only. I will have a log up front with dual dead head regulators. I'm looking to lose some plumbing and weight.

[djracer]

I'm with Marv if you aren't going Fuel injected in the future or all out race I would just put a 16 gallon cell with sender and a nice filter/pump in the rear with a dead head regulator up front you should be fine.

I had a dual pump setup on my truck with a return line on the motor side and a dead head on the nitrous pump. I am switching to a magnafuel pump/filter with a return from the pump only. I will have a log up front with dual dead head regulators. I'm looking to lose some plumbing and weight.

[Pyrotechnic]

OK you guys are right. 20 feet of -8AN is $99, but the 90 degree fittings are $16 each

The reason I wanted a return style system was because this truck does 4 hour at a time highway trips. If I never ran the truck more than 30 min at a time, I wouldn't worry about it, but deadheading 14 PSI down to 7 PSI for hours at a time can't be good for the life of the pump. More for reliability than anything else.

[djracer]

I think you would be fine but its your money.

[Pyrotechnic]

I just did a rough add up on Summit. I'm looking at a good $350 just in the lines, fittings, and filters. Don't have that kind of money to spend right now.

I know for sure I'm going to sump the tank, and I know I'm going to run a return style system. I have most of the stuff to do the sump already just need to fab it and have it welded, and the return style regular wont hurt the wallet too much. I figure after I do these mods the only thing that's gonna hold the system back is line diameter. I don't have to worry about the stock pickup tube coming uncovered.

I'm considering doing a free flow test (see how long it takes to pump a gallon into a bucket) with the lines and filters I have, just to get an idea of where I'm at. It would at least give me some solid data as to how I need, or don't need to spend my money.

You guys are right though, from your own examples and others I've heard you it's clear you don't have to be super extravagant with the fuel system to go fast reliably.

[Pyrotechnic]

http://forums.corvetteforum.com/c4-f...line-size.html

I found that post and it's a bit different than the overkill method I first read. He uses math and science to back up the way he sizes fuel lines. Basically states that as long as the lines are big enough to maintain fuel pressure at full throttle with the given fuel pump, then the volume is adequate.

I have a extra factory steel fuel line off another truck that I can mount next to the one that's already on there to be the return line, and the new return regulator will bolt in place of the existing deadhead regulator. From there I can set the new regulator to 7 PSI, turn the pump on, and time how long it takes to pump a gallon into a bucket.

If that setup proves to flow enough, a cheaper route I thought of would be to buy some lengths of stainless steel tubing from a industrial/hydraulic supply place and use them along the frame. The only downside is there would be short sections of rubber line between the tank and metal line, and between the regulator and metal line, though this is not any worse than the way it came from the factory. Would this still pass NHRA tech ?

[team39763]

I believe NHRA says you can only use 12" of rubber hose in your fuel system.

I have a question too. Is using a deadhead regulator better than using a return style when running small lines like 3/8"?

[KQQL IT]

I bought the summit 250$ or so kit all in 1 kit pump, filter fittings and -6 line dead head reg. it'll run 12.2xx and 50 miles each way to the track?

[shortbed70]

I have some areoquipt -8 line about 20' I was going to use as feed line because I have it and most of the fittings but am thinking of selling and going with something different but all the race cars Ive worked on mods latemodels and stockcars all used -8 for 355's-421's pushing well over 500 hp and no problems with fuel being too much. The carbs will only use what they need regardless of line size so go bigger rather than smaller.

[shortbed70]

BTW if you havent purchased yet go -6 for street app because its smaller than -8 and cheaper including fittings.

[Pyrotechnic]

I just got done doing the flow test and the results are good.

This is with the Holley blue pump, drawing fuel through the stock pickup tube, through a mesh screen filter, pumping the fuel through the stock fuel line, and then through a paper filter. This was a simple free flow test to see just how much of a restriction the stock fuel system and my filters were.

I had a bucket marked off at a gallon, and my dad watching it with a stop watch. When the fuel hit the bucket, the clock was started, and it was stopped when the level reached 1 gallon.

It took 37 seconds to fill the bucket. All the math aside, that come out to 97 GPH. Holley rates that pump at 110 GPH free flow, so the fuel system is a restriction to a small degree, but this pump has the power to maintain flow rate through it.

Of course this is free flow, but even at 7 PSI the pump is capable of 95 GPH. Adding the restriction of the system will lower that slightly, but even then that's enough flow for a very powerful motor. I'll also be adding the sump to the tank which will gravity feed the pump, and the new lines won't have any funky bends.

Knowing this real world data, I am going to use 3/8 stainless steel tubing along the frame.

[raveer2000]

My plan is (2) -8 that Y into a -10 line. Flow through a -10 log filter and into an aeromotive pump. From there it is -10 all the way up to the next TEE fitting into a barry grant regulator and -6 out to 2 edelbrock 500 carbs. At the for mentioned TEE it will run into a small inline regulator and then it-8 all the way back to the return. 2 regulators is overkill I know but I can't stand the thought of dead heading this pump I have. Total price right at about $700 not including the pump. That was for all the fitting, lines, filter, and second small regulator. Believe it or not EBAY had some great deals on fittings.

[Tech @ BG]

Originally Posted by raveer2000

My plan is (2) -8 that Y into a -10 line. Flow through a -10 log filter and into an aeromotive pump. From there it is -10 all the way up to the next TEE fitting into a barry grant regulator and -6 out to 2 edelbrock 500 carbs. At the for mentioned TEE it will run into a small inline regulator and then it-8 all the way back to the return. 2 regulators is overkill I know but I can't stand the thought of dead heading this pump I have. Total price right at about $700 not including the pump. That was for all the fitting, lines, filter, and second small regulator. Believe it or not EBAY had some great deals on fittings.

You may want to change the 2 -8's into the 10 and pull one of the existing 8's out and replace it with the correct size. I'm not sure what aero recommend for their pump but on ours we run 1 size larger to the pump then what is going forward so the pump does not cavitate.

The other issue with the 2 -8's is with a high volume pump there is the chance for it to run one of the 8's dry and cavitate the pump or even lean the engine out.

[raveer2000]

Originally Posted by Tech @ BG

You may want to change the 2 -8's into the 10 and pull one of the existing 8's out and replace it with the correct size. I'm not sure what aero recommend for their pump but on ours we run 1 size larger to the pump then what is going forward so the pump does not cavitate.

The other issue with the 2 -8's is with a high volume pump there is the chance for it to run one of the 8's dry and cavitate the pump or even lean the engine out.

I was afraid of messing with the new fuel cell cause it has foam and all that in it. The fuel cell is sumped so it shouldn't ever run dry and its 20 gallon. If I'm wrong let me know, I would rather make adjustments now then after I tear up something.

[Tech @ BG]

Originally Posted by raveer2000

I was afraid of messing with the new fuel cell cause it has foam and all that in it. The fuel cell is sumped so it shouldn't ever run dry and its 20 gallon. If I'm wrong let me know, I would rather make adjustments now then after I tear up something.

Would still change the fitting on it. You can take the foam out while you work on it. As mentioned when trying to run 2 smaller lines into a bigger one like that the restriction is still the smaller line and it does not give you more volume contrary to what you would think.

[hotrod 80]

Kinda crummy picture , but i sumped the tank in the Luv and went with aluminum tubing and compression type fittings to 2 old style fram can style filters to 2 Holley blue pumps to 2 Holley cheapy regulators . i used the factory steel line as the return back to the tank . The trick to get the cheap Holley ones not to creep is to restrict the returns with a carb jet . That's right , come off the return line with a brass fitting , tap the fitting to fit the smallest carb jet you got , take the jet and heat it with a propane torch and fill it with solder , take a small .015 index bit and drill through the solder . Now the regulator is not dead headed and won't creep , but you have no pressure loss from the return . i had the nitrous guy use his big 1-8 # gauge and flow everything . Never had a problem . Sprayed 250 this way . I have been told that a single blue pump is good for 500hp , N/A or N/A + N2O .

[Pyrotechnic]

Good info ! I installed the Holley bypass regulator and return line on my truck last week. What's the issue with pressure creeping and under what conditions does it happen ?

I've noticed that my fuel pressure is more consistent than with the deadhead regulator.

[hotrod 80]

When you dead head the cheapie regulators that come with the pumps they creep up high . So if you use one on a Nitrous kit the shot starts out fat .
This is the kit i used X 2

the 12-803 with a very small orfice back to the tank will be steady as a rock and you won't be able to drop pressure as it will almost be deadheaded ,

[Pyrotechnic]

Originally Posted by hotrod 80

When you dead head the cheapie regulators that come with the pumps they creep up high . So if you use one on a Nitrous kit the shot starts out fat .
This is the kit i used X 2

the 12-803 with a very small orfice back to the tank will be steady as a rock and you won't be able to drop pressure as it will almost be deadheaded ,

That's a pretty good idea to make those deadhead regulators work better.

[raveer2000]

Originally Posted by Tech @ BG

Would still change the fitting on it. You can take the foam out while you work on it. As mentioned when trying to run 2 smaller lines into a bigger one like that the restriction is still the smaller line and it does not give you more volume contrary to what you would think.

Well I looked closely at the fuel cell. It is not a plastic cell It is a RCI aluminum and the fitting are welded into the tank, so I cannot change it to a -10. Looks like I am stuck with 2 -8s