I am selecting the fuel pressure regualtor for my EFI motor that will make 1200HP. I have access to some local EZ street caliber race car builders and their input has been contrary to what most "internet racers" would suggest. That being:

1) From the gas tank to the engine bay can be -8AN, and I can have parallel -6AN fuel lines into each fuel rail that meet back up at the regulator and make 1200HP.

2) I can have a single -8AN line and run the fuel rails in series and well exceed that 1200HP.


Doug,
What say you? Why do people always error on the high side? Perhaps for the same reason people build 7000RPM rectangle head big blocks for cruise ins and car shows?

Do the smaller lines cause more heat to build? I do have a motor controller for the pump.

I need some line sizes before I can purchase a fuel pressure regulator.

I can't see doing everything you're doing and NOT going to -8. But if you're pushing the fuel through the hose I don't know that it matters the same as pulling, except your pump may work harder.

By the way, love watching what you're doing - wish you posted more in a progress-type thread.

Not sure what is contrary as most EFI racers say what you have posted. Carb systems run larger due to lower pressure. I never see anything over an 8 on way more than 1200 HP. Unless you are running methanol and high HP.

I would run larger on the feed to the pump would be the only place for larger. Otherwise 8 feed is fine. 8 or 6 after the Y. 8 or 10 for the feed to pump.

The key is a properly sized pump. If the pump is to small, line size doesn't matter. Don't want any 90 degree or restrictive fittings (swept 90 is fine). And want gravity feed to pump. Use a regulator designed for the pump. Don't mix and match to be sure.

And as far as the return, personally I'd run the same return as feed. I run an 8 feed and 6 return on mine, wtih two 255 LPH pumps. Turn the second one on spray.

You don't want much pressure building up in the return. 8 feed and 6 return usually is fine like I run, but run the same and you will be fine for sure.

Thanks doug! sorry for falling alseep over here. been in the garage grinding away...

this is my idea so far:

-10AN from tank to filter to pump.
-8AN up the frame rail to the engine.
Y out to two -6AN lines.
6AN line in to the fuel rail, but with a -6AN to -8AN coupler at the rail. *(see note)
Out of the fuel rail with a similiar -8AN to -6AN coupler
-6AN lines to the fuel pressure regulator This Trick flow / aeromotive part (http://www.summitracing.com/parts/TFS-5158REG1/)
-6AN to -8AN step up on the return.
-8AN return back down the frame rail to the tank.

*The note is my concern because I have -8AN fuel rails, so is it just extra work to step down to a -6AN before the rails? But it's equally frustrating to just Y out from one -8 to two -8s.

The largest teflon lined hose I can get is -8AN, so that's what will run up the frame rail. Is it sensless to run a Y that is "-8AN in and two -8AN out", and then just run -8AN into the fuel rails and save myself the size stepping??

Any input is appreciated. I had some folks telling me -10AN up the frame rail and Y to two 8s and don't even think about -6AN at the FPR. One local guy making around 2000 HP said I would be fine with -8AN in series at the rails! Aeromotive tech support said I would be stupid not to do the rails in parallel.

My pump right now is a Weldon piece, but I really really want to use the new Aeromotive A1000 in tank kit and put it on my factor tank. Either way, both big honkin' pumps!

Here is an article about fuel line sizing. Don't know if it is helpful or not.

http://www.centuryperformance.com/fuelish-tendencies-understanding-fuel-pressure-and-volume-spg-140.html

I would also run a hardline down the length of the chassis. When I got my replacement fuel lines I asked them to make it in 1/2" stainless. It came pre-bent and fit well. I think I got it from Fine Lines, but it may be another place. It's been over 10 years since I put all that together.

Andrew

I can't see doing everything you're doing and NOT going to -8. But if you're pushing the fuel through the hose I don't know that it matters the same as pulling, except your pump may work harder.

By the way, love watching what you're doing - wish you posted more in a progress-type thread.

LOL - Ok, so I MEANT -10. You probably knew that... :D

There are late model guys running 1000+hp on stock 3/8" hard lines with 5/16" return.

8 an line should be plenty for 1200 hp. I run -8 an feed and plumb into my rails in series but I'm closer to 800-850hp at the moment until i can try to put good gas in this thing and tune it. Plan for 1000hp and my fuel system has been take to 1000whp by some late model LSx guys

What you outline is nice.

I definately Y rather than loop. Even though many loop.

Most all those old fuel line size recommendations are based on low pressure Carb fuel systems. Port injected EFI systems run at 5-10 times higher pressure and therefore can get away with smaller fuel lines.
Its ironic, EFI guys adopted the practice from Carb fuel systems of running -8 and -10 fuel lines which often tend to be serious overkill, but they (as a general rule) usually fail to think of paralleling fuel pumps for more volume. I dont know if they still do, but one centrifugal supercharger manufacturer used to sell a "booster" pump that was to be put in series with the factory fuel pump. Series = dumb!
We had one particular Firebird up on the dyno one night with a stout 355 LT1 and good size centrifugal blower (forgot the brand) it leaned out and bucked really bad on the top end. So we added the INLINE T-Rex or whatever it was called pump that came in the blower kit. Guess what, NO DIFFERENCE!!! Adding an in-line pump was useless. A bigger in-tank pump is what it ended up getting in the end, with a heavy gauge wire and relay (which on the stock pump helped more than the "T-Rex" inline nonsense.
And BTW, that car had stock plastic 3/8 fuel lines and rails and made well over 600 at the rear wheels. While I was there I also put a supercharged 383-LT1 in a 4thgen Camaro that I remember making a bit over 750 at the rear wheels (thats probably in the mid 800hp range at the crank). That was on 3/8 lines and factory LT1 fuel rails.

Hydraulic flow and pressure work very much like electrical voltage and amperage. For the same Wattage;
Low voltage/high amps = big wires
High Voltage/low amps = small wires
both flow the same number of electrons, liquids in a tube work the same way.
I do like big fuel lines and rails though, but mostly because they dampen out pulses.

usually fail to think of paralleling fuel pumps for more volume.

This is more popular with late model guys. I run twin walbro 255 l/hr intank pumps on my setup. Second is activated with boost switch, 4-5 psi turns it on. Most i've heard used was 3 walbros in the tank and I believe it put out over 1100-1200whp but not sure.

I thought of running another pump if on the off chance I did make the motor sick enough :D
Now that I am reading this, never mind.. There is no way I could make that kind of ponies... 1200 horses... I was worried about 500, silly me
I will need to keep the GPS on tracking mode of all local gas tankers i the area and do an "in air" refuel...:thumbsup:with a set up like that.