WHP limit with stock TII fuel rails and lines
 

I was wondering what the limit would be with the stock fuel rails and lines, don't worry, everything else is good for at least 700whp but how far could I take these stock parts? Anyone test the limit or push their stock rails and lines pretty far?

You could/should probably ask this in the second gen section :)

Figured more people have pushed bigger numbers in here

run a 1/2 inch drill bit thru them and weld on -8 AN or -6 AN bungs.


you shouldnt use the stock lines in the bay...

I have upgraded lines in the bay but stock lines from pump to firewall and stock rails

This is the exact reason I did not want it in this section

i wouldn't push more than about 500whp with a sub 300lph pump on the stock lines/rails.

for 500+ i would run a walbro 400 and the rising RPM rails.

I have dual walbro 400's now Ben, and 4x id2000's, and a BW s400sx lol. I was planning on running those rails but am not gonna do it unless I also upgrade all my lines, just trying to decide if I should upgrade it all right now and put off finishing this or if I would be able to get decent power on the stock stuff

with that i would probably do a -6 parallel line setup with all new hardlines under the car, they're cheap enough.

you should hook up the fuel line to like a 5 gallon bucket, and turn the pump on for a 30 seconds, and see how much fuel you actually get.

400liters per hour, divide by 60 to get liters per minute. ~7 liters a minute, or 1.8 gallons.

Then I should have plenty of fuel right lol

I only bought two of those pumps cause I got such a great deal on them, if I can make 600-650 on 1 of them with my KB BAP then I'll just use 1 but if I need both I have them already

you should only need 1 for over 600whp on pump gas but i haven't really pushed them up there to really know their limits.

Easy rule of thumb for fuel line sizing from A. Graham Bell:
1/4" OD (-4 AN) - 165bhp EFI, 110bhp Carb
5/16" OD (-5 AN) - 300bhp EFI, 200bhp Carb
3/8" OD (-6 AN) - 500bhp EFI, 335bhp Carb
1/2" OD (-8 AN) - 1000bhp EFI, 675bhp Carb

Also, the Aeromotive website has a power planner section.
Aeromotive | Power Planner

That's some good info right there, about what size is stock lines? What about rails? Is it just that they look better or do rising rpm rails also flow better?

Stock FC fuel line under the chassis is 5/16 I think. Super tiny and a bottleneck with that pump. Run -6 or 8 for safe hp like 350+

The stock lines are 5/16". The stock S4 fuel rails are M14x1.5 on one end and M12x1.25 on the other, which can be fitted with a -6 or -8 AN adapter (available from Earl's). The Rising RPM fuel rails have 3/8" NPT fittings, so there is no functional advantage to using them unless you have the crummy stock S5 rails that are not worth modifying.

i think those flow rates are a bit broad, since i've already managed several cars right at 500whp with the stock hard lines.

also iirc the RRPM rails accomodate -8 without much of a step down. the stock rails have a smaller bore but i don't have specific numbers on hand, all i do know for certain is they provide enough fuel for over 500whp with no problem.

They are broad because they are based on a generally-accepted velocity limit, Reynolds number, flow rate, fuel weight, and friction coefficient, and BSFC is not taken into account except for a generalized "forced induction" and "naturally aspirated" rating on the Aeromotive website. The guidance also does not take into account line length and gravity effects. Given that most of the people on this forum do not have a physics background, the basic guidance should be sufficient. Using a fuel line much smaller than recommended results in an undesirable amount of pressure loss and turbulence.

and too large and the pump will have a difficult time keeping the pressure up.

Yes, the outlet size of the pump is a good indicator of the line size that it was intended to support. The entire system should be matched.

Oh and I just went to check the outlet size (11mm) and realized they are both walbro 450lph not 400

I'm curious how many people with high hp redo the lines under the car. It seems like most people just modify the lines in the engine bay

Well that's what I am talking about and started this thread for, I mean all the lines, from pump to rail, even the fuel pump hanger, does anyone modify the line that goes through the lid? Seems like it's the same size as the hard lines under the car

Nobody?

I don't think that anybody who is making serious power still has the original fuel tank or the lid. What are you going to do with a 500+hp car that doesn't have a fuel cell? :scratch: