Fuel line sizes
Turbo Mini Forums

Right, ive always gone with 8mm there and back to be fair but with the new car im considering:

1/4" ID (6.35mm) feed
3/8" ID (9.53mm) return

Then i wont have to worry about putting a restriction in.

Im assuming that 1/4" will be more than enough to supply the engine upto 200bhp ish? Or should i go with 5/16" ID (7.94mm)?

using 10mm to the pump as thats what the pump has as an entry, then the 1/4" from the exit of the pump with a ???? filter between the tank and pump

Edited by iain on 11th Apr, 2005.

Iain,

As regards 1/4" being able to supply 200hp - the amount that can flow through any tube is dependant on the smallest cross-section at any point; hence a 1" supply with a 5mm restrictor at the entry to the regulator will still only flow the same as running a 5mm ID pipe all the way from the pump.
As regards 5mm ID being enough, work out how much fuel is needed (lites/min) for 200hp forced induction - the maths are available in good engineering books or off google. Then ramp your fuel pressure up to 20/22psi - basicslly whatever MAX boost you're going to run.
Disconnect the return line and feed it into a suitable container (empty). Turn the fuel pump on for 60 seconds (maybe thirty if the container looks to be filling up quickly) and do the math to see how that compares to the fuel required for 200hp.
Allow 25% reserve. If you have that, it's plenty.

I think you should actually do this, so we will all know how much power the stock metro pump can 'theoretically' support...


D

Ok will do, fortunately i work right next to the fuel systems guys at work now so I'm sure they can help me out with the maths too

Ill *try* to find out this week what the theoretical size is, obviously the return just needs to be the next size up. Supply is what really matters.

Are plastic fuel lines ok for the MOT,I have poly flo(american make) tubing on my golf and its petrol proof comes in yellow red and green 1/4 to 1" dia free from work ! joins using stainless compression fittings and nylon or stainless olives.can remember my mk2 escort had black plastic petrol pipe just wonderd if the rules changed.

Metro turbo weekend driver,Mini turbo in the making again!

they should be as i think most new cars nowdays run plastic fuel line under the bonnet.
but i can't be sure this runs from the tank in plastic.

Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe.

Quote from

"Use these figures as a fuel line sizing standard:

Up to 250HP = 5/16" or -04 AN
Up to 375HP = 3/8" or -06 AN
Up to 550HP = 1/2" or -08 AN
Up to 800HP = 5/8" or -10 AN
Up to 1200HP = 3/4" or -12 AN

If you use a return-style regulator, you will also need a return line from the regulator back to the tank. The size of the return line is dependent on the size of the pump you are using, regardless of the engine's horsepower output. The return line must have limited or NO pressure in it. In most cases, the minimum return line size will match that of the supply line, but a larger return line is sometimes preferred.

Use these ratings to decide your return line sizing based upon fuel pump output:

Up to 45GPH = 5/16" or -04 AN
Up to 90GPH = 3/8" or -06 AN
Up to 180GPH = 1/2" or -08 AN
Up to 360GPH = 5/8" or -10 AN
up to 720GPH = 3/4"or -12 AN "

Im going to go on the side of caution and spec for 250bhp. that then means my system should be spec'd for more than what i require.

Il still try dig out the proper figures for it though

I'll need the next size up from you then iain, LOL

Team Racing

Just trying to find the rating of the fuel pump in gph to find out what return to use..

im thinking 5/16 feed and 3/8 return

ps im getting the hose prices this week, they're in the post.

If 8mm + fuel line is used do the inlets/ returns on the fuel reg need drilling out to 8mm as it's only 6mm normally so could be restrictive.

Metro turbo weekend driver,Mini turbo in the making again!

fueling noob question... whats the deal with a restrictor? I'm just about to plan my fueling so am i correct is saying..

Place a filter between tank and pump
That then feeds the reg (restrictor needed?)
Return from reg to tank needs to be bigger bore than feed?

Only aiming for about 12psi boost (c. 130bhp?) so what ID sizes would i need, and what type of fuel line? Copper, hose, plastic?

I presume estates dont require anything special?

Restrictor reasoning here:

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=1456

so am i right in saying that if i'm using 6mm feed, i wont need a restrictor if i have an 8mm return? The restrictor only reads as being nessesary if the feed and return are the same size.

Edited by Mike on 27th May, 2005.

got it in one!

been using the standard supply pipe, ie. 6mm and a 9mm return with std bosch 36psi pump on my turbo for 12 years now with no problems, I hope this old set up will be OK with my FI system, I can't see why not? I am currently at 138bhp with no problems?
I guess as always there is more than one way to skin a cat though!

sorr yam confused surely the regulator will need drilling out to 10mm as well then otherwise that will be the restrictor as it isnt that big

In the Queens English please....


????????????????

Edited by TurboDave16V on 19th Jan, 2006.

Metro turbo weekend driver,Mini turbo in the making again!

sorry what dangerous said above

Fuel regulator pipes are (i recall) 8mm?

So good luck drilling them out to 10mm...

no way you will drill out to 10mm 8mm max

1293 Turbo mini

so there is no point in using a 10mm return line at all, just restrict the feed?

dave how are you going to use a 10mm return then if the regulator is 8mm? sorry to bring this up again, gav

Perhaps you can highlight where i said i was going to run 10mm return?

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=1456 sixth paragraph down

ah - no wonder i couldn't see it here ^^^^^^


Well - the reason i said that was because it's better to have a larger return than feed. This has been proven again and again. So - if running an 8mm supply, the next one up is..... Yes, 10mm.

I do believe I also said: