fuel lines
Turbo Mini Forums

i need to know what size fuel lines i'm going to need to put in my car. is it best to replace the original fuel line seeing as i've got to put in a return feed?

what exactly do i need to do to my fuel tank? is it just add a return near the top of the tank or do i have to change the outlet aswell? i've got the standard metro turbo fuel pump aswell. where would i get the bits to weld onto my tank from?

any help is greatly appreciated as im now in a rush to get this done for the riv run as my 1275 has decided it doesn't want any oil pressure at all now.

Nick

I run 10mm from tank to pump then 8mm feed from pump to fpr and 8mm return (all id's). I had a 8mm return braized in the top of the tank and a 10mm in place of the normal outlet. All bits of pipe from the metty turbo i scrapped off.

Hmmm.. I've got a load of 8mm fuel line from Avonbar and was planning on using this all through the car. For the return I was gonna use the Metty Turbo's fuel pump (mounted externally) with a t-piece fitted before the pump allowing the returning fuel to re-enter the system, thereby removing the ned to bugger about with the tank.

Not sure how that would work as you'll be pressurising the fuel going into the pump. Plus you'd get reverse flow back into the tank.

I run 8mm both ways...

The return needs to be into the tank.

Jim,

Why is your return bigger? Theres less fuel in the return line than the supply line :S

Alex

AlexF

All evidence is suggesting that that jims (not jimster) proposal does indeed work. Jukka has used it for a number of years and done another 'turbo' the same way...
Only thing against it is the 'first' time it is fitted, the fuel supply and return lines, and regulator, will all be full of air, which will get circulated again and again, until it gradually finds its way to the float bowl where it escapes. As no-one goes straight to 'full bore' after fitting new fuel lines, it is probably fine.
There is also a question about 'heating' the fuel by continually circulating it... Again, Jukka (and lets be honest, he knows what he's doing) doesn't have a problem as far as i'm aware.

food for thought...

Alex - the metro ran 1/4" supply and 5/16" return.
These fuel regulators will throw a 'wobbly' if it sees even a slight restriction in the return line - even more apparant if a pump with a very high flow-rate is used...
Easy way to ensure there is no restriction is to make the return line larger than the supply.

Edited by turbodave16v on 23rd Mar, 2004.

just done the math - 5/16" is 1.5 times larger in cross sectional area than 1/4"

By the same calcs, a 10mm return is 1.56 times larger sectional area than 8mm...

Is this why jimster is running a near standard needle in his mini at 15psi, whereas everyone else has theirs modified??????

Edited by turbodave16v on 23rd Mar, 2004.

I run 10mm for both. Used a roll of flexible copper pipe from the local plumb centre.

Phil.

WWW.TURBO-MINI.COM

I have a 10mm return pipe going into the neck of my tank, but there is a very sharp bend in it, I think this may cause a restriction. I have new ally tank being made for me with no restrictions, if when I fit this, I start running lean, I'll have to put my old tank back in for the rolling road

Team Racing

My fuel lines are the other way around i.e. 10mm supply and 8mm return.

I have been having problems but I think that is due to the pump (see other thread).

The retuen pipe is into an open end so (in theory) it's under no pressure and it will be carrying less fuel. Equal size lines is probably the best option, mine are only different as that's what I had at the time.

Hoe this is of some confusion!

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

It may have less fuel but on idle etc not a significant amount less compared to how much it pumps. This will put strain on the pump which isnt a good thing i guess :)

There is still more restriction in the supply line than there is in the return.

The open return will flow more fuel than the supply line as the regulator itself will act as restriction to flow.

But strain on the pump won't be a good thing as you say...

Alex

AlexF

but as the biggest restriction in the whole fuel system is the carb, I don't think that the lines will affect it much at all. If they are at least a reasonable size to start with.

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

the pumps are designed to work against a restriction however - so this shouldn't be considered a bad thing surely.?.?.?.?

The biggest restriction has to be the regulator... the carb as no return so can't really be considered as part of the same circuit.

Your right there Dave :)

alex

AlexF

Yer, sorry. I was meaning that the return system wouldn't put much strain on the pump compared to the carb. So dave was right in saying it's not a problem for the pump.

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph