When do I need bigger fuel lines? - TurboDodge.Com - Turbo Dodge forum for Turbo Mopars, Shelbys, Daytona, SRT-4, PT Cruiser, Omni and more!

John B · **When do I need bigger fuel lines?**

I've upgraded to a hi flow rail from stock, and to +40's from +20's but I still have stock fuel lines. Am I kidding myself? When do stock lines become inadequate?

John B · 07-10-2005, 02:21 PM

Right now? Never? Above 300 HP?

DakotaKid · 07-10-2005, 02:34 PM

Most people say 300 whp to be safe.

kedavis · 07-12-2005, 10:26 PM

You can flow enough fuel through a 5/16 line at 40 psi to support over 450 hp.

Frank · 07-12-2005, 10:33 PM

I dont know about that dude... each car is different. What may work for some, may not work for others. Reeves has had to upgrade his line to supply enough fuel at higher fuel psi on his 400hp Omni. Mine is upgraded to 3/8" line just to be sure for reliability reasons. 2.5L love fuel.

I personally would run on the safe side by going bigger line unless you have a 4 probe EGT meter/gauge. That way you can detect inefficencies in individual cylinders.

Frank

kedavis · 07-12-2005, 10:40 PM

Quote:

Originally Posted by Frank

I dont know about that dude... each car is different. What may work for some, may not work for others. Reeves has had to upgrade his line to supply enough fuel at higher fuel psi on his 400hp Omni. Mine is upgraded to 3/8" line just to be sure for reliability reasons. 2.5L love fuel.

I personally would run on the safe side by going bigger line unless you have a 4 probe EGT meter/gauge. That way you can detect inefficencies in individual cylinders.

Frank

straight from the sds site some good info also stephane has made 500 whp on stock fuel lines.

Quote:

The proper course is to use a system designed for turbocharged operation with appropriately sized injectors for the job. The OE regulator in most cases is well capable of controlling the pressure and because you can flow a lot of fuel through a 5/16 hole at 40 psi, they are entirely adequate up to 500 hp in most cases. There is no need to install larger fuel lines or massive regulators for most applications. Most aftermarket regulators are not required and a waste of time and money for street applications. They might be required at extreme hp levels on race applications or those using methanol where higher fuel flow rates demand larger lines and regulator passages. The fuel pump may have to be upgraded if the power levels are increased substantially over stock however.

John B · 07-12-2005, 11:37 PM

My concern about the stock 5/16" is that it's not really 5/16"! Although the fuel hose is 5/16" the steel factory line necks down to as small as 3/16" on the way from the tank.

John B · 07-13-2005, 12:03 AM

So, back to the original question, does it make sense that a high flow fuel rail will help if the feedline is restricted?

Frank · 07-13-2005, 06:08 AM

A high flow rail has a few advantages... higher flow capability and even distrubution across all the injectors. I have a TU fuel rail with -AN lines in the engine bay connected to the 3/8" feed line. The return line is really the old supply line of 5/16". I then just swapped the lines at the pump, and inserted a fuel filter next to the tank. I will probably delete that next year, and put an -AN filter in the engine bay.

Frank

kedavis · 07-13-2005, 09:31 AM

Like kenne bell says fuel flow is only as good to the smallest hole if your not -6an all the way right out of the tank it doesnt make sense.Im not saying not a good Idea just a waste of money at this point high flow fuel rail will help because the stock one is a little restrictive.

Frank · 07-13-2005, 09:55 AM

I agree. All of my components I bought for the engine compartment was -6 and -4 lines, so I used -an to keep the number of adapters down. Under the car is 3/8" line.

Frank

kedavis · 07-13-2005, 10:14 AM

Your return line should always be the same size or one size larger than your feed line or your asking for pressure problems.

Frank · 07-13-2005, 10:28 AM

Well there used to be issues when Andy still owned the car. He was running stock lines with a RRFPR, so he replaced the return line with 3/8" line. He then went with a calibration after that. I upgraded the engine bay fuel components, changed the 3/8" line to the supply, and used the old supply as a return. I have 4probe EGT and a F/P Gauge in the car, so I will keep that in mind if I start to have any issues.

Thanks
Frank

DakotaKid · 07-13-2005, 10:56 AM

Quote:

Originally Posted by kedavis

Your return line should always be the same size or one size larger than your feed line or your asking for pressure problems.

Can you explain that a little further?
I am running big feed and a small return. (always have)

Pat · 07-13-2005, 11:07 AM

Quote:

Originally Posted by kedavis

You can flow enough fuel through a 5/16 line at 40 psi to support over 450 hp.

That's somewhat misleading. How much a certain size line will flow depends on other factors...how long of a line it is, how many bends, turns, etc. If you're running a line that's 2 feet long from a fuel cell to the rail, 40 psi at the rail might be 40 psi coming from the pump. If you're running the stock lines that might be 18 feet long with all of the bends (which are also restrictions, 40 psi at the rail might be 50 psi at the pump, which then taxes the pumps flow abilities even more.