IS the stock fuel rail setup good for high horsepower?

[chrisman]

i was wondering what is the most HP that lextreme members have gotten from the stock rail setup.. what i mean is that i have a feeling that the way the stock fuel rails are plumbed(in series) limts the potentila HP to about 400.. has anybody gotton big HP not touching the plumbing on the stock rails?
has anybod modified the original rails to be run in parrallel?

 

[Zuffen]

I'm in the process of building new rails for my engine.

They will be parrallel rails with a balance line.

This will alow me to run the same pressure in both rails and control it with a single Malpasi FPR.

I've rifle bored them to 12mm internal diameter and will have alloy plugs welded to the ends of them for AN8 fittings.

I plan on introducing fuel from each end of both rails so any one supply line only needs to feed 2 injectors.

 

[Peewee]

The stock rails are in parallel.

 

[chrisman]

peewee,, there is one suply line that goes into one rail, then into the other, then out to fuel return line.. that is in series( one after the other).. i have read that this is not a good way to run a fuel supply for a high horse aplication..
sounds like zufffen is aiming for high horse power..maybe even the 1000 hp goal for "The Lextreme Challenge"
Zuffen,,are you making the fuel supply chages because you felt limited when it came to fuel supply of the original setup? did you notice any limit of the original fuel setup?

 

[Peewee]

As far as I can remember both ends of one rail connect to both ends of the other rail, in parallel setup.

 

[Zuffen]

I think you're both right.

The rails are fed by one source (into the left hand rail) then it is transferred to the right hand rail (at both front and rear) and then out the right hand rail.

I guess yes they are parrallel whilst the fuel flows in a series way. I hope that all makes sense.

As far as why I'm modifying my fuel rails it's because it looked like something to do!

I'm only running 420cc injectors so can't get much over 600-650HP even with increased fuel pressure.

I just felt it would be a challenge to see how big they could go and retain the stock look of the rails. It would be fun to tell people they can flow enough fuel for 650HP. At least I'll know it's one less item to worry about restricting what I can screw out of the engine.

My current set up is a stock Crown engine with CAI, BFI & Headers into twin 2.5" cat and a single 3" system to the rear. At a guess I have 300-310HP at the fly wheel.

1,000HP looks like fun but finding a 4x4 transmission to cope would be near impossible.

I figure with Kelford head and cam work, Ross 8.5:1 pistons, Some tough rods, Motec management, a mega ignition system and the Eaton pumping out 14lb a 1,000 may???? be achievable.

I want it drivable and not a HP show case so I don't see me in the race for the prize. I'd rather have 650 usable horses over 1,000 unbroken, difficult to handle horses.

 

[autronic]

Zuffen:

Amen to the 1000hp/4wd combo.

BTW, I'm still looking for a GMC Cyclone/GMC Typoon centre diff anybody know of one ?

 

[Zuffen]

US eBay would be a great starting point.

 

[ozvenom]

fuel rail feeds

Hi guys when we first twin turboed a 1uz we had a problem with fuel flow pulsing at high load which is caused by having a single feed line . the fix was to feed fuel in the back of both rails and have twin returns off the front of the rails . that has fixed the pulsing problem. what zuffen is doing is the next stage with 4 feeds and i assume centre returns. which should support over 600 hp.
after that you can buy billet fuel rails and custom machine the injector holes. you can buy the billet rail from places like petrotech ect.
Fuel sytems seems to be the last place people look when going for big hp.
My cobra had 2 x 600 hp bosch pumps 5/8 s/s feed line and 1/2 return . absloute over kill, but i never worried if i had enough fuel flow.

 

[chrisman]

ozvenm,,where about-hp wise- did you notice the prob with the fuel rail?.. im asking because i think at about 400 hp,the fuel rail system, as it is, becomes restrictive.. it would be nice if we could say for certain.. in my opinion, this modification,like you and zuffen have done, and are doing should become a common modification for guys looking for high hp..

 

[ozvenom]

fuel rail

Hi the pulsing started when we getting up around 350 to 400 hp at the wheels. at this point the fuel mixtures started jumping all over the place.

oz

 

[morris]

Noob question here, but how do you know that you have a fuel rail probnlem in the first place? Do you look for pulsing on a fuel pressure guage? If so how do you know it is the rail and not something like the pump or regulator?

 

[chrisman]

i dont hink its necessarily the rails,, it is the single line feeding into one rail, then the other.. i will try and take a pic of the setup tomorow.. i want to make sure im describing it correctly..

 

[mycarhasposessedme]

Hi,
There is an earlier thread on this subject in another section, I posted some pictures of the standard rail setup and the mods that I have done, which is the same as what Ozvenom is describing. here is a link to it http://www.lextreme.com/forums/showthread.php?t=2569&page=1&pp=20
Cheers
Trev

 

[chrisman]

after looking at that thread, i am almost certain that the limit for hp using the originall fuel setup is about 350-400 hp..
unless someone has proof that the single feed setup is good for more, i will say that the stock fuel setup will be one of the first limits people will encounter in the search for some serious HP..not a hard fix, but something people should be aware of..
i should have been more aware of the previous thread..