400+ HP stock fuel system

[Stratman]

Who has experience with taking the stock fuel lines and fuel rails to it's maximum HP level before making things larger? After removing some very melted stopped up catalyst from the exhaust I believe my 52 pph injectors are maxing out at 26 psi instead of 30 psi like it was before. Before F4 cam and the melted cat was removed the CSX was hitting 352 HP to the wheels with the A-413 trans and I can say that over 400 HP at 5800 RPMs at the wheels is feasible prediction now. 72 pph inj are being ordered today.
Eventually I will be changing this anyway, but I am at work and feel like posting.:)

[moparzrule]

I believe the rail is more of a restriction than the stock lines. I would trust the stock lines far before the rail.
What fuel pump are you running?

[cordes]

I believe that 376 was put to the wheels with the stock lines and with the stock rail on a certain SC. This was with a manual trans.

Were you running 26PSI on pump gas alone, or was that race gas, or even race ga/alky mix?

[Stratman]

I believe the rail is more of a restriction than the stock lines. I would trust the stock lines far before the rail.
What fuel pump are you running?

255 Warbro

[Stratman]

I believe that 376 was put to the wheels with the stock lines and with the stock rail on a certain SC. This was with a manual trans.

Were you running 26PSI on pump gas alone, or was that race gas, or even race ga/alky mix?

This past week I have been running a 93 pump/111 leaded mixture, heavy on the 111. No Alky.

[csxtra]

The stock rail is definitely a restriction...as I was building up my CSX (2.5, so fuel system limitations show up earlier), I hit a point where I was getting knock. I had already switched to 3/8" feed lines and dual Walbro 255s (the high-pressure one in the tank and the other one inline - to avoid the high pressure flow drop issue that the in-tank pump has).

I checked my logs, and I had no knock in cylinders 3 & 4, a little in cylinder 2, and a lot in #1. After talking it over with Reeves and BroKen, we theorized that the stock rail didn't have enough internal volume to support the +40s needs, so the internal pressure drops as the fuel flows from #4 to #1, so #1 was seeing less fuel pressure (and thus flow) so it was running lean and causing the knock. When I swapped to an aftermarket rail, the problem went away.

Hope this helps,
Warren

[Stratman]

When I swapped to an aftermarket rail, the problem went away.

Hope this helps,
Warren

Was your stock rail modified in any way?

[csxtra]

Was your stock rail modified in any way?

No, it was completely stock. However, if you do the mod that takes out the internal tube that allows both inlet and outlet on the same side, the volume/flow may be sufficient for the +40s, but I don't know about 72pphs.

I didn't want to cut up a 2-piece rail since they are made of unobtanium, and there was an unused aftermarket rail in stock at the "OVC parts warehouse":D, so I went that way instead.

Warren

[moparzrule]

What about dual inlets? I've seen that before, mod the rail so that there's an inlet on both sides of the rail and T off the fuel line going to the rail.

[cordes]

What about dual inlets? I've seen that before, mod the rail so that there's an inlet on both sides of the rail and T off the fuel line going to the rail.

That might work, but once you have the rail open, why not just take out the smaller inner portion and be done with it. If this was a suggestion that is in conjuction with removing the inner liner then I could see how feeding it from both sides would equalize flow acoss the injectors to an extent.

Also we talk about if the stock rail can support the +40s, but when you look at the DC of the injectors at these levels the +40s are past what most would considder to be their safe limit too. Just something to keep in mind.

[moparzrule]

Yeah I was assuming taking the inner part out, but the number 4 will still be the first to get starved.
There's also no point in upgrading the fuel line to 3/8'' if you are keeping the tiny stock inlet to the fuel rail! If you would open up the other end, put a fuel inlet there, you wouldn't have to touch the stock inlet side then.
I understand about maxxing out +40's, I'm past that. This is assuming 72's.

[Stratman]

I think me and my buddy have it planned for this weekend. We will removed the inner tube, take another stock size metal line to the opposite end, braze it and the existing stock line to a 3/8" nipple which should distribute the fuel well to both sides and run the larger line to the pump.
Seems my only issues would be adapting the 3/8" line to the nipple on the pump. Isn't it smaller than 3/8"?

[cordes]

I think me and my buddy have it planned for this weekend. We will removed the inner tube, take another stock size metal line to the opposite end, braze it and the existing stock line to a 3/8" nipple which should distribute the fuel well to both sides and run the larger line to the pump.
Seems my only issues would be adapting the 3/8" line to the nipple on the pump. Isn't it smaller than 3/8"?

Although I am uncertain what size the nipple on the pump is, I know that Earl's makes a fitting that will go from 5/16ths hard line to -6AN. I am not sure if that will be of use to you, but here is some information off of my site regarding this piece. I got it from Jegs.

Earls -6 AN Male to 5/16" Tubing Adapter Jegs PN: 361-165056 Price: 11.99

[Directconnection]

I believe that 376 was put to the wheels with the stock lines and with the stock rail on a certain SC. This was with a manual trans.

Were you running 26PSI on pump gas alone, or was that race gas, or even race ga/alky mix?

I know of one person that made over 400whp on the stock rail. (2-piece rail)

[johnl]

I'm no math whiz, so gotta ask you all - what volume of fuel is required for 400 HP? Then, can that volume be delivered by a 3/8th line at boost plus base pressure? Or do I have it wrong?

[Speedeuphoria]

I'm no math whiz, so gotta ask you all - what volume of fuel is required for 400 HP? Then, can that volume be delivered by a 3/8th line at boost plus base pressure? Or do I have it wrong?
-6AN or 3/8ths line can support 600whp, and theres no definate answer to either question as everyones setup is different.

But overall from what I've came across its the rail thats could be the culprit

[moparzrule]

Yeah the stock 5/16 line is good for 99% of us.
The question I have is what is the walbro 255 good for? Isn't 400 WHP getting close?

[Stratman]

I thought the 255 can support 600 HP.

[moparzrule]

Maybe on lower pressure's, but our fuel systems run pretty high pressure and the pump doesn't flow nearly as much at 70-80 PSI than it does at 40-50 like most others run.

[cordes]

Maybe on lower pressure's, but our fuel systems run pretty high pressure and the pump doesn't flow nearly as much at 70-80 PSI than it does at 40-50 like most others run.

That is where switching to the 72pph injectors and the like is a huge advantage pump wise, as they are rated at the lower FP. That frees up a lot of head room for the added pressure from high boost.

[8valves]

That is where switching to the 72pph injectors and the like is a huge advantage pump wise, as they are rated at the lower FP. That frees up a lot of head room for the added pressure from high boost.


Ding ding ding.

[Stratman]

Ok, I need to go ahead and look at the specs of that injector. I was thinking they were rated at 55 psi.

[moparzrule]

That is where switching to the 72pph injectors and the like is a huge advantage pump wise, as they are rated at the lower FP. That frees up a lot of head room for the added pressure from high boost.

+1, I just said what I said because it didn't sound like he was interested in getting the 72's.

[Stratman]

I'm having a hard time finding specs for this injector for some reason! What pressure are these injectors rated at?

[mock_glh]

The 72's are rated at 3 bar or 43.5 pounds,as are most of the other performance injectors.

[Stratman]

Thanks.

[8valves]

The 72's are rated at 3 bar or 43.5 pounds,as are most of the other performance injectors.

Just so long as we're not talking about MP's :)

[Stratman]

Started on the fuel rail yesterday and worked on it a little more tonight. Possibillities are great at this point!

http://www.turbofreak.com/csxhead/railside.jpg
http://www.turbofreak.com/csxhead/railend.jpg
http://www.turbofreak.com/csxhead/railinlet.jpg
http://www.turbofreak.com/csxhead/railinside.jpg

[moparzrule]

Does taking the damper off the end have any affect on anything negatively?

[Stratman]

I had thought that it might have some effect, but if I went with and aftermarket one it would have no damper.

[badandy]

I had thought that it might have some effect, but if I went with and aftermarket one it would have no damper.

The damper is needed on a stock rail due to the small volume. Due to this small volume the fuel is very succeptible to fuel pressure fluctuation due to the injectors opening and closing. The aftermarket rails do not have this damper because the increased volume allows the fuel to dampen itself.

[badandy]

Does taking the damper off the end have any affect on anything negatively?
I should have answered this first...

YES!...and unfortunately I found out the hard way:p

[moparzrule]

OK, but doesn't taking out the inner tube increase the volume? Not enough I assume?

[karlak]

Thought the damper was there to eliminate noise and vibration from the pump.

[Turbodave]

The damper was not present on the 90 and newer 2.5's after they switched to sequential injection.

[moparzrule]

Can someone explain how to get the inner tube out? Does the damper come off and the tube come out?

[mock_glh]

Started on the fuel rail yesterday and worked on it a little more tonight. Possibillities are great at this point!

http://www.turbofreak.com/csxhead/railinlet.jpg

I did a much simpler mod to my stock rail. I drilled through the inlet end until I broke past the tube, effectively exposing both ends to the inlet flow. Then I plugged the hole with a shallow plug, and the inlet tube still remains. It seems to work pretty well and it's a whole lot less work than removing the inside tube. I'll test it at the track this week.:)

[Stratman]

I did a much simpler mod to my stock rail.

Yea, I tend to take the long way home, LOL, but I wanted to go larger with the inlet size if I am going to run 3/8" from the tank to the rail. I got the fittings I needed today and I set it up to be able to change nipple size from 1/4" to 7/16". I also bought a fitting and a plug to install for the damper end incase I want to change the return location or add an additional feed to that side with ease.

[badandy]

OK, but doesn't taking out the inner tube increase the volume? Not enough I assume?
I never experimented with that but I would be willing to bet not.

Turbodave hit the nail on the head with the sequential vs. batch fire situation. Sequential didn't disturb the pressure across the rail. Evidently the fluid dynamics (or would it be harmonics?) of the batch fire setup needed a damper to keep fuel pressure constant across the rail.

[turbovanman²]

Also we talk about if the stock rail can support the +40s, but when you look at the DC of the injectors at these levels the +40s are past what most would considder to be their safe limit too. Just something to keep in mind.

Thats good info but I would throw into the mix that your only maxxed out for the length of the 1/4mile pass, ;)


Yeah I was assuming taking the inner part out, but the number 4 will still be the first to get starved.
There's also no point in upgrading the fuel line to 3/8'' if you are keeping the tiny stock inlet to the fuel rail! If you would open up the other end, put a fuel inlet there, you wouldn't have to touch the stock inlet side then.
I understand about maxxing out +40's, I'm past that. This is assuming 72's.

How would #4 lean out? with the tube gone, the volume is much more equalized, ;)


Can someone explain how to get the inner tube out? Does the damper come off and the tube come out?


On one rail, I drilled out the drivers side end, thus loosening the tube and it fell out. Another one, it was tack welded in the middle so I had to cut the rail in half and reweld it back together.

[Stratman]

There really isn't enough mass in that tube to create more volume, but removing it sure seems to open up the rail where the injector is fed since that tube passes right beneath the feed hole in the injector bung. It also looks like fuel can feed into the rail easier since it won't be traveling through that tube, pushing past the damper, and then filling the rail.
The only concern I have now is how close the stock pressure regulator bung is to the fuel feed into the rail. With the tube installed before, the regulator is on the opposite end from the the feed.

[Stratman]

Picked up the rail from the welder this morning. Going to pressure test it tonight and maybe go ahead and install the 72 pph inj to start tuning it for the races next weekend.
http://turbofreak.com/csxhead/fuelrail1.jpg
http://turbofreak.com/csxhead/fuelrail2.jpg

[cordes]

That looks pretty good. Let us know how it works out for you.

[Stratman]

That looks pretty good. Let us know how it works out for you.


Flawless!
I ended up having a very tiny leak at the base of the pressure regulator bung, but we brazed it more and stopped the leak. I tuned the ecu for the 72 pph injectors, pulled the fuel pressure down some, and it cranked with no hesitation.
The lean problem at higher boost levels I developed after removing the melted catalyst is no longer an issue. Part throttle is great on the highway, full throttle is very smooth, and idle seems to be a bit smoother than with the 40s as well. The fuel pump is not whining NEAR as loud as it was before, actually, you can hardly hear it.
This is great news for next week!

[87csx2.4]

the volume/flow may be sufficient for the +40s, but I don't know about 72pphs.
Yeah I ran a modified stock rail on my sc with 72 pph injectors and it worked very well.The injectors will help keep the fuel pump in it's most efficient volume range that is the main thing but you need to keep the static pressure were the injector is rated .As you can see the 255 pump falls off quite a bit under high pressure.

[cordes]

Flawless!
I ended up having a very tiny leak at the base of the pressure regulator bung, but we brazed it more and stopped the leak. I tuned the ecu for the 72 pph injectors, pulled the fuel pressure down some, and it cranked with no hesitation.
The lean problem at higher boost levels I developed after removing the melted catalyst is no longer an issue. Part throttle is great on the highway, full throttle is very smooth, and idle seems to be a bit smoother than with the 40s as well. The fuel pump is not whining NEAR as loud as it was before, actually, you can hardly hear it.
This is great news for next week!

That sounds wonderful. I can't wait to hear your times, as that car should be flying with the new setup.


Yeah I ran a modified stock rail on my sc with 72 pph injectors and it worked very well.The injectors will help keep the fuel pump in it's most efficient volume range that is the main thing but you need to keep the static pressure were the injector is rated .As you can see the 255 pump falls off quite a bit under high pressure.

Thanks for posting that up. Not too many people realize how hard that pump is working at higher boost.

[Stratman]

Yeah I ran a modified stock rail on my sc with 72 pph injectors and it worked very well.The injectors will help keep the fuel pump in it's most efficient volume range that is the main thing but you need to keep the static pressure were the injector is rated .As you can see the 255 pump falls off quite a bit under high pressure.

Yes, thank you for posting that chart.
Nearly an amp is a good load to take off.