Fuel Rail Idea, Do You Like?

blageo23 · 10-30-2007

Im not going to take credit for this because I saw one for sale on ebay but need to know if it makes sense.
Here is the basic idea. Our cars have a problem with cylinder #1 not getting enough fuel(less then the others). So I thought this would work but Im not an expert like some of you guys.

Take your stock fuel rail and drill a whole in the center of the fuel rail(inbetween injectors 2 and 3) and you make that where the return line goes. Then you make both sides of your fuel rail inlets. So have fuel inlet on both sides of the rail and the return in the middle.

Does that make any sense to you guys? would this give you optimal fuel or would the fuel get all F'd up in the middle of the rail?

**Kracka** · 10-30-2007

#2 is actually the cylinder that runs the leanest generally.

TwoTalons · 10-30-2007

Quote:

Originally Posted by S2kracka

#2 is actually the cylinder that runs the leanest generally.

I thought that was due to air distribution, not fuel?

**Kracka** · 10-30-2007

Quote:

Originally Posted by TwoTalons

I thought that was due to air distribution, not fuel?

From how I understand it is because fuel pressure is at its lowest at injector #2 since the fuel enters at #4 and hits a "wall" at #1.

Pushit2.0 · 10-30-2007

When did DSMers turn into 3Sers?

~John

Super Bleeder!! · 10-30-2007

If there is infact a lean condition in a certain cylinder i would not attribute it to fuel distribution in the rail. Its an incompressible fluid moving at a relatively slow rate.

**Shane@DBPerformance** · 10-30-2007

Wait, where is all this bad info coming from? Our cars have no problem with #1 not getting enough fuel. There is something like .00000000000001psi of pressure drop across a 1' fuel rail, I am might be exaggerating, someone with the math skills could figure it out, but it is inconsiquencial. Variance in flow from one injector to another from dirty or just bad fuel injectors is much more likely. We have been able to track down a bad fuel injector on the dyno a couple times that caused a car to detonate too easy, but they were flowing so much less that you could tell in plug coloring.

**Kracka** · 10-30-2007

Good to know. Back in my days of hardcore DSM researching on 'Talk it was the general consensus that #2 ran leanest b/c of fuel pressure drop across the rail.

What is the proper explanation for why cylinders 1 and 2 generally have lower compression than 3 and 4?

Scrmegl · 10-30-2007

My #2 plug discolors first on a plug swap every time. Not major but noticeable. I always heard the same things. Some myth busting on this would be great.

niterydr · 10-30-2007

HAHA lean cylinders from fuel distribution!
Man tooners must be busy...

**Kracka** · 10-30-2007

Quote:

Originally Posted by niterydr

HAHA lean cylinders from fuel distribution!
Man tooners must be busy...

So...what is the reason behind some cylinders running leaner than others?

FattyBoomBatty · 10-30-2007

Actually, you guys sound like starquesters, who really do have fuel distribution problems.

Andrew7dg · 10-30-2007

I thought it was because of air flow as well. Wouldn't that be more of a problem then fuel?

Would buying a bigger fuel rail just solve this problem?

I suppose this become a problem when running E85 and lots of fuel

Super Bleeder!! · 10-30-2007

Quote:

Originally Posted by FattyBoomBatty

Actually, you guys sound like starquesters, who really do have fuel distribution problems.

TBI for the ultimate loss

FattyBoomBatty · 10-30-2007

Quote:

Originally Posted by Super Bleeder!!

TBI for the ultimate loss

No plenum to speak of, injectors before the TB, tri-y intake design. w00t. dsm people have it easy.

blageo23 · 10-30-2007

Lean=not enough fuel, no matter how you slice it.

**Shane@DBPerformance** · 10-30-2007

Quote:

Originally Posted by blageo23

Lean=not enough fuel, no matter how you slice it.

Yes, but it has nothing to do with the fuel system. We met a Pro Mustang drag racer last year at PRI who was in a class that didn't allow individual cylinder trimming. He drilled holes into each intake runner and screwed bolts in and out to block airflow to cylinders that got too much air and melted shit.

FattyBoomBatty · 10-30-2007

Quote:

Originally Posted by ecoli

Yes, but it has nothing to do with the fuel system. We met a Pro Mustang drag racer last year at PRI who was in a class that didn't allow individual cylinder trimming. He drilled holes into each intake runner and screwed bolts in and out to block airflow to cylinders that got too much air and melted shit.

Wouldn't that be "trimming" the cylinders, just in a caveman-style way?

**Shane@DBPerformance** · 10-30-2007

Airflow. It is much harder to get perfect air distribution to 4 cylinders through a throttle body, plenum, runners, intake port, past the valves, in an environment that is always changing. Versus a straight tube in which the pressure delta should always be the same, unless the fuel pump can't keep up. Even regardless of airflow, temperature can cause one cylinder like #2 to be more prone to detonation, because it is sandwiched between 2 other hot cylinders. Often with a standalone system, you might give more fuel or less timing to the center cylinders. The 03-04 Supercharged Cobra has 2 cylinders on side of the motor that are most likely to go first because of the stock cooling system.

niterydr · 10-30-2007

Thanks Shane

.
Cooling (heat dissipation) and airflow (aka more than adjacent cylinders) are reasons why some cylinders are more prone to detonation.
Also exhaust manifold design can also play a role in detonation prone cylinders (yet again that is airflow).
Pressure drop across a fuel rail isn't going to be severe, even with garden hoses and minimal fuel pressure. Now if we low volume flow/extremely low pressures+massive injectors we could run into a starvation issue, but this isn't the case on dsm's.
Ebay owns!