Anyone know what the leanest cylinder is??
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This information you need what for? Curious I am.
I'd suggest looking at removed cylinder heads for evidence of burning leaner than others, problem is injectors can vary by a few percent also. Search under my username and you will find some leakdown numbers on one of my SHO engines, you might infer that the cylinders with higher leakdown probably ran a little leaner over their lifetime. Based on plugs and such I think cylinder 5 runs a little hotter than the others, being in the rear center.
Off Road SHO
Moderator
Lean burn has a lot more to do with fuel delivery than air delivery. As mentioned above, the SHO's air intake does a magnificent job of delivering a balanced amount of air to each cylinder. The fuel system on the other hand can vary the amount of fuel delivered to each cylinder by quite a bit. Our fuel rail is a loop, with the fat fuel line coming in and the small one returning to the tank. The rail closest to the firewall feeds the cylinders closest to the radiator and vice versa. The closer the injector is to the incoming feed line, the more pressure it will have. Not a lot more pressure just a little. The difference is small in a good pump/filter scenario at low rpms, but as the revs go up, the pressure differential does also. I believe the back rail is first so that means the back cylinders get the lower pressure at high rpms, specifically cylinder 1 is last in line for fuel delivery. Hope that helps.
In the Other Woman, I split my fuel loop into two shorter loops with a T at both ends. The way I did it was quite ingenious (Simple) and I can post a pic if anyone is interested.
Tom
In the Other Woman, I split my fuel loop into two shorter loops with a T at both ends. The way I did it was quite ingenious (Simple) and I can post a pic if anyone is interested.
Tom
Instead of doing this,I've been thinking -8 feed line from the tank to a Y feeding -6 to each rail,then at the end of each rail(for the return)-6 line off each of those to a fuel pressure regulator and then off the fuel pressure regulator back to the tank.
This is how a lot of high HP turbo cars run there fuel system.
Somthing that won't work and is not needed according to the experts here
Thanks for the info,#5 is the leanest.
Somthing that won't work and is not needed according to the experts here
Thanks for the info,#5 is the leanest.
Ha, a comedian. Unlike some other areas of the SHO, the fuel delivery/return system can benefit from upgrade/alteration. The one you describe is exactly how many of us have been running our systems for some years. I'm honored it meets with your approval.
That isn't the system that ShoNut sells and I see guys running?
Josh sells a few configurations. The hi-flow one has -8 tank to a T, and individual -6 feed lines for each rail, with excess fuel getting bypassed back to the tank.
My personal setup is similar, but among other things uses a -6 return line, while I think Josh's system used the stock return lines.
My personal setup is similar, but among other things uses a -6 return line, while I think Josh's system used the stock return lines.
I just saw the 1 listed on his site....the high flow one.
-8 from tank to filter to 8-10" long surge tank that has -6 to feed the rails halfway down the length of it and at the end of the surge tank it has the fuel pressure reg,the return line goes from the fuel pressure reg back to the tank.
No offence to ShoNut,I'm sure it works great but I'd run it how I described if I was replacing everything,esp for forced Induction.
Now the standard fp reg kit(non high flow) is a different story. I'm pretty sure it's the most effective way if you are still using the factory lines for sure. If I have any problems with fp,I'll def be installing one of the non high flow kits. I don't think I will have a need tho(I have a 155 Walbro already)
I don't plan on forced induction ever,just nitrous.
I just think if you are gonna go all out and replace it,might as well run it like any other 1000hp car.....albeit one that makes substantially less.
A 255lph pump will be about maxed at 550whp on a forced Induction 3000lb+ car anyways
-8 from tank to filter to 8-10" long surge tank that has -6 to feed the rails halfway down the length of it and at the end of the surge tank it has the fuel pressure reg,the return line goes from the fuel pressure reg back to the tank.
No offence to ShoNut,I'm sure it works great but I'd run it how I described if I was replacing everything,esp for forced Induction.
Now the standard fp reg kit(non high flow) is a different story. I'm pretty sure it's the most effective way if you are still using the factory lines for sure. If I have any problems with fp,I'll def be installing one of the non high flow kits. I don't think I will have a need tho(I have a 155 Walbro already)
I don't plan on forced induction ever,just nitrous.
I just think if you are gonna go all out and replace it,might as well run it like any other 1000hp car.....albeit one that makes substantially less.
A 255lph pump will be about maxed at 550whp on a forced Induction 3000lb+ car anyways
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To find the answer, you would need to instrument the exhaust manifolds with a six probe Exhaust Gas Temperature gauge. When the engine is being asked to produce significant power, the fuel delivery is undoubtedly mapped sufficiently rich that the cylinder to cylinder variation has little effect on performance, but perhaps you are asking the question from another angle. It would be interesting to measure.
Dirk37
Mr. Resourceful
You can either use 6 EGT probes as stated above, or find some way to get a wideband into each cylinder. You could tap the exhaust manifold on each cylinder, then do identical test runs and move the wideband around and test one cylinder at a time. Unless you have the engine tuned on the very verge of blowing up though you don't really need to worry about it. The drivetrain will grenade long before you'll reach the point where this is necessary to know.
On rant.....
We'll surely if you are saying it won't work or isn't needed you have experience with it?? Oh,you don't? Well then what makes u so sure it's not needed? None of you even know what's it's for for gods sake.
Some folks wonder what happened to our great country but I don't...
We are modifying a fwd American made car with a NA v6 for gods sake so I think we should all be up for somthing different.
I know not many of you own many other high performance automobiles but I do and I can tell you with certainty that those with the fastest cars usually try a ton of stuff others say won't work....An engine is a air pump and they all work very similarly. Even the most perfectly designed intake manifold in the world is always going to have distribution problems on multiple cylinder engines.That's a fact......
Any day you fail to learn somthing new or fail to help Others,you fail as a human being....
Off rant.
We'll surely if you are saying it won't work or isn't needed you have experience with it?? Oh,you don't? Well then what makes u so sure it's not needed? None of you even know what's it's for for gods sake.
Some folks wonder what happened to our great country but I don't...
We are modifying a fwd American made car with a NA v6 for gods sake so I think we should all be up for somthing different.
I know not many of you own many other high performance automobiles but I do and I can tell you with certainty that those with the fastest cars usually try a ton of stuff others say won't work....An engine is a air pump and they all work very similarly. Even the most perfectly designed intake manifold in the world is always going to have distribution problems on multiple cylinder engines.That's a fact......
Any day you fail to learn somthing new or fail to help Others,you fail as a human being....
Off rant.
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And as far as saying it's caused by the fuel system.....
I'm willing to bet only when you are doing high speed pulls does it become an issue. 1/8 mile and 1/4 mile drag racing,I'd have a hard time doubting a 300hp engine would/could suck fuel rails dry in short sprints.
SHO ME SOMTHING!lol
I'm willing to bet only when you are doing high speed pulls does it become an issue. 1/8 mile and 1/4 mile drag racing,I'd have a hard time doubting a 300hp engine would/could suck fuel rails dry in short sprints.
SHO ME SOMTHING!lol
Dirk37
Mr. Resourceful
The fuel system doesn't care if its a 1 minute pull or 1 second pull. If the rail setup causes a pressure drop and reduction in flow past a certain amount of fuel, its going to happen whenever that amount of fuel is exceeded.
I'm assuming you think you're going to put a massive shot of nitrous on and drag race this thing. If that is the case, you don't need to worry about all this goofy theoretical stuff. You need to worry about the transmission, getting traction, and not exceeding about 400 hp so the piston rings don't expand and snap off (unless you're getting forged pistons). You'll also need an upgraded clutch as the stock one slips around 350 chp or 8 psi.
Also, what would knowing what the leanest cylinder is allow you to do? You can't tune the stock ECU cylinder by cylinder. I don't think you can even do that with megasquirt.
I'm assuming you think you're going to put a massive shot of nitrous on and drag race this thing. If that is the case, you don't need to worry about all this goofy theoretical stuff. You need to worry about the transmission, getting traction, and not exceeding about 400 hp so the piston rings don't expand and snap off (unless you're getting forged pistons). You'll also need an upgraded clutch as the stock one slips around 350 chp or 8 psi.
Also, what would knowing what the leanest cylinder is allow you to do? You can't tune the stock ECU cylinder by cylinder. I don't think you can even do that with megasquirt.
If you are smarter than everyone else on this board, stop asking questions. If you aren't and need a question answered, stop being an ass and listen instead of ranting about how unAmerican we are when we warn you the transmission is going to blow up long before the leaness of a particular cylinder is going to even remotely matter.
To what are you even referring? How can we know what "it" is for when you haven't given us any clue what "it" is?
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