Junk Motor

[ByronRACE]

Originally Posted by jeffko

Well we have found it, I would even say remarkably easy to break a Ford engine under a lean condition. Let me just say I am convinced of it, but the engine has not been disassembled yet. However, I think they will find severe heat destruction due to the fuel delivery system being inadequate, very inadequate.

This engine dynoed at 670 with 42lb injectors. We still do not know what the fuel delivery was at that time, but the fuel delivery system that was sold as a kit with the car was a 110 gallon/hr pump that was delivering 40 psi. Keep in mind that this engine has a 9lb supercharger?

Hold the phone! Supercharged, then OF COURSE you can kill it VERY easily with a lean condition; I concur. However, I'll still bet that the failure mode was detonation...which is even easier to achieve with a supercharged engine; especially if the timing was too high. What was the total advance?

Injector size. If it dyno'd 670 on an engine dyno with 42lb/hr injectors without running lean, that's the first Ford I've ever seen do that. You should not have been able to get past 630fwhp at 12:1 AFR and I wouldn't be running a 670fwhp supercharged engine any leaner than 11.5:1 AFR personally; so it should not have made it past 600fwhp with those injectors unless you did something and raised the fuel pressure well beyond the 40ish psi typical operating pressure.

That said, 42's are too small, 48's are barely large enough; and I'd go directly to the Mototron 55/60's...why not; there's little reason not to...they can be tuned down just fine. I street 160lb/hr injectors in my cobra...if I can do it with 160's, you can do it with 60's easy.

Spark. Tell me what heads are on it, and what the static compression ratio is, and I can tell you what the spark should have been up top for CA 91 fuel with 9lbs of boost. Also, what kind of supercharger? Centrifugal or screw? I keep experimental records of every engine I've tuned since the late 80's...I have notebbooks full of small block ford data.

If you're building your fuel system now, you should use a -6 feed/return minimum; and there's little reason not to go to a -8 feed...it's about the same cost. What are you using for a fuel pump? Hopefully not one of the A1000's or similar; seen many many of those not live, and when they die the failure mode takes the engine with it. The seals start to give and pump output decreases as the pump warms up...which leans out the engine and kills it every time. I'd use either a pair of walbro pumps in parallel, or go directly to a pump design like a weldon or similar that doesn't use the fuel as a pump coolant; the best solution. Those flow-through pumps heat the fuel up. Using a pump controller helps, but the best solution is to not use the fuel as a motor coolant.

Anyway, rambling...

Byron