392 stroker REDLINE Help please???
 

Hi Gang,

I have a fairly new 392 Ford Crate stroker (430 horse) in my Backdraft and have been told by one person) to keep the maximum REV's on these storkers fairly low. I have about 1,500 miles on the motor now and it is doing great so far and I don't want to GRENADE it! I have been running a 6,000 RPM chip in my MSD Rev limiter but that sure seems low to me.

What do you think? What would you feel might be the maximum
RedLine for this motor?

Here's more details if it will help you:
Stainless steel engine compartment panels. Ford Motor Sports (crate) 351 (392) CID 430 HP, 450 ft/lb. of torque @ 4,000 r.p.m., 9.7 to1 compression. GT-40 Ford Aluminum 1.94" and 1.54" Racing heads # M-6049-X303 and GT-40 valve train. Hydraulic roller cam and roller lifters. .566" intake and .576" exhaust @ .050" is 232 degrees intake and 240 degrees exhaust. Firing order 1-3-7-2-6-5-4-8 It uses a Victor Jr. single plane manifold and a Demon 750 carburetor. Motor # 351W FMS 6007-A392 with MSD AL6 ignition w/rev limiter.

You in-put please!

THANKS
Doc

Redlines are different for different reasons. Most redlines are determined by the practical application of physics. That, is if you go to fast for too far, things break. There is however a point most engines just don't make any more power no matter how fast they turn.

The question of how far how fast must be determined by you and your engine builder. I say by you because you spec'd the parts he installed and I say by him because he's got to warranty the thing if it breaks.

Most performance engines will rev well past the point we may usefully drive them. A well built small block (stroker or otherwise) may have a mechanical limit of over 8,000 rpm. It may only make useful power to 6,200 rpm depending on camshaft selection, duration, lifter choice etc.

You should know where this point is and know going past it is useless. If the point is sufficiently high enough to begin worrying about mechanical failure you may want to find it once (typically during dyno tuning) and set a livable value (say 80-85% of that number) and call that redline.

I know one 1966 427 Cobra owner that has the word "think" in Dymo label stuck to his tach. I know another with red paint marks on the glass of his. Both are examples of self imposed redline well below the mechanical ability of their machines.

If you must have a number and are not going to dyno tune the engine take it out after it is run in and wind it up in 3rd. Note the rpm where power begins to fall off. Take a couple hundred rpm off that and call it redline (this allows for the amount of time it took your brain to realize power was falling off).

If you get to a point power has not fallen off but you decide enough is too much call that redline. 80% of 8,000 is 6400 rpm

I understand and plan to DYNO it this next week to see where the power starts falling off for sure. But the damn thing pull so hard at any time, any gear it's really hard to tell. Ha

Thanks for your input. I think I will run a 6,400 RPM chip in it for the next race (unless the Dyno tells me otherwise.).

Thanks
Doc

The dyno is the only way to tell....But generally a longer stroke engine will have a lower redline just due to the mass of the reciprocating assembly.

My engine is 425ci.....using a 4.100" stroke and a 4.060" bore. Max torque was at 4500 and max power was at 5400. I have it chipped at 6000. We spun it to 6500 on the dyno....I didn't think that was too awful high considering the quality of the bottom end components that I put in it....but it just quit making power above 5400....so there's no need to spin it any faster.

I've heard of more than one Ford Racing 392 stroker that came apart so it might be prudent not too push to hard until the dyno tune. Find yourself a Nov 2000 issue of Muscle Mustangs & Fast Fords, in their article a 392 crate stroker with 30 degress of timing and through mufflers they made 461 Hp and 454 lbs.-ft. of torque. Peak power occured at 5800 rpm, peak torque at 4600 rpm. Changing to AFR 185 heads yeilded 537 Hp at 5900 rpm and 505 lbs.-ft. torque at 4900 rpm with no other changes.

Thanks guys for your input and I do understand all of what you've said and I totally agree with you.

My only point of wanting to raise the RPM just a tade is so I can hang it in one gear a bit longer down the straights of a road course. I just hate to have to shift into 4th for only a hundred feet and them back donw in to 3rd. The extra 400 to 500 RPM's might be able to carry me the extra distance. At that point I'm not worrying about MAX horsepower or the curve. It's all about getting past the car next to you and beating them into the next turn.

Doc

Doc, you should shift it below 6k if you can and give the crate motor a longer life. Buzzing it past 6k at the end of a staight is probably ok. I do the same thing with mine. Scott