Roush vs 427FE vs Keith Craft

[blykins]

Originally Posted by CobraEd

I agree with you on the oil 347 issue. It is just an old wives tale. I also agree about long stroke vs short stroke, but that has nothing to do with the issue at hand. An FE or 385 series crank and rods are noticably heavier and it takes more power/time to spin them up vs a small block unit. It is about rotational weight and nothing more. Again, think of an aluminum flywheel vs a steel one. A proven scenario over and over again and universally accepted that an aluminum unit will spin up much faster. The exact same physics applies to a heavier crank and rods. The premise cannot apply to one and not the other. Both are about accelerating rotational mass. No difference. :-)



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My point was Ed, that was too broad of a statement to make: "the small block will rev much quicker"...

Which FE's? Which small block? What does "rev" mean? Peak hp rpm? Sitting at idle and winging the throttle?

I will say that you are correct in that *some* FE's rotating assemblies are heavier, but not all. If you compare the bobweights between a 427W and a 428 FE, depending on what parts you use, the bobweights can be very similar.

I have also built many 4.250" stroke FE's that rev like chainsaws and pull past 7000 rpm.

It is certainly a case of physics, but you just can't make that broad of a statement, because it's not always true...thus being a lot of the issues about forum misconceptions.

BTW, thanks for the bump.

[CobraEd]

Originally Posted by blykins

My point was Ed, that was too broad of a statement to make: "the small block will rev much quicker"...

Which FE's? Which small block? What does "rev" mean? Peak hp rpm? Sitting at idle and winging the throttle?

I will say that you are correct in that *some* FE's rotating assemblies are heavier, but not all. If you compare the bobweights between a 427W and a 428 FE, depending on what parts you use, the bobweights can be very similar.

I have also built many 4.250" stroke FE's that rev like chainsaws and pull past 7000 rpm.

It is certainly a case of physics, but you just can't make that broad of a statement, because it's not always true...thus being a lot of the issues about forum misconceptions.

BTW, thanks for the bump.

Brent Brent Brent . . . . bobweights have nothing to do with it. They just tune the balance. It also has nothing to do with how high the engine will rev. It has to do with how FAST the engine will get to 7,000 rpm. It is about the TOTAL mass difference of the crank and rods. And of course it is a very general statement and cannot be applied to specific engines. Not a determining factor in building/buying an engine but just a general difference that does exist as a minor factor. As a hypothetical example, if you had a 90lb wheel on a hand crank and a 9lb wheel on the same hand crank, which one would take you longer to spin to 7,000? Obviously the 90lb one. They could both reach the exact same rpm (7,000?) but the heavier one would take longer to get there.


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