FastKat

iTrader: (10)

Ya know, the more I think about it, I wonder if there's a difference between the torque at the flywheel and the total load on the crankshaft? Like you said, that procharger is going to put an extra load on the crank. I think most of it will be on the power stroke, because that is where torque is actually being applied to the crank. Since the power stroke (at the peak of the burn) is a compressive load, you should be okay from a piston and con rod point of view. However, it is going to put an extra load on the crank. Say you have 800ft/lb of torque at the flywheel.... and the procharger requires 200ft/lb of torque to run... that means that 1000ft/lb of torque is actually being generated by the pistons pushing down on the crank. I think that is the "real load" that I mentioned above and I think that is what you really need to pay attention to and compare with what other people are running on stock and aftermarket stroked cranks!

99.9percenter

iTrader: (2)

"I notice alot of the fast guys are not using big strokes. Is this because of the greater exposure to harmonics which probably could be a real issue with such high stress loads on the crank (especially with a blower) or is this because they blow the tires off with all of the torque."
I believe alot of the fast guys spent all their money on cylinder heads,power adders, and chasis work and don't have money left over for bigger motors.

DAPSUPRSLO

iTrader: (14)

But these guys aren't on stock cranks and it wouldn't cost them anything to get a 3.622 version or a 4" or larger version. Ronnie Duke for instance, he runs a smaller then 4" stroke (maybe smaller then 3.622" stroke). Just curious why they would choose the smaller crank when money has nothing to do with it. This does not include the stock crank guys.

99.9percenter

iTrader: (2)

Well... a bigger stroke will lower the rpm of max power but not change max power much (cylinder head flow limited). Also if a class is based on pounds per cubic inch a smaller motor is an advantage. The risk of preignition goes down as rpm goes up. During (most) races they are not cruiseing around at low rpm looking for throttle response (like me with my stroker) Its ALL done at way high rpm.

sb427f-car

Um, not nessecarily FastKat. HotRod just ran an article about a month ago. Of course we debated the hell out of this while many other people were still going "which cam" but here's the other read that semi-dispells this "myth"

https://ls1tech.com/forums/showthrea...ore+vs.+Stroke

FastKat

iTrader: (10)

If you're fixed by a rulebook on a number of cubes allowed, then the decision becomes much more complicated. If you're trying to decide whether or not you want to stroke your own car, then that's a little different... I think I'd have a hard time finding people to say adding cubes to a 346 LS1 whether in stroke or bore is a bad thing for the strip or a daily driver.

The article excerpt did bring a lot of stuff to light... I haven't really gotten into BMEP yet... that's my next topic to research

And to be fair, increasing your stroke DOES increase your torque arm but it also increases your total displacement, all other things held equal.

Pro Stock John

iTrader: (34)

Piston velocity.