How does it do that?
Didn't Grumpy and Smokey disagree about rod length? I thought Smokey said to "use the longest d_mn rod you can fit," but Grumpy liked shorter rods. Could it have had anything to do with the fact that Yunick built motors for extended high rpm use, and Jenkins built (and still builds) engines that operate at high rpm only for very brief periods of time?

 

Yep, endurance and drag motors are built a little differently. Tough to compare one to the other because all the components work as a system... at least the good ones do.

What Bret is referring to is in the fact that shorter rod motors pull harder on the cylinder head from just after TDC of the intake stroke to 90º ATDC. So... if you have a port that is sub-optimal, with say.. a long duration camshaft, you might see some power using a longer rod.

I do like the idea of using a longer rod and it's lighter/shorter piston but I don't think there's any need in losing sleep thinking about the effects of a 5.7 to 6.0" swap in a street build.

-Mindgame

 

This effect can also be used to allow a few things:

1. A shorter rod will allow a larger head port to create good midrange TQ
2. A longer rod will allow a smaller head port to pull higher RPM
3. A longer rod will allow a shorter duration camshaft for a given RPM
4. A shorter rod will allow longer duration camshaft for a given RPM

Running these things in combination can do some interesting things like Mindgame mentioned. I've used a Long Rod, Short Duration cam effectively to extend the operating range of that particular combination. Also a short rod, short duration cam to counter act larger port on a motor. By short duration I mean relative to the RPM, cubes and standard size cam you would run in that situation.

Another good thing is looking at a large small block.... with a longer rod you will allow the heads which are usually small for the application to do a bit better with the extra cubes under them. For example a 6" rod in a 396 LT1.

Bret

 

I think it was Racer Brown that liked short rods.....

Both Smokey and Grump were playing with 327-358 cube motors that they were trying to twist the snot out of with heads that started at 160cc. Today a 9500rpm Cup motor has a port thats in the 280-300cc range on a 358 cube motor.

Bret