Originally Posted by topwrench
You cant prove a negative,Ralph Johnson,(Smokey's right hand man) went to work for Crane cams he was the head of r/d at Crane,I believe you can still call him.
So when it is said that Smoke didnt have the current technology and that he was years ahead of his time,those 2 staments,in a big way,contardict each other,this long rod theory is a matter of physics and thermodynamics and it works for me.
And as far as head flow go,I can tell you Smoke had the biggest rootes blower flow bench I've ever seen,the numbers he got in '85/86' were incredible!
Reverse flow cooling was invented and developed by Smoke.
The experiment I mentioned above is absosutely correct and that should speak for itself .
One thing about it is ,throwing a long rod in an engine without tuning the engine for this is at best futile,kinda like puttin a wild cam in a stock engine,wont work.
Think about when piston dwell is increased what you can do with.
2 piston/combustion chamber shape
3 valve size
4 rocker arm ratio
5 Induction and exhaust system
Rod lenght is tied to the stroke lenght of the crank and the ratio beteew the two is most definetly a significant factor.
On a dyno the engine will always produce more torque and horsepower when the rod ratio is increased,I dont know how the experiment you mentioned was conducted, I just know what i personally have seen and studied and long rods definetly work!
One catch, engine HAS to be tuned for long rods so you cant just change the rod lenght on the same engine and expect to see results.
69cst wanted to know why and i just explained it to him,thats all.
So maybe insted of just saying somebody tried to prove it wrong,please tell me in thermodynamic and entropy terms.why not?
And you can,with me anyway go in this rabbit hole as deep as you want.
And it is a deep one.
It has a lot less to do with thermodynamics than you think. If anything it would fall under fluid or gas flow dynamics. And piston dwell at TDC is only a small part of it. You're making a decision based on 10 degrees of a firing cycle and there are 710 other degrees that have an impact.
Short and long rods both have their place. For a lower RPM engine (5500 RPM redline in this OP's question) with moderately sized heads short rods will do better- albeit not a very large difference between the two. The biggest advantage in this case is simply oil ring support (no pin through the ring pack), it'll also allow you more room to place the top and second ring.
Long rods would work well in a 383 trying to spin to 6500 RPM's with stock Vortec heads. In this case the 5.7" rods will give slightly better throttle response, slightly better torque, and (MOST IMPORTANTLY) increased durability over both 5.565" and 6" rods.