I have head a rumor floating around on a way to get 15-20 more horse power and I was wondering if anyone else has heard of this. Susposedly if you get a camshaft machined so that the cylinder 4 and 7 lobes are switched and then you switch thewires so that the fireing order goes from 18436572 to 18736542 it allows the motor to get 15-20 more hp but will decrease the life of the motor (wont last 100,000 miles) because the change will cause more stress to the crankshaft.
Has anyone else heard of this before????
-Doug

 

It has to do with a theory about exhaust scavenging and firing order. Not sure if it is true, but it is based on some sort of science.

 

wouldnt it be a hell of alot easier to just put a better intake or carb or anything instead of grinding a custom cam and installing it?
I would think if it were true and it would not damage the motor gm would be building them??

 

Ok, I found the basis for this theory. Witht he way that a cross plane V8 fires, technically the #4 primary should join the collector on the other cylinder bank, and the #7 primary should join its opposite cylinder bank for correct scavenging. I have no idea in the world if changing the lobes and firing order would produce any gains at all, but I am guessing that is where that theory comes from.

I would imagine that the inceased wear would come from the firing order being incorrect for the balance of the engine, and if you remember physics correcty, the firing order does affect the balance of the engine, since everything is balanced based ont he acceleration of certain components, as well as their weight. With the pistons accelerating at different times than they were meant to, stuff will get screwed up real quick. Maybe not noticable, but your bearings might feel it through the crank. This is why an inline 4 sufferes third order vibrations. Mechanically, everything is balanced perfectly, but the outside piston accelerating faster than its counterpart on the other side of the engine causes third order vibrations.

 

Well there is only so much you can do with intake and carb and other stuff.My thought is it would be better for more of a raceing engine. And GM does know about it but dosent build them because they want their motors to have a long life

 

The 12-2004 issue of Chevy High Performance mag did just this. The theory was that since #5 & #7 fire in sequence, #7 wasn't getting as much fuel/air and theory wasn't developing as much power. The results: (drum roll) No Change!

 

Good heads, manifold, nasty cam and Flowmaster exhaust and you could be looking at 75-100HP.

 

And don't forget ignition... no matter what you do in the intake- exhaust department... it really won't matter if you are still using points and that weak *** stock coil. 40,000 volts or better... why light up with a match when you can use a torch...
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I hear you, that't why I run MSD etc.

 

simple answer: DONT DO IT!