Indexing a crankshaft

[L.Fite]

Originally Posted by SS/AM

Read again, ALL stock and super stock combos are induction limited, your gains are theoretical and do not exist in the real world.

So...
396 BBC makes same HP as 413 BBC?
Or 396 Vs. 427 or 443cu.?
Same cam same carb..?
Or are we just talking about the 2-4cu. from the .013 in the crank?

May not mean much but if you're serious why wouldn't you take all that's allowed by rules...

[Billy Nees]

Originally Posted by SS/AM

Stroking a crank for a stock or super stock is worth nothing, you're induction limited, so increasing cubic inches is pissing in the wind. Narrowing the bearings is worth something.

Torque accelerates the vehicle.
(I can't wait to see/hear the responses to this one!)

[Alan Roehrich]

Traditional class cars get fast by the gain of hundredths of a second now. For any combination already run by anyone who can go reasonably fast, all of the tenths have long since been found. Especially when it comes to truly legal cars.


Until the engine reaches the speed at which the limitations come into play, every little bit of bore and stroke helps, creating displacement and compression. Yes, at a certain RPM, the gains reach the point of diminishing returns. Part of it depends upon how much pumping losses begin to eat power, or at least prevent it from being produced. Yeah, a couple of mine in Stock well exceed the 1.5" of vacuum, I've seen as much as 2.2". The question is, how do you make sure that the cfm moved there doesn't get out the exhaust before it is used to create power?

[Billy Nees]

Originally Posted by Alan Roehrich

Yeah, a couple of mine in Stock well exceed the 1.5" of vacuum, I've seen as much as 2.2". The question is, how do you make sure that the cfm moved there doesn't get out the exhaust before it is used to create power?

It wasn't uncommon for my 6 cylinders to pull 5" of vacuum on the finish line (ask Doug, the newly graduated engineer!).
In a "Stocker" because there are limits to the cylinder head and intake designs allowed on a combo the biggest gains will be found in the camshaft designs.
When I'm asked, I will generally tell a Racer to find the restriction in his combo and design the cam and the combo around that RPM. Of course the Racer will have to find that RPM limit and that will take some trial-and-error. There's no sense in putting a 8000 RPM cam in a 6000 RPM combo. A mistake that I see too often.

[Alan Roehrich]

I kinda got caught up in the idea of having to have X duration, and Y LSA, to run Z RPM.Got to talking to George Bryce, and he told me that duration, overlap, LSA, and ICL were all PRODUCTS of where your opening and closing events needed to be.


Yes, torque is the force that moves the vehicle. HP is the result of a formula, and a measurement of how much work is being done in a given amount of time.