Does this prove David Vizard's 128 lsa formula ?

rumblefish360 said

@273 Did you read DV’s book(s)?

I think to many are over thinking this. DV spelled it out.
I also think your posted amount of power loss is a lot. But this may depend on the engine/head/etc combo and how good vs how bad a cam choice can be.

Click to expand...

I've got all his books, I'm not knocking the guy, I'm just not seeing the evidence that his formula is gonna give most optimal results, I'm sure it does ok, and I'd probably use it to a point, see what says for your combo and keep that in mind as choosing a cam. But if you look at what it says for a 340-416 it recommends 109-105 pretty much what people know they would have to run if they wanted a more serious cam for these engine.

The I do like is the basic idea run the better lsa and compromise on duration, so basically if you gonna run a 108 vs 110 lsa you would run about 4 degrees less duration. Which to me sounds like it make sense especially in a street car but there's no proof on that.

But eg.. Low cr 318 the formula say 105 lsa, and say we keep with AJs 48* lvc that would a 254 on a 105 lsa sounds like it would work compared to say 270 on a 113 lsa would have same over lap.