Quote:
Originally Posted by Demon Z
What are the determining factors that make the former more desirable in high hp apps?
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Let me see if I have a simpler answer:
Detonation.
Can't speak for every motor made nor even for a Nissan motor, but the later model small block Chevys limit for safe boost using stock hypereutectic pistons is right around 6 psi. You can do water or alcohol injections to raise it some, but seen a ton of supercharged F-bodies break stock pistons when taken over that limit.
So.......the simple answer is you can safely run higher boost vs stock pistons/stock compression. The bottom line is if you're going to run a relatively mild amount of boost, stock pistons/compression is fine. Only an inexperienced fool would try to run high boost w/o proper block prep as your begging for almost instant trouble.
On a side tangent, the upper limits regarding N/A compression depends upon the particular motor. We put the wrong head gasket on my Corvette and unknowingly ran 13.3 to 1 thinking we were only 12.8 to 1.
Except for running a bit hot during Dallas 100 degrees days, the car ran perfect on 93 octane gas using timing tables higher than the stock. This was mainly due to the reverse cooling head design for the LTx motor.
The commonly held urban legend taboo is about 12.5 to 1, however that's how urban legends self-promote and propagate themselves as no one tries anything different.
Again, clueless regarding Nissan but it sounds like a moot point if increasing compression requires replacing pistons as I doubt there is much more to be had in power gains vs the hassle.