2G pistons on 1G rods----will it knock?

[jfdid]

Hi guys, just sent my block to the machine shop. I have a 6 bolt and I'm replacing the pistons/rings. I'm leaning towards the 2G 8.5:1 compression pistons instead of the 1G's.

Will this jump in compression be a factor in knocking? I'm looking to run about 19PSI on a 16G, with 650's, 190lph, MAFT setup.

Is the little gain in the low end worth the hassel of machining and the probability of more knock.

Thanks guys.

 

[swing lo]

The piston selection that you are leaning towards will have no effect on knock. As you know, knock is detonation ( too lean), which is eliminated in most cars by correct fuel tuning.

You will most likely alway's have knock(unless you play it safe by running way rich, and you still might get some) which is fine as long as you don't get a ridiculous knock count consistantley. As some do, i try and tune for no knock or no more than 7 depending i what my goals are, and what i'm trying to do. The higher compression piston's are worth it as far as more power with less boost, and many have done that mod. Go for it and don't worry about the knock factor; however, it's all in tuning.

 

[kpt4321]

You won't necessarily always have some knock, if the car is tuned right.

Knock is not necessarily a fuel problem, it can also be due to timing (most likely), and charge temp, internal engine temp, etc.

 

[jfdid]

So does everyone agree on this?

 

[jdurston]

The higher the compression ratio the more likely is it that you will have detonation. But 8.5:1 is still faily low. People turbo charge honda b series with a way high compression. Less boost though.
I think 8.5:1 is still safe.