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2JZ Na+T, CR and Quench

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Hello there,

I am building 2jz GE VVTI engine, that will be my first that I will tune myself :)

My old engine ended with 2 snapped valves, melted or crush piston, bend rod and a hole in the block.

I was using the stock GE pistons with ZRP I-Beam rods and thicker HG. The fuel was E50 and CR 9.31.

I suspect pre-ignition was the cause for failure.

After that happened I decide to check my tune, and I found there is no knock protection... so I completed HPA tuning courses, to be sure what is going on with my engine.

However the topic is for my new build, I will write in details soon about it.

Got an another 2JZGE VVTI engine, new rods (ZRP I beam - R-TOY-006-I) and new pistons (K677M8650AP).

Here is the issue - the pistons are rated 9.5 CR but in GTE motor...

That is my mistake here!

Good news are they are flat top and milling is possible, but I don't prefer it.

I know the quench has to be from 0.8mm to 1.5mm to be some use of it.

But with those pistons and without milling them I got very high CR.

The engine goal is 600-700 WHP, that is Drift engine with a lot of time on rev limiter.

So after some math I got this:

Head Gasket - 0.6858 mm, CR - 11.07, Quench - 1.36 mm

Head Gasket - 0.762 mm, CR - 10.98, Quench - 1.43 mm

Head Gasket - 0.9144 mm, CR - 10.81, Quench - 1.59 mm

I am not sure that is save CR even on E85 tune.

So what road to take

CR below 9?

Quench below 1.5mm ?

Or maybe Quench below 1.5 and milling the new wiseco pistons 2-3 mm?

Or Quench doesn't meter on 22-25 psi of boost on E50/E85?

I will be happy to get some advice and opinions here.

Quench helps to speed up combustion process and as the result of that reduces knock threshold. With high octane rating fuels knock is much less of an issue. Secondly, the spirit fuels burn faster than gasoline. So in my opinion the way to go is to reduce CR by thicker gasket. That's what I have done on my drag race engine seeing up to 3.4 Bar of boost on E66( ethanol mixed wirh Q16)- decreased CR to 8.4

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