Quench

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What engine exactly are you spraying and how much?
 
Stock. Had this together already but needs new pistons oversized but same pistons. The pistons never hit the heads and i turned it 7000+ rpm. But I'll tell you there is no carbon on the pistons in the closed part of the chamber. Just asking cause I heard quench is bad for nitrous.
 
The more efficient a chamber is the less timing you need as we all know, with a small 100 shot I wouldn't worry at all but would come back on the timing a bit more than normal first (especially with a lean fuel jet) and then perhaps creep up 1 deg at a time and watch your plugs and mph to tune for both.
 
aaronk785 said:
Stock. Had this together already but needs new pistons oversized but same pistons. The pistons never hit the heads and i turned it 7000+ rpm. But I'll tell you there is no carbon on the pistons in the closed part of the chamber. Just asking cause I heard quench is bad for nitrous.
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I agree the clearance might be tight for nitrous. I asked about the rods because if you were running aluminum rods, then you'd be in trouble. Probably will be good like it is. I would maybe open it up to .045.
 
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What head gasket are you planning on running? Reducing quench makes nitrous more easily (i.e. safer/more forgiving) tunable according to the folks who market and sale systems.
 
aaronk785 said:
Is .032 quench to tight for nitrous.
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40 is good 35 is better. If you have good machine work done. Aka piston don’t rock in the bore, deck is square. Pistons all at the same height in the bore................now add more heat in the combustion chamber aks more expansion.
If it was my engine I would say .032 is to tight. ????????
 
Yes. Depending on how much or long your spraying it for and and how much. I myself would play it safe and have the chambers radiused too for a little extra clearance. As far as how much it is radiused, I l would use these head gaskets to use both as a template and to run with. https://www.summitracing.com/parts/fel-17050
 
Are you taking about radius the bore, combustion chamber, or both.

I would imagine if you radius the combustion chamber to the above gasket size, there would be a shelf between the head and bore.?.?
I guess what i'm asking is why does a radius combustion chamber make it safer when you spray.
 
Well I will say it’s probably overkill with a 100 shot, but the Felpro 8553 has a gasket bore of 4.18, so that gasket reduces said shelf amount by .020. And there is still a space between and the decks, but it’s not a .045-.055 inch gap that’s recessed back .070 from the bore between the block and head. Now it ‘s hopefully a 1/16 inch gap that is roughly 1/32 (with a .030 overbore) distanced from the edge of the cylinder between the block and head that gradually blends as it makes its way to the chamber. The idea is to get rid of the gap between the chamber that end gasses can wait around in to potentially cause detonation. The best option is a cometic gasket that is .020-.030 larger than the bore size (if you have the proper RA finish on the decks. Then you could go with a thick enough head gasket to avoid having radius the chamber. Another option (and the one I would use if the bottom end is already together) is a Mr. Gasket .040 thick rubber coated MLS head gasket with a 4-1/8 inch bore, and the chamber recessed.030 deep. It is overkill for a 100 shot, but I’ve never met anyone who was content with a hundred shot. Once the nitrous bug bites, you’ll eventually want to see how much it can run on. And that’s why I believe in overbuilding anything that’s going to be sprayed. It’s just too easy to turn the power level up on to see what you can get out of it.
 
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.035 is considered optimum quench for a street engine, .032 ant much tighter!! pretty sure AJ/FormS is running a tighter quench that that on his street 367!!
 
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