Quench talk
- Thread starter Chevy1925
- Start date
My stock turbo spooled better with socal's 6460 cam but it required valve reliefs iirc
Quick note:
The Quench area is where any fuel/air mix will not burn because the surrounding metal sucks the temperature of the air down below what is needed to light the fuel off.
Running hard, it doesn't matter much. Plenty of heat and pressure to burn off the Quench when it becomes exposed later in the stroke. However, in low power, economy power levels. The fire is mostly out by the time the area opens up. So it never attains combustion temp. So any fuel that gets in the area will not burn or will burn poorly.
So reducing the clearance reduces the opening for fuel to sneak into the dead area.
When there are valve reliefs, The actual small gap quenched area is tiny compared to a stock piston without reliefs. The valve relief, however, will have a quenching affect too, and I have found that anything less than around 0.060" will have quench issues.
So even if you don't really need it, I would go at least 0.075" or greater with the reliefs.
I also don't recommend anything over 16.5 : 1 for compression. You just don't need it and gain nothing from the higher compression other than a engine that rattles.
The Quench area is where any fuel/air mix will not burn because the surrounding metal sucks the temperature of the air down below what is needed to light the fuel off.
Running hard, it doesn't matter much. Plenty of heat and pressure to burn off the Quench when it becomes exposed later in the stroke. However, in low power, economy power levels. The fire is mostly out by the time the area opens up. So it never attains combustion temp. So any fuel that gets in the area will not burn or will burn poorly.
So reducing the clearance reduces the opening for fuel to sneak into the dead area.
When there are valve reliefs, The actual small gap quenched area is tiny compared to a stock piston without reliefs. The valve relief, however, will have a quenching affect too, and I have found that anything less than around 0.060" will have quench issues.
So even if you don't really need it, I would go at least 0.075" or greater with the reliefs.
I also don't recommend anything over 16.5 : 1 for compression. You just don't need it and gain nothing from the higher compression other than a engine that rattles.
So you want a deep relief to keep the fire going in the reliefs and keep from quenching? Never thought about that.
Out if curiosity, what can you expect a cast piston to grow to under a situation where more fuel is used to generate max power than air to 800hp with no use of nitrous? I would assume that due to the higher heat from more fuel than air, the piston would grow more than visa versa going for the same power.
Out if curiosity, what can you expect a cast piston to grow to under a situation where more fuel is used to generate max power than air to 800hp with no use of nitrous? I would assume that due to the higher heat from more fuel than air, the piston would grow more than visa versa going for the same power.
You can expect the piston to expand more with more heat in the chamber. But with cast, I would be more worried about melting the tops than seizing the piston in the bore. Air is your friend.
I mean more for the fact of the piston growing upwards, tightening up quench. We are not talking 100% overs on a stock turbo at 3000uS. Just not making 800hp with no smoke. I leave a good little trail like a stock truck on a max effort tune for all out racing