Proper Quench distance for LT1
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Pro
Joined: Jan 2009
Posts: 686
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From: Austin Texas
Proper Quench distance for LT1
From:
http://home.hiwaay.net/~langford/corvair/valvejob.html
"Since I did my heads, I learned from Corvair high performance expert Ray Sedman that best resistance to detonation is obtained by keeping the total deck height (distance between top of piston and the head's flattened "quench area") at somewhere between about .042" and .025". This kind of close quench distance allows running higher compression, lower grade fuel, and more "headroom" before the onset of detonation. "
Certainly would seem to be applicable to LT1's. Is this a good range for LT1's as well ? Seems so.
I'm pondering also the significance of the two small plateau areas cast in to the LT1 heads on the sparkplug side wall of the combustion chamber. One, having an area of about 2 square centimeters is recessed from the head's main flat portion about 10 thousandths, and the second, smaller area plateau is recessed about 20 thousandths. They're probably cast in there like that for a reason, but I don't understand it - yet.
http://home.hiwaay.net/~langford/corvair/valvejob.html
"Since I did my heads, I learned from Corvair high performance expert Ray Sedman that best resistance to detonation is obtained by keeping the total deck height (distance between top of piston and the head's flattened "quench area") at somewhere between about .042" and .025". This kind of close quench distance allows running higher compression, lower grade fuel, and more "headroom" before the onset of detonation. "
Certainly would seem to be applicable to LT1's. Is this a good range for LT1's as well ? Seems so.
I'm pondering also the significance of the two small plateau areas cast in to the LT1 heads on the sparkplug side wall of the combustion chamber. One, having an area of about 2 square centimeters is recessed from the head's main flat portion about 10 thousandths, and the second, smaller area plateau is recessed about 20 thousandths. They're probably cast in there like that for a reason, but I don't understand it - yet.
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
From:
http://home.hiwaay.net/~langford/corvair/valvejob.html
"Since I did my heads, I learned from Corvair high performance expert Ray Sedman that best resistance to detonation is obtained by keeping the total deck height (distance between top of piston and the head's flattened "quench area") at somewhere between about .042" and .025". This kind of close quench distance allows running higher compression, lower grade fuel, and more "headroom" before the onset of detonation. "
Certainly would seem to be applicable to LT1's. Is this a good range for LT1's as well ? Seems so.
I'm pondering also the significance of the two small plateau areas cast in to the LT1 heads on the sparkplug side wall of the combustion chamber. One, having an area of about 2 square centimeters is recessed from the head's main flat portion about 10 thousandths, and the second, smaller area plateau is recessed about 20 thousandths. They're probably cast in there like that for a reason, but I don't understand it - yet.
http://home.hiwaay.net/~langford/corvair/valvejob.html
"Since I did my heads, I learned from Corvair high performance expert Ray Sedman that best resistance to detonation is obtained by keeping the total deck height (distance between top of piston and the head's flattened "quench area") at somewhere between about .042" and .025". This kind of close quench distance allows running higher compression, lower grade fuel, and more "headroom" before the onset of detonation. "
Certainly would seem to be applicable to LT1's. Is this a good range for LT1's as well ? Seems so.
I'm pondering also the significance of the two small plateau areas cast in to the LT1 heads on the sparkplug side wall of the combustion chamber. One, having an area of about 2 square centimeters is recessed from the head's main flat portion about 10 thousandths, and the second, smaller area plateau is recessed about 20 thousandths. They're probably cast in there like that for a reason, but I don't understand it - yet.
Quench is a tricky thing to start tightening up too much on. RPM, Piston alloy, weight and Rod type play into it.
With good light weight 2618 pistons and good 4340 H beam rods you can get away with the quench around .035 to .040.
I've had oval track motors bump when we run it less than .030.
Will
Last edited by rklessdriver; May 3, 2009 at 03:09 PM.
