quench article

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I love quench. My current motor has .040 of quench and is 12.34:1. sounds like 13.5
Don't need as much timing either... less neg torque.
I built a street motor 20 yrs ago with quench that was 9.9:1 that was very detonation resistant.
 
I'm running with .029 - .030" quench height on my 360:1
KB pistons, shaved '302'-heads. 11.3:1cr.
I haven't found the need for less timing yet, but I'm running propane which likes plenty of advance, but limited to 32° at 2800.
I've streettuned my digital timing table for well over a year and can't really find more torque in much of the lower rpm-ranges.
But maybe with the aluminium heads I will install soon, that might change again.
 
I run .028 even on my 440 and .025 on a chev 6 (305 pistons)
that .035 absolute minimum is crap
that .040 works
.050 less so
no quench sucks big time for reason above (timing and detonation, gas)
 
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Big Block
We developed those pistons (if you are using the pop up ones) with TMS propane performance and Speed-O-Motve- lots of dyno time (which kb piston?)
great combination
also really lowers EGT with proper (low overlap) cam selection
works even better on 440 which has a much worse spark plug location (like trying to ignite a pancake from the side) 413 truck motor was much better
(TMS saw 800 degree reduction on 440 propane buses for City of San Jose and others)(just piston and cam)
 
I've known people who run .020 quench. I've never read one single time about .035 being minimum, but I have read that .035 is OPTIMUM in just about every article.

That said, Plenty of engines run without quench and make plenty of power.
 
RustyRatRod said:
I've known people who run .020 quench. I've never read one single time about .035 being minimum, but I have read that .035 is OPTIMUM in just about every article.

That said, Plenty of engines run without quench and make plenty of power.
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So true. Quench is over rated unless you are talking about early SBC junk. Specifically, the spark plug location on the SBM is about the best it can be, outside of the Hemi. That's more important than quench. By a long stretch.
 
you can make plenty of power without quench- we did running stock classes high rpm and not running below the torque peak
it's making a big fat torque curve down low where it really helps- less fussy on timing and fuel
read the article about turbulence in the chamber
btw LA likes long reach plugs (not for racing)
why is that if the plug location is so great?-- well it is compared to a big block
or as said above early SBC (that's why the TRW "TURBO" piston)
 
dartfreak75 said:
Can you run pump gas with quench @ that high of a compression?
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Yes but it is also a matter of the cams size in order to reduce the dynamic compression ratio down to a pump gas level. Otherwise, you can run ether a mix of race fuel with it or E-85 as the octane rating is high.

The wife’s and my current 360 are very close to 11-1 & use 93 octane.

Pay attention to the timing!
 
I still don't get why Chrysler bothered to use closed-chamber heads on engines where the pistons are .050"+ down in the hole. Even the Magnums are .050" below deck, no quench to speak of in those. I bet if the pistons were at or close to zero-deck those engines could handle a full extra point of compression, heck the 5.9s had occasional pinging issues on low-grade gas and they were only 8.8:1.

I was complaining about that to friend of mine up the street who is a serious Ford guy and builds engines with his dad, he told me Fords don't really have that problem. They all came with essentially zero-deck pistons and compression ratio was determined by head chamber volume. It's not fair!! lol
 
MopaR&D said:
I still don't get why Chrysler bothered to use closed-chamber heads on engines where the pistons are .050"+ down in the hole. Even the Magnums are .050" below deck, no quench to speak of in those. I bet if the pistons were at or close to zero-deck those engines could handle a full extra point of compression, heck the 5.9s had occasional pinging issues on low-grade gas and they were only 8.8:1.

I was complaining about that to friend of mine up the street who is a serious Ford guy and builds engines with his dad, he told me Fords don't really have that problem. They all came with essentially zero-deck pistons and compression ratio was determined by head chamber volume. It's not fair!! lol
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Crap fuel and emissions
And reliably. A low compression engine will run forever!
 
MopaR&D said:
I still don't get why Chrysler bothered to use closed-chamber heads on engines where the pistons are .050"+ down in the hole. Even the Magnums are .050" below deck, no quench to speak of in those. I bet if the pistons were at or close to zero-deck those engines could handle a full extra point of compression, heck the 5.9s had occasional pinging issues on low-grade gas and they were only 8.8:1.

I was complaining about that to friend of mine up the street who is a serious Ford guy and builds engines with his dad, he told me Fords don't really have that problem. They all came with essentially zero-deck pistons and compression ratio was determined by head chamber volume. It's not fair!! lol
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I think it was Pontiac also did that, cylinder head cc thing.
The thing with the Chrysler engine is they used basically 2 cylinder heads. 273/318 & 340/360. This keeps expenses down and variations low. On the Magnum series, it’s just one head.
With another full point of ratio, the engine would be premium fuel only and probably cranky with the super small cam that they used in production.
 
I believe Jim Laroy's made 700 plus HP without quench so it must not be real important.
 
no one is saying you can't make hp with an open chamber head
In fact you might may make more top end than with a closed head
but the closed head will run much better when not rowing the gears
 
Wyrmrider said:
no one is saying you can't make hp with an open chamber head
In fact you might may make more top end than with a closed head
but the closed head will run much better when not rowing the gears
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All I'm sayin is, quench ain't the end all be all that all the magazines and forum heroes make it out to be. Everybody reads all these articles in these magazines that have sponsors throwin expensive parts at them push. There's your clue. Those editors will say anything their sponsors want them too.

People go runnin out and spend all kinda money on a quench engine so they can push the boundaries of what pump gas will run on for what? 20 more HP? Ok, let's say everything is a great match and say 50 HP. Then, if they make one tiny mistake guess what? they have a big heavy expensive pile of metal that has to be spiked with race gas.

The bottom line is, you want to be safe on pump gas? Keep static no more than 9:1 and dynamic no more than 7.5.

There's a LOT more at play than "JUST" SCR and DCR. There's load, temperature, humidity, traffic, how good the cooling system is, how many fat women you're haulin around.......all that stuff can make an otherwise pump gas friendly not so pump gas friendly......and at the WORST possible time is when it WILL happen.

This right here is why we keep seein threads like "my engine is runnin hot" over and over and over and over again.

Boundaries are just that. With a 100% street car, they should be adhered to. Want that 9:1 motor to haul butt? Put good heads on it.
 
RustyRatRod said:
All I'm sayin is, quench ain't the end all be all that all the magazines and forum heroes make it out to be. Everybody reads all these articles in these magazines that have sponsors throwin expensive parts at them push. There's your clue. Those editors will say anything their sponsors want them too.

People go runnin out and spend all kinda money on a quench engine so they can push the boundaries of what pump gas will run on for what? 20 more HP? Ok, let's say everything is a great match and say 50 HP. Then, if they make one tiny mistake guess what? they have a big heavy expensive pile of metal that has to be spiked with race gas.

The bottom line is, you want to be safe on pump gas? Keep static no more than 9:1 and dynamic no more than 7.5.

There's a LOT more at play than "JUST" SCR and DCR. There's load, temperature, humidity, traffic, how good the cooling system is, how many fat women you're haulin around.......all that stuff can make an otherwise pump gas friendly not so pump gas friendly......and at the WORST possible time is when it WILL happen.

This right here is why we keep seein threads like "my engine is runnin hot" over and over and over and over again.

Boundaries are just that. With a 100% street car, they should be adhered to. Want that 9:1 motor to haul butt? Put good heads on it.
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All true , but I like to quench them all. I ran a 426 hemi for 14 yrs with the pistons kissing the heads just enough to keep the carbon cleaned off at 6500 rpm, Tom Hoover said it was just right . Works for me , I have .039 on my 505, and have been running 91 octane , but have since found 93 , 3 miles from my house.
Strangely enough the new "kum and go" convenience store is right beside a new dodge dealer ship that sells hellcats, wondering if the dealership had anything to do with the 93 being sold there. First 93 I`ve ran across around here .
 
famous bob said:
All true , but I like to quench them all. I ran a 426 hemi for 14 yrs with the pistons kissing the heads just enough to keep the carbon cleaned off at 6500 rpm, Tom Hoover said it was just right . Works for me , I have .039 on my 505, and have been running 91 octane , but have since found 93 , 3 miles from my house.
Strangely enough the new "kum and go" convenience store is right beside a new dodge dealer ship that sells hellcats, wondering if the dealership had anything to do with the 93 being sold there. First 93 I`ve ran across around here .
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I don't disagree at all. I'm just sayin I think people put too much stock in it. In other words, if you have everything for a non quench build, don't reinvent the wheel and change it up. Build what you have.
 
RustyRatRod said:
I believe Jim Laroy's made 700 plus HP without quench so it must not be real important.
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I had 160 thou quench Bob. Zero deck, .120" deep combustion chamber on the 906 heads and a .040" gasket. 160 thou.
 
RustyRatRod said:
All I'm sayin is, quench ain't the end all be all that all the magazines and forum heroes make it out to be. Everybody reads all these articles in these magazines that have sponsors throwin expensive parts at them push. There's your clue. Those editors will say anything their sponsors want them too.

People go runnin out and spend all kinda money on a quench engine so they can push the boundaries of what pump gas will run on for what? 20 more HP? Ok, let's say everything is a great match and say 50 HP. Then, if they make one tiny mistake guess what? they have a big heavy expensive pile of metal that has to be spiked with race gas.

I'm glad you could put in print what my jumbled mind thinks. How many projects are never completed or sold for pennies on the dollar because it has to be built a certain way and no other will work. Or so they are told. Not saying the other way is wrong, maybe just not right for the majority of people. I'd love to have a zero deck, flat top piston 360 with Edelbrock Magnums with all sorts of neat valvetrain pieces. But the stock 360 short block with pocket ported 587's and stamped steel rockers arms would get the engine in the car a bunch quicker and a whole lot of more smiles per dollar. IF the beater 360 could run 13's and the sophisticated quench engine ran 12's, which would be a bigger surprise to people? Thanks for letting me rant. No rights, no wrongs, just what the $$$ will allow.
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Oh absolutely. ....and I'll reiterate, I'm not saying quench is wrong. I'm simply saying build what you have. There are advantages to each.
 
I like the tight Q cuz I can run 87E10@185psi (or more) with aluminum heads, and with one size smaller cam,than I wanted to run;and so, that makes tons of low-rpm torque,and gets mega-fuel-economy.Over 100,000 miles, that would add up to a lotta lotta cash saved.
That combo was very happy with idle-timing of 12, and 28*@2800, and topped out at 32 to 34@3400.
The Q was .039, and Scr was 10.8............... wiped lobes.
Changed cams ( next bigger), and decked the block for KB107s at plus .005 out of the holes, and latest combo is .034Q/10.95Scr. Lost some low-rpm torque, gained some power at the top, ruined my fuel economy. About same psi.About same timing curve. Different trans to make up for the lost first-gear torque. I could hardly believe the low-rpm torque loss of just 7* difference in durations. New cam likes more idle-timing, but with a manual trans it gets too jumpy at the bottom of first gear, so 14* is all it gets.
 
7*’s is a good bump up and I’m not surprised to read that.
 
IQ52 said:
I had 160 thou quench Bob. Zero deck, .120" deep combustion chamber on the 906 heads and a .040" gasket. 160 thou.
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How much timing could u put in them ? What is the lowest octane u could run with enough timing to make it run best ?

Interesting -----
 
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