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At what point is QUENCH not effective? #1459361 06/28/13 05:56 AM 06/28/13 05:56 AM
Joined: Apr 2012 Posts: 1,235 Phoenix, AZ Jjs72D OP Deep in the closet
Jjs72D OP Deep in the closet Joined: Apr 2012 Posts: 1,235 Phoenix, AZ	I have read many, many threads and posts but haven't seen this topic clearly defined. Maybe it is a gray area and hard to determine? Lets say you have a closed chambered Small block head with pistons .020 in the hole with a .039 head gasket. You have a .059 distance between the piston and the head. How effective is the quench? From what I have read, the sweet spot of quench is between .035-.045. What if this engine has a spark knock issue due in part to the high compression ratio. If the .059 gap results in limited quench, would it be safe to assume that a thicker head gasket could be used to drop compression a 1/2 point without a penalty? Jeff I have read that lowering compression via thicker head gaskets can result in more spark knock because of lost quench. My question is: If the engine is already out of the quench zone, would the thicker gasket help matters?

Re: At what point is QUENCH not effective? [Re: Jjs72D] #1459362 06/28/13 09:08 AM 06/28/13 09:08 AM
Joined: Jan 2003 Posts: 10,000 Frostbitefalls MN (Rocky&Bullw... gregsdart I Live Here
gregsdart I Live Here Joined: Jan 2003 Posts: 10,000 Frostbitefalls MN (Rocky&Bullw...	You would lose some benefit, but a lot of it is not there due to being at .059 already, IMHO. If you can, fix it right with setting the proper quench. Study what happened to the same motor when compression dropped from the factory back in the early 70s. That is a big clue as to what will happen to your motor. It all depends on what you want. Do you want it to run the best and spend the money, or do a quick fix and live with a motor that is down on torque? The other thing to consider is what cam you have. If it is bigger than stock, then reducing compression will be a double whammy. The motor will suffer even more loss, because your true compression will take a bigger hit. A total run down on what you are working with would help you get better responses also. There may be other options here, but we need facts to work with. Last edited by gregsdart; 06/28/13 09:10 AM. 8..603 156 mph best, 2905 lbs 549, indy 572-13, alky

Re: At what point is QUENCH not effective? [Re: Jjs72D] #1459363 06/28/13 09:09 AM 06/28/13 09:09 AM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	I cant answer your question(I dont have the smarts or the experience)but I would ask what fuel, timing, cam and where its installed at.. also how hot do you run the engine at and what plugs you run... yes your correct that .040 seems to be the best point for it.. a thicker gasket can cause it to detonate even more (just like the low compression engines can detonate)

Re: At what point is QUENCH not effective? [Re: MR_P_BODY] #1459364 06/28/13 09:24 AM 06/28/13 09:24 AM
Joined: Jan 2003 Posts: 75,015 U.S.S.A. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,015 U.S.S.A.	I'm with the guys above, what is your combo, what timing , fuel octane and what's your elevation?

Re: At what point is QUENCH not effective? [Re: JohnRR] #1459365 06/28/13 09:30 AM 06/28/13 09:30 AM
Joined: Dec 2006 Posts: 3,395 Pa Hot 340 master
Hot 340 master Joined: Dec 2006 Posts: 3,395 Pa	https://board.moparts.org/ubbthreads/show...rue#Post7600787 I asked this same exact question a few months ago. My conclusion was to err on the side of caution because how do you measure these clearances accurately when the piston rocks in the bore? And heat changes everything too. And so does the quality and material of parts.

Re: At what point is QUENCH not effective? [Re: Jjs72D] #1459366 06/28/13 09:37 AM 06/28/13 09:37 AM
Joined: Jan 2003 Posts: 6,988 Warren, MI J Jerry master
Jerry master J Joined: Jan 2003 Posts: 6,988 Warren, MI	ideal quench is good at .040 or less. ultimately your trying to not allow room for the gas mixture to ignite. however, in real world driving applications your never really at the point of needing ideal quench. you may have to back your timing down a few degrees and you may lose a couple of hp. but are your really going to notice the difference? you might if your worried about your top speed or best performance all the time. most of us just want to drive our cars, and whether you have 580 hp or 560hp, you'd never tell by the seat of your pants. Superior Design Concepts 2574 Elliott Dr Troy MI 48083 jerry@sdconcepts.com www.sdconcepts.com Facebook page: Superior Design Concepts www.bcrproducts.com

Re: At what point is QUENCH not effective? [Re: Jerry] #1459367 06/28/13 10:05 AM 06/28/13 10:05 AM
Joined: Dec 2005 Posts: 293 Kansas City Metro M mbogina enthusiast
mbogina enthusiast M Joined: Dec 2005 Posts: 293 Kansas City Metro	I agree that the ideal quench clearance is about .035, dependent on piston rock. The detrimental area is clearances of about .040 to .100, which generally leaves areas of combustion that are too small to efficiently ignite the mixture. Above .100 will be more efficient because the area is large enough to allow the flame travel to burn the mixture within a short enough time span. Be a Rebel- Break the Laws of Physics!

Re: At what point is QUENCH not effective? [Re: Jerry] #1459368 06/28/13 10:06 AM 06/28/13 10:06 AM
Joined: Jan 2003 Posts: 4,448 Phoenix, AZ M MoparBilly master
MoparBilly master M Joined: Jan 2003 Posts: 4,448 Phoenix, AZ	When you are spraying 400hp of Nitrous, quench is not effective, head gaskets aren't either. "Livin' in a powder keg and givin' off sparks" 4 Street cars, 5 Race engines

Re: At what point is QUENCH not effective? [Re: MoparBilly] #1459369 06/28/13 11:05 AM 06/28/13 11:05 AM
Joined: May 2003 Posts: 6,562 Downtown Roebuck Ont Twostick Still wishing...
Twostick Still wishing... Joined: May 2003 Posts: 6,562 Downtown Roebuck Ont	Quote: When you are spraying 400hp of Nitrous, quench is not effective, head gaskets aren't either. Funny. Too bad it's true. Although I would think having quench couldn't hurt. Kevin

Re: At what point is QUENCH not effective? [Re: Jjs72D] #1459370 06/28/13 11:09 AM 06/28/13 11:09 AM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Quote: I have read many, many threads and posts but haven't seen this topic clearly defined. Maybe it is a gray area and hard to determine? Lets say you have a closed chambered Small block head with pistons .020 in the hole with a .039 head gasket. You have a .059 distance between the piston and the head. How effective is the quench? From what I have read, the sweet spot of quench is between .035-.045. What if this engine has a spark knock issue due in part to the high compression ratio. If the .059 gap results in limited quench, would it be safe to assume that a thicker head gasket could be used to drop compression a 1/2 point without a penalty? Jeff I have read that lowering compression via thicker head gaskets can result in more spark knock because of lost quench. My question is: If the engine is already out of the quench zone, would the thicker gasket help matters? Address the quench first. There is no magic #. Tighter is better. .035' - .040" is safer. Address the detonation with fuel, ignition timing, cam timing, water. Fastest 300

Re: At what point is QUENCH not effective? [Re: Crizila] #1459371 06/28/13 11:17 AM 06/28/13 11:17 AM
Joined: Jan 2003 Posts: 27,421 Balt. Md 3 383man Too Many Posts
383man Too Many Posts 3 Joined: Jan 2003 Posts: 27,421 Balt. Md	I can tell you my 493 came out about .046 to .047 and I thought about decking the block a tad more as my pistons were about .007 down in the cylinder. Two other eng builders told me its not worth the worry to deck it another .007 so I went with it and it has worked great. I run 37 total on 92 pump with zero ping and it runs fine. Ron

Re: At what point is QUENCH not effective? [Re: Crizila] #1459372 06/28/13 12:27 PM 06/28/13 12:27 PM
Joined: Dec 2003 Posts: 22,696 Bitopia J jcc If you can't dazzle em with diamonds..
jcc If you can't dazzle em with diamonds.. J Joined: Dec 2003 Posts: 22,696 Bitopia	Address the quench first. There is no magic #. Tighter is better. .035' - .040" is safer. Address the detonation with fuel, ignition timing, cam timing, water. So my first assumption is the purpose of quench is to keep the mixture uniform in temp and maintain fuel/air mixture, and possibly cool relative hot spots in the chamber. And I freely admit we are not speaking F1/Nasacar here, but to move the amount of air that quench does, in 8 cyls, at 7K?, I bet it takes/absorbs a reasonable amount of horsepower to move all that air from a dead stop, really fast. But if it allows greater hp to be made, that offsets and exceeds the pumping losses, we then chase quench. Forgetting mechanical issues of quench, regarding rod stretch, growth, etc, it would seem there should be a magic quench goal for each engine combination. What that is, I have no clue.071 Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.

Re: At what point is QUENCH not effective? [Re: Jjs72D] #1459373 06/28/13 12:31 PM 06/28/13 12:31 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH Taking time off to work on my car
BradH Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	FWIW, the general rules of thumb I've heard for years re: quench are: 1. .040" is a good target (steel rod motor, not aluminum) 2. < .040" can be better until things like piston rock start to cause piston-to-head collision issues 3. > .050" is where the benefits start to diminish and... 4. at .060"+, you're probably getting no quench benefits

Re: At what point is QUENCH not effective? [Re: BradH] #1459374 06/28/13 01:11 PM 06/28/13 01:11 PM
Joined: Jul 2010 Posts: 2,091 Delray beach, Florida P Performance Only top fuel
Performance Only top fuel P Joined: Jul 2010 Posts: 2,091 Delray beach, Florida	Quote: FWIW, the general rules of thumb I've heard for years re: quench are: 1. .040" is a good target (steel rod motor, not aluminum) 2. < .040" can be better until things like piston rock start to cause piston-to-head collision issues 3. > .050" is where the benefits start to diminish and... 4. at .060"+, you're probably getting no quench benefits Brad pretty much nailed it IMO. check your cranking compression. Different engine combinations will tolerate more or less cylinder pressure depending on other factors. Cam, heads, etc. etc. Often times you can increase compression and quench at the same time and rid yourself of detonation issues in one fell swoop. More info on your exact combination would help you get more detailed information to fix your issues. machine shop owner and engine builder

Re: At what point is QUENCH not effective? [Re: Jjs72D] #1459375 06/28/13 01:27 PM 06/28/13 01:27 PM
Joined: Oct 2007 Posts: 4,206 New York polyspheric master
polyspheric master Joined: Oct 2007 Posts: 4,206 New York	Everyone speaks, no one listens Boffin Emeritus

Re: At what point is QUENCH not effective? [Re: polyspheric] #1459376 06/28/13 01:35 PM 06/28/13 01:35 PM
Joined: Dec 2003 Posts: 22,696 Bitopia J jcc If you can't dazzle em with diamonds..
jcc If you can't dazzle em with diamonds.. J Joined: Dec 2003 Posts: 22,696 Bitopia	So all? the benefit arises from the additional power obtained from the now lessened volume of quench area, and that the quench area no longer pre ignites from the shock wave, because its cooled by its close proximity to the piston and the head, and burns later, correct? Interesting. Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.

Re: At what point is QUENCH not effective? [Re: jcc] #1459377 06/28/13 01:36 PM 06/28/13 01:36 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Quote: Address the quench first. There is no magic #. Tighter is better. .035' - .040" is safer. Address the detonation with fuel, ignition timing, cam timing, water. So my first assumption is the purpose of quench is to keep the mixture uniform in temp and maintain fuel/air mixture, and possibly cool relative hot spots in the chamber. And I freely admit we are not speaking F1/Nasacar here, but to move the amount of air that quench does, in 8 cyls, at 7K?, I bet it takes/absorbs a reasonable amount of horsepower to move all that air from a dead stop, really fast. But if it allows greater hp to be made, that offsets and exceeds the pumping losses, we then chase quench. Forgetting mechanical issues of quench, regarding rod stretch, growth, etc, it would seem there should be a magic quench goal for each engine combination. What that is, I have no clue.071 The #1 purpose of quench is to try and eliminate a second flame front. Then do what you said, which also helps to eliminate a second flame front. Since everyone likes .040', that makes it the magic #. There is a reason why the most common head gasket thickness sold ( for wedge motors ) is .039" - and it's because most aftermarket and race engines are built with "0" deck height - or close to it. So now that you have the "magic" quench #, I hope your build is just as magic. With pistons .020 in the hole at TDC, a little magic could be in order. Last edited by Crizila; 06/28/13 01:43 PM. Fastest 300

Re: At what point is QUENCH not effective? [Re: polyspheric] #1459378 06/28/13 01:40 PM 06/28/13 01:40 PM
Joined: Jan 2003 Posts: 8,027 Tulsa OK Bad340fish master
Bad340fish master Joined: Jan 2003 Posts: 8,027 Tulsa OK	Ive seen a few good examples of good effort being put into quench and what happens when its not. I have seen two 360s very similar other than one being a quench motor and one not. The quench motor was a 10:1 deal and the non quench was in the 9s. The quench motor was able to run a good amount more timing with little problems with knock. The other motor constantly fought with knock and would put some race gas in so he could run the timing where it needed to be on the track. The quench motor was also about .75 faster in the 1/4 in a slightly heavier car. This was like 15 years ago so the details are a little fuzzy, it did however burn "quench is good" into my head for life. I often wonder about the stroker 4.0 in my jeep. I built it in a hurry and didn't put forth any effort into quench etc. I just followed a canned recipe for a budget stroker motor. Its mid 9s compresion and fights detonation with premium fuel in the warmer months. I often wonder how much power and efficiency I left on the table by not going the extra mile and putting some effort into quench. I was however in a time crunch as it was my daily driver and I blew the motor up(ingested water). 68 Barracuda Formula S 340

Re: At what point is QUENCH not effective? [Re: Crizila] #1459379 06/28/13 02:38 PM 06/28/13 02:38 PM
Joined: Jan 2003 Posts: 27,421 Balt. Md 3 383man Too Many Posts
383man Too Many Posts 3 Joined: Jan 2003 Posts: 27,421 Balt. Md	[The #1 purpose of quench is to try and eliminate a second flame front. Then do what you said, which also helps to eliminate a second flame front. Since everyone likes .040', that makes it the magic #. There is a reason why the most common head gasket thickness sold ( for wedge motors ) is .039" - and it's because most aftermarket and race engines are built with "0" deck height - or close to it. So now that you have the "magic" quench #, I hope your build is just as magic. With pistons .020 in the hole at TDC, a little magic could be in order. That is the truth as quench helps fight having more then one flame front. Thats what causes detonation is 2 flame fronts collide and cause the knocking which is bad for the eng mechanical contition. Here is what one of the good eng books I have says..........The closeness of the cyl head to the piston and the relative coolness of these metallic surfaces cause heat to be extracted from the end gas so the tendency for detonation to occur is quenched. Knocking results when the end gas temps go to high and the end gas explodes before the flame front reaches it. Ron

Re: At what point is QUENCH not effective? [Re: 383man] #1459380 06/28/13 07:46 PM 06/28/13 07:46 PM
Joined: Nov 2004 Posts: 4,330 Lynchburg, VA Leon441 master
Leon441 master Joined: Nov 2004 Posts: 4,330 Lynchburg, VA	My small chamber W8 468 CID nitrous combo had huge compression. We installed a dish piston with. Lost so much compression the engine was down on power. Then installed a.032 head gasket and power came back and the rings ran cooler. My 421 with same heads and flat tops was also high on compression. It made great power over a broad range. My Durango RT needed a rebuild. I cut a bunch off the block to develop quench as this thing detonated terrible. Raised compression at least a half a point. Well it spark knocks more now. So win some loose some. Race engines like quench. Nitrous engines love it even more. In my experience. But, the Durango said I was full of crap. So who knows. Two out of Three I will build quench in future builds. Career best 8.02 @ 169 at 3050# and 10" tires small block power.

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