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Re: At what point is QUENCH not effective?
[Re: Leon441]
#1459381
06/29/13 01:57 AM
06/29/13 01:57 AM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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The whole topic of "quench" give me hives. The name is all wrong, it was called that by someone who didn't understand what it really does. The subject is properly called SQUISH. That's what Sir Harry Ricardo called it when he developed it and actually patented the idea back around 1919. If you understand about flame travel it'll help. If the mixture isn't moving around much, the actual flame travel is on the same order of magnitude as piston speed. That's slow. While the slow burn is heating the contents of the combustion chamber, the fuel in the farthest out places is turning into compounds that self-ignite much more easily than the original fuel. So how to get the mixture to burn quicker? By bringing two surfaces together very closely, a high speed jet is expelled and physically mixes the flame through the chamber. Thus the burn completes faster than the knocking compounds can form. So the good idea is speeding up the burn. The wrong idea is that somehow the surfaces are "quenching" the knock. But it is the speed that the burn is completed that makes the difference. If one could get the piston to come within 0.001" of the head every single time it would be better. Check out www.theoldone.com for more. R.
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Re: At what point is QUENCH not effective?
[Re: Jjs72D]
#1459383
06/29/13 07:55 AM
06/29/13 07:55 AM
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Joined: Jan 2003
Posts: 10,018
Frostbitefalls MN (Rocky&Bullw...
gregsdart
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,018
Frostbitefalls MN (Rocky&Bullw...
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I don't think you wasted anyone's' time. That is what we are about. Helping each other get better performance. With a clean sheet, you can put together a REAL stout peace, given the time to glean all you can from this web site and others. For some very interesting reading that goes deeply into what happens in the combustion chamber, get a copy of David Vizzards book Porting cylinder heads. There is a wealth of knowledge there.
Last edited by gregsdart; 06/29/13 08:02 AM.
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Re: At what point is QUENCH not effective?
[Re: gregsdart]
#1459384
06/29/13 09:02 AM
06/29/13 09:02 AM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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As Dogdays says one of my books does call it Squish and sometimes if you read enough about it you wonder if all the engineers who design the engines all agree on the Quench/Squish therory. I found it is easiest for me to just remember that when you think about Quench to remember its about if more then one flame front comes about and flame fronts collide. Ideal is one nice flame front and anything that helps that helps fight eng knock. And of course ideal quench is about .040. It was pretty basic for me as when I built my 493 which of course is the Mopar wedge eng I wanted to build a simple zero deck flattop piston eng with a wedge combustion chamber and a .040 head gasket for perfect quench. After I decked my block and fit everything I was about .005 off as my pistons came out about .007 down and it was close enough for my setup. But it is easy to build a good quench bigblock Mopar wedge when starting from scratch. Just shoot for .040 quench and dont worry if you totally understand its therory. And this is never a waste of time because know matter how matter times this board talks about quench it seems everytime I always learn more about it. I agree with what Brad posted that after .050 you start to loose the quench effect. Ron
Last edited by 383man; 06/29/13 09:03 AM.
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Re: At what point is QUENCH not effective?
[Re: JohnRR]
#1459386
06/29/13 10:55 AM
06/29/13 10:55 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Well the good thing is you haven't built it yet so you can buy the parts you need to get things right. I don't know what you plan on using for pistons but you should contact one of the board members that is a Diamond WD to choose which piston you want , if it's a shelf stock piston you can go semi custom for a small up charge and get it with the pin move and possibly a small D dish to give you a pump gas friendly compression ratio and take advantage of SQUISH 
That was the nice thing about dealing with Diamond..
they changed the pin height for $35 a set and will
do other changes for cheap.. so you end up with a
semi custom piston from a shelf blank
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Re: At what point is QUENCH not effective?
[Re: dogdays]
#1459387
06/29/13 11:26 AM
06/29/13 11:26 AM
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Joined: Dec 2003
Posts: 22,727
Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,727
Bitopia
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Quote:
The whole topic of "quench" give me hives. The name is all wrong, it was called that by someone who didn't understand what it really does.
The subject is properly called SQUISH. That's what Sir Harry Ricardo called it when he developed it and actually patented the idea back around 1919.
If you understand about flame travel it'll help. If the mixture isn't moving around much, the actual flame travel is on the same order of magnitude as piston speed. That's slow. While the slow burn is heating the contents of the combustion chamber, the fuel in the farthest out places is turning into compounds that self-ignite much more easily than the original fuel. So how to get the mixture to burn quicker?
By bringing two surfaces together very closely, a high speed jet is expelled and physically mixes the flame through the chamber. Thus the burn completes faster than the knocking compounds can form.
So the good idea is speeding up the burn. The wrong idea is that somehow the surfaces are "quenching" the knock. But it is the speed that the burn is completed that makes the difference.
If one could get the piston to come within 0.001" of the head every single time it would be better.
Check out www.theoldone.com for more.
R.
So with this explanation, does that also mean because of a "faster burn", timing can be dialed back?
I was mentioning to 383 last night a question about thermal coatings interfering with the heat absorption based on the earlier explanation of the nearby surfaces cooling the fuel air mixture preventing pre ignition. Seems to me if coating reject heat from being absorbed by the piston, etc, the coating would also retard heat being absobed from the mixture. 
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: At what point is QUENCH not effective?
[Re: dOc !]
#1459389
06/29/13 12:25 PM
06/29/13 12:25 PM
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Joined: Jan 2010
Posts: 1,089
st.cloud fl
d-150
Smarter than a 5th grader?
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Smarter than a 5th grader?
Joined: Jan 2010
Posts: 1,089
st.cloud fl
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shorter the piston the more rock you will have,like stroker pistons,also where does flat top pistons and flame travel without squish fit into engine building .
Last edited by d-150; 06/29/13 12:27 PM.
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Re: At what point is QUENCH not effective?
[Re: dOc !]
#1459390
06/29/13 12:27 PM
06/29/13 12:27 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
OK ....who makes the best piston with the least amount of "rock" ?
Probably KB... they tend to run the closest piston to
wall clearances but they arent the strongest
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Re: At what point is QUENCH not effective?
[Re: MR_P_BODY]
#1459392
06/29/13 12:42 PM
06/29/13 12:42 PM
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Joined: Jul 2008
Posts: 30,479
Florida STAYcation
dOc !
The village idiot's idiot
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The village idiot's idiot
Joined: Jul 2008
Posts: 30,479
Florida STAYcation
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Quote:
Quote:
OK ....who makes the best piston with the least amount of "rock" ?
Probably KB... they tend to run the closest piston to
wall clearances but they arent the strongest
Does Diamond have a piston design that can be run with less p2w clearance ?
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Re: At what point is QUENCH not effective?
[Re: dOc !]
#1459393
06/29/13 01:01 PM
06/29/13 01:01 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
Quote:
OK ....who makes the best piston with the least amount of "rock" ?
Probably KB... they tend to run the closest piston to
wall clearances but they arent the strongest
Does Diamond have a piston design that can be run with less p2w clearance ?
That I cant say... you would have to talk with them...
they are close to me so it was nice to deal with them
and when they had them done I just drove over there
and picked them up... plus I know the owner and see
him fairly regular at a car club thing.. if I can
find another 340 block I'm gonna start another engine
build for my Rampage.... but it might end up as a
stroker 318... still unknown... but I'm running out
of 340 blocks unless I start putting sleeves in them
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Re: At what point is QUENCH not effective?
[Re: MR_P_BODY]
#1459395
06/29/13 02:53 PM
06/29/13 02:53 PM
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Joined: Jul 2008
Posts: 30,479
Florida STAYcation
dOc !
The village idiot's idiot
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The village idiot's idiot
Joined: Jul 2008
Posts: 30,479
Florida STAYcation
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Quote:
Does Diamond have a piston design that can be run with less p2w clearance ?
That I cant say... you would have to talk with them...
they are close to me so it was nice to deal with them
and when they had them done I just drove over there
and picked them up... plus I know the owner and see
him fairly regular at a car club thing.. if I can
find another 340 block I'm gonna start another engine
build for my Rampage.... but it might end up as a
stroker 318... still unknown... but I'm running out
of 340 blocks unless I start putting sleeves in them
P-guy ... do you have an email addy for your guy ....I could drop him a note later today and he could digest it at his convenience on Monday.
ANOTHER point on max-squish ... the less "open area" beyond the combustion chamber gives more swirl to the AF mixture THUS a better and more complete burn.
ONE of my projects that could definately use-this would be my 413 motorhome moder ...with those goofy heads. HUGE CC closed chambered head design ... 100 PLUS CC's ... so a +.010 deck piston with a slight dome with a fire-slot would be in order IMO .....
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Re: At what point is QUENCH not effective?
[Re: polyspheric]
#1459398
06/29/13 10:39 PM
06/29/13 10:39 PM
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Joined: Jan 2007
Posts: 3,695
nc
emarine01
master
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master
Joined: Jan 2007
Posts: 3,695
nc
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Quote:
Everyone speaks, no one listens
I will listen....
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I started using the close alloy pistons years ago in NHRA legal stocker motors I was building, .004 to .0047 Piston to wall clearances at 70 F 
The hypertutetic(SP?) type pistons(cast) can run a lot tighter P to W clearances than the forged pistons, make sure you don't detonate them or allow any foriegn objects(FOD) go into the combustion chambers 
They dpon't like that at all 
