Big time! I think quench and DCR are easily the two most overlooked details in designing a build and can make all the difference in the world.
Quench - explained
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Adding to C4 Tech FAQ. This is great stuff!!! Well done!!!
Now, a thought... modern engine designers are moving more and more of the combustion event into the cylinder head, in an attempt to reduce emissions blow-by. if I understand what they are doing, it essentially creates a seal at the piston to head area and really does weird things to the quench.
The downside to all of this is carbon buildup. I understand that the Northstar engine is very prone to this... as are some Mopar V6s.
Now, a thought... modern engine designers are moving more and more of the combustion event into the cylinder head, in an attempt to reduce emissions blow-by. if I understand what they are doing, it essentially creates a seal at the piston to head area and really does weird things to the quench.
The downside to all of this is carbon buildup. I understand that the Northstar engine is very prone to this... as are some Mopar V6s.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by bogus
Adding to C4 Tech FAQ. This is great stuff!!! Well done!!!
Now, a thought... modern engine designers are moving more and more of the combustion event into the cylinder head, in an attempt to reduce emissions blow-by. if I understand what they are doing, it essentially creates a seal at the piston to head area and really does weird things to the quench.
The downside to all of this is carbon buildup. I understand that the Northstar engine is very prone to this... as are some Mopar V6s.
Now, a thought... modern engine designers are moving more and more of the combustion event into the cylinder head, in an attempt to reduce emissions blow-by. if I understand what they are doing, it essentially creates a seal at the piston to head area and really does weird things to the quench.
The downside to all of this is carbon buildup. I understand that the Northstar engine is very prone to this... as are some Mopar V6s.
Race Director
Joined: Nov 2003
Posts: 12,220
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Well we FINALLY have a good resurrection!
I think it's great that you popped this old thread up to the top (and updated/corrected the links. I, too, agree that very few people understand quench, it's importance, and it's relevance. Even some of the so-called guru's didn't get it.
I recommend anyone building/rebuilding a motor take a closer look at this.
Good stuff!
I think it's great that you popped this old thread up to the top (and updated/corrected the links. I, too, agree that very few people understand quench, it's importance, and it's relevance. Even some of the so-called guru's didn't get it.
I recommend anyone building/rebuilding a motor take a closer look at this.
Good stuff!
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Drifting
Joined: Dec 2007
Posts: 1,647
Likes: 4
From: Argillite KY
That was the clearest explanation that I've seen. Great job and thanks for the effort. That also explains why all dish pistons aren't created equal. Some are impossible to get a good quench like the one shown below. notice that the whole top is dished making it nearly impossible to get the distance required for a good quench
Now this style of dished piston has a very nice "Quench Pad" and will be able to squish the air from that area and into the combustion chamber.
The idea is to get the mixture in the combustion chamber as turbulent as possible before it's lit off by the spark. Here's a video that shows how rapidly the mixture enters the engine. It may be a little faster than you think.
http://youtu.be/UvmBLqjaZxY
Now this style of dished piston has a very nice "Quench Pad" and will be able to squish the air from that area and into the combustion chamber.
The idea is to get the mixture in the combustion chamber as turbulent as possible before it's lit off by the spark. Here's a video that shows how rapidly the mixture enters the engine. It may be a little faster than you think.
http://youtu.be/UvmBLqjaZxY
Drifting
Joined: Mar 2009
Posts: 1,253
Likes: 4
From: East Wenatchee (2hours from n e where) WA
Great thread! 1963 ss As you point out the piston shape is critical. To get 9.5 to 11 to 1 with a 64 cc head the best piston is the shape I affectionately call the D cup.
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Drifting
Joined: Dec 2007
Posts: 1,647
Likes: 4
From: Argillite KY
the best piston is the shape I affectionately call the D cup
Sorry mods.I use quite a few of the -16cc D Dished pistons on LT4's to get 11:1 compression. Mainly I'll use Mahle, JE/SRP or Diamond if I need to modify something. A lot of folks don't know it but Diamond will give you any dish volume you want for an additional 6 bucks a piston. It's no longer necessary to accept a compromise in quench, head gasket, combustion chamber or anything else. That may be one of the best deals on the planet. 6 dollars per change to get exactly what you need and want. Pretty cool.....huh?
Last edited by 1963SS; Dec 29, 2011 at 03:39 PM.
Race Director
Joined: Nov 2003
Posts: 12,220
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Some sites liken inverted dome pistons to the most efficient burn design.
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
yep...its like the "other half" of the hemi (sphere)
Racer
Joined: Nov 2006
Posts: 420
Likes: 0
From: Sierra Madre California
Great info! Thanks for taking the time to do this, and for bumping it in front of us again. This is very helpful for us guys who are trying to figure out what to do to upgrade our engines and want to do it once and do it right.
Last edited by jesredvette; Feb 19, 2012 at 11:55 PM.
Thread Starter
Burning Brakes
Joined: Sep 2003
Posts: 875
Likes: 0
From: Louisville KY
Thanks for the kind words guys 
I will periodically check up on this to make sure that the images are still in place. Glad I could give something back to a community that has provided me with enough knowledge to be dangers. lol
I will periodically check up on this to make sure that the images are still in place. Glad I could give something back to a community that has provided me with enough knowledge to be dangers. lol
