General quench question
#293643
04/20/09 01:40 AM
04/20/09 01:40 AM
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Joined: Oct 2007
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Oregon
hooziewhatsit
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So I was reading on KBs site the other day, and I think I finally figured out how quench works.  I've read you need to have around 0.035" piston to head clearance, but was wondering how you could have that over the entire chamber and still have a sane compression ratio  In the red box in the picture below, is that the quench area? It sounds to me like when the piston comes up to TDC, it 'squishes' the mixture in that area, which then shoots it across the chamber. This then helps mix everything together and burn better. It also helps ensure that every cylinder fires more consistently cylinder to cylinder, and cycle to cycle. The green line is exaggerated to show where they would cut dished pistons to raise/lower the overall compression ratio, right? So, for an open chambered head, the piston would have a portion that goes above the deck to make up space to the head, while the other half is recessed in the form of valve reliefs to maintain a sane CR (the green line)? (ie, KB399 ) This picture portrays a closed head, so it would need a flat top piston, right? (ie, KB167 ) Here's the article from KB that started to make sense (needs more paragraphs  ) http://kb-silvolite.com/article.php?action=read&A_id=39So am I right, wrong, kinda-sorta-maybe? Any other pearls of wisdom about quench? -Dave
If you ever find yourself in a fair fight, your tactics suck.
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Re: General quench question
[Re: hooziewhatsit]
#293644
04/20/09 02:04 AM
04/20/09 02:04 AM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
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Circle Track
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Lincoln Nebraska
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(1) not over the whole chamber,if so the CR would be sky high (2) yes the red box is the quench area(only part of the piston to head is in close contact) (3) A dish to lower CR would be more towards the center (4) the flat plateau in the kb399's is to take up some of the distance in an open chambered head then there's the recessed eyebrows for v/p clearance.(5) the last set of KB pistons(flat tops w valve reliefs) would be for closed chamber heads & at zero deck height & a .039" gasket would be perfect quench.
Last edited by RapidRobert; 04/20/09 02:41 AM.
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Re: General quench question
[Re: polkat]
#293647
04/20/09 02:31 AM
04/20/09 02:31 AM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
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Circle Track
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Lincoln Nebraska
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Quote:
How does this work, as the open chamber slightly rises from the edge of the chamber to the center? Does the pad on the piston also slightly rise?
Slope like the recess does? no, On the KB399's in the OP & since the open chamber recesses vary in depth AND slope they need to be checked & probably machined to an equal depth(which also takes care of the slope then the quench flat plateau needs to be machined a certain amount to agree with the amount you cut to get that magical .035-.040" quench distance which is why open chambered heads are a PITA & should be avoided at (almost) all costs in favor of closed chambered ones.
Last edited by RapidRobert; 04/20/09 02:53 AM.
live every 24 hour block of time like it's your last day on earth
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Re: General quench question
[Re: RapidRobert]
#293648
04/20/09 02:38 AM
04/20/09 02:38 AM
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Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT
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Management Trainee
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Posts: 27,347
Today? Who Knows?
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Quote:
Quote:
How does this work, as the open chamber slightly rises from the edge of the chamber to the center? Does the pad on the piston also slightly rise?
yes like on the KB399's in the OP & since the open chamber recesses vary in depth AND slope they need to be checked & probably machined to an equal depth(which also takes care of the slope then the quench flat plateau needs to be machined a certain amount to agree with the amount you cut to get that magical .035-.040" quench distance which is why open chambered heads are a PITA & should be avoided at (almost) all costs in favor of open chambered ones.
Robert intended to say Closed Chambered..
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Re: General quench question
[Re: RapidRobert]
#293650
04/20/09 02:17 PM
04/20/09 02:17 PM
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Joined: Oct 2007
Posts: 3,903
Oregon
hooziewhatsit
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Thanks for the replies.  Now I understand how quench works. Hadn't yet come across an article that specifically explained it (with pictures!). Reading them again now they make sense. So with open chamber heads, to check the clearance between piston & head, do you have to put clay on the pistons, assemble everything, crank it around once, take it apart, measure the gap, then machine as necessary? That does seem like a lot of work In my case I have a 318 with open chamber heads. I'd probably be better off going with some closed chamber 302s & KB167s than making the open chambers work? -Dave
If you ever find yourself in a fair fight, your tactics suck.
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Re: General quench question
[Re: hooziewhatsit]
#293653
04/20/09 03:29 PM
04/20/09 03:29 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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I Live Here
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Posts: 16,123
Grand Haven, MI
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Quote:
Thanks for the replies. Now I understand how quench works. Hadn't yet come across an article that specifically explained it (with pictures!). Reading them again now they make sense.
So with open chamber heads, to check the clearance between piston & head, do you have to put clay on the pistons, assemble everything, crank it around once, take it apart, measure the gap, then machine as necessary? That does seem like a lot of work
In my case I have a 318 with open chamber heads. I'd probably be better off going with some closed chamber 302s & KB167s than making the open chambers work?
-Dave
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