Lets talk a little more about quench
#483126
09/29/09 12:04 AM
09/29/09 12:04 AM
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Joined: Aug 2003
Posts: 2,682 Clinton Twp. Michigan
coronet1966d
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Joined: Aug 2003
Posts: 2,682
Clinton Twp. Michigan
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so ive read and read then i read some more about compression ratios dynamic, static and so on ive read a bunch about quench and why its important heres my question: assuming that .040 is the IDEAL "safe" quench meaning you shouldnt get it any closer than that, how wide can you go on quench and still be effective? lets say .050 - .060 the reason i ask is im playing around with these online calculators with different head and piston combos trying to find something that works for me. the one thing ive kept the same is a zero deck with a .040 head gasket i believe undecked the pistons will sit about .015 in the hole so undecked i would be at .055 quench, is that still a good thing or is it too wide? just playing around with numbers and learning as i go i apretiate all you guys helping me this far or id be asking alot dumber questions lol
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Re: Lets talk a little more about quench
[Re: coronet1966d]
#483131
09/29/09 05:54 AM
09/29/09 05:54 AM
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Joined: Feb 2003
Posts: 12,675 Columbia, CT
moper
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Columbia, CT
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A lot depends on the mahining on your block. I typical block, decked with an older miller will typically be out of flat and parallel by up to .003", the bad ones as much as .020" off over the length of the deck. So when you say you're building with quench you have to take into account the accuracy of the parts and machining. Minimum safe distance for a forged piston/steel rod engine can vary from .015-.030" depending on the compression height, the bore size, and the rpm of peak power. Normal "safe" is no closer than .030. I target .035. To get that accurracy I have to index and correct the cranks' stroke in some cases, match and set rod lengths, align hone the mains, and have the block square decked. Only then do you have the package that is accurate to run tight. Tighter is better right up until they hit. Anything farther than .050 IMO is not worth aiming for as the cost of machining will be great for little or no benefit.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: Lets talk a little more about quench
[Re: coronet1966d]
#483132
09/29/09 07:31 AM
09/29/09 07:31 AM
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Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
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Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
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David Vizard writing on another person's Quench testing in 0.010 increments: http://www.enginebuildermag.com/Article/2266/surfacing_equipment_can_increase_horsepower.aspxsample quote I knew that minimizing the quench area clearance was also good for normally aspirated engines as well, and had it in mind to do some tests that would establish just what it may be worth. These got put off time-after-time because it is a time consuming and relatively costly experiment for a one-man business to do. Fortunately, while lecturing at the SuperFlow Advanced Engine Technology Conference in 1998 I met a gentleman who had actually done these tests. As I remember it, the 350 SB Chevy test engine was in the 380-400 hp range and started with a CR of just 9.9:1. After baselining with the piston-to-head quench at .065; (.040; for the head gasket and .025; down the hole for the piston) the quench clearance was reduced in steps of .010; until the quench clearance was .035. When you are looking at potentially small changes in power data, scatter is a consideration. However, by averaging out the numbers the results appeared to consistently indicate that each .010; reduction in quench clearance was worth 6-7 hp or 5.5 to 6.5 ft.lbs. of torque. The .030 change in quench clearance increased the CR from 9.9 to 10.6. So I made some relatively sophisticated calculations to establish what the increase in output from this factor alone would be. The answers I came up with indicate that, at best, the increases seen were only 60 percent attributable to the increased CR. Other issues of note were that the engine needed less total timing to make the power seen. Along with this, the ignition swings in the advance direction indicated it to be no more prone to detonate even with the higher compression. ......So how close can the quench clearance be run? Good question. A friend of mine who ran a machine and dyno shop until recently has, using good stiff race bottom end parts, run down to .022 before contact was seen. I have run a SB Chevy with stock crank and rods down to .025 where it showed that contact had just occurred. This was a motor that peaked at 5750 rpm. In practice I usually build a typical domestic V8 for a customer with .035 total quench clearance and that seems to be safe so long as the pistons are close fitting in the bores. For my own motors I typically go to .028 when using a known combination of good bottom end parts.
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Re: Lets talk a little more about quench
[Re: 360view]
#483133
09/29/09 07:49 AM
09/29/09 07:49 AM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
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Grand Haven, MI
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FWIW, a friend's LT1 stroker was less prone to detonation on pump gas after he replaced the old head gaskets which gave him .054" quench to gaskets that gave him just under .040, while increasing compression about .3 points....
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Re: Lets talk a little more about quench
[Re: classof65]
#483137
09/29/09 07:06 PM
09/29/09 07:06 PM
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Joined: Feb 2003
Posts: 12,675 Columbia, CT
moper
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I Live Here
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Rev, thanks, but you have me confused with another fellow who has a MUCH more satisfying job than I do...lol. plus, the post is about quench.. not static or dynamic ratios, the differences, or what else affects it...lol.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: Lets talk a little more about quench
[Re: coronet1966d]
#483141
09/30/09 10:05 AM
09/30/09 10:05 AM
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Joined: Nov 2008
Posts: 671 Wisconsin USA
Bill MeLater
mopar
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mopar
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Wisconsin USA
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Quote:
so ive read and read then i read some more about compression ratios dynamic, static and so on ive read a bunch about quench and why its important
heres my question: assuming that .040 is the IDEAL "safe" quench meaning you shouldnt get it any closer than that, how wide can you go on quench and still be effective? lets say .050 - .060 the reason i ask is im playing around with these online calculators with different head and piston combos trying to find something that works for me. the one thing ive kept the same is a zero deck with a .040 head gasket
i believe undecked the pistons will sit about .015 in the hole so undecked i would be at .055 quench, is that still a good thing or is it too wide?
just playing around with numbers and learning as i go
i apretiate all you guys helping me this far or id be asking alot dumber questions lol
I went through the same thing due to the usual lack of $. I used steel shim head gaskets, pistons around (deck hts of stock block out .008 end to end) .024 w/tightest @.016. W/ .016 steel shims I regularly spun it to 6500 ( a couple of missed shifts went to 7k or better),and had absolutely no contact. The pistons even had a pretty heavy carbon build up from tuning issues so I had at least one hole w quench as tight as .030. The problem I did have was keeping a set of head gaskets in it, 4 sets this season. Just tore it down and had the block zero decked/ squared. It will go back together this weekend with .040 gaskets. Spend it now or spend it later. BTW, It ran great on 93 pump when it was holding a gasket....
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