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Re: quench, gasket bore and compressed height [Re: NachoRT74] #2396034 10/31/17 01:32 PM 10/31/17 01:32 PM
Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska	other than a low performance daily driver, I would want .035"-.040" quench. live every 24 hour block of time like it's your last day on earth

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2396037 10/31/17 01:36 PM 10/31/17 01:36 PM
Joined: Aug 2007 Posts: 6,096 Valencia, España NachoRT74 OP master
NachoRT74 OP master Joined: Aug 2007 Posts: 6,096 Valencia, España	sure... but meaning I can still mill down heads still using 0.039 gaskets... and still have to confirm the corrected block decking. ( I have read around 0.050 is still good ) Once again I still have to get the parts correctly machined ( if that's posible locally!!!!! ) to get the final decision... With a Charger born in Chrysler assembly plant in Valencia, Venezuela

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2396131 10/31/17 04:12 PM 10/31/17 04:12 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	I wouldn't bother about the differences you describe. Here's my reasoning: The late roller 318s had the 302 closed chamber heads. The stock replacement piston I can find is 1.745". Block height is 9.577. 9.577 - 1.745 -6.123 - (3.31/2) = 0.054". I measured 0.055" on my '86 318. add the gasket of at least 0.027 and you get 0.082" from head to piston top Look at the 5.2 Mag. The Mag cylinder head has an area that was most likely added for squish. Yet the 5.2 Mag piston is at least 0.072" from the deck at TDC. So while I'm sure that narrowing the gap would make a good thing even better, there may be a lot of cost between "good" and "good enough". R. Moving to Spain, huh? I've enjoyed my times there, in Madrid and Andalusia.

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2396146 10/31/17 04:30 PM 10/31/17 04:30 PM
Joined: Aug 2007 Posts: 6,096 Valencia, España NachoRT74 OP master
NachoRT74 OP master Joined: Aug 2007 Posts: 6,096 Valencia, España	I'm actually working on a good enough job... trying to keep the static CR lower as posible keeping on good enough quench numbers, also trying TO NOT SEND MORE PARTS TO UNNEFICIENT MACHINE SHOPS!!! I get really scared everytime I have to send anything to any machine shop!. Before all this squared deck deal I was riding on 10.2-10.3 CR. I guess had pinging due of course the bad quench. Front ones pistons down the deck around 0.015-0.017 and the rears right on zero deck, and using stock composite headgaskets. Diff combustion chambers deepness everywhere, etc... well, what you already know. I have asked about this many times, I know, and being tiresome. This project has being taking an eternity. With a Charger born in Chrysler assembly plant in Valencia, Venezuela

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2396301 10/31/17 09:46 PM 10/31/17 09:46 PM
Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska	Quote: I have asked about this many times, I know, and being tiresome. This project has being taking an eternity. Nacho, Keep em coming, we are here to help as much as we can/solve as manny issues as we can/gain & share as much knowledge as we can. live every 24 hour block of time like it's your last day on earth

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2396667 11/01/17 02:09 PM 11/01/17 02:09 PM
Joined: Jan 2003 Posts: 75,066 U.S.S.A. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,066 U.S.S.A.	Originally Posted By NachoRT74 dogdays: yes that was my thought, but my doubt was that because per what I have read on several places the quench/squish area can be on 0.050" rate and still be good even the advice is around 0.040" John: that could be good too! and will make to keep the heads unmilled, saving from ANOTHER mistake from machine shop. However that could make also to get really close the piston diameter out of the quench pad close to the head around the combustion chamber to allmost 0.020" I think... isn't that some dangerous ? I recall the combustion chamber bore is sligthly smaller bore than the cylinder bore... isn't ? Wouldn't actually need to cut 0.020" but maybe the 0.010-12 extras the thicker felpro headgaskets got with bigger bore, and keep using the 0.39 with small bore... in another words, cut the combustion chamber quench area same ammount the pistons leaves the deck. Maybe in fact they are actually close to what I need. I'm pretty sure this area is deeper than the piston quench pad height and maybe close to what I need as mentioned on a previous reply. I will know just once the block is correctly decked and once assembled measured with clay Once the block is decked drop the heads on the empty block without a gasket ... mark heads for what side they are on ... , now turn the block upside down and look in at the heads for chamber overhang into the bores , scribe the areas that overhang and clean them back to a little outside the scribed marks on the open chamber side of the head and roll over the edge on the plug side , or blend the plug side back also if you need to lower the compression some. the .039 you are getting , is that from the web or from actual crushed gasket that is measured ? I have found the 8519 to be more like .041 ??? running up my post count some more .

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2396982 11/01/17 09:52 PM 11/01/17 09:52 PM
Joined: Aug 2007 Posts: 6,096 Valencia, España NachoRT74 OP master
NachoRT74 OP master Joined: Aug 2007 Posts: 6,096 Valencia, España	From manufacturer specs ( good idea on the method you described ) With a Charger born in Chrysler assembly plant in Valencia, Venezuela

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2397188 11/02/17 09:02 AM 11/02/17 09:02 AM
Joined: Jan 2006 Posts: 8,162 USA 3 360view Moparts resident spammer
360view Moparts resident spammer 3 Joined: Jan 2006 Posts: 8,162 USA	General Motors research on effect of a tight quench where they varied the percent area of the flat piston surface that nearly touches a matching surface on the cylinder head. Note that if you multiply a 4.00 inch bore by their ratio it is 0.026 inches, which is very tight. Many years later Honda wrote up a technical paper on the science of their first V-Tec design. Honda wrote that the quench had to be a tight 0.75 millimeters, nearly the same clearance as GM found.

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2397189 11/02/17 09:15 AM 11/02/17 09:15 AM
Joined: Jan 2006 Posts: 8,162 USA 3 360view Moparts resident spammer
360view Moparts resident spammer 3 Joined: Jan 2006 Posts: 8,162 USA	Look at the left figure, with (a) at bottom. Look at the lowermost dotted line, for 50% Quench Area. Notice that at a 10 to 1 static compression ratio, the engine can run with fuel of 78 AN Performance Number. What is AN Performance Number? It is the Army Navy improved Octane rating number, A "new & better" test method than either the original 1930s RON (research octane number) or the somewhat newer MON (motor octane number) Pure 100% chemical Octane is rated a number of 100 in all three test methods: AN Performance Number, RON and MON. 78 AN Performance number is approximately 85 AKI like we see on USA gas pump signs.

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2397190 11/02/17 09:18 AM 11/02/17 09:18 AM
Joined: Jan 2006 Posts: 8,162 USA 3 360view Moparts resident spammer
360view Moparts resident spammer 3 Joined: Jan 2006 Posts: 8,162 USA	So what compression ratio does figure (a) predict you could run with just "a trace of knock" on 100% pure chemical Octane which rates 100 in all three methods? At a quench clearance of 0.026 inches with 50% quench area Static compression should not be above 12.2

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2397192 11/02/17 09:26 AM 11/02/17 09:26 AM
Joined: Jan 2006 Posts: 8,162 USA 3 360view Moparts resident spammer
360view Moparts resident spammer 3 Joined: Jan 2006 Posts: 8,162 USA	Also look at the 0% quench area black solid line at top way above the doted 50% quench line. Only a static compression ratio of 10.4 could be run with "trace knock" on 100% pure chemical Octane. There is approximately a 7% gain in both torque and horsepower going from 10.4 to 12.2 static compression ratio How much money and aggravation should you endure to get that 7% gain? Would it be better to just get 7% more cubic inches? Would it be better to just buy more expensive higher Octane number rated fuel? Your choice.

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2397194 11/02/17 09:28 AM 11/02/17 09:28 AM
Joined: Jan 2006 Posts: 8,162 USA 3 360view Moparts resident spammer
360view Moparts resident spammer 3 Joined: Jan 2006 Posts: 8,162 USA	Now study the ignition timing stuff in figure (b)

Re: quench, gasket bore and compressed height [Re: 360view] #2397619 11/03/17 12:31 AM 11/03/17 12:31 AM
Joined: Aug 2007 Posts: 6,096 Valencia, España NachoRT74 OP master
NachoRT74 OP master Joined: Aug 2007 Posts: 6,096 Valencia, España	Originally Posted By 360view General Motors research on effect of a tight quench where they varied the percent area of the flat piston surface that nearly touches a matching surface on the cylinder head. Note that if you multiply a 4.00 inch bore by their ratio it is 0.026 inches, which is very tight. Many years later Honda wrote up a technical paper on the science of their first V-Tec design. Honda wrote that the quench had to be a tight 0.75 millimeters, nearly the same clearance as GM found. we talked about this on an old thread I asked about a similar topic, and I remember this diagram being posted, and being honest, I'm not clear on everything said there With a Charger born in Chrysler assembly plant in Valencia, Venezuela

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2397746 11/03/17 10:12 AM 11/03/17 10:12 AM
Joined: Jan 2006 Posts: 8,162 USA 3 360view Moparts resident spammer
360view Moparts resident spammer 3 Joined: Jan 2006 Posts: 8,162 USA	In a nutshell: A tight quench combined with 50% piston flat area is helpful to get 100 Octane gasoline like performance on cheaper lower Octane pump gasoline. On a 500 hp engine you might gain 60 hp or so, after taking considerable care and extra steps during assembly. The main problem in the graph above is that GM only shared with the public the 2000 rpm results on a small bore 2.75" bore by 2.75" stroke engine. They kept the valuable to racing big bore, big stroke, 4000 to 6000 rpm results they certainly also tested for confidential. It is possible that a big bore engine at 4000+ rpm only needs 0.060 or more quench clearance, perhaps with piston quench flats area less than 50%.

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2397856 11/03/17 12:51 PM 11/03/17 12:51 PM
Joined: Aug 2007 Posts: 6,096 Valencia, España NachoRT74 OP master
NachoRT74 OP master Joined: Aug 2007 Posts: 6,096 Valencia, España	KB pistons quench step are less than 50% of the piston, that's a fact. Maybe 25% being optimistic With a Charger born in Chrysler assembly plant in Valencia, Venezuela

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2397876 11/03/17 01:11 PM 11/03/17 01:11 PM
Joined: Jan 2006 Posts: 8,162 USA 3 360view Moparts resident spammer
360view Moparts resident spammer 3 Joined: Jan 2006 Posts: 8,162 USA	Flat top pistons seem to be the recent trend. Perhaps a totally flat top allows the flame kernel to grow fastest? Maybe a flat top piston crown has less "hot spots" at edges. Maybe a flat top piston under heat is easier to keep round for bore seal? Maybe flat tops are inherently stronger and therefore lighter?

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2398210 11/04/17 12:25 AM 11/04/17 12:25 AM
Joined: Feb 2014 Posts: 234 Brisvegas, Australia A Alchemi enthusiast
Alchemi enthusiast A Joined: Feb 2014 Posts: 234 Brisvegas, Australia	Kb made those pistons for stock heads That pistons pad fits the 452 head pad area close to perfectly - any more meat towards the valve would have been excess weight and more compression Last edited by Alchemi; 11/04/17 12:33 AM.

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2398356 11/04/17 12:19 PM 11/04/17 12:19 PM
Joined: Aug 2007 Posts: 6,096 Valencia, España NachoRT74 OP master
NachoRT74 OP master Joined: Aug 2007 Posts: 6,096 Valencia, España	Yes I know, and not just 452s, but any open chambers. The deal is that quench pad area is quite often deeper than 0.095" which is the KB215 pistons step height ( my heads were NOS and they are closer to 0.110", but I got them after the pistons ). For a custom step will need KB251s, which are cheaper just right because they need to be cut to needs. I went with KB215s trusting on published expects around for the heads. Maybe KB251 was to be easier to match everything. Of course the quench step surface on piston matches the quench pad on open chambers, but still is maybe just 25% of the piston area LOL... thats just what I said, not saying just matches 25% of the quench pad on heads With a Charger born in Chrysler assembly plant in Valencia, Venezuela

Re: quench, gasket bore and compressed height [Re: NachoRT74] #2398847 11/05/17 02:37 PM 11/05/17 02:37 PM
Joined: Jan 2006 Posts: 8,162 USA 3 360view Moparts resident spammer
360view Moparts resident spammer 3 Joined: Jan 2006 Posts: 8,162 USA	25% quench area at a C.R. of roughly 10 still allows you to run 82 grade instead of 92 grade on the AN PN Octane gasoline scale. Every little bit helps. Better to have that aid than not. Another way to think of it is if the engine runs hot for some reason it is a degree of protection from damaging detonation.

Re: quench, gasket bore and compressed height [Re: 360view] #2398921 11/05/17 04:53 PM 11/05/17 04:53 PM
Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska	If I may hijack: with 9-1 SCR (class rules) & adequate octane so detonation ain't a concern, would there be a significant power bennie from achieveing quench? better mixture homogenization (sp)?? and less timing needed cuz of a faster burn?? If so I wanna do it the next build. live every 24 hour block of time like it's your last day on earth

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