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It makes the most sense to zero deck the block .030" because the quench blocks just arent sticking out enough.

Haven't calculated the new CR yet. Will do that shortly.


If that's the case, I'd mill the heads if the short block is already together.

If you are doing this for CR I'm all for it. Not for it just to gain quench.
 
Ok, so I went back and looked at your first post so I could figure out WTH is going on.

In the first post you didn't say a thing about the CR. All you said was you were going to do all this work to get quench.

Two entirely different and unrelated topics for sure.

So...if you need to stick the piston out of the hole .050 I don't care. If (and it's a big IF) you are doing it to get the CR where you want it.

Nothing wrong with that. But to do all that work to get quench is worth nothing.

At your elevation, 10.56:1 may be low. I'd get it to 11:1 and make sure the rest of the engine combo is set up for it.

The material the head is made of makes ZERO diffence regarding detonation resistance, compression ratio or any other voodoo bull crap the magazines push.

I'm running 11.1:1 on pump gas with iron heads, running full timing (36 total) and I can't make it rattle unless I'm just being stupid.

My next build will be 12:1 on pump gas, maybe a bit more.

And I don't calculate my CR based on an online calculator and and the piston manufacturers advertised numbers so I'm 100% sure where my CR is at. And I'm about 800 feet above sea level. I know, because I was talking with my mentor the other day and this discussion came up so I verified my altitude.
 
Not trying to ruffle any feathers or be contentious, but 1st and 2nd gen Hemis have 360 degree squish and quench, and 3rd gen Hemis have two large quench and squish areas on the sides of the combustion chamber. I have had (or still have) all three generations of Hemi engines and run them.
So I respectfully disagree with the assertion that Hemi engines don't have squish and quench. Besides the wonderful unshrouded valves and direct, cross flow, the large squish and quench are what make the design so effective.

Second, head material does make a large difference in detonation tolerance. Most aluminum head engines can tolerate at least a point higher in static CR.

Also, smogger low compression 440's pinged like crazy with very low compression ratios, reason... no quench and squish.

Just my 2 cents derived from experience and study.

I respect your opinions and am in no way trying to discount your assertions.

Thanks,
Mark

Ok, so I went back and looked at your first post so I could figure out WTH is going on.

In the first post you didn't say a thing about the CR. All you said was you were going to do all this work to get quench.

Two entirely different and unrelated topics for sure.

So...if you need to stick the piston out of the hole .050 I don't care. If (and it's a big IF) you are doing it to get the CR where you want it.

Nothing wrong with that. But to do all that work to get quench is worth nothing.

At your elevation, 10.56:1 may be low. I'd get it to 11:1 and make sure the rest of the engine combo is set up for it.

The material the head is made of makes ZERO diffence regarding detonation resistance, compression ratio or any other voodoo bull crap the magazines push.

I'm running 11.1:1 on pump gas with iron heads, running full timing (36 total) and I can't make it rattle unless I'm just being stupid.

My next build will be 12:1 on pump gas, maybe a bit more.

And I don't calculate my CR based on an online calculator and and the piston manufacturers advertised numbers so I'm 100% sure where my CR is at. And I'm about 800 feet above sea level. I know, because I was talking with my mentor the other day and this discussion came up so I verified my altitude.
 
Not trying to ruffle any feathers or be contentious, but 1st and 2nd gen Hemis have 360 degree squish and quench, and 3rd gen Hemis have two large quench and squish areas on the sides of the combustion chamber. I have had (or still have) all three generations of Hemi engines and run them.
So I respectfully disagree with the assertion that Hemi engines don't have squish and quench. Besides the wonderful unshrouded valves and direct, cross flow, the large squish and quench are what make the design so effective.

Second, head material does make a large difference in detonation tolerance. Most aluminum head engines can tolerate at least a point higher in static CR.

Also, smogger low compression 440's pinged like crazy with very low compression ratios, reason... no quench and squish.

Just my 2 cents derived from experience and study.

I respect your opinions and am in no way trying to discount your assertions.

Thanks,
Mark



Ok, first we need to use the correct terms or we will never come to an understanding.

I don't care what you do, I'm just trying to erase decades of absolute nonsense. You can believe what you want, but I've tested quench to the point it was just a stupid waste of money. It's not cheap to buy Pistons and do all the work to correctly test it. And I can say unequivocally that there isn't any power in quench. There isn't any detonation resistance in quench. There is an emissions factor in it, but I can tell you crevice volume is just as bad or worse for emissions as is lack of quench. That's just the facts.

Second, and for the last time, a Hemi does NOT have quench. Does NOT. The Gen III has it, but that again, has zero to do with power. It's an emissions deal. So I say piss on Jimmy Carter and his CAFE standards and his blackmail of the states over 55 MPH law.

What the Gen I and II Hemi does have is SQUISH. It's not the same. Not even close. Two totally different things. Anyone with any basic knowledge of 2 stroke operation knows what I'm talking about.

Look again at the small block Chrylser. It a really cool design if you know what you're looking at. Done correctly, the SBM has quench AND squish. You need the correctly shaped dome, but you can get both (I have it...that's one reason why the highly loved Magnum chamber is highly overrated...you can't get any squish) and then look closely at the spark plug location. It's about as close to Hemi plug location as you can get in a true wedge head.

So I'm saying to you that sadly, you are trying to gain something where there is no gain to be had. None. Every single test we made any power gains came from raising the CR and not quench. Every time. I know that goes against current thinking, but I looked at the crapola Marlan Davis was palming off in the link you posted. He had a lot of "theory" in his short article, and some speculation and some good old fashion conjecture. That's what he's paid to do.

In fact, if you read the last sentence of the first paragraph, he either knowingly or unknowingly explained why everything he was going to say was wrong. Go read that sentence over and over until it makes sense to you.

Then consider plug location. I get that low Cr smog her big block junk would rattle it's brains out. It has a garbage plug location. Just like a SBC. Horrible spark plug location. Has nothing to do with quench. Zero. So let's use you example of a pig smogger big block (which BTW if you look at cam timing and ignition timing on that garbage and you can see other sources of detonation, all in the name of emissions and quench won't fix that) and let's keep the 7.8:1 CR right where it is, but get the beloved and worshipped quench. What would you have. A low CR ping monster. You didn't fix the plug location, the *** backwards cam timing and ignition timing only a moron would, or a smart man would use when the government told him you have to do "this" and the only way to do "this" is to do other things so stupid anyone with the IQ above a slice of bread would see how ignorant what they do really is.

Again, quench is just what it says it is. Closing off a part of the chamber to cool it down. Pushing the air/fuel load to the plug doesn't really matter, because things like stratification, fuel droplet size, chamber temperature and some other stuff cat be fixed with quench.

Squish, which is what a Hemi has (and a SBM if you do it correctly) pushes any air/fuel from the edges of the chamber and around the dome and it cleans up the possible trapped crevice volume around that area.

Not the same as quench. Look at a 2 stroke. It's the same principal.

Now, to another long told fib...that aluminum "carries away heat so fast that you can run a point of CR more than with nasty old iron because it gets so hot and retains all that heat" or some similar shinola like that.

It isn't true. I've typed it out so many times on this very web site, in more than one place that I ain't going to do it again.

If you stop and think about a running IC engine, you'll see how silly that idea really is. That's why I can run 11:1 on iron heads, run full timing at near sea level and to get it into detonation I'd have to be just plain ignorant. I'm going to go to 12:1 or maybe a bit more on my next build, on straight pump gas and I'll run full timing and not have detonation issues either.

I've been a proponent of, and have been doing higher than whatever the popular CR number of the month is since the very early 1980's. It's not new. None of them had quench. None of them run less than full timing. And it wasn't just on small block Chrysler's.

I remember when 9.5:1 was IT. Anything over that was a taboo worse than screwing your own mother. Yet I was doing it. With success. You have to have the entire system correct (you should be doing that anyway, regardless of the CR you want to use but you'd be surprised how many people have no concept of a systems approach to engine building) and IF you do that, you can run any CR on iron as you can with aluminum.

That's just a fact. If you're engine builder can't or won't do that, find another one.

I have a measured 10.5:1 small block on the stand at home with a couple hours of work to finish it off. I'm working with a FABO member on his SBM hopefully going together this spring with what will be a measured 10:1 engine.

Both will have very mild cam timing, both will run on pump gas, both will run full timing and both won't be hard to tune or be ping monsters.

BTDT many, many times.
 
I have a customer who builds several open chamber iron headed BB Mopars each year.

They all get quench dome pistons, set up to achieve effective quench.

Why? Because without it they are miserable pinging pains in the ***.
 
To the OP:
What is the quench dome height of the piston, and what is your current deck clearance for the other part of the piston?

What is the quench pad area depth set to on the heads?
 
To the OP:
What is the quench dome height of the piston, and what is your current deck clearance for the other part of the piston?

What is the quench pad area depth set to on the heads?

If I bolt it together with a .022" compressed steel shim head gasket I will have .062" between the quench dome and the head, that is more than I want. Again, with my cam I will have an issue controlling detonation at .062" (coming from Big Block experience). I am rethinking which way to go, might be cheaper and easier to take .030" off the heads instead. That way the radius that the open chamber has as it curves to the head deck will be reduced, making the quench block fit in the head with less dead space around it, making it more efficient.
Glad (for the most part) I posted this. I love the exchange of ideas!
 
To the OP:
What is the quench dome height of the piston, and what is your current deck clearance for the other part of the piston?

What is the quench pad area depth set to on the heads?

Dome height .075", deck clearance to piston flat .030", head open chamber depth .085"
 
I have a customer who builds several open chamber iron headed BB Mopars each year.

They all get quench dome pistons, set up to achieve effective quench.

Why? Because without it they are miserable pinging pains in the ***.


I'm not opposed to using a piston like that. It's near impossible to get much
If I bolt it together with a .022" compressed steel shim head gasket I will have .062" between the quench dome and the head, that is more than I want. Again, with my cam I will have an issue controlling detonation at .062" (coming from Big Block experience). I am rethinking which way to go, might be cheaper and easier to take .030" off the heads instead. That way the radius that the open chamber has as it curves to the head deck will be reduced, making the quench block fit in the head with less dead space around it, making it more efficient.
Glad (for the most part) I posted this. I love the exchange of ideas!


LOL. I asked are you doing this for CR or quench? You didn't answer. You are going to fix something with CR and tell everyone quench fixed it.

So...are you doing all this for CR, or for quench? If the former, I'd deck the block. That's how Chrysler designed it to be done.

If it's for quench, you are peeing into a fan. And, you'll be raising the CR.
 
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I'll go back and read SOME of the links a bit later. I don't give a crap what Summit and HR magazine publish.

I'd actually rather read an SAE paper on it, but I don't know where to find a good one specifically on the topic. I may make a few phone calls and see if I can scrounge a few SAE papers to read.

That said, I'll say this again. Real world testing, to the point it became ignorant proved there isn't jack squat to be had.

I was working my own program whole also working on a circle track 9.5:1 engine program. Low CR engines are a giant pain in the *** for several reasons. Exhaust heat being one of them. This was about the time all the Pistons became available that had reverse domes, and trench cut valve reliefs and all that other trick of the minute crap.

At the time we were using a full round dish piston and every whiz bang in gym shorts was telling us we left power on the table. I can't hear that an pad not try to fix it. So the sponsor boned up for brand new, reversed domed Pistons for us.

Bad news. That came with the pin .015 low so instead of the .045 piston to head we had, we now we're at .060, the so called "death rattle" distance.

I'd already spent way too much volunteer time and WAY TOO MUCH of my money on this wild goose chase to stop and deck the block or mill the heads again (a thing I hate to do anyway) so we made the decision to run them and prepare to reduce the timing to control the detonation we were promised which would destroy the whole engine in a matter of a couple of pulls on the dyno.

Dyno day gets there and the three of us prepare for a significant power loss just from the reduced timing, let alone.

And guess what?? The exact same CR with the new piston and the extra quench and you lay one dyno pull over the other. How could that be? Every single engine wizard in the country said quench mattered. Lash loops and timing changes showed us the exact same everything as the so called junk dished Pistons.

The sponsor watched all this and was mighty pissed. We were told we would now rotate the earth with his new slugs. It didn't happen. We even changed the ICL twice to see if the Newcombe wanted something else. Didn't matter. So the sponsor called the piston guy and he said they'd make the piston with the pin .015 higher and a deeper reverse dome, but the Pistons would be heavier. And we were told this would gain us what everyone promised So we paid half cost on those.

All the work, all the time and absolutely zero. Nothing. We ended up with 3 more designs that we paid for and not a single one made any difference.

One piston dude said the reverse dome needed to be very shallow. Another said it needed to be deep and mirror the chamber. Another said a round dish was the best.

Due to the limits of the compression ratio, the various changes to the different Pistons required a different compression distance.

I used to remember how many pulls we made, but we wasted a whole offseason chasing that infamous quench distance down. And it didn't make a pinch of crapola difference.

We thought we were just stupid so we just ran the car and ran very well. I was still working on my drag engine and I stopped worrying quench.

Almost 15 years later, I was working with another local engine builder, sharing flow data from our two different flow benches and discussing things we found using various valve jobs and such and we eventually came around to quench. He says he went through a time where all they did was chase quench. He found zero, just like we did.

In the end, he said I only do quench to get the CR I want. If I don't need the CR I don't do quench, unless the customer is brainwashed into the quench fantasy.

Across the years, I've run across several engine builders who found the same thing. And the answer was always the same. You can't out educate the interwebs and the comic books. So they never try and convince anyone that quench isn't what they are told it is.

I can recount other trips to the dyno to find the same results.

Quench doesn't matter in the grand scheme of things. It may help with a crap plug location. It will help with emissions.

That's about it. If you need the CR, by all means close it up.

BTW, in subsequent testing (we were hard headed and stupid and just couldn't believe all the hero's were wrong) we started playing with quench verses compression ratio.

Every. Single. Time. The power went up, it was CR related. Never once did power go up based on quench alone.

I can't say any more. Other than quench won't fix your issues. If you have too much CR for your fuel, closing the quench (which raises the CR BTW) will do zero for the detonation issues.

Before I forget, we tried locked out timing, slow curves, fast curves...much anything you can imagine. In the end, they all ran the best with with virtually identical timing curves. None liked to be locked out.
 
I'll go back and read SOME of the links a bit later. I don't give a crap what Summit and HR magazine publish.

I'd actually rather read an SAE paper on it, but I don't know where to find a good one specifically on the topic. I may make a few phone calls and see if I can scrounge a few SAE papers to read.

That said, I'll say this again. Real world testing, to the point it became ignorant proved there isn't jack squat to be had.

I was working my own program whole also working on a circle track 9.5:1 engine program. Low CR engines are a giant pain in the *** for several reasons. Exhaust heat being one of them. This was about the time all the Pistons became available that had reverse domes, and trench cut valve reliefs and all that other trick of the minute crap.

At the time we were using a full round dish piston and every whiz bang in gym shorts was telling us we left power on the table. I can't hear that an pad not try to fix it. So the sponsor boned up for brand new, reversed domed Pistons for us.

Bad news. That came with the pin .015 low so instead of the .045 piston to head we had, we now we're at .060, the so called "death rattle" distance.

I'd already spent way too much volunteer time and WAY TOO MUCH of my money on this wild goose chase to stop and deck the block or mill the heads again (a thing I hate to do anyway) so we made the decision to run them and prepare to reduce the timing to control the detonation we were promised which would destroy the whole engine in a matter of a couple of pulls on the dyno.

Dyno day gets there and the three of us prepare for a significant power loss just from the reduced timing, let alone.

And guess what?? The exact same CR with the new piston and the extra quench and you lay one dyno pull over the other. How could that be? Every single engine wizard in the country said quench mattered. Lash loops and timing changes showed us the exact same everything as the so called junk dished Pistons.

The sponsor watched all this and was mighty pissed. We were told we would now rotate the earth with his new slugs. It didn't happen. We even changed the ICL twice to see if the Newcombe wanted something else. Didn't matter. So the sponsor called the piston guy and he said they'd make the piston with the pin .015 higher and a deeper reverse dome, but the Pistons would be heavier. And we were told this would gain us what everyone promised So we paid half cost on those.

All the work, all the time and absolutely zero. Nothing. We ended up with 3 more designs that we paid for and not a single one made any difference.

One piston dude said the reverse dome needed to be very shallow. Another said it needed to be deep and mirror the chamber. Another said a round dish was the best.

Due to the limits of the compression ratio, the various changes to the different Pistons required a different compression distance.

I used to remember how many pulls we made, but we wasted a whole offseason chasing that infamous quench distance down. And it didn't make a pinch of crapola difference.

We thought we were just stupid so we just ran the car and ran very well. I was still working on my drag engine and I stopped worrying quench.

Almost 15 years later, I was working with another local engine builder, sharing flow data from our two different flow benches and discussing things we found using various valve jobs and such and we eventually came around to quench. He says he went through a time where all they did was chase quench. He found zero, just like we did.

In the end, he said I only do quench to get the CR I want. If I don't need the CR I don't do quench, unless the customer is brainwashed into the quench fantasy.

Across the years, I've run across several engine builders who found the same thing. And the answer was always the same. You can't out educate the interwebs and the comic books. So they never try and convince anyone that quench isn't what they are told it is.

I can recount other trips to the dyno to find the same results.

Quench doesn't matter in the grand scheme of things. It may help with a crap plug location. It will help with emissions.

That's about it. If you need the CR, by all means close it up.

BTW, in subsequent testing (we were hard headed and stupid and just couldn't believe all the hero's were wrong) we started playing with quench verses compression ratio.

Every. Single. Time. The power went up, it was CR related. Never once did power go up based on quench alone.

I can't say any more. Other than quench won't fix your issues. If you have too much CR for your fuel, closing the quench (which raises the CR BTW) will do zero for the detonation issues.

Before I forget, we tried locked out timing, slow curves, fast curves...much anything you can imagine. In the end, they all ran the best with with virtually identical timing curves. None liked to be locked out.

I am amazed , the only engine builder in the world w/ that opinion .
I always thot squish created the quench !!
 
I just did a quick Google search and some are using the terms quench and squish the same.

It certainly is not the same. It's more pronounced in a 2 stroke, but it's the same principal.

Either way, it's overrated.
 
So am I to assume that quench isn't considered by some builders in the specs of an engine build.
 
So am I to assume that quench isn't considered by some builders in the specs of an engine build.


Yes. If I can get the CR I want with .085 quench then I let I go, as it won't make any difference. If I need to squeeze it down, I will.

That's the whole point of what I'm saying. You need to get the CR where you want it for your combination.

I can build an 11:1 engine you can make rattle. I can build an 8:1 engine that will rattle it's brains out. What's the diffence? I say it's in the combo. You can't use the cam timing the OE's used with that low CR and NOT expect it to rattle. Emissions were much more important because the government can do or build anything without f*#king it up.

It's that simple. As I've said so many times, it's all about the combustion chamber, spark plug location and Rod/stroke ratio that actually determines detonation resistance and timing requirements.

And I've given examples of that very thing many times. Yet the people won't think for themselves. They'd rather be lied to than do the work to learn on their own. I've paid to learn. I'm stupid for sharing. Maybe I shouldn't. I can't change a fact. And you won't find many facts in comic books, which are advertisements for their advertisers.

Group think. Want another example? I can give many.

Here's a good one.

Holley has said forever you set power valve opening from idle vacuum.

This was wrong then and it's wrong now. Yet every web site, every book, every magazine article to this very day is teaching people to set PV opening off idle vacuum!! It's been proven wrong so many times it's stupid to argue that idle vacuum is the correct way to set it. Yet people will go bat crap crazy if you say anything other than what the books, magazines and web sites say. And Holley knows for damn sure it's wrong. I actually had an idiot at Holley tell me they want the PV opening set at idle because it isn't "safe" to look at a vacuum gauge while driving!!!! WTF???

That's just one example of group think. Quench is not only group think, it's Chevy think. That's why most roller lifters have .750 wheels...because that's all the junk .842 GM lifters can use.

It is what it is, and why Chrylser guys live with marginal GM **** I'll never know.
 
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