best cam for a 6.0
Feb 14, 2009 | 05:41 PM
#21
Correction. Flat top - higher compression than a dished piston, all other variables the same.
Again, piston type has nothing to do with actual quench distance. Please go back and do your homework. When you eventually understand the inner workings of this discussion feel free to edit your post that I quoted, and I will follow suit to reflect your correction. Hopefully this will save you embarrassment later on.
Again, piston type has nothing to do with actual quench distance. Please go back and do your homework. When you eventually understand the inner workings of this discussion feel free to edit your post that I quoted, and I will follow suit to reflect your correction. Hopefully this will save you embarrassment later on.
Feb 14, 2009 | 06:00 PM
#22
The quench area is the flat part of the piston that would contact a similar part of the head if you had .000 assembled quench height. In a running engine, the .040 quench height decreases to a close collision between the piston and the cylinder head. The shock wave from the near collision drives air at high velocity through the combustion chamber. This movement tends to cool hot spots, averages the chamber temperature, reduces detonation and increases power. The shock wave also provides better fuel/air mixing, and this allows the fuel to ignite better and burn faster. A faster burning fuel charge means less timing is required for optimum power output.
From what I see, given 2 identical setups, the one with flat top pistons will have a smaller quench.
If this is incorrect, please correct it. There's no reason to be a snob about it.
Feb 14, 2009 | 06:08 PM
#23
The quote is correct, but how you were using the word "quench" was not. Perhaps a definition could best aid this misunderstanding.
Quench- Commonly referred in text as "quench height or quench distance" - It is the distance between the piston ATDC and the combustion chamber of the head.
Quench- Commonly referred in text as "quench height or quench distance" - It is the distance between the piston ATDC and the combustion chamber of the head.
Feb 14, 2009 | 06:11 PM
#24
Given that statement (which is how I always understood quench)....a flat top piston will always be closer to the combustion chamber of the head than a dished piston at TDC given that both pistons come out of the hole the same amount (if any)
Feb 14, 2009 | 06:13 PM
#25
Apr 11, 2009 | 01:04 PM
#28
Apr 12, 2009 | 11:55 PM
#29
Im interested in this as well as there seems to be a lot of conflicting information out there. I posted this in the GM section a week a go but didn't get a response from anyone. I have trick flow 225s (65cc chambers) on a LQ4 and am trying to figure out how much to have them milled to get to 10.8 or 10.9:1 cr. If my calcs below are correct, you cant get there with a stock gasket without milling greater than .040. My numbers are consistent with what SynergyV8 is describing but could just be dumb luck on my part.
My numbers would also indicate that an LQ4 with 243s (64 cc chambers) is closer to 10.1:1 although many people have stated that they are getting 10.5:1 on that combo. The inputs I used in the CR calculator are below. Does anything look off? Looking to figure this out once and for all.
From earlier post:
This is what I get.
62 cc = 10.35:1 (would need to mill .018 off current 65 cc chamber)
61 cc = 10.47:1 (mill .024)
60 cc = 10.59:1 (mill .030)
59 cc = 10.71:1 (mill .036)
I'm using the following inputs into a compression ratio calculator:
bore 4.0
stroke 3.622
chamber size 71cc (stock)
piston dish -7.5 (plugged this value to get to stock cr of 9.4:1)
gasket thickness .05 (stock)
piston deck clearance 0
These inputs get me to 9.4:1 which is the stock cr on a lq4. From there I just played with different chamber ccs. Anyone see any flaws in what I am doing here?
My numbers would also indicate that an LQ4 with 243s (64 cc chambers) is closer to 10.1:1 although many people have stated that they are getting 10.5:1 on that combo. The inputs I used in the CR calculator are below. Does anything look off? Looking to figure this out once and for all.
From earlier post:
This is what I get.
62 cc = 10.35:1 (would need to mill .018 off current 65 cc chamber)
61 cc = 10.47:1 (mill .024)
60 cc = 10.59:1 (mill .030)
59 cc = 10.71:1 (mill .036)
I'm using the following inputs into a compression ratio calculator:
bore 4.0
stroke 3.622
chamber size 71cc (stock)
piston dish -7.5 (plugged this value to get to stock cr of 9.4:1)
gasket thickness .05 (stock)
piston deck clearance 0
These inputs get me to 9.4:1 which is the stock cr on a lq4. From there I just played with different chamber ccs. Anyone see any flaws in what I am doing here?
Apr 16, 2009 | 01:26 PM
#30
Im interested in this as well as there seems to be a lot of conflicting information out there. I posted this in the GM section a week a go but didn't get a response from anyone. I have trick flow 225s (65cc chambers) on a LQ4 and am trying to figure out how much to have them milled to get to 10.8 or 10.9:1 cr. If my calcs below are correct, you cant get there with a stock gasket without milling greater than .040. My numbers are consistent with what SynergyV8 is describing but could just be dumb luck on my part.
My numbers would also indicate that an LQ4 with 243s (64 cc chambers) is closer to 10.1:1 although many people have stated that they are getting 10.5:1 on that combo. The inputs I used in the CR calculator are below. Does anything look off? Looking to figure this out once and for all.
From earlier post:
This is what I get.
62 cc = 10.35:1 (would need to mill .018 off current 65 cc chamber)
61 cc = 10.47:1 (mill .024)
60 cc = 10.59:1 (mill .030)
59 cc = 10.71:1 (mill .036)
I'm using the following inputs into a compression ratio calculator:
bore 4.0
stroke 3.622
chamber size 71cc (stock)
piston dish -7.5 (plugged this value to get to stock cr of 9.4:1)
gasket thickness .05 (stock)
piston deck clearance 0
These inputs get me to 9.4:1 which is the stock cr on a lq4. From there I just played with different chamber ccs. Anyone see any flaws in what I am doing here?
My numbers would also indicate that an LQ4 with 243s (64 cc chambers) is closer to 10.1:1 although many people have stated that they are getting 10.5:1 on that combo. The inputs I used in the CR calculator are below. Does anything look off? Looking to figure this out once and for all.
From earlier post:
This is what I get.
62 cc = 10.35:1 (would need to mill .018 off current 65 cc chamber)
61 cc = 10.47:1 (mill .024)
60 cc = 10.59:1 (mill .030)
59 cc = 10.71:1 (mill .036)
I'm using the following inputs into a compression ratio calculator:
bore 4.0
stroke 3.622
chamber size 71cc (stock)
piston dish -7.5 (plugged this value to get to stock cr of 9.4:1)
gasket thickness .05 (stock)
piston deck clearance 0
These inputs get me to 9.4:1 which is the stock cr on a lq4. From there I just played with different chamber ccs. Anyone see any flaws in what I am doing here?