View Poll Results: AFR or TEA
Spend the extra money on the better head
97
68.31%
Save a bit of money and put it toward another mod or tuning
45
31.69%
Voters: 142. You may not vote on this poll
AFR vs TEA
08-07-2005, 12:06 PM
#121
10 Second Club
iTrader: (15)
Join Date: Nov 2001
Location: St. Michael, MN.
Posts: 4,519
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by 99ssleeper
I still get 11.07:1 with 60cc chambers and .060" gaskets....
Cyl vol= 43.2595 cid
Chamber vol= 3.661425 cid
Clearance vol (piston out)= -.0835356 cid
.060 Head Gasket Vol= .7160194 cid
So,
Swept vol= 43.2595 + 3.661425 - .0835356 + .7160194 = 47.553409 cid
Unswept vol= 3.661425 - .0835356 + .7160194 = 4.293909 cid
Swept/Unswept= 11.07..............11.07:1 SCR
Anyone back me up on this?
Cyl vol= 43.2595 cid
Chamber vol= 3.661425 cid
Clearance vol (piston out)= -.0835356 cid
.060 Head Gasket Vol= .7160194 cid
So,
Swept vol= 43.2595 + 3.661425 - .0835356 + .7160194 = 47.553409 cid
Unswept vol= 3.661425 - .0835356 + .7160194 = 4.293909 cid
Swept/Unswept= 11.07..............11.07:1 SCR
Anyone back me up on this?
Using: 3.898/3.622 stroke/bore, .060 head gasket, -.008 deck height, 0.00 for piston top, and 60cc combustion chamber it indicates a 11.09 static compression. Not far off from your numbers. Did you measure the deck height?
BTW - Do you still need the tools? Let me know, I'm heading to Sean's right now.
08-07-2005, 12:14 PM
#123
Originally Posted by PREDATOR-Z
Beast, believe me I like your calculations better.
For me it would be 10.6 VS 10.97
For me it would be 10.6 VS 10.97
08-07-2005, 12:28 PM
#124
Gonna change my post as the last one didn't make since and was hard to read.
Using the -.007 number why is it that a stock LS1 will now read 10.19 compression?
I used 3.898 bore
3.622 stroke
.060 head gasket
-.007 piston
0 for the flat top piston
66.67cc for the heads which from what I have read is a stock LS1 head.
It shoes 10.19
Now if GM made the LS1 a 10:1 motor and all my figures are correct then things dont add up.
With a compressed .054 gasket you get 10.33
Using the .060 gasket and 66.67 head a .001 piston deck would give you 10.01 compression.
Using a .054 gasket and 66.67 head you would need a .007 piston deck.
These numbers add up better according to all the other numbers we have.
What is correct?
Using the -.007 number why is it that a stock LS1 will now read 10.19 compression?
I used 3.898 bore
3.622 stroke
.060 head gasket
-.007 piston
0 for the flat top piston
66.67cc for the heads which from what I have read is a stock LS1 head.
It shoes 10.19
Now if GM made the LS1 a 10:1 motor and all my figures are correct then things dont add up.
With a compressed .054 gasket you get 10.33
Using the .060 gasket and 66.67 head a .001 piston deck would give you 10.01 compression.
Using a .054 gasket and 66.67 head you would need a .007 piston deck.
These numbers add up better according to all the other numbers we have.
What is correct?
Last edited by JZ'sTA; 08-07-2005 at 12:38 PM.
08-07-2005, 12:45 PM
#128
Now it gets even more confusing.
From what I am seeing maybe the cc's of the heads are incorrect.
Ran some more numbers based on the LS6 10.5:1 compression.
3.898 bore
3.622 stroke
.054 head gasket
-.007 piston
0 for flat tops
64.45 which again is what is "said" to be a stock LS6 head
Compression equals 10.46 which is very close.
With the .054 gasket you get 10.61, which I can still live with.
With a .007 instead of the -.007 you get 10.13 with the .060 gasket and 10.27 with the .054 gasket.
This just messes everything up now.
With the 10:1 compression LS1 the calc looks better at +.007 with the 10.5:1 LS6 the calc looks right at -.007.
That leads me to the heads being incorrect.
From what I am seeing maybe the cc's of the heads are incorrect.
Ran some more numbers based on the LS6 10.5:1 compression.
3.898 bore
3.622 stroke
.054 head gasket
-.007 piston
0 for flat tops
64.45 which again is what is "said" to be a stock LS6 head
Compression equals 10.46 which is very close.
With the .054 gasket you get 10.61, which I can still live with.
With a .007 instead of the -.007 you get 10.13 with the .060 gasket and 10.27 with the .054 gasket.
This just messes everything up now.
With the 10:1 compression LS1 the calc looks better at +.007 with the 10.5:1 LS6 the calc looks right at -.007.
That leads me to the heads being incorrect.
08-07-2005, 12:51 PM
#129
Originally Posted by PREDATOR-Z
LOL, this is funny.
On a stock LS1, I've read 10.0:1 and 10.2:1 in different articles and magazines.
BTW, how can you physically measure SCR again?
On a stock LS1, I've read 10.0:1 and 10.2:1 in different articles and magazines.
BTW, how can you physically measure SCR again?
Well if 10.2 is the answer then we have a winner.
66.67cc's and -.007 with a .060 gasket equals 10.19:1
That means GM is too damn dumb to know what compression the LS1 motor is, or I am to damn dumb to find the facts.
Now if the LS1 is really a 10.1 then the head would have to be a 68 cc chamber using a .060 gasket and a 69.5 using a .054 gasket.
08-07-2005, 01:15 PM
#131
I'm not trying to sound like a know it all here, but the negative number is fact not fiction. It isn't anything that can be questioned. If the piston sticks up past the deck, it is now at negative height. This is the way it has always been. There aren't that many motors out there were the pistons comes out of the hole. This is why most calculators measure in the hole. As for the stock numbers, you have to remeber you are dealing with a mass produced casting. cc's on each head will vary. I've seen up to 3cc's diffrence on diffrent heads that were untouched factory castings. I understand what you are saying about GM's calculations. I think they throw out an average number to the consumer, but it really will vary from car to car. You can also consider this: On the cars that came with the .054 gasket, what's diffrent between them and the cars that came with the .064 gaskets? Nothing, other than the gasket, but yet there was no change in compression according to GM. Makes you wonder.... Oh, since when have the MLS gaskets gone down to .o60? I thought they were rated at .o64"?
08-07-2005, 01:21 PM
#132
guys, when it comes down to it just measure your own **** and then use the calculator too figure out the compression. with GM's tolerances no two motors are exactly the same, i've seen deck heights vary from .002 to .010 out the hole, head volumes from 66 to 68, ect.
08-07-2005, 01:30 PM
#133
Originally Posted by Beast96Z
I'm not trying to sound like a know it all here, but the negative number is fact not fiction. It isn't anything that can be questioned. If the piston sticks up past the deck, it is now at negative height. This is the way it has always been. There aren't that many motors out there were the pistons comes out of the hole. This is why most calculators measure in the hole. As for the stock numbers, you have to remeber you are dealing with a mass produced casting. cc's on each head will vary. I've seen up to 3cc's diffrence on diffrent heads that were untouched factory castings. I understand what you are saying about GM's calculations. I think they throw out an average number to the consumer, but it really will vary from car to car. You can also consider this: On the cars that came with the .054 gasket, what's diffrent between them and the cars that came with the .064 gaskets? Nothing, other than the gasket, but yet there was no change in compression according to GM. Makes you wonder.... Oh, since when have the MLS gaskets gone down to .o60? I thought they were rated at .o64"?
I agree 100% Beast.
I have always guessed at the number and this just makes it easy to guess more accurately.
I know not every setup is the same from GM but thought it would be fun to throw some different numbers out there.
Not instead of guessing .3 -.4 more compression then what Ross says I can acturally guess on the "avarage" head cc and -.007 "avarage".
My old guess on my motor was 12.23 and now I see it is 12.36. Guess my guessing wasn't that bad.
Anyways at least were not discussing the "TEA vs AFR" same old **** anymore.
Thanks for the link. It is a favorite now and I trashed the ross compression calculator.
08-07-2005, 01:55 PM
#134
Originally Posted by DrkPhx
Have you tried the rbracing-rsr.com calculator mentioned above to back up your calculations?
Using: 3.898/3.622 stroke/bore, .060 head gasket, -.008 deck height, 0.00 for piston top, and 60cc combustion chamber it indicates a 11.09 static compression. Not far off from your numbers. Did you measure the deck height?
BTW - Do you still need the tools? Let me know, I'm heading to Sean's right now.
Using: 3.898/3.622 stroke/bore, .060 head gasket, -.008 deck height, 0.00 for piston top, and 60cc combustion chamber it indicates a 11.09 static compression. Not far off from your numbers. Did you measure the deck height?
BTW - Do you still need the tools? Let me know, I'm heading to Sean's right now.
Yeah, I could use those tools if you dont mind. I can pick them up sometime this or next week (I work in Eden Prairie...cant be that far from ya)...
Thanks Gino
08-07-2005, 03:33 PM
#136
At least this is a technical thread now.
Why would Deck Height be negative? It's not volume you are measuring, because that's another formula. Deck Height is simply the space or distance between the piston and the combustion chamber at top dead center (TDC).
The calculation you plug into my earlier reference is: Clearance volume = 0.7853982 x bore^2 x deck height
I can see why you assume that if a piston protrudes past the block than it must cut into the volume of the clearance, but you aren't concerned with that for SCR. At least not in any formulas I know. You only need to worry about the actual volume between the piston and combustion chamber.
??
Why would Deck Height be negative? It's not volume you are measuring, because that's another formula. Deck Height is simply the space or distance between the piston and the combustion chamber at top dead center (TDC).
The calculation you plug into my earlier reference is: Clearance volume = 0.7853982 x bore^2 x deck height
I can see why you assume that if a piston protrudes past the block than it must cut into the volume of the clearance, but you aren't concerned with that for SCR. At least not in any formulas I know. You only need to worry about the actual volume between the piston and combustion chamber.
??
Last edited by JakeFusion; 08-07-2005 at 03:44 PM.
08-07-2005, 03:55 PM
#137
Yes you do have to worry about it because that measurement needs to be subtracted from the combustion chamber + head gasket volume.
If it was zero deck height, then it wouldnt be an issue. When the deck height is positive, that gets added to the combustion chamber and head gasket volume because the Unswept volume is larger.
Trust me...it has to be factored in.
Edit: .78whatever is the volume. It is the protrusion amount (.007) times bore^2 divided by 4.
If it was zero deck height, then it wouldnt be an issue. When the deck height is positive, that gets added to the combustion chamber and head gasket volume because the Unswept volume is larger.
Trust me...it has to be factored in.
Edit: .78whatever is the volume. It is the protrusion amount (.007) times bore^2 divided by 4.
08-07-2005, 04:05 PM
#139
Originally Posted by 99ssleeper
Yes you do have to worry about it because that measurement needs to be subtracted from the combustion chamber + head gasket volume.
If it was zero deck height, then it wouldnt be an issue. When the deck height is positive, that gets added to the combustion chamber and head gasket volume because the Unswept volume is larger.
Trust me...it has to be factored in.
Edit: .78whatever is the volume. It is the protrusion amount (.007) times bore^2 divided by 4.
If it was zero deck height, then it wouldnt be an issue. When the deck height is positive, that gets added to the combustion chamber and head gasket volume because the Unswept volume is larger.
Trust me...it has to be factored in.
Edit: .78whatever is the volume. It is the protrusion amount (.007) times bore^2 divided by 4.
And the clearance volume forumla is 0.7853982 x bore2 x deck height
I'm not going to write a proof, but if the piston actually protrudes .007" then sure your formula works, but you are measuring the distance from chamber to piston when you enter that value in my formula or on any of these online calculators. I have no idea how far the piston is actually out of the hole, nor is it necessary for my forumla. I am assuming that when someone says that the LS1 has a deck height of .006-.008 it has nothing to do with the actual protrustion and recession of a piston. Perhaps that is why these forumlas are not spot on. But I know that my forumla looks for deck height, not piston out of the hole.
Thus, I don't care if the piston is down in the cylinder .5" or if it sticks out .006, it will still be a positive number in my formula, because my value is that distance from the combustion chamber to the piston. It will just be a larger number if the piston is recessed.