Too much compression with my heads and LQ9???
#22
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Is the calculator you are using on line?
I made sure i put in a negative value for the piston protruding out of the deck, calclulated the volume of the head gasket and still can't get 11.4
I got this using this calculator and these numbers:
http://www.ajdesigner.com/phpengine/...sion_ratio.php
Conversions:
BORE = 4 inch = 4 inch
STROKE = 3.622 inch = 3.622 inch
CCV = 60 centimeter^3 = 3.6614246456839 inch^3
HGV = .5740 inch^3 = 0.574 inch^3
PDV = -.125664 inch^3 = -0.125664 inch^3
Solution:
compression ratio (CR) = 12.074976068935
It is lower if I use PDV as a positive number.... but that would mean that it is in the hole. Like I said, not doubting, just trying to understand.
thanks
I made sure i put in a negative value for the piston protruding out of the deck, calclulated the volume of the head gasket and still can't get 11.4
I got this using this calculator and these numbers:
http://www.ajdesigner.com/phpengine/...sion_ratio.php
Conversions:
BORE = 4 inch = 4 inch
STROKE = 3.622 inch = 3.622 inch
CCV = 60 centimeter^3 = 3.6614246456839 inch^3
HGV = .5740 inch^3 = 0.574 inch^3
PDV = -.125664 inch^3 = -0.125664 inch^3
Solution:
compression ratio (CR) = 12.074976068935
It is lower if I use PDV as a positive number.... but that would mean that it is in the hole. Like I said, not doubting, just trying to understand.
thanks
#23
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there is one piece left out from alot of the CR calculators if you want a very true reading. that one does not use deck height, rod length, compression height, or height from top of piston to first ring land. all of those things will factor in as well.
this one is a little more inclusive, plus gives good info on piston speed and how elevation and boost will effect CR. http://www.zealautowerks.com/
this one is a little more inclusive, plus gives good info on piston speed and how elevation and boost will effect CR. http://www.zealautowerks.com/
#24
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This is horrifying, stating a given static compression as being okay or not, without specifying your elevation above sea level. It makes a huge difference. When I moved up here from Florida, I was able to add more than a full ratio of static compression, and even so switch from premium unleaded to regular unleaded. The thing that remains constant is that 200 psi cranking compression is fairly safe on 91 octane. But for a given engine and a given cam, you'll need more static compression the higher you go to get 200 psi.
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The bigger duration the cam is , the higher you can run static compression , the smaller duration the cam is the higher the dynamic is going to be which means you will have to drop static.
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Running the 11.44:1 is better for hp and for N2O also depending on the cam you need to make sure that your cam is a N2O friendly. While 100 N2O is considered a small shot I have been advised never run dry or wet with anything less than 100 octane if its bigger than a 50 shot due to detonation.
Good Luck
Good Luck
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If you are going to use an online calculator use this one. http://golenengineservice.com/calc/calccr.htm. I did a little searching and this calculator has everything you need to make sure it gives correct information. Let me know how it works out for you.
Now, if i put in +.01, I get 11.4 But since the piston is above the deck, it says to put in (-)
Looks like I am back in the 12:1 range......
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If I use a stock MLS 6.0L gasket, it looks like I will be back in the 11.7 range.
That is if the thickness is .055.
Can someone please explain the quench stuff to me? I read about .o35, but why does GM use .055 and .058 gaskets stock on LS1's?
Thanks!
That is if the thickness is .055.
Can someone please explain the quench stuff to me? I read about .o35, but why does GM use .055 and .058 gaskets stock on LS1's?
Thanks!
#34
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I'm pretty sure I know this one. In the early '80s, GM was building a lot of iron-headed SBCs with the pistons about 0.025" in the hole, and steel-shim head gaskets about 0.020" thick. But they were working on giving the Corvette aluminum heads. Steelshims didn't work, and MLS wasn't even an option. By the time they made a composite work the way they liked, it was 0.051" thick. Great, now they had a proven thing that would survive. It survived the warranty period, but it also survived into the days of our LSx.
GM realized that 0.076" quench was too much, yet they were stuck with 0.051" thick head gaskets, so they designed the LS to have the pistons out of the cylinders about 0.008" . And that gives 0.043", which is safe but not excessive.
GM realized that 0.076" quench was too much, yet they were stuck with 0.051" thick head gaskets, so they designed the LS to have the pistons out of the cylinders about 0.008" . And that gives 0.043", which is safe but not excessive.
#36
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Quench= Crushed gasket thickness - piston deck height
If your pistons are .010 out of hole, then with MLS 6.0 GM, your quench would be .042 (which is good)
And .050 lifts have almost nothing to do with PTV. Max lift occurs at or near BDC while contact with valve is at or near TDC (usualy 10* BTDC to 10* ATDC) <= Danger zone.
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My MLS 6.0 is .052 crushed.
Quench= Crushed gasket thickness - piston deck height
If your pistons are .010 out of hole, then with MLS 6.0 GM, your quench would be .042 (which is good)
And .050 lifts have almost nothing to do with PTV. Max lift occurs at or near BDC while contact with valve is at or near TDC (usualy 10* BTDC to 10* ATDC) <= Danger zone.
Quench= Crushed gasket thickness - piston deck height
If your pistons are .010 out of hole, then with MLS 6.0 GM, your quench would be .042 (which is good)
And .050 lifts have almost nothing to do with PTV. Max lift occurs at or near BDC while contact with valve is at or near TDC (usualy 10* BTDC to 10* ATDC) <= Danger zone.
If my old 236/236 .550 cam is not bent, I am going to try to use it to determine piston to valve clearance. If you guys were guessing or know.... what is the biggest you think would work?
How about any of the sponsors that sell cams and gaskets and stuff..... what do you sell that will work form my application???
thanks
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I would put that .550 lift cam in , clay a piston and set one of the heads on the motor and roll it over by hand so that you know for sure exactly what your dealing with .
Any thing less and you wont know Exactly what your numbers are .
Any thing less and you wont know Exactly what your numbers are .