Need help picking MLS Gasket thickness!
Need help picking MLS Gasket thickness! Well I've been researching the sites, and I stuck between to MLS gasket sizes.
1) .040
2) .045
I'm looking to achieve an optimal quench, CR, and DCR. Which gasket should I go with? Can some of the brains around here help me out?
Mod info:
-Bore: Stock, 3.898
-Stroke: Stock, 3.622
-Piston Height: Stock, so I'm assuming .007-.009
-TSP PRC Stage II CNC Darts (62 cc)
-LPE 228/228 .588/.588 114 cam
Thanks in advance.
1) .040
2) .045
I'm looking to achieve an optimal quench, CR, and DCR. Which gasket should I go with? Can some of the brains around here help me out?
Mod info:
-Bore: Stock, 3.898
-Stroke: Stock, 3.622
-Piston Height: Stock, so I'm assuming .007-.009
-TSP PRC Stage II CNC Darts (62 cc)
-LPE 228/228 .588/.588 114 cam
Thanks in advance.
Last edited by tru_ice; Mar 14, 2006 at 01:09 PM.
Ok here it goes...
If you look online you can find calculators for the CR and the DCR by inputting your specs. I can figure both but it takes a while doing the calculations the long way.
Also, the DCR is dependent upon where the cam is in the engine, meaning it will change if you advance or retard the cam any. For street applications, 8-8.5:1 is about max for 92 octane. You'll need your cam printout with the intake closing angle (in degrees after bottom dead center, ABDC).
Static Compression Ratio...The volume calculations are simple using pi*rad^2 and all you do is take the volume of the cylinder at BDC plus the volume of the chamber plus the volume of the head gaskets....divide by the volume of the chamber plus the volume of the head gaskets plus the volume of the cylinder at TDC (keep in mind if the piston is out of the hole ~.008", the number is negative and it will be subtracted). Figure these in cc's...they will cancel and you're left with a ratio....compression ratio.
You have flat top pistons so there is no calculation for the valve reliefs or domes.
Now, to find the DCR, you need to find where the piston is when the intake valve closes. Let's assume that the ICA (intake closing angle) is 40 degrees after bottom dead center. Draw yourself a diagram of the piston, connecting rod, and crankshaft. Add in the rod length (6.100 if I remember correctly), the crank throw length (1/2 the stroke), and label the crank as 40° ABDC. Using some geometry you can find how far up the piston is in the cylinder. What you need to do is find the "new" stroke...this is because the engine cannot build compression until the intake valve closes. This number should be between 8 and 8.5:1.
Do the calculations for the .040 and .045 gaksets. This is just some of the stuff I've done to get my auto. eng. degree. There's really not much to it...looks overwhelming, but it's not. Good luck and have fun. You will learn a lot from doing it rather than having someone tell you what they would do.
Thats my best advice.
If you look online you can find calculators for the CR and the DCR by inputting your specs. I can figure both but it takes a while doing the calculations the long way.
Also, the DCR is dependent upon where the cam is in the engine, meaning it will change if you advance or retard the cam any. For street applications, 8-8.5:1 is about max for 92 octane. You'll need your cam printout with the intake closing angle (in degrees after bottom dead center, ABDC).
Static Compression Ratio...The volume calculations are simple using pi*rad^2 and all you do is take the volume of the cylinder at BDC plus the volume of the chamber plus the volume of the head gaskets....divide by the volume of the chamber plus the volume of the head gaskets plus the volume of the cylinder at TDC (keep in mind if the piston is out of the hole ~.008", the number is negative and it will be subtracted). Figure these in cc's...they will cancel and you're left with a ratio....compression ratio.
You have flat top pistons so there is no calculation for the valve reliefs or domes.
Now, to find the DCR, you need to find where the piston is when the intake valve closes. Let's assume that the ICA (intake closing angle) is 40 degrees after bottom dead center. Draw yourself a diagram of the piston, connecting rod, and crankshaft. Add in the rod length (6.100 if I remember correctly), the crank throw length (1/2 the stroke), and label the crank as 40° ABDC. Using some geometry you can find how far up the piston is in the cylinder. What you need to do is find the "new" stroke...this is because the engine cannot build compression until the intake valve closes. This number should be between 8 and 8.5:1.
Do the calculations for the .040 and .045 gaksets. This is just some of the stuff I've done to get my auto. eng. degree. There's really not much to it...looks overwhelming, but it's not. Good luck and have fun. You will learn a lot from doing it rather than having someone tell you what they would do.
Thats my best advice.
I should also add that the quench is the gasket thickness +/- the clearance height. That height is negative since the pistons are out of the hole, so .045 gaskets minus .007 is a quench os .038. Thats decent.
Originally Posted by 99ssleeper
Ok here it goes...
If you look online you can find calculators for the CR and the DCR by inputting your specs. I can figure both but it takes a while doing the calculations the long way.
Also, the DCR is dependent upon where the cam is in the engine, meaning it will change if you advance or retard the cam any. For street applications, 8-8.5:1 is about max for 92 octane. You'll need your cam printout with the intake closing angle (in degrees after bottom dead center, ABDC).
Static Compression Ratio...The volume calculations are simple using pi*rad^2 and all you do is take the volume of the cylinder at BDC plus the volume of the chamber plus the volume of the head gaskets....divide by the volume of the chamber plus the volume of the head gaskets plus the volume of the cylinder at TDC (keep in mind if the piston is out of the hole ~.008", the number is negative and it will be subtracted). Figure these in cc's...they will cancel and you're left with a ratio....compression ratio.
You have flat top pistons so there is no calculation for the valve reliefs or domes.
Now, to find the DCR, you need to find where the piston is when the intake valve closes. Let's assume that the ICA (intake closing angle) is 40 degrees after bottom dead center. Draw yourself a diagram of the piston, connecting rod, and crankshaft. Add in the rod length (6.100 if I remember correctly), the crank throw length (1/2 the stroke), and label the crank as 40° ABDC. Using some geometry you can find how far up the piston is in the cylinder. What you need to do is find the "new" stroke...this is because the engine cannot build compression until the intake valve closes. This number should be between 8 and 8.5:1.
Do the calculations for the .040 and .045 gaksets. This is just some of the stuff I've done to get my auto. eng. degree. There's really not much to it...looks overwhelming, but it's not. Good luck and have fun. You will learn a lot from doing it rather than having someone tell you what they would do.
Thats my best advice.
If you look online you can find calculators for the CR and the DCR by inputting your specs. I can figure both but it takes a while doing the calculations the long way.
Also, the DCR is dependent upon where the cam is in the engine, meaning it will change if you advance or retard the cam any. For street applications, 8-8.5:1 is about max for 92 octane. You'll need your cam printout with the intake closing angle (in degrees after bottom dead center, ABDC).
Static Compression Ratio...The volume calculations are simple using pi*rad^2 and all you do is take the volume of the cylinder at BDC plus the volume of the chamber plus the volume of the head gaskets....divide by the volume of the chamber plus the volume of the head gaskets plus the volume of the cylinder at TDC (keep in mind if the piston is out of the hole ~.008", the number is negative and it will be subtracted). Figure these in cc's...they will cancel and you're left with a ratio....compression ratio.
You have flat top pistons so there is no calculation for the valve reliefs or domes.
Now, to find the DCR, you need to find where the piston is when the intake valve closes. Let's assume that the ICA (intake closing angle) is 40 degrees after bottom dead center. Draw yourself a diagram of the piston, connecting rod, and crankshaft. Add in the rod length (6.100 if I remember correctly), the crank throw length (1/2 the stroke), and label the crank as 40° ABDC. Using some geometry you can find how far up the piston is in the cylinder. What you need to do is find the "new" stroke...this is because the engine cannot build compression until the intake valve closes. This number should be between 8 and 8.5:1.
Do the calculations for the .040 and .045 gaksets. This is just some of the stuff I've done to get my auto. eng. degree. There's really not much to it...looks overwhelming, but it's not. Good luck and have fun. You will learn a lot from doing it rather than having someone tell you what they would do.
Thats my best advice.
Now what are my calculations, just to check my answers of course.
You'd have to post the ICA for anyone to give you the DCR.
I've seen some guys say they like a quench around .036 and you can only get that buy choosing a .045 gasket assuming the pistons are out ~.008....that would be my choice.
I've seen some guys say they like a quench around .036 and you can only get that buy choosing a .045 gasket assuming the pistons are out ~.008....that would be my choice.
Don't forget to take into account that the block grows .010 or more when it warms up.
This should be added into your quench calculation as well. I run mine at .027 with good
results.
This should be added into your quench calculation as well. I run mine at .027 with good
results.
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Originally Posted by z-ya
Don't forget to take into account that the block grows .010 or more when it warms up.
This should be added into your quench calculation as well. I run mine at .027 with good
results.
This should be added into your quench calculation as well. I run mine at .027 with good
results.
Thats going a little too far I think.
Originally Posted by 99ssleeper
Wouldnt the rods also grow, as well as the pistons...
Thats going a little too far I think.
Thats going a little too far I think.
Nate
Originally Posted by 99ssleeper
Wouldnt the rods also grow, as well as the pistons...
Thats going a little too far I think.
Thats going a little too far I think.
(high silicon content) so they can be run tight in the bore since they don't grow much.The rods are powdered metal steel and don't grow anywhere near
as much as cast aluminum.That .010+ figure I quoted is from people who
have measured the difference between hot and cold valve lash on solid lifter
engines and is somewhat of a guess as theirs changed more but also had to
account for the heads growing.
