Compression for the layman
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Grand HDF Member
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From: Northeast, NJ
Compression for the layman
Greetings,
Slowly acquiring parts this winter to add a little uummpphhh for the engine. Just cams and what not.
Regarding compression...
I confess, I read about static compression and this and that, and I'm a little lost.
Bottom line, is bumping up compression a relatively easy thing to do? I've read about changing out the head gaskets to .30 and this brings the compression to about 10. Is this something the layman can do? Is this recommended? Are there other things involved?
By the way, I'm installing Andrews 57H cams and lifters/pushrods.
I assume bumping up compression reduces the longevity of the motor? How does compression affect mileage?
Sorry for the newb'ish questions....
Slowly acquiring parts this winter to add a little uummpphhh for the engine. Just cams and what not.
Regarding compression...
I confess, I read about static compression and this and that, and I'm a little lost.
Bottom line, is bumping up compression a relatively easy thing to do? I've read about changing out the head gaskets to .30 and this brings the compression to about 10. Is this something the layman can do? Is this recommended? Are there other things involved?
By the way, I'm installing Andrews 57H cams and lifters/pushrods.
I assume bumping up compression reduces the longevity of the motor? How does compression affect mileage?
Sorry for the newb'ish questions....
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Joined: Dec 2007
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Greetings,
Slowly acquiring parts this winter to add a little uummpphhh for the engine. Just cams and what not.
Regarding compression...
I confess, I read about static compression and this and that, and I'm a little lost.
Bottom line, is bumping up compression a relatively easy thing to do? I've read about changing out the head gaskets to .30 and this brings the compression to about 10. Is this something the layman can do? Is this recommended? Are there other things involved?
By the way, I'm installing Andrews 57H cams and lifters/pushrods.
I assume bumping up compression reduces the longevity of the motor? How does compression affect mileage?
Sorry for the newb'ish questions....
Slowly acquiring parts this winter to add a little uummpphhh for the engine. Just cams and what not.
Regarding compression...
I confess, I read about static compression and this and that, and I'm a little lost.
Bottom line, is bumping up compression a relatively easy thing to do? I've read about changing out the head gaskets to .30 and this brings the compression to about 10. Is this something the layman can do? Is this recommended? Are there other things involved?
By the way, I'm installing Andrews 57H cams and lifters/pushrods.
I assume bumping up compression reduces the longevity of the motor? How does compression affect mileage?
Sorry for the newb'ish questions....
Scott
HDF Community Team
Joined: Jun 2006
Posts: 12,763
Likes: 2,597
From: san antonio
Greetings,
Slowly acquiring parts this winter to add a little uummpphhh for the engine. Just cams and what not.
Regarding compression...
I confess, I read about static compression and this and that, and I'm a little lost. Bottom line, is bumping up compression a relatively easy thing to do? I've read about changing out the head gaskets to .30 and this brings the compression to about 10. Is this something the layman can do? Is this recommended? Are there other things involved? By the way, I'm installing Andrews 57H cams and lifters/pushrods.
I assume bumping up compression reduces the longevity of the motor? How does compression affect mileage?
Slowly acquiring parts this winter to add a little uummpphhh for the engine. Just cams and what not.
Regarding compression...
I confess, I read about static compression and this and that, and I'm a little lost. Bottom line, is bumping up compression a relatively easy thing to do? I've read about changing out the head gaskets to .30 and this brings the compression to about 10. Is this something the layman can do? Is this recommended? Are there other things involved? By the way, I'm installing Andrews 57H cams and lifters/pushrods.
I assume bumping up compression reduces the longevity of the motor? How does compression affect mileage?
A .030" head gasket will raise static CR .25 to .30 points; the increase will vary a bit depending on the CID of the motor which you have not provided. As an example; if static compression is 9.6 with a stock head gasket which is about .045" thick, replacing that head gasket with a .030" head gasket will increase static CR to about 9.9. Of course there are other ways to increase compression. Dome pistons can be used or cylinder heads can be "decked" to reduce the volume of the combustion chamber.
Static CR is just a number. An operating motor never sees static CR but runs on dynamic compression, sometimes referred to as corrected compression. Dynamic compression is a function of the timing of the closing of the intake valve which is why cam selection is so important. Reasonable increases in compression will not affect the longevity of a motor. Actually, all other factors being equal, increasing compression will improve the efficiency of the combustion process resulting in better fuel economy.
I would suggest that you spend some time reading about compression; it's not that complicated and the information is out there. If you don't want to take the time to do the reading, talk to someone that knows how to get the most out of those 57 cams.
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Grand HDF Member
Joined: Sep 2008
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From: Northeast, NJ
Thank you all for the info.
So, if I have this correct, along with the Andrews 57H cams, I can install the .030 gasket without worry to raise the compression.
I have no idea what the engine CID is? I can tell you, it's a standard 103 engine in a Switchback, if that helps.
Edited to add: Does CID stand for Cubic Inch Displacement? If so, my engine is a 103
So, if I have this correct, along with the Andrews 57H cams, I can install the .030 gasket without worry to raise the compression.
I have no idea what the engine CID is? I can tell you, it's a standard 103 engine in a Switchback, if that helps.
Edited to add: Does CID stand for Cubic Inch Displacement? If so, my engine is a 103
Last edited by rauchman; Jan 22, 2016 at 11:10 AM.
Thread Starter
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Grand HDF Member
Joined: Sep 2008
Posts: 3,684
Likes: 4,294
From: Northeast, NJ
Anything else that needs to be done in conjunction with the .030" gasket?
Thanks!
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