I was using the C-speedracing calculator to find compression and I noticed the displacement changed when I changed the gasket thickness, piston to deck clearance, or head cc. Why is this?

 

according to vehicle manufacturers, displacement is strictly bore and stroke, but when you get more internal and start to build engines, you get more variables.
so basically, your 1797cc GSR might actually be 1799.4cc or whatever.

 

You are right,displacement is bore and stroke only.They went out so many decimal point its probably a rounding error in the program.
Glenn

 

I used a calculator like that, too (might have been the same one), and saw the same problem. It is wrong. Those other variables don't affect displacement.

 

Displacement is just a function of bore and stroke!

Compression is more complex and would include head volume, volume at the head gasket, and displaced volume of the piston top and how high it goes into the head volume (deck height).

Wes.

 

I meant to say chamber volume would increase by adding a thicker gasket


Modified by aj99si at 11:21 AM 12/26/2004

 

Bore x bore x stroke x # of cyls x .7854 = displacement

Head gskt changes compression not cubic inch

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by aj99si &raquo;</TD></TR><TR><TD CLASS="quote">If you add a thicker head gasket you increase the displacement of the engine </TD></TR></TABLE>

You can add fifty head gaskets and the displacement won't change.

 

Or for a 4 cyl. its...... bore x borex3.14x stroke=

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos &raquo;</TD></TR><TR><TD CLASS="quote">

You can add fifty head gaskets and the displacement won't change.</TD></TR></TABLE>

lol umm...yes bob for 1000 plz, it will change.

displacement is bore and stroke, the distance from TDC to BDC the piston travels. As mentioned before with the cylinder volume, thats going to effect the compression ratio rather than the displacment as that will be a fixed variable.

Diesel engines have a higher compression ratio bcuz they have a lower head volume bcuz they dont need the clearence for a spark plug....hence the piston can get right up there and compress the gas/fuel more

 

nevermind.. i agreed with the post before lol... if ya add 50 head gaskets, the displacment wil be the same yes, but the compression ratio will suck *****