Can someone put this to rest for me? I'm not understanding the difference between the two. I thought they both were the travel path of the cylinder, times the dimeter of the cylinder, times 8. But in looking at 6.0L and 5.7L heads and I've seen that you can get them in stock 67cc or 73cc chambers for lower compression. So is my LS1 with 6.0L and 67cc chambers a 346cc 6.0L? And what about with 5.7L heads and 73cc chambers... Is that a 5.7L 352cc engine?

Can someone clear this up for me? Thanks guys.

Mike

<small>[ February 25, 2003, 05:07 PM: Message edited by: buschman ]</small>

 

The heads have nothing to do with the displacement rating of an engine.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by buschman:
<strong> Can someone put this to rest for me? I'm not understanding the difference between the two. I thought they both were the travel path of the cylinder, times the dimeter of the cylinder, times 8. But in looking at 6.0L and 5.7L heads and I've seen that you can get them in stock 67cc or 73cc chambers for lower compression. So is my LS1 with 6.0L and 67cc chambers a 346cc 6.0L? And what about with 5.7L heads and 73cc chambers... Is that a 5.7L 352cc engine?

Can someone clear this up for me? Thanks guys.

Mike </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The 67 and 73cc numbers are the volume of the combustion chamber in the head, not the swept volume of the cylinder. It's the swept volume of the cylinder that determines an engines displacement. The volume of the combustion chamber is important because it determines the compression ratio:

(volume at bottom-dead-center)/(volume at top-dead-center) = comrpession ratio.

The volume at top dead center is approximately the same as the combustion chamber (plus whatever amount the piston stick up above the bottom of the head, or minus the amount it stays below). The volume at bottom dead center is the same as top-dead-center, plus the swept volume of the cylinder.

There are 1000 cubic centimeters (cc) in 1 liter. The 5.7 liter is 5672.3cc.

<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

<small>[ February 25, 2003, 06:46 PM: Message edited by: Miles in Michigan ]</small>

 

OK, I think I was confusing the 346 cubic inch with the cubic centimeter heads. Is an engine's cubic inch measured with the same piston sweep?

Thanks, great replies.

Mike

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by buschman:
<strong> OK, I think I was confusing the 346 cubic inch with the cubic centimeter heads. Is an engine's cubic inch measured with the same piston sweep?

Thanks, great replies.

Mike </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yes. This piston sweep is what is normally refered to as the "stroke" of an engine. If you take one half of a cylinder's diameter, or bore size, square that, mulitiply by pi and by the stroke, you have the volume or displacement of one cylinder. Then multiply by eight and you should come up with 346 cubic inches for the LS1's total displacement which is roughly the 5.7 liters you hear about. This of course is the traditional way to rate engine size, even though it takes two full revolutions of the crank to fire each cylinder only once.

<small>[ February 25, 2003, 09:41 PM: Message edited by: Cal ]</small>