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Ennio Paolo Ennio Paolo is offline
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Join Date: Jun 2008
Location: Naples, Italy
Posts: 7
real compression ratio using 2.4 heads

John, Bobby, thank you very much.

I have read the discussion between YTNUKLR and Steve Weiner in a past thread:

“Originally Posted by YTNUKLR:
I like! They make a GREAT engine with a 66mm crankshaft. 2.63L short-stroke. "10.3:1" was advertised with the RSR heads, which had bigger head volume than 2.7 engines. On a 2.4/2.7 70.4mm crankshaft with 2.7 heads (usually about 76cc chamber volume), compression is probably around 12:1. With a 2.0/2.2 crankshaft it drops to about 11:1, maybe even a little higher..no other modifications needed with a 2.7 case. VERY snappy! Twin spark plugs are a MUST”

Hi Scott,
The 92mm RSR P/C's make around 11.5-11.7:1 with the 70.4mm crank using the normal 2.2-2.4-2.7 heads. With a 66mm crank and the same heads, they make around 10.5-10.6:1.

B. Anderson, page 139, figure, comparing 2.8 RSR and 2.7 heads, showed the effects of the head volume on the compression ratio.

So, my error.
Concluding, 92 mm bore pistons by JE have a compression ratio referred to 2.4/2.7 head, differing by mahle 92 mm bore….



….wonderful forum!!

Last edited by 304065; 06-16-2008 at 04:39 PM.. Reason: removed line breaks to make easier to read
Old 06-16-2008, 04:17 PM
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