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| Joined: | 03-14-2005 |
| Location: | Atlanta, Georgia USA |
| Posts: | 406 |
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Just to help everyone else, I'm listing a number of different piston Compression Heights I've assembled over the years:
2.0 Configuration: Stock=1.615", JE Flat-top=1.640"
2.2 Configuration: Turbo=1.470", JE Flat-top=1.480", JE 'H/C' Flat-top=1.535"
All use the 5.5 rod (Turbos use different rod-bolts) including the 300HP Esprit S4 SE.
The 2.2 JE 'h/c' Flat-tops I understand are a special designed by Garry Kemp available on the shelf from Delta Motorsports. As is the case with the 2.0 Flat-top, the 2.2 JE 'h/c' is a zero-deck-height version of the stock/regular flat-top piston.
Complicating matters when it comes to compression ratio is the newer head gasket that is about 0.020" thicker than the original.
Back to the problem...
Assuming you are NOT using the special H/C JE pistons from Delta, and you ARE using the newer head-gasket; there should be about 0.050" - 0.070" clearance between the head and the top of the piston. Even an Aluminum rod won't stretch that far.
I think the problem is elsewhere, and may be a combination of effects.
Could the engine be leaning-out at that higher RPM? Any idea of what Exhaust Gas Temperature you are running at that RPM? I assume you are keeping the engine operating temp well below 200^F?
What about piston-to-wall clearance and ring gap? Again, with high temps, lots of RPMs, a lack of oil, and no where to expand; the pistons could simply be heat fracturing.
I want to stress the JE pistons supplied by JHPS are of VERY high quality design. I run them in my cars as well as engines I've built for numerous clients. However, it may be that in a racing situation at sustained RPM levels; you may need an alternate design.
Judson
Last edited on 11-13-2006 09:10 pm by Judson Manning