2000 up GM crate motors

[ace58]

Are all 2000 up 6.5 engines 18 to 1? Or is it just the crate motors?

[computer monkey]

None of the 6.5 had 18 to 1 pistons unless they where custom build. I do believe that when American Motors started to build them the 6.5 went to 20 to 1 pistons.

[Kennedy]

If anything, the CR has gone UP since AMG started building them. It seems that pushing the piston up closer to the head helps them pass emissions certification. Who'd have thought? ;)

[richard7]

CR was lowered to 20.2 to 1 since 2000 (probably 1999), since the introduction of the "enhanced block".
Lowering compression ratio helps reduce NOx emissions.

[lupey6.5]

i have specs on the '99 L65 motor.this claims 19.5:1 is this the same motor you guys are talking about? i have other specs on this motor too.

[richard7]

This variation of the engine at 19.5 CR was never put into production. It was for a 215 HP rating; but GM decided to go the "Duramax" route.

The problems with the electronic injection pump are in the equation...

[Kennedy]

And when we toured the plant for the 2001 Rendezvous, it was stated that the CR was never dropped, in fact the protrusion of the piston was actually INCREASED which would raise the CR...

[rjschoolcraft]

The General Engine Products web site shows factory built marine engines at 18:1 compression ratio. All of the commercial stuff has the higher ratio. Here's a link to the GEP brochure (http://www.amgeneralcorp.com/gepbroc/page4.html).

[computer monkey]

General Engine Product spec page (http://www.gep-inc.com/)

Best viewed if you download the power point. Website is a little hard to see.