I have seen the boost gauges in cummins running in excess of 40 psi. Holset HX40 turbos and a really modded engine for pulling competition so I don't know where the 20psi theoretical limit is coming from. The new Duramax runs 20psi stock...... Plenty more is available when chipped. GM may have a ***** history regarding design but Detroit Diesel designed the 6.2-6.5 liter and it is a good engine when used within its design limits. That said GM's, volvos, VWs, MBs, etc. with high compression definitely last a long time, many over 300K. What I said was they would not last if they were operated at maximum usable power ALL the time. Especially without intercooling. Peninsular found that in marine environments 21:1 compression ratio GMs operating under marine constant type loads would fail piston ring lands and blow headgaskets. Going to 18:1 pistons solved the problem with no real decrease in efficiency. GM trucks (6.2-6.5) won't survive for long hauling 10K loads unless modified. Your volvo won't last long hauling a comparable load either. Its been 8 years since 1994 in a very competitive diesel market and the technology in the new engines reflect it. Navistar, Cummins, Isuzu, etc. know what they are doing when it comes to diesel truck engines. If it was beneficial for them to run 21:1 ratios then they would redesign the engines and thats what they would offer. But they haven't, at least not to my knowledge, YET..... Maybe the super-high compression, high boost, multiple stage compressor diesel is just around the corner. I hope it is. Sounds good to me. RT

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When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
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