The Best Duramax Diesel Ever Built — For Now

Weblog - Duramax Diesel

I often am asked the question, which is the best Duramax diesel to buy? I usually provide a range of answers, based on the strengths of the various Duramax engines. Here is a quick run-down of the strong points of each generation of Duramax diesel:

Top Duramax Diesel for Fuel Economy

This one is easy – the original LB7 Duramax. It's produces the best fuel economy of any of the Duramax engines. The big question is: why? Well, that gets a bit complicated to answer, but suffice to say that there are 2 major reasons. Firstly the conventional wastegated turbocharger on the LB7 allows free-breathing under light to mild loads, whereas the VVT turbocharger on the newer engines seems to require more drive pressure, robbing the engine of some efficiency. Secondly, the compression ratio of the newer Duramax engines has been lowered in an attempt to help control NOx emissions.

So why don't I drive an LB7? Firstly, I can tune the newer engines with EFILive to produce similar fuel economy numbers as the LB7. Secondly, the LB7 has old-school 15 second glow plugs which I find an annoyance. Also, living in a cold-climate, I appreciate the automated high idle in the newer engines. Thirdly, although injector reliability has been improved, I'm still not keen on buying a used LB7 with the possibility that there has already been some injector damage done.


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