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Duramax airboats


Looking for info.. trying to build a 2008 lmm duramax airboat.. I already have engine,ecm,stand-alone harness,going on a 20 ft air ranger.. three blade whirlwind 84 inch props.. engine runs great till props are installed.. she will not come off idle.. how are they getting this rectified?

John Fenner

Well-known member
Ok, not very familiar with the Duramax platform, nor the stand alone harness you are using, my observation here is that it will run up, assembled to the gear box-belt drive, but once you bolt the prop on and attempt to run it up it won't come off idle.
Does the stand alone system have a knock sensor? If so, it could be picking up chatter from the drive train and putting it in a limp mode to where it won't come off idle, might need a program to adjust the parameters and allow for the chatter.

Slidin Gator

Well-known member
I have read this same issue on a few past diesel threads on this forum. I suggest you spend more time searching as I have seen this resolved. I'm pretty sure the answer in each case was an aftermarket ECU with custom tuning. There is a lot of flex in an airboat system that produces different feedback to the engine vs. it's intended application. I would suggest that you install a soft drive to help dampen out some of the feedback the engine is seeing from the prop (but I do not expect this to solve your original complaint).

I would also suggest you talk to Pela Motorsports here in Jupiter, these guys have had their hand in all kinds of diesel builds.

Homepage - PELA Motorsports


Well-known member
Not to discourage but I have seen several of these builds over the past 10 years and none of them really were worth the grief.

The last one I saw over our way was at BrownWater about 2 years ago getting some rigging. There were some factory built BIG MONEY rigs built around 2008-2010 right before the economy tanked. Those boats were bought and sold so many times since then it was like holding a “hot potato” nobody wanted them after a few weeks.

Wish you the best with it, maybe you will find success but to date the back yard private boats have seen very limited success. Maybe look to Texas or Louisiana and the oilfield outfitters. That said, I think they have shifted to multi engine turbo big blocks in recent years.

Keep a thread up and we will follow ur journey