Rigging Mods And Tricks For Performance Marine

History of Duramax Marinisation

The video above is of my 1995 Ultimate Warlock 210 LXI, powered by a marinised 2005 "LLY" 6.6L Duramax diesel. Over a dozen back to back kilo style runs were recorded that day to promote biodiesel as an alternative marine fuel. The runs were made on B100, a 100% pure biofuel made from vegetable oil. Speeds were certified by twin on-board GPS units, and K-band radar by a local police chief.

While I would love to take credit for conceiving the first Duramax marinisation, credit belongs to the guys at California based tuner Pacific Performance Engineering [PPE]. Back in early 2007 they started rigging this Warlock hull with a Duramax engine salvaged from a 3/4 ton GMC truck. Later that year the boat was featured in Diesel Power magazine, and displayed at SEMA in Las Vegas.

After extensive testing including participation in a west coast marine endurance race, the boat was sold to a local customer of PPE. According to the Duramax forums, it was spotted a couple times the following year on lakes in California and Arizona. In the fall of 2009 I stumbled onto it listed on eBay, where it received few views, and zero bids. Seems a custom diesel speed boat wasn't something many people were looking for.

After several conversations with the owner and Joe at PPE, I decided it would be a good fit with our biodiesel production business. I made plans to fly out and inspect it, but at the last minute something came up, so we had to cancel. Purchased it sight unseen. The following spring it was shipped to Ohio where it would call home the next four years. But this story isn't about love at first site...

Shortly after purchasing the boat, it was nothing but trouble. Hence the name, "Bad Investment".. Little things at first, like electrical bugs, blown turbo boots, fuel starvation problems, and a couple minor cooling issues. That July while attending an SBI race in Florida, she spun a rod bearing and trashed the crank. The crankshaft was repaired, then only a couple weeks later it cracked a piston. This all within the first 30 hours on the meter. I began to consider scrapping the Duramax platform, even replacing it with a Powerstroke. That's how unhappy I was with it.

My earlier background and training as a professional automotive technician kept me thinking something else was up. The local GM tech who'd performed all engine repairs agreed, these were not common Duramax failures. Then it cracked a second piston, only a couple meter hours after the last one. That was it, everything came out and we started rebuilding from scratch. Punched out the block for new MAHLE pistons with a lower compression ratio. Inspecting every engine related part, at least twice. That's when we found the problem...

A small piece of rubber (pictured below) from the oil cooler and remote filter lines had broken free and was lodged in a main passage of the block. Starving the engines oil flow, while maintaining normal pressure on the gauge. It was stuck so far up in the block, two different machine shops missed it when they'd cleaned and inspected after the previous failures. Seems the stab type AN fittings used in the original rigging job are known to cause this "liner pealing" issue. All oil system lines were replaced, using only crimp style hydraulic fittings.

Pulled from the block     Smoked Piston

By the time we found the oiling issues, I'd already decided to upgrade several features based off advice from well respected Duramax gurus. What went back in the boat was a true 800hp capable bottom end. With upgraded oiling, fueling, major airflow improvements, and on-the-fly selectable power levels via EFIlive. It was now a solid engine platform, engineered to handle the rigorous marine environment. At a cost about equal to what I had paid for the whole boat the previous year. Duramax parts are not cheap.

Duramax Pistons    Duramax Engine

After a proper engine break in and a some final rigging adjustments, she was ready to go. And go she did. Her maiden voyage was a 15 mile wide open run down against a built Baja Outlaw SST who'd been itching to jump on this "supposedly fast" diesel. He was impressed. Said so when he pulled into the beach behind us.. And so was I, she'd actually held together spinning 600 RPM's above her factory red line for 10 minutes straight. All the hours addressing the engines weak points looked to have finally paid off.

Now it was time to fine tune parameters and take her on the road. That we certainly did. Logging over 300 problem free hours the next three years. Boating every major Eastern body of water between Canada and Florida. Did a few poker runs, shootouts, volunteered as a rescue boat for SBI, and even crossed two of the Great Lakes in this 21' open bow. Not only is she respectfully fast reaching up to 86mph, she is more amazingly fuel efficient. Offering A cruising range of over 350 miles on a 82 gallon tank. My last ride in her was the fall of 2014 on Lake Mead Nevada, where she was handed over to the present owner and returned to California.

This was definitely a learning experience, but it demonstrated the Duramax is a very solid platform when properly rigged. While attending the 2013 Lake Cumberland poker run, I was approached twice by individuals who knew the boats history well. They both worked at GM's Duramax engine assembly plant in Dayton Ohio. Each told me about how a picture of my boat proudly hangs on the wall in one of the break rooms. That's when I realized, all the time and money spent working through those bugs was well worth it. And how disappointed those guys would been had I'd given up and swapped in a 6.0L Powerstroke...

That first Duramax powered boat received plenty of recognition over the years. Featured in multiple print and online articles, along with tens of thousands views on YouTube. She'd also proven going green can be cool. Logging the majority of engine hours burning extremely clean biodiesel. Yes it was an expensive endeavor, but in the end it's performance quickly became legendary. Proving 409 cubic inches of marinised V8 diesel power can turn heads. It's also inspired at least 10 more Duramax conversions that I'm aware of. Counting my own 38 ft Warlock, there is currently three twin engine versions under construction. Along with a commercial marinised variant being offered.

Duramax Powered
"Bad Inve$tment" October 20 2012


Related Links

Duramax Warlock Photo Album
B100 Record Run Photo Album
Duramax Conversion Parts List
Custom E60 ECU Tuning Details
Other Duramax Conversions
YouTube Videos Page

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