44 Tolly repower

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Veteran Member
May 30, 2013
Vessel Name
Shear Bliss
Vessel Make
Tollycraft 44
Our ‘88 44’ Tolly has the DD 8.2s. Contemplating or more out of curiousity wondering about a repower. I am aware of their history and the opinions of them. At this particular point, we are in a better position to repower than if the engines implode years down the line.

Our 8.2s have 250hp and I run them like a trawler. However, if I had a few more ponies……If you could, what would be the optimal repower option? Cummins 370hp? Would Cummins fit height wise? John Deere? Detroit? Has anyone done this recently and what sort of budget were you at? 100k?

First world problems and I like to dream.
For sure 100K and maybe more depending on choice. I have never been able to make the math work on a repower. It always pencils out to be cheaper to sell and buy what you want.

Even with a dead engine it usually pencils out to rebuild over repower.

In the commercial world where you operate 1000 hours a year, fuel savings can pay for a repower, but not at 100 hours a year.

Everyone always thinks the expensive part is buying a new engine. They gloss over the fact that new engine mounts must not only be built but designed. Same with the exhaust system and a thousand other little items.
Height wise a Cummins 6BTA or QSB will definitely fit. They're not as tall as a Cat 3208 and those were used in Tolly 44s in some years.
Thank you both. Tiltrider-agree on cost to rebuild vs replace. What I am worried about is; heaven forbid I blow one of these 8.2s, but I think that ithe engine has to come out to rebuild. Then the adage of ‘do one do both, plays in my head because you’ve already shelled out $$$ for the dismantling of windows, etc to do one engine.

I’m putting cart before the horse. I just am leary of throwing good money after bad. I may just limp these girls along. It’s always in the back of my head that these engines aren’t the most robust even if I operate them in trawler mode.
I think some of the issues with the 8.2s had been resolved by 1988, so yours should be some of the better ones. Not a bad idea to have a plan in mind, but if they're doing adequately for your needs, I'd be inclined to run them until there's signs of an issue forming.
I would say that any 8.2’s running today are likely to continue running for a long time.
I understand your trepidation with those engines based on the 'history', because I refused to buy a boat that had them installed because of the 'reputation'. However, I wonder if that thought was a partial mistake. Agree with tilrider1 that if they are still operational at this point in time then it is likely they will continue to do so provided you keep up on the normal maintenance and don't run them like a rental.
My current Tolly has Mercruiser 454's and I now wish I had stuck to my original plan of only buying a diesel powered boat. Since your Tolly is already a diesel you are mostly there already... tanks, electrical, transmissions and such. Best advice I would provide is asking who is going to do the work?? You or a boat yard/vendor? If you are going to pay to have this done then you would be best served to reach out to those that do this work frequently/daily and avoid a yard that wants to learn how to accomplish this on your dime.
Yes, the 6BTA will fit as many folks have gone that route already. CATs are installed in many as well.... but you might be better off going with the modern power options for serviceability and all that.. not much sense installing a set of engines that have parts that are hard to come by because they are no longer supported by the vendor or the aftermarket.
I to dream of the power conversion as well, but would likely sell this boat and buy another if it really comes to being more than a dream. This assumes that the rest of the boat isn't already perfect in every respect.
Our 8.2s have 250hp and I run them like a trawler. However, if I had a few more ponies……If you could, what would be the optimal repower option? Cummins 370hp?
If you run your boat like a trawler, say 7-8 knots, then you're likely not using more than 40-60 hp even in wind/waves. You're planning to run a 370 down at idle speed of 20-30 hp for 8 hours a day. That's realistic for a modern electronically controlled common rail, but for an old fashioned mechanical 6B it may not be ideal, even with a hard run-up at the end of each day.
What's your use pattern? 90% trawler speed with an occasional higher run? Or vice versa?
You may decide to power with a couple of 4B's, maybe even naturals, if you want to turn that tank into a trawler. (BTW, don't forget to increase your rudder area if you do).
I’ve a friend with a Tolly 44. The 8.2s were removed and 6BTs dropped in. The fit was good and install done right. The boat was positively transformed from a performance standpoint. He was so thrilled as he could reliably cruise a few thousand nm from WA to AK without the fear of the next gotcha.

The Tolly 44 is a great boat and a pair of 6BT remans would be a real nice addition.
I had a 1975 Tolly 37 that was re powered from gas in about 1992 with 8.2’s. Never had any problems with the engines and never saw any reason to replace them. I expect they’ll run fine for many years (sold the boat a couple of years ago).
Thank you for the responses. Right now, we are probably 90% trawler speeds with the occasional run up. I also have the minor fear in the back of my head of keeping them low and slow to avoid the problems 8.2’s can have. Ours don’t exhibit any of those symptoms. However, if the opportunity arose to run her up a little more, I may take that opportunity. My wife and I both still work so our time can be limited. Getting to our spot or to our vacation grounds sooner may be nicer? Getting there is our joy also.

I’m not looking for trouble out of these engines….
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