Mercedes 300 d in my Bertram

I found this on the web about the 300d turbo diesel...…"well,we all know that it does 120hp stock". If that is true, your boat will be an underpowered slug, the idea that it planes OK with just one of these engines, I am doubting in the extreme.

 

Just following along....I still don't know exactly what size Bertram we're talking about here. As for the 300d, based on what I can determine it's a car model. MB used its OM617 (naturally aspirated) and OM617A turbocharged diesels in those models. Weight on those engines was a little north of 600 pounds versus around 510 for a Ford 351C, you'd need to factor in the weight of the manifolds/mufflers to compare the power plants fairly but based on what I see it may well be close to a wash. While it's true that the OM617A could produce 227 HP, this was only in an extreme high performance design that was used to set some records in a Mercedes c111 but that was a concept car. Mercedes-Benz C111 | Mercedes-Benz https://www.fanmercedesbenz.com/1969-mercedes-benz-c111-i/
I'm by no means a MB expert. I just got curious and decided to do a little digging. So what kinda Bertie is this anyway?

 

I mentioned 28 feet, he has not corrected that. It is Walter Mitty stuff to imagine 1 x 120 hp will get that on plane.

 

Hey Gonzo, Yes ,I am changing the oil cooler to a heat exchanger, the conversion kit made by Drinkwaard in the netherlands did all of the technical data for the cooling and have the proper size for this engine. I may end up repropping, wont know until I get both engines in and in the water, then I can do the RPM to speed test and see where were at, I hope I dont have to , these props aint cheap, but it could make a world of difference.. As far as cooling, Im not going to cover the turbo, however I really do need to keep it cooled, it will get super hot. This Bertram has these outlets on the Gunwhales that I can run some flexible 3 inch tubing into for all the out take so it wont be in the cabin area. Its a pretty open cabin area, ( Im in San Diego). But I want to do it right the first time. Ill try to put up a little diagram to show what I mean soon. Happy Thanksgiving and tight lines!

 

Unless you route the turbo intake outside of the engine room, you cannot run high negative pressure in there.
The engine requires copious amounts of (cool) air to run correctly.
You will need to insulate the turbo and dry riser heavily.

 

You need to have heat shields on the turbo to comply with regulations. The USCG and CFR defer to ABYC on exhaust systems on small boats.
https://law.resource.org/pub/us/cfr/ibr/001/abyc.P-01.1993.pdf

 

Hey all, Yea,i figured I will have to have some sort of heat shield on these turbos. By the way ,I think that I did say that this boat is a 28 ft. My mistake on this, This boat is specifically an Bertram 26 ii (2) sport convertible model 261. 26 ft. The beam is 10'-0 and weighs 7700 lbs. The draft at the propellers is 2' - 7 1/2" Approx. The propeller shafts are 1 inch stainless and 66 inches long The current Propellers are 3 blade ,14 inch NIBRAL. The original engines that came with this boat were Crusader CH165 (165 HP. ea) So I think that I will be good on HP. When this boat had the 351s in them, it was a rocket ship! The original ventilation plans for the engine compartments port and starboard were ATWOOD 130 cfm blowers vented through 3 in flexaust to cowlings on the rails .Ill use a couple of more modern 130-150 cfm ones. Any recommendations? I think that I will REALLY need to cool the hell out of these but if I insulate the turbo too much, will it get too hot? I am insulating the dry risers with fiberglass tape a couple of inches thick.

 

Heavy lagging on the exhaust parts and turbo will not cook them, but will enable the heat to be carried away by the exhaust flow.
Original ventilation was built as required for gasoline engines - exhaust blowers whose primary function is to remove gas fumes from the engine compartment before the motors were started.
With diesels, the entire ventilation scheme has changed, you now must re-engineer it to accommodate the needs of the new motors, they will want a LOT of cool air when running.
Driveshafts will likely be marginal at 1”, and 14” dia props probably too small for diesel power, so you may need bigger shafts to handle the torque, and struts redesigned to give greater propeller clearance.
Your raw water supply seacock is probably undersized, and your fuel tanks will need revision.
The exhaust system may be too small as well.
I’m not real familiar with the motor you’re using, but in very general terms, automotive diesels that are converted for marine use need to be derated (hp), as their duty cycle in marine use will be very different than what is expected of them in a car.
I hope you have looked carefully at all the aspects of doing this conversion, it can be very costly, and can easily exceed the value of the vessel.

 

The automotive rating is for very short periods of acceleration. In general, they will run at no more than 50% of that power. The equivalent to marine service, would be a fully loaded car with an attached trailer going full speed up a hill continuously for hours.​

 

Man, you guys are doom and gloom, I took a real close look at some numerous conversions in Europe, there will be some stuff that i will have to address, especially the cooling air,hes right about that. Fuel tank is brand new. But the ones I looked at were very simple engineering. The conversion kit has all the coolers, bell housing, Engine mounts,brackets , even bolts and nuts required. The one inch shafts handle the torque just fine according to Drinkwaard. My raw water seacocks are 2 and 1/2 inch for each engine, this was plenty for the 351s, why wouldnt it be for these? My Exhaust system is 2 and 1/2 inch, waaaay bigger than what came off originally. I think that my biggest challenge is going to be , how to keep them cool enough air wise,thinking maybe 150-200 cfm quiet in line blowers? Capn D mentioned not having negative pressure in the engine compartments, hes right, what I want to do is draw in outside air with a nice high CFM quiet blower (in line) and pump it into the engine room, which will in turn, POSITVE pressure the the engine compartment with cool outside air and push the heat out through the cowlings constantly.Maybe? sooo,should I heavily insulate the turbo and dry exhaust,whats the consensus?? Also, remember that I have twins,not just one engine. I dont think from what Ive seen in other conversions in a couple of 28 footers that I will be underpowered. Love the input, trying not to miss anything.. Appreciate any suggestions, my engineering expertise is in physics, not much in mechanical data, so again, much obliged!

 

Hi Gary, we're not doom and gloom, there is a lot of experience here, practical experience. As I watch the snow fall and the Packers/Giants, I finally understand what you have there. I think. There might be some misunderstanding. Bertram called your boat a convertible. I also own a small convertible. A 25.5 from Silverton. Mine looks like this......



Yours looks something like this, right?


Bertram calls this boat a 26 convertible but typically convertibles are flybridge boats where the Bertie is an open cockpit v-berth design. Your engines are enclosed in those two compartments rather than an "engine room" as would be the norm in a typical convertible like mine.

I'm just doing you a favor (I hope) by clarifying things. If I'm reading the posts correctly I think that people are assuming you're modifying a boat something like mine. That's not at all the case based on what I'm looking at. It would seem that modifying your boat is much different than modding something like I have.

Regards,

MIA

 

Hey missing! another Bertie owner! My boat looks like a combo between the two , has a hardtop roof, but no flybridge, waay bigger engine covers, and a berthing in the bow. Its called a Bertram 26- 2 ( the 2 is actually a roman numeral 2) sport convertible, model261. I will try to get a couple of pics for everyone, nice boat by the way! do you have Diesels?

 

I had a Mercedes 300 turbo with the 5 cylinder diesel. Ran very very smooth. They did an amazing job engineering that engine and getting it perfectly balanced. Normally a 5 cyl would shake itself to pieces. Extremely reliable. I don't recall what HP it was but I never had any issues with it in the mountains. Can't say the same for the transmission. It went bad, real bad.

If you can get this working it should be a very reliable power plant. Don't know if it will be very fast though. By the way, you can run it on biodiesel and even vegetable oil. I didn't but I knew people who did. Smelled funny but better for the environment.

 

Hey Ike, did alot of research,( kind of my thing) on diesels, marine and commercial and out of all diesels ever built that met my parameters that could actually be used for multiple types of applications, this mercedes 300 d turbo is one of the best ever built, for dependability, low maintenance and simplicity. Soo, after a year of trying to figure out how to convert it, I found a company in the Netherlands that specifically makes the whole damn kit to do it, from start to finish.. I did change the transmission for this for better use of torque in a marine application. I am using a borg Warner transmission. For marine applications, they highly recommended either a Hurth or the Bw. I have one in and running, so far ,so good. I hope it turns out to be the million mile engine that mercedes brags about!

 

I don't know about a million miles but I had both a 240D and the 300. The 240 D was still running like a fine swiss watch at 310K when the body started rusting out, and the 300 had over 200K on it when the trans went and I trade it for a 300TE wagon (gas engine) I gave the TE to my son with over 200K and he ran it up to over 300K, not bad for a gas engine. I can't say the same for other parts of the cars. The first part to go on all three was the Air Conditioning. I hate to say it but the AC systems on those cars was the only part that was made in the USA. Over the years I replaced starters, alternators, fuel pumps etc but the engines just kept on running with routine maintenance.