Putting diesels in Bertram

[ske11y]

Im finally about to have my engines put my 79 Bertram 28. It originally had gas engines(305s i believe) but they were already taken out when i purchased the boat. I bought two 6.9 International diesels for it and am going to have them put in within the next month or two. My question is What all will have to be done since the change from gas to diesel? Im wanting to know ahead of time so ill have an idea when i talk to the mechanic more about it and possibly even do some work my self.
Thanks in advance

 

[smokeonthewater]

Re: Putting diesels in Bertram

control for glow plugs
different tachs. (lower rpm) possibly mechanical?
fuel tank(s) /hoses must be compatible
gearing/prop changes (again lower rpm)
additional sound proofing would be a good idea

 

[Steve91T]

Re: Putting diesels in Bertram

Huge turbo's! My dream is to someday have a smaller turbo diesel boat.

Make sure you get the drive and prop right, obviously lower RPM, but high torque.

 

[dingbat]

Re: Putting diesels in Bertram

Be prepared to spend some money

http://www.sbmar.com/Repowers.php

 

[DuckHunterJon]

Re: Putting diesels in Bertram

As stated before, I hope you are upgrading the drives as well as the motors. The difference in torque from a 5.0 L gas to a 6.9 L diesel is going to be 3 -4x. If you don't upgrade the drives, chances are good they grenade themselves in short order.

Otherwise, the some other changes that haven't been mentioned would be motor mounts - not only are the motors different size, but remember that torque - the mounts have to be able to withstand that.

One other change I can think of is weight distribution. Not sure if it's an issue, but those 6.9's will weigh considerably more than the old motors, might be worth moving some other stuff around to rebalance the load.

 

[sasto]

Re: Putting diesels in Bertram

Is she a flybridge with duel controls or an express? Bertram 28 is one of my favorite boats of all. I own a Penn Yan...a Bertram wannabe. What transmission are you going with?

 

[Luhrs28]

Re: Putting diesels in Bertram

The changes mostly involve the fuel system. You're going to need a coarse fuel filter and fine filter for each engine, if the engines don't already have them. Racor is a good brand.

You'll also need a fuel return hose to the tanks from each injection system. Assuming dual thanks that means you need a 3-way valve for each fuel supply line and a 3-way valve for each return. (you always have to return the fuel to the same tank you're drawing it from, to avoid overflowing the offline tank)

You also need a glow-plug circuit for each engine. Use a heavy-duty relay and make sure your wire is heavy enough gauge for the amps.

You'll need 2 batteries to start each engine so that might involve changing how your battery selector switch is wired (your gas engines probably only used 1 battery to start) Use #2 AWG cables for the batteries and starter. Your existing cables might be #4 cable which isn't heavy enough.

Do the engines already have water-cooled manifolds and a raw water pump?

 

[Greg Mrozinski]

Re: Putting diesels in Bertram

Skelly,

If it were me, I would sell the diesels and reinstalled new gas engines. Diesel conversions in this size range are almost never worth it. The extra money for the engines, the conversions, and the extra maintenance far outweigh any fuel savings and durability gains. Reinstall a pair of fuel injected Crusaders. They will drop right in and the fuel burn won't be too bad over the long haul.

 

[Don S]

Re: Putting diesels in Bertram

I have moved your post from the Boat topics forum to here in the Diesel forum, please don't post the same question in two different forums.
I have also merged the two posts together.

 

[QC]

Re: Putting diesels in Bertram

It is not 3 - 4x torque. Maybe 1.5x . . . Depending on the existing gear, may be fine. We can't just say "Big turbos" either. This stuff has to match the application, and they have to be water cooled. With that siad I am with Greg as far as caution is concerned. Are these marinised engines or truck engines?

 

[DJ]

Re: Putting diesels in Bertram

Agree with QC ^^^^.

The 6.9 was never one for big performance. Turbo'd it was better but International never really sanctioned that. They did with the 7.3L (T444E and the Ford Powerstroke).

I think there may be better diesel choices out there with a better weight/size to performance ratio.

Besides, the 6.9 is a physically large engine. A V-8 configuration is going to be very difficult to fit into a tight engine compartment.

 

[kahuna123]

Re: Putting diesels in Bertram

I been involved in quite a few of these when I still had my shop. If you are really set on this go find a good pair of 671's. Cheap, you get enough hours out of them to make it worth you while.

 

[HT32BSX115]

Re: Putting diesels in Bertram

I been involved in quite a few of these when I still had my shop. If you are really set on this go find a good pair of 671's. Cheap, you get enough hours out of them to make it worth you while.

Yeah.....but removing two engines that weigh around 600 each and replacing them with 2 engines that weigh more than 2000lbs EACH??

I am not thinking that would work that well if the boat sank!!!

They'd make good anchors though!

 

[wi4x4man]

Re: Putting diesels in Bertram

One thing that I haven't heard much talk about on here is that diesel engines produce more torsional vibration than a gas engine, not just the torque.
You need to make sure that the correct type of coupling connects the flywheel to the gear, or you will destroy the gear. Most of these problems happen at lower RPM's too.

In terms of selection, that is a whole other story. You would need to know what the gear can handle from the manufacturer and then size a coupling accordingly. Some companies that make these couplings are Lovejoy, Hayes, Centa, Vulkan, and etc. You also need to be able to tell them what type of flywheel you have (OCC, flat faced, and etc). Be prepared to fork over a lot of money for one of these too. Depending on the requirements, you could spend anywhere from $200.00 to $2000.00 per engine. It has been my experience to use Vulkan couplers on marine gears. The diesel engines I deal with are John Deere with ZF gears and I am pretty familar with them.

 

[Howard Sterndrive]

Re: Putting diesels in Bertram

are these dressed Mercruiser 6.9's? or we talking about a couple of old pickup truck engines?