Twins with Twins, Anyone?

[IdahoRob]

I ran a set of the Mahle Dmax monotherm pistons a few years ago. This was one of two sets they made basically by hand from what I was told. Guy built the engine and I knew it was an experiment.

The pistons were run for about 15, 1/4 mile passes and the engine started pushing water. I pulled the heads and found that the pistons had worn right through the cylinder walls and into the water jackets. Pistons looked great, lol. They were returned but have never heard what the findings were. I've spoken with the Mahle guys at Sema and PRI about it but no one seems to know or want to tell if they do.

As this was basically a one off set for testing, please don't take this example as what the final product will be like. I'm really doubting that there will be a mono out for the Dmax. They've been talking about it for many, many years and still nothing but talk. I'm not in the loop so maybe I'm wrong, just a feeling.

 

[Burn Down]

The Monotherms Caterpillar uses in the 3500 series and the C175 engines is a beast of a piston... I have seen them eat all 4 valves and ask for seconds:rofl: Piston face was beat up but the ring lands and cylinder walls were perfect.

If they get them figured out for the Duramax it would be an almost indestructible piston.

 

[kidturbo]

Thanks for that info Rob.

The examination on returned set I was told of sure sounds like yours. Leaving a couple sets floating around out there somewhere. If I'd built three sets lets say, and only one returned in good shape, but had eaten a block.

Yup, gonna require more research... Maybe in some matching sleeves. As I believe they do in all the big engines correct?

 

[Hawk 40]

Did you run into Will up there? He sent me some fancy pictures.

 

[PureHybrid]

The Monotherms Caterpillar uses in the 3500 series and the C175 engines is a beast of a piston... I have seen them eat all 4 valves and ask for seconds:rofl: Piston face was beat up but the ring lands and cylinder walls were perfect.

If they get them figured out for the Duramax it would be an almost indestructible piston.

Agreed. Steel pistons in the ISX are the same way, seen many engines cut in half by a monotherm swinging around.

I don't see it being practical for a Dmax, even with the demands we have.

 

[kidturbo]

Did you run into Will up there? He sent me some fancy pictures.

Yeah went to dinner on Friday, and then ran into him again on Saturday walking the halls. He's a hardcore, did all three days..

 

[kidturbo]

Here is what will put the power to the water. Very rare pieces, designed by Pat Weismann and specifically built to handle big diesel torque. Can fit up to like a 20" prop. Unfortunately the majority of these were sold to the US Gov. But somehow I own all the spare parts now...

These two drives were last pushing the 50' Vee below with 1700hp turbines to over 100mph. Before that, on the white blown BBC boat for a few years. I know this cause I just blasted all those old paint colors off them while freshening everything up.

One of these drives showed up at a military surplus auction last year, but I missed out on it. So if anyone sees these funky looking units on a auction site, please let me know.

 

[solidrunner]

Are those a #6 gimbal housing, or is that all Weismann stuff? Those drives look awesome. Were Arneson's not an option for this? Bad ass project, serious dream of mine to have a Duramax powered boat.

 

[kidturbo]

That's all Weismann. Hinge pins are exactly same as the #6. The ring is basically a 6 turned upside down. Transom bolt pattern is also same as Speedmaster. If you notice what's laying on the stand is a 6" extension box that allows for adjusting drive height.

This BAJA was actually rigged with early #6's, so we sold them when we stumbled onto these much stronger drives. But it's a long ways from being a direct swap....

Cleaned up the braided hoses and put some black separators on them. One down..

 

[lutzjk913]

Man this thing is looking good

When you hoping to have it in the water?

 

[kidturbo]

When you hoping to have it in the water?

Thanksgiving... :rofl:

I'm hauling these drives to Fl on Tuesday along with a mock up block to get the mounting points all wrapped up. So getting closer.

Long blocks are done, just down to tubing turbos and the small plumbing work. Which we've decided that plumbing these for marine consumes 4x more time than building two engines... But history has taught me not to rush this part or it will come back to bite ya.

 

[lutzjk913]

Thanksgiving... :rofl:

I'm hauling these drives to Fl on Tuesday along with a mock up block to get the mounting points all wrapped up. So getting closer.

Long blocks are done, just down to tubing turbos and the small plumbing work. Which we've decided that plumbing these for marine consumes 4x more time than building two engines... But history has taught me not to rush this part or it will come back to bite ya.

Stuff happens and you can easily get behind. Lol

I can't wait to see the finished product on these though.

 

[solidrunner]

That's all Weismann. Hinge pins are exactly same as the #6. The ring is basically a 6 turned upside down. Transom bolt pattern is also same as Speedmaster. If you notice what's laying on the stand is a 6" extension box that allows for adjusting drive height.

This BAJA was actually rigged with early #6's, so we sold them when we stumbled onto these much stronger drives. But it's a long ways from being a direct swap....

Cleaned up the braided hoses and put some black separators on them. One down..

That is some awesome stuff, the adjustable extension box is sweet. This boat is going to be bad ass when it's done.

 

[kidturbo]

Closing up the bottom end on the first one today. Then it's heading off to the fab shop for up pipes and turbos mounting.

For those who like modified stuff, see attached... Medium duty upper pan, switched to rear pick up design, custom baffle plate, modified LML oil pump, and custom 15 quart lower pan. Just typing all that was a pain.

Also couple pics of the mock up work to lay out front and rear engine mounting plates. Back to CAD software again.

 

[oscyjack]

look sgreat! this one is alittle more my speed hehe
https://www.youtube.com/watch?v=E-0BvFk7vTo

 

[kidturbo]

I've always wanted to own a RIB.

Guessing that is a Marine Diesel VGT500 powering it? While the jet setup removes some issues with drive gearing and long term reliability, it does come at the cost of lower speed and fuel efficiency.

 

[oscyjack]

They are a blast, but not for every occasion haha. I would take it always except straight winter, but i also like to go fast and fly high whereas most of my passengers prefer to put around lol.

Yeah thats the engine. caught it while searching used safeboats as an ad, google did me good by finding a kickass dmax rib haha.

Im pulling the twin perkins out of my buddies 33 fortier right now for 2 D6 pods . its just so tough to beat the maneuverability of them. When looking at full repower figures, for the fortier at least it made total sense. We had a hull speed gap on this old model of almost 4 knts we are hoping to pick back up. Te D6's are so small, it's crazy. We gained 50% of the engine room for more cabin that we are mocking up now, and still have more service area than before.

I like em on the rib, or at least the idea of them, for safety and shoreability. Me and my knucklehead friends do some crazy things, and eliminating the variable of a prop is prudent on a machine like that. Plus id get a kick out of pulling a dmax with a dmax

 

[Hawk 40]

Kidturbo, the 40 Outlaw had sixes right?
I'm assuming it has a Char Lynn for the helm pump.
You wouldn't know offhand which series?
I think the 10 is common in marine but not sure about flow requirements for these drives and want to be about 3 turns lock to lock.

 

[kidturbo]

I don't know right off, however there is no gauges in it now so you can easily take a peak.

Sent from my SAMSUNG-SM-G870A using Tapatalk

 

[Hawk 40]

I'll run by there this week sometime and take a look, thanks.