bertram 35" mercrusier bmw d219 diesel repower ???????

[tomuchstuff]

I have a 1973 35 bertram I bought from a school in town the boat has two nice running 454 from a re-power 10 years back. The 454 's run well but eat 40 galons an hour. I picked up two d219 out of a 70ft cat that a boom crane fell on at dry dock they have only 40 hours.

I know lots of guys are putting big 400hp diesels in the old bertrams just to find the boat is best at 20 knots. And if you take in to account that the 3208 with gear that was put in to the 35" in the 80's are 1600lbs each, the 3116 are not much lighter, cummins 555 that were in the 70 35 were at least as heavy if not worse than the 3208 and I think rated at 170hp, now most modern hi out put diesels that get in the 350 to 400 hp range also end up in the 1600 to 2000lbs range.

It seams there are two choices owners of the older 40,000 pound bertram have, the first to burn 4 or 6 gallons more an hour at sea to brag about the extra 2600 lbs of hi out put engine & gear they take with them fishing to make up for there extra small jock size. The other choice is to try to match the torq curve that the boat was design for, to trust the guys who calculated the hull drag co efficiency that they knew what they were doing, maybe that there engineered ride is most what created the bertram name and brought you to want one to start with. Thoughts?

any one do a similar re-power?

I think the d219 is only 800lbs and I was told they were 225 hp, but have only seen 170 to 190 hp on line. Any one know more about the bmw d219?

With the hp and torq I can keep my shafts & struts & rudders, but drives? I talked to the guy at zf and he told me to stay with the same drive spec, he also told me that zf runs at the same gear and hp foward and back so on a diesel you are just reversing on one side all the time, I do not know if this is the same with the velvets in my boat and if I can just revers one drive. The torq curve is close to a 454 torq curve from what the guy at mercrusier told me so the drives can take it but. any help with drives?

[FAST FRED]

Yanmar I think is now a BMW converter , rather than Toyota blocks.

Check with them for marine power curves and rating , M1 to M4.

FF

[Frosty]

As far as I know Borg Warners can not just be run in reverse as the ZF but I believe it is possible to convert.

I have a pair of ZF's and I have run either in forward or reverse. The book says it what you do . However it is annoying when your ratio in forward is 2:50 and in reverse is 2:54. Even though you can compensate for it you get the humming resonating drone. My Stbd engine always uses more than port.

[tomuchstuff]

so in 88 merc bought bmw and you think they sold it to yanmar when the started selling cummins?

[tomuchstuff]

I think your right about the velvet that they must be converted I saw a converted rebuild on ebay but at that price I will go with new zf.


I also think theres a slight drop in the out put of the inline drive and velvet is truly in line so the engine will have to pitch up if I go with zf .

that sucks about the two ratio do they sell match ratio at zf, do you think twin disk and hurth are the same as far as offset and ratio?

thanks
Larry

[FAST FRED]

do you think twin disk and hurth are the same as far as offset and ratio?


In terms of reliability the ZF or Twin Disc is heads above the Hurth.

If using the Hurth for cost reasons use a 2 sizes larger than their table would suggest.

FF

[tomuchstuff]

I do not know about the offset of twin disk or hurth. any who know can kick in on that.

and I think hurth is a more of a velvet level more of a gas gear, twin and zf seam better to suit the torq of diesle.

I'd like to stick with zf that is the gear merk sold the package with.

any one know what ratio I may want to run? or how I can calculate it.

[FAST FRED]

Go to Boatdiesel.com, join and use their computer.

I would attempt to match everything so the least has to be changed.Shafts struts props.

As a thought, what you're really matching is the torque peaks , the really efficient spot on most engines.

So if the gasser peak was at 3200 , and spun the prop at a cruise speed you can live with attempt to be at low RPM on the torque peak for the diesel at the same approximate torque output and prop RPM.

FF

[tomuchstuff]

I have a thred on that site and the site sucks. on one tries to help there just sell you bigger engines. I will have to brake out my slide ruler

the 72c velvet thats is in the boat will bolt up the the bmw's so I have to get one drive. the rest stays the way bertram built it


thanks Larry