1st post...

I've been reading about upgrading at 72C to handle a little more torque/hp and offshoreonly seems to be the place to go for this information. I'm not really in the same league at you guys as far as speed goes but I have the same issues. Currently running a Cummins 5.9 6BT 210 hp through a 72C (1:1) jackshafted to a Konrad 520 (1.43:1). Current 6BT 210 puts out 210 hp @ 2600rpm and 534 lb-ft of torque @1800 rpm. (Konrad 520 is rated for 738 lb-ft for highly intermittent use in planing hulls and 557 lb-ft for commercial use)

1. I'm thinking of upgrading to a 6BTA 370 which puts out 355hp @3000rpm and 737 lb-ft of torque at 2000 rpm.
2. A friend of mine (same boat set-up) just bought a Cummins QSB330 which puts out 325hp @2865rpm and 830 lb-ft of torque at 1800 rpm.

So, since you guys stress your transmissions out, I though you'd be the best to ask. New transmissions needed? Upgrade the current 72C's? Would both of us need to do it or just him?

I found (from reading here):

BAM - http://www.cyborgtransmissions.com/OurServices.aspx
Huber - http://www.hubermarine.com/performance.html
Harbor Marine - http://www.harbormarine.net/transmission-service

Is there anyone else in the country that I should look at (West Coast preferred) that does these upgrades? I know IMCO is close but I don't think that they do transmissions.

Thanks for your help!

I've spoken with Huber about rebuilding a pair of 72C's to use behind a couple Duramax's making 550hp @ 3600 & 1200ft lbs. They said it's not a problem. Far as I've really gotten into researching those trannys.

-K

I've had nothing but fantastic results with Marc @ BAM, his trannies work very well. -Tried others with less than desirable results.

Kurt

Thanks, The rebuilt 72C route seems the way to go. I think that I might be ok going to the 6BTA370 but he'll be over spec with a QSB330.

He's been looking at other transmissions but I think for simplicity sake (engine mounts, jackshaft length, etc), he's better off rebuilding. He like the idea of a ZF280 with a 0.8:1 gear ratio but said they're impossible to find ($11K and 18 week wait for a new one). Staying 1:1 though with the 72C and propping up to 25 in pitch (from 23) won't quite get him the performance he wanted...but he might do it just due to $$$. The Powertech & Merc Bravo 2 propellers seem to only go to a 25 inch pitch.

Huber does a good job and won't bend you over

Innovation bought Huber, moving the works to sarasota .
They do lots of big HP diesels for the military

Found a decent US contact on the ZF's when shopping for options to overdrive Arnesons. Here is what I got back.
The 300-1ATS has been discontinued. The product line(for down angle) goes from 115ATS and the next up is 325ATS.

They quoted me $16k on a pair of the smaller 115ats 2-speed .80 OD, and claimed they'll handle up to 500hp @ 3600. My deliver time was 20 weeks... I'm thinking those would be a nice units behind 400hp diesels, but not sure they are big enough to do 500hp/1200lbs all day.

If he decides to stay with the 72's, I also know a decent prop guy who'll build about any custom pitch ya want for a decent price..

contact federal marine,,jim use to be a engineer at B&W...knows his chit..

http://www.federalmarinecorporation.com/