I've been reading alot about how diesels don't make good performance boat engines because they run at low RPM's. Why couldn't you use a two speed transmission? I haven't heard anyone even discuss this option. Didn't Merc offer a two speed at one time call "Black-Trac" or something like that. And I also recall a number of years ago that, I believe his name was Laith Pharaon, went undefeated one year on the APBA circuit. I know some of you experts out there can tell my why!

Wiessman would be the one to talk to about multi speed trannies.

They should work on Diesels, if they can handle the torque.

Not trying to be smart but this is not something new. I have lots of posts on here in regards to 2 speeds, check them out you'll see it's been done years ago and worked just fine. There are many great comments in the posts about the newer diesels and some of the members here have great wisdom about the newer stuff.

With today's modern ZF 2 speeds diesel are a snap.

Diesels make good performance boat engines, you need to gear and prop them right. Also, don't expect out of the hole performance like a blown gas engine, doesn't happen.

Joe Gere

also check with Tyson on the board..he makes 2 speeds and is now working on a 3 speed.

Diesels don't make good for performance? Ask any one in a go fast boat thats been run down or even like the green peace pukes been run over by a diesel powered patrol boat. Or what about all them world speed records set by diesels.

http://youtube.com/watch?v=Gin68TIr2Rg

Joe! long time no smell

we just sold a pair of yanmar 480's to Nortec to go in a 36 cat with number 6 drives. If I was told correctly the boat ran something like 100-104 mph with some zf 2 speeds.

I have surveyed big Fountains and big Sunseekers with Yanmar power and 2 speed transmissions. Works great. Felt like hitting passing gear in your car.

HabanaJoe is correct this has been discussed pretty extensively on OSO. Many in depth and technical threads by very knowledgeable folks.

Didn't think you could stay out of this thread.

Jim thats only a 90hp difference. Faulty figuring again huh