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-   -   Two Speed Trannys for Diesels (https://www.offshoreonly.com/forums/general-boating-discussion/191170-two-speed-trannys-diesels.html)

gofastwannabe 07-15-2008 09:28 PM

Two Speed Trannys for Diesels
 
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!

Ron P 07-15-2008 09:47 PM

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

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

HabanaJoe 07-15-2008 11:31 PM

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

Jassman 07-16-2008 02:47 AM

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

29Firefox 07-18-2008 06:00 PM

Yeah Right....
 
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.:p

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

Joe! long time no smell:ernaehrung004:

obrien 07-18-2008 06:28 PM

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.

Edward R. Cozzi 07-18-2008 08:37 PM

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.

NJgr8ful 07-18-2008 08:48 PM

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

DirtyMoney 07-18-2008 09:18 PM


Originally Posted by dazzright40 (Post 2628360)
don't think with 480's over 100mph speeds are possible, the 36 will run only 100mph with merc 525's with 120hp more, low to mid 90's would be about right. Tysons new tranny's work well,


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

29Firefox 07-20-2008 01:31 PM


Originally Posted by dazzright40 (Post 2628360)
don't think with 480's over 100mph speeds are possible, the 36 will run only 100mph with merc 525's with 120hp more, low to mid 90's would be about right. Tysons new tranny's work well,

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


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