rustnrot
11-07-2005, 07:31 PM
Remember those pair of supercharged rotaries I have? Well, one of them is going in a Donzi 16 hull with a ZF 63V drive transmission, the other I am considering running the supercharged Mazda rotary engine (240 hp) into a new alpha gen II drive. This engine is rated for 6500 rpm continuous-duty. Certainly the Alpha will handle the 240 hp with no problem. These engines are also not very torquey, again not a problem.
However, will the drive live at 6500 rpms sustained? Certainly there is a design rpm limit to these drives, for example, 10,000 rpms would destroy the drive I would imagine. I cannot get information on the drive rpm limit from Mercruiser. I can speculate, though. My guess is that the drive will be ok, but I would like some hard facts or experience before pursueing this project.
As an aside, the ZF transmissions are rated for 5500 rpms (different animal I know) but a high speed pump can be provided to take the 6500 rpms. Now I realize that there is no pump inside an alpha drive but nevertheless there must be issues with lubrication and bearing clearances that, by design, limit the rpms the alpha can withstand.
BTW, when I called Mercruiser they were very mum and, frankly, rather rude. I just called their "information" number and the guy would tell me nothing, fearing, I guess, they would be sued if I did this and it blew up. When I asked to speak with Engineering, I got the response they are "too busy working on new products". Wow, when I was in engineering (not in the marine industry) for 20 years I wish somebody would have told me that! I could have just stayed in hiding in my cubical, refusing to answer questions from salesman or customers!!!
I also sent a version of this question to OSO.
However, will the drive live at 6500 rpms sustained? Certainly there is a design rpm limit to these drives, for example, 10,000 rpms would destroy the drive I would imagine. I cannot get information on the drive rpm limit from Mercruiser. I can speculate, though. My guess is that the drive will be ok, but I would like some hard facts or experience before pursueing this project.
As an aside, the ZF transmissions are rated for 5500 rpms (different animal I know) but a high speed pump can be provided to take the 6500 rpms. Now I realize that there is no pump inside an alpha drive but nevertheless there must be issues with lubrication and bearing clearances that, by design, limit the rpms the alpha can withstand.
BTW, when I called Mercruiser they were very mum and, frankly, rather rude. I just called their "information" number and the guy would tell me nothing, fearing, I guess, they would be sued if I did this and it blew up. When I asked to speak with Engineering, I got the response they are "too busy working on new products". Wow, when I was in engineering (not in the marine industry) for 20 years I wish somebody would have told me that! I could have just stayed in hiding in my cubical, refusing to answer questions from salesman or customers!!!
I also sent a version of this question to OSO.