twin engines

[superiormgmt]

I just baught a 30" velocity boat hull for a winter project. It is set up for twin engines. my question, do the motors on a twin engine set ep rotate the same direction or does one counter rotate?

 

[bomar76]

Re: twin engines

The current way to do it is the engines are both standard rotation and the drives are 1 standard and 1 counterrotation.

 

[rodbolt]

Re: twin engines

depends on the engines and drive types. can ya describe what ya have in a bit more detail as far as engines and drives or clutch type.

 

[superiormgmt]

Re: twin engines

This boat has no engines or drives. I will be putting 454's with near 500 hp each. I'm not sure of the drives. I'm guessing Bravo's but, not sure about a gear ratio. I havent came across any reverse rotation out drives yet. If I have a reverse rotation engine I'll still need a reverse rotation OD right?

 

[rodbolt]

Re: twin engines

if using outdrives both engines will be standard(left hand) rotation. the reversing will be done in the drive. if using a drive such as the bravo III or a volvo DP the engines will be standard rotation. about the only designs that use a counter rotating engine are the direct drive type transmissions and the older gear reduction clutches. most everything of late is standard rotation engines with the clutch or drive doing the reversing. 500 HP may mean ya have to step up to black hawks or speed masters. the new volvo dpH may be able to handle 500 hp as well. <br /> my advice would be to contact merc or VP and discuss what you have and what your trying to do with a factory service rep. <br /> myself I would ditch the 7.4 motor plan and go with the 8.1 MPI motors.

 

[baja power]

Re: twin engines

What are the cut outs? if there steup for brave drives, go for a Bravo XR, if not set up for TRS i would recomend KONRAD drives. direct replacement for TRS because parts are getting hard to find. if your looking into Speed master drives, you will run into problems with 454's.

 

[superiormgmt]

Re: twin engines

Well, I've decided to put in a good preforming set of 350's to cut cost on this project. Next question....the cut outs are for TRS drives. Again, to limit my costs I would like to go with alpha drives. I belive I will have to use an adapter plade for this to work....? I have not been able to locate a reverse rotating drive, Alpha or Bravo. Is there a certain gear ratio I should be looking for? (all the motors and drives will be upgraded in due time.)

 

[superiormgmt]

Re: twin engines

Can you have both drives Standard rotation?

 

[bomar76]

Re: twin engines

You want 1 of the drives counter rotation.<br />The drives MUST be specifically designed to counter rotate..you can't run it in reverse w/ a left hand prop and expect it to not grenade.<br /><br />The advantage of having two drives rotating in opposite directions are<br />increased speed, improved slow and high speed handling, better course tracking,<br />more level ride, improved fuel economy and easier docking<br /><br />In most applications the RH (standard) drive is mounted on the starboard side.<br />The LH (counter rotation) drive is mounted on the port side.<br />The LH drive must have a LH propeller. The LH shift cable must be reversed at the binnacle to pull instead of push.<br /><br />Most SBC mercruisers are 1.47 <br /><br />Google "Alpha Drive" and get tons of hits for sources....they are not uncommon at all.

 

[Weirdwalt]

Re: twin engines

All volvo drives can be set up to rotate lefty easily. It's a simple matter of changing the shift cable and shifter hookup. Use standard rotation engines.