tranny

What tranny do they reccomend?
What reduction ratio?
Gary

Hi Massive,

Cat is right. I am putting a 1500 dual Pulse Drive on my 35 Cafe Racer. I have 475 hp 454's. Figured I'd pickup around 5-7 on the top, but more importantly, nothing to break. My drive will be here on Monday and will begin the project then. I figure it will take 7-10 days (you know how it goes when you take the motors out) and will be posting pics through out along with before and after performance results. You are building exactly what my next boat will be (in a couple of years). A 37 (or maybe 42) AT AVH with Pulse Drive. I was thinking 500's, but will probably end with 575SC's or something similar. I will keep the board posted as the project progresses.

Mongo

Oh, Gary... I am using ZF63A's. 1.53 ratio. PSI recommends ZF or Twin Disk. Greg, to reverse rotation, you just flip the cable and run the tranny in reverse.

imongo - I know my trans (BW for a TRS) doesn't like to run at power in reverse. The ZF's must be built different. Do the trannies also include the vertical drop required to get the output shaft at the transom lower? Any idea how much the parasitic power loss difference is for the trans which is running in "reverse"? Gear "theory" says at least 3% for each gear stage, practice is usually higher.

-Greg

My thought on the subject is the use of a reverse rotation engine it’s not a big deal. As we know prices are paid for any change along the power transmission line such as in gear reduction/multiplication/reversal of rotation.

What do the gear/transmission suppliers have to say about the higher RPM side of the reverse Equation? With diesels really no big deal there as the RPM parameters are on the low side.

The ZF's are designed to run either direction. It is just a matter of which direction you attach the cable. There are provisions for either direction.

Yes, the ZF's have an offset down to accomodate the need to have the output shaft as low as possible.

As far as power loss goes, it is around 10 hp (I think). It is less than the loss from a Bravo and a lot less than the loss on a TRS. The other thing to consider is you have reduced the under water drag to almost nothing (just a small piece of the tips of the rudders and about 2" worth of skeg on the strut).

Dan, the Pulse 3000 is rated to 1600 HP and 6100 lbs of torque. Even at that level, they carry a 5 year warranty! If I were in the market for a big, high end boat, I couldn't justify using anything else. #6's? Spend all that money just so you can get "surface drive" performance? Why not just get a surface drive?

Mongo

pulse drives
 

An (A) class boat raced in Ft. Myers a few years back. Saw the boat at a Marina in Marathon Fl. Got a pic somewhere and might be able to I.D. and talk to someone that raced it.
I inquired and talked to Pulse Drive engineers.They were very helpful. I'm tired of all the hassel with I/O 's.Simplicity also offers this kind of arrangement.

Pulse and Avh are to A.T. reliable and awesome ride;) :D Thats the way to go on A.T.'s new 45 Avh:D

Stillcrazy,

Yeah, the race boat is a 29 infinity. It won all the races that year except one in which it finished 2nd. Then they promptly outlawed surface drives for A class. Some of the interesting things about that rig...

The boat was using the wrong size (too small) drive for it's HP. It had a 1500 series and should have been running a 1750. They ran the whole year with NO faliures. One of the races, the crew forgot to put the trim pin in. They had no trim at all! Ran the whole race with the drive just "floating". They won the race anyway. It was kinda funny to see the news video footage and hear the announcer talk about it, watching the drive going up and down with the seas. Another interesting note is that the crew doesn't throttle the boat except for turns. They would simply drop the hammer and let it fly. The crew would trim the drive up and down depending on how much bite or speed they needed (turns again). When the boat would catch air, they just let the rev limiter take care of the motor.

Like I said, I will be reporting all along the project and post the performance figures for my boat.

Mongo