Looking to raise TRS drives on a Formula 302LS
 

Looking to raise TRS drives on a Formula 302LS. I read some posts. I know the konrads raise are 1.7 shorter and this works well. So can I raise stock TRS drives 2" without too much ventilation? Thoughts. Thanks.

The TrS is not a surfacing drive. Other than that maybe people who know more will chime in.

Wannabe

What is your current x dimension?

Sure you can but why waste your time.its a lot of work for what maybe 3 mph top end..

Like lil red said, what is your current x dimension.

I can tell you, a friend of mine did this on a 1979 30FT Scarab hull with TRS when he did a new transom. With a pair of 540's, the boat ran 92mph and was very stable with the raised drive height.

At the risk of not looking like I know what talking about, how does one measure the x dimension with twin engines and a vee hull? I will measure and report if someone can point me in the right direction.

Thanks.

draw a T on back of boat. crossbar of T thru crank centerlines. vert line goes to bottom of V. now take a long 2 by 4 and stick it against bottom of V sticking out a lil in back. raise[lower front of boat until 2 by 4 is level. now hang a plum bob from top of T and measure distance down the plumb bob to the 2 by 4 where the plum bob hits. you can really eyeball this up. but this sort of explains what you are measuring. not distance down transom, but vertical distance up from bottom of boat on the OUTSIDE of the boat. if you were to take a T square and set it inside boat and measure down from crank centers to inside of hull at lowest point, you probably would be off by the thickness of the hull. add a half inch and would prolly be close enough.

Or, you can just get a long carpenter level or straight 2x4, and put it against your hulls running surface directly in front of the bullet on the drive Make sure the drive is trimmed parallel with the bottom, and measure how far below the running surface the propshaft is to get an idea of where you're at currently.

The X dimension is also determined by the transom angle!
For a 10* transom angle the x dimension should be 13-5/16 while a larger 16* transom require a deeper drive location at 14-5/16 from keel to engine centerline.
Wouldn't go more then 2" higher from this measurement, getting on plane might take for ever.

I'd really like to know more about that set up. I have the identical rig (minus raising the X-dimension). What was the X-dimension he started with and what was it after he raised it? What prop is he using? And how did changing the X-dimension affect getting up on plane? Any chance I could talk to your friend about it?

I'd really like to know more about that set up. I have the identical rig (minus raising the X-dimension). What was the X-dimension he started with and what was it after he raised it? What prop is he using? And how did changing the X-dimension affect getting up on plane? Any chance I could talk to your friend about it?

Shoot me a PM, and I will put you in touch with him. He doesn't post on here much.

I know he was running a 26P Hydromotive quad IV-X rounded tip 4 blade, spinning them to around 6k RPM. His 540's were solid roller, Dart heads, made a tad over 700hp each. He had good luck with the TRS staying together on that setup. I think the key was letting the engines rev to get the load off the drives.

I made the mistake of not doing that - 540 w/ just less than 600hp spinning only 5,200... blew 5 TRS's in 5 years.