Speedmaster Two Drives

[phughes69]

Ok, I have to admit that i am still new to being able to understand how the X dimension works and how it affect speed and handeling. Is there a book that I can get that explaines some of these things. The other thing I wanted to know was what makes the TRS lower stronger than the speedmaster II lower, is it because to speedmaster lower has less material around the gears to give it a smaller profile. I am curious about all this because I don't want to have problems with the drives next year. I just got this thing ('80 38 scarab special edition which has factory installed twin turbo 454's hooked to the speedmaster II's)

[Gary Anderson]

Ed wrote:
"as most people simply bolt them up to their exsisting TRS drive with it's low X"
Yep, I've seen that on a few V hulls. They are usually slower without a raised X dimension.
Compare Chris Cats (a lot of them came with TRS or IIs), prop height is about 1" above the bottom of the hull with IIs. I've seen TRSs at least 2-3" below the bottom of the hull. It's the drive height and being able to use a surface piercing prop that makes IIs faster.
BTW, when you get around 100mph, IIIs are faster than IIs.
Gary

[Gary Anderson]

phughes69
I'm not sure IIs are significantly weaker than TRS. All the speedmaster drives use 2 verticle shafts in the lower which also allows use of smaller lower gears (3 or 4 in speedmasters vs 2 in TRS). The smaller gears may be weaker or it may be a surface piercing prop is just harder on the lowers. Bravos tend to break a lot more in applications where there is a very high X dimension too.
Gary

[bryanspeedracer]

Thanks guys,

I plan on running it the way it sits. This was a twin turbo boat from Fountain, so I'd guess that it has a raised X dimension to start with. I'm planning on running about 500 hp (conservative as well). I'm just happy to have the boat, I don't have the wallet to support big horse motors no matter how much fun it is to talk about it...

[phughes69]

Bryan, does your boat still have the turbo motors in it? If so I think you and I have the same motor/outdrive package. I also have twin turbo motors in mine('80 scarab KV) with speedmaster II outdrives.

Pat

[KAAMA]

Pat/phughes,

A friend of mine has practically the same boat as you do---a 1980 Scarab KV with Speedmaster II drives. He also had the 475hp twin turbo'd 454's in it that came stock from Merc at that time. He has since removed the turbos along time ago and has gone with 509 inch engines with 420 mega blowers---about 750hp or so. He has broke his drives twice now.

Does your boat happen to be red with black and white accent stripes? If it is, I have seen it a few times years ago----once up in Traverse City. Nice boat.

[bryanspeedracer]

Pat,

No, the turbos are long gone. I'm going with naturally aspirated power. Best of luck w/your KV. I love those flat deck scarabs...

[phughes69]

Kaama.
I think the color mine is called sunburst. It is yellow fading to burgundy with orange in the middle, with a black border The old owner of it has had it for the last 10 years and has put in at lake St. Clair. It hasn't been in the water in 2 years.