Lower unit "profile"

[onesubdrvr]

Hello!!

I am new to the site, and have a question regarding lower unit profiles.

I have a 1972 Donzi X-18 with a Volvo 280 out drive. I have been trying to locate a "E" unit lower to no avail. They say that this "E" lower is good for about 8-10mph. That being said, at this time, I don't want to glass in the transom to install a newer style drive. People seem to contend that due to the lack of streamline shaping of the 280 lower, that at about 60-65 there is enough disruption in the flow of water that you can't get any decent prop bite - thus, requiring significantly more HP to go the same speed. My new engine should easily carry me into the 70's (same hull with Mercruiser Bravo I drive, 320 PSHP will do approx. 74mph). Now, I think alot of improvements can be made via the prop, and Ron is helping me there. I've also considered, and am going to install a Hydromotive nose cone.

Does anyone have any additional input for possible solutions to this problem?

Is there any other lowers that will mount to the 280 upper?

Thanks
Wayne

ps I know I'm talking sterndrive, and most stuff here is outboard, but the theories should be the same.

[largecar91]

Years ago. I ran several Volvo Drives. They are good strong drives(within reason) but you are correct in the fact that the lower unit has the hydrodynamics of a rock. I have coned them and I have also owned a few Volvo "e" speedmasters. The speedies cannot take much torque in their stock configuration. There used to be some heavy duty parts but I doubt if many are still around. With a lot of horsepower and torque, the gears would blow out the side. There was a guy in St Louis years ago that had a 23' Eliminator with a big block blower motor and he could make them survive for quite a while before blowing them apart. So I guess with proper care, anything is possible. The speedies look cool!