2:1 Belt Reduction and Motor Combination

[calndux]

I have a 2:1 belt redution unit that says it is rated for 400hp max. Can I safely run a 400hp engine?

My boat had a GM 350, but I now must decide what engine to go with. I have been weighing the options. Which are: another 350, a LQ9 or similar marine 6.0L (about 375hp), or larger hp engine (LS2 or LS 364/440) and a new reduction unit.

I talked with the guy who built my boat and he said that a big block would be too heavy and lower the performance of my boat. Besides I think my engine stand will only handle a small block.

If anyone knows where to get a complete drop in airboat engine that can be shipped to Alaska let me know. I have talked with Waterthunder a few months back, but I am not sure if he does 350s if I have to go with one of them, so I would appreciate hearing about all the options.

A little info about my boat: 6' bottom (7' gunnel), 16' long, currently 6 blade warp drive, windsheild, and fairly heavy.

Any help would be helpful.

Thanks,

calndux (Gary)
calndux@gci.net

 

[Ol Yeller]

Hi Calndux,

Chevy small blocks and big blocks have the same engine mounting points I believe. LS-1 engines are 348 cubic inch small blocks that can put out up to 500 hp reliably. I got one on order from Waterthunder. LS-1s are also made out of aluminum with aluminum heads so they are a lot lighter that cast iron engines. I have also heard that belt drives rated for 400 hp will take up to 500 hp. I wonder what happens when you give a belt drive more power than it can handle. Does it come apart all at once or die with a wimper?

 

[Olf Art]

When we're talking about belt drives in this case I assume we're talking about the unit made by Airboat Drives, the one we commonly refer to as the Franklin because it's manufactured in Franklin, PA.

I run one of them, and the weakest component in them in my opinion is the lower drum assembly and the way it's attached to the engine flexplate. If that were to let go under heavy throttle it would probably break some major stuff instantly. My gut feeling is that around 400hp is about everything I'd want to put through one day in / day out.

The new Blue Lightning belt drive is a much better design (IMO) and 80 lbs. lighter to boot.

 

[basketcase0302]

calndux,

I'd go with the WT motor if you can afford it! Got a new bookmark for ya'll, guess I hadn't been on the airboat drive unit site for awhile :roll: Seems it is no longer in existance? I'd heard there was things going on with the franklin bros.

http://www.centurydrivesystemsinc.com/

I'd shoot em' an e-mail with your model number to get a good answer. I have 454/425 H.P on a CH-3. And I know the viper aint' no 400 HP and it's running a Franklin

Had to edit for sure...on the website is the following information.
product line under development.. 2.583 and 2.783
YEE-HAH!!! :hello1:

Basketcase

 

[calndux]

My drive is a CH-2 with the 400hp max. I think WaterThunder's motors are more horsepower than 400hp. I don't think I have the money for a new motor and reduction unit, but I will contact WT again before I rule out one of his motors. I do hear his are awesome.

Thanks for the info and I would appreciate any other advice. For example, will a small block last as long as a big block and should I consider a big block with my size of boat?

calndux

 

[Waterthunder]

I could build you a conventional motor if you want but I would recommend an LS motor to get rid of some weight and be more durable. I have a few LS motors in Alaska and everyone is very happy with them. If you want I could build a 400HP motor for you and it would be a little cheaper then 450HP!