swampdonkey":2k5ti7nx said:
Need some advice. I purchased a 18x8 panther with 2:1 gear box. I need to put a engine in her. Thunder talked about a 496 in a earlier thread and that engine struck my fancy. A 496 is a stroked 454, Now I'm thinking would it make sense to stroke a 455 olds just for the weight factor. If so would it be as good? Next is a big block the best motor to put in a boat this size. Would a 383 stroker be sufficiant? Once I decide on which block I'm going to use then I will be asking for your help as far as what cam, intake and heads I should use. I sure wish I wasn't so far North then I would definately be talking to THUNDER AND FELBER and get me an awesome motor. My engine knowledge for airboat application is zero. This is my second airboat that I purchased my first boat is a 18x8 and I put a 455 olds Direct Drive. She runs fairly well but this one will be much better will the gear box. I have so many more questions but I will save them for other post.
Thanks in Advance
Swampdonkey
Sorry for my last two rants, and I will get to your original question, and hopefully answer things the best I can from my side of the street without mudding it up anymore. I think I can can skip some topics since many have been covered already by others and myself.
You are pushing a decent sized boat with a conservative gearbox. I'm not sure what performance expectaions you're looking for, but bare-minimum you will need a pretty stout powerplant/TQ curve if you want it to do much more than cruise down the river. You will need an engine that makes great lowend TQ with a broad curve (Avg HP). But in an airboat the more power it makes and the heavier the load, the more heat/stress it goes through. Now this is where I stress a BBC over an Olds...An Olds cannot take the abuse that a BBC can in my honest opinion, and that's pretty tongue in cheek. Ask an offshore boat racer to run an Olds, and you get my point. An Olds in stock-slightly modified form is a beast...NO question...But under long-term stress and heat........
Now as for the 496 BBC...Actually, it's an engine I HATE in car...It doesn't rev quick enough, and makes less HP per CID than a 454 or 427. BUT in an airboat with a gearbox...It's just what the doctor ordered. It has a good bore/stroke ratio to avoid detonation and has a cylinder head that will allow you to make whatever power you want. And the platform of the MK IV block is second to none in terms of integrity. Combine that with relatively low expence, and insane parts availability...It's a no-brainer to me.