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motor advice


i am interested in buying an airboat. it is a 15 foot fiberglass hull. it has everything except for a motor. there is no way that i am going to find the right engine for it. i do not know the pitch of the propeller but my main concern is the engine for now. is there any automotive engine that i could use? is there a brand that holds up better? what horsepower range should i be looking for? how about cooling? can i just mount the radiator onto the cage? or is the pump strong enough to suck and discharge the river water?
thank you for your help,

Welcome to Southern Airboat!

A thought to really ponder is the hull itself! The 15 foot fiberglass would probably push easily with the 350 chebby but if you wanted an aircraft engine you might be limited to a few different engines.

I'm giving this advice as I've learned the hard way, (like most things it seems in my life)! I've got a 14 ft. aluminum hull with a 454 chebby. My boat is borderline if a submarine when leaving a plane if not loaded properly!

Choose your engine and prop wisely as those items are the "heart" of the airboat! I think that UncleBubba and Moodfood both have nice fiberglass hulls with small block engines, (one with chebby and one with Ford). Those two guys would be more than willing to answer a bunch of questions for ya'!

Does it still have a motor stand? If so maybe the owner can tell you what was in it. Also, if you can find out more about the prop, that would help.

To be brutally honest with you are right on the border of what combination you need. Anything 15ft or over I recommend a Big Block Chevy here is why. On an airboat that is 14ft or smaller unless it’s a barge can get on top of the water and plan out and once it does it’s drag is lowered and you can let off the gas to cruise and it remains on a plane. On a heavy boat 15ft plus or a very heavy 14ft the boat never breaks free and plows all the time requiring lot’s of power just to run on the river. So if your 14ft boat is of reasonable weight, such as seats only 3 people has standard rigging I would run a 383 Small Block Chevy. I have a great 450 and 500HP version airboat motor combo designed specifically for a larger boat. Now if your boat is one of those fancy party barges with two batteries, spare boxes and lockers, radio, three seats and all the creature comforts stuff like cup holders and KC lights you boat never will truly run free and will always run under a heavy load even when just cruising then you must run a BBC. I have seen this a 100 times. Be careful because a small block Chevy on a party boat is very hard to make it perform well and even harder to build one that will live under these brutal loads. It took me 5 or so 383’s before I developed a motor for these conditions that performed to my standards. That’s why all the manufactures just put Big Blocks on them it’s the easier to make them live. The only down fall to that is most the time the extra weight of the Big block turns the boat into a plowing barge. I hope this helps to sum it all up if your boat is med to light weight go SBC so it will ride and plane out nice if it heavy run a Big Block.
And any explaination about motor & hull combos doesn't get better than that!

If the prop is wood, it should have two numbers stamped in the center part (sometimes). It will look something like this ## x ##. If it has those, let us know. You might have a prop that is just going to be a leaf blower.

Like Basket said, the prop is critical as well. The best motor in the world will perform poorly with the wrong prop.

It may $eem like we want you to $pend more money, but that i$ what happen$ with Airboat$$$. But nothing is worst than thinking you have a pig and selling it and finding out that all it needed was this or that before it became a nice dream machine.

These Guys are answering a couple questions I had also & would like to insert the following if I may;

If John finds that he has or has had a SB setup & wants togo a BB engine will he run into stress probs with the hull that would prevent this choice?

Would understand the other way around but?????? :roll:

Thnx, Gben
thank you for all your help. i was told that it takes a lycombing 0320 aircraft engine (160 hp). I have seen them for sale, but not for a price i want to pay. the hull says aircat on the side so it was manufactured as a complete airboat. it is a really shallow draft hull. i just want to make sure that i will be able to do something with it rather than to buy it and have it be another half compleated project.