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aircraft versus automotive

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Hi , I am a new airboat owner and I got the shaft from the seller who sold me an aircraft engine with the boat. The engine has a cracked case and I need to repower the boat and I am having a hard time trying to decide wether to go aircraft or auotmotive engine any advice would be greatly appreciated.
Hey acslammer read this thread A/C - Automotive
Goto page 1, 2, 3, 4, 5, 6

there pros and cons to both engines it is all what you want to run we all take pot shots at each other engines but one thing they all produce horse power to a turn prop to push our rides and get you where you want to go and back safely.

but most of all HAVE FUN :D :eek:ccasion5:
I'd just weld up the case ya got and keep on trucking. Run it til its finished then decide on a repower. Could last years and years.

go to an aircraft mechanic and see if he can repair it. don't go to some joe blow welder......don't quote me but i think that case is made of an aluminum magnesium alloy that requires welding rod AZ 101. if you try to weld that alloy (if it is that alloy) with regular rods.......ping ping ping!!! i went through that with my oil sump. but, i'm not exactly sure what the case is made of......
Duck, your exactly right, ya have to have the rod that matches the case alloy. The rods are easily obtainable by any welding shop that competatent to do the job. Its not a big job either. Depending on the location of the crack it can even be welded wthout disassembeling the engine. Most of the WWII vintage cases are a magnesium alloy. Some new engines are the same aluminum you will find in automotive aluminum engines. There is nothing out of the ordinary about welding the cases, same practices as welding any cast metal. preheating, cooling and temperature control are all pretty much standard, as is surface preparation.

Hope this helps some. I would expect a lot of A&P folks to tell ya to get a new case when the one ya got can easily be repaired though. They are trained for aircraft safety not tactical repairs. So your kinda on your own there.


Welcome to the best airboat enthusiast group that has ever gathered. If you'll look at the header of SA, you'll see "Profile". Fill that out and we might be able to suggest a couple of folks who could evaluate your cracked case fairly close to where you live.

Give us a few specs on what you bought and you might get some money saving advice for free. If all you have is a cracked case, but otherwise a healthy engine, get the case fixed.

Changing an airboat from ac to auto is no easy task, but it can be done. The easiest shift would likely be from AC to Cadilac or Buick direct drive because the engine lengths are closer than an auto / reduction unit would be.
You can get that case fixed I have been a FAA certified welder for 27 years and that case can be repaired but take it to some one who knows what they are doing the best way is to take the whole motor apart and clean it real good then the whole case needs to be preheated before welding with a TIG machine and use Argon back up on the back side of the weld. and then put it back in a oven after welding and let it cool slowly and have the case stresed relived afterwords
What kind of engine is it? I prefer aircraft engines because they are easier to work on and weigh less. If your set up is for the aircraft engine it will probably be easier to get the engine fixed rather than go to the expense of rerigging for a car motor. A lot depends on your boat too. I know my boat is too small for a car motor, even direct drive.
It depends on you budget and what you want your boat to do. The cheap and smart thing to do is fix what you have now and get some seat time then decide what you want in an airboat. Then you can sell your running boat and build or buy exactly what you prefer. Me personally I prefer car motors because an aircraft can't do what I want my airboat to do.
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