I found an RC airboat at garage sale. It has a nitro engine that the seller claims has never been used and has been sitting in a closet for the last 10 years or so, but she couldnt tell me anything else about it. I have no experience with nitro RC's, but I really want to buy something to throw this engine into (have been looking at monster trucks for a while now). The engine says "gp" on one side, and "40" on the other. It looks like an airplane engine and has a prop mounted on it for the airboat. Can anybody tell me if I can use this thing in a truck or if it is too big/small/etc?

no I'm 99.99% sure it will not fit.

No it won't work in a car. It's most likely a Thunder Tiger GP-40, which is .40 size engine. The block would be way to big for any production vehicle, and the cooling head is too small to work without being right behind a huge prop. Lastly the carb won't work for a vehicle because they lack an idle stop screw for setting the idle speed.

I found the engine on the internet - it is a Tiger Shark GS 40. I guess I will have to wait on the monster truck and put this boat together instead. Still a great deal for how much I paid for the thing. Thanks for the help!