Boat Fuel different from Car Fuel??

[smokin al]

Hello, I recently picked up a nitro boat and the paperwork says to use a 40-45% airplane fuel in it. It says you can use 20-30% car fuel but engine may not tune as well. I know it seems like an easy answer...use what they say right....just curious if anyone has used their car fuel (I use 20% Blue Thunder Race in my Losi) in their boat and how it worked? What's the difference in car and airplane fuel?
Thanks

 

[bishiman]

I would use what they reccomend if you want to get all the performance out of the engine you can. You can also damage it with the wrong fuel.

 

[Lessen]

I would guess it may have something to do with the running temperature. Boat engines are water cooled and probably cool more efficiently than car engines.... (researching)...

yep, I'm kind of on the right track. The type of oil is generally different between airplain fuel and car fuel. Car fuels use more caster oil whereas airplanes use more synthetic oil. From what I've read, when caster oil breaks down at high temperatures it creates a film which is good for lubrication. However, synthetic oils lubricate well at lower temps but when it breaks down at high temperatures it offers little lubrication. Since airplane (also boats due to more efficient cooling) engines don't run as hot as car engines there is no need for fuel with an oil that is so much more stable at higher temps. This probably also explains why I've seen some higher end boat engines that can run on as high as 60% nitro content.

 

[Racer 1966]

I've seen 70%. I've also been thinking that my original Savvy 25 engine has had a long good life and I have new engine ready so I may see how quick 70% will burn it up

 

[gnarkill]

Boat nitro has more oil in it.