toyotatruckin

Im just wondering since there are so many more choices in air cooled engines what are the pros and cons of putting one in an open boat like a speedmaster or a seaducer and would it still be able to hold its own in a race?

oldlugs

The air cooled car engines can be just as fast, but not as easy to restrict/adjust the cooling... You also need to adapt a flywheel for starting.

toyotatruckin

on the cooling couldnt you just cut some fins from the head?

Cracker Box

Cutting the fins off to restrict cooling works just fine. Most car engines use a slide carb that require a different linkage to open it. Make sure you get a standard shaft, not an SG shaft. I run an OS 18 tz in a 24 inch crackerbox and have too much power to keep the boat on the water. I also have a Dynamite Mach .26 in a Dumas Hawk 3.5. Most car engines can be had in both pull start and non pull start versions. I like the pull start, it cuts down on field equiptment.

Ron Olson

My Feedback: (1)

K&B makes the SS OB with an air-cooled head and some have taken the Andy Brown MAC's and have used his buggy head on the OB's also. Most .21's don't need a lot of water cooling so air cooling has proven to be an option but for those others that talk about using plane engines in their boats, there simply isn't enough in the way of heat sinks to keep them cool. I threw that in there for them.
I've got 3 .12 monos and 2 .12 'riggers that use car and truck engines. All get plenty of air, a lot more than cars and trucks do under a Lexan body so you can cut a few fins off the top to keep from overcooling the engine.
Cracker Box pretty well hit things right on the head as far as using the engines in boats. The SG shafts are a pain in the rear as even when you cut off the pilot shaft it might not leave enough threads to put the flex cable collet on after the flywheel is installed. Slide carbs can be used but rotary carbs are a lot easier to set up.
A Speedmaster 21 hull would be one of the ideal ones as they do have the air channel to help get the air to the heat sink but any low profile hull should work.

Yeah, an OS .18 in a 24" C-box is a little overkill.

vamp131

you can water cool the head but not too much dont want to make it run troo cold get some lead piping ot copper pipe brake pip is a bit too narrow but it will do if thats all you can get ie its cheep lol

use potting compond for electronics wrap the pipe around the head use the potting compound get a water pick up and that shjould be okay
to run dont cut off the fins you need them to get rid of the heat ! i hope this helps

Ron Olson

My Feedback: (1)

Not neccessarily. My .12's are at the point with uncut heat sinks to where they are running too cool, even when I cut the top 3 fins off one engine. The cooler air off the water is why they run this way.
The current IMPBA record holder in the "A" hydro class, Glenn Quarles, has only enough to keep the head button on.

toyotatruckin

great replies! This is great info and Ill agree with ron on cutting the head down, constant high speed airflow on the water would be way cooler than stuck under a lexan body thats not moving at full speed all the time plus you would be able to run it out of water longer to tinker with it!

lay28

yes you can run a air cooled motor in a mono or any boat, as a matter of fact i'm looking for a picco P7 21 tech any thoughts on a dealer?

Ron Olson

My Feedback: (1)

You might want to check out www.teamtrinity.com as I think that they are the US distributor of Picco car and truck engines.
I picked up a spare head in very good shape cheap for one of my air-cooled engines to experiment with. You'll find that the car and truck racers seem to like the larger aftermarket heat sinks or will replace one if it gets damaged from too many roll-overs. This way you have a good one and other to hack on.