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Can a corvair motor work on an airboat?

A

airboats4me

Member
I have a small beginner airboat I built out of alumium...It has a 20 hp. koler engine....Its only 10ftx4ft and is just right for what i use it for...The only problem is i cant make it plane out .....Any suggestion???Ijust recently found an old corvair car and the motor runs good...Do you think i could make it plane with that motor???
 
There use to be some small froging type boats with corvair motors although I haven't seen any running around lately. The last one I saw was a neighbors boat that sat in his back yard for at least 4 years. There are some out there, just keep looking. For single person, they worked good although 4 ft wide seems a little narrow.
 
Those corvairs were not a powerhouse engine, but can do very well on an airboat. Keep the forced air cooling on it, and it will run forever without getting hot.

I say go for it, if the engine won't cost much. You'll need a bigger prop.$

Could be a good thing for you, but as mentioned above, the boat may be a little small or narrow for it.

Be careful.
 
welcome to the forum 4me I personally dont know much about corvair motors but there's a lot of info on here about small boats to start try a search on mini air-boats and maybe some other key words there's some great knowledge on this site
 
Back in the mid 80ts when Bowfishing Assoc. of Mich. was formed Their were several john boats with Corvair motors --direct drive . In fact my youngest son just bought one of them 2 years ago and is using it for bowfishing.
The first thing that you should do is weigh the corvair motor then add 50lbs to it for a total weight.. take your 20hp off your boat then lay a piece of plywood across the gunnel's ware the motor sets and add the weight of the corvair motor + 50lbs .. This will give you an idea as to what the boat will draft with the extra motor weight. I know that this sounds like a lot of work But most of the boats were 52" wide and 14' long as my son's is and he added 6" pontoons to the sides and transom because it set so low in the water --Plus he sunk it doing a slow 180 turn in a ?10mph current =back corner went down== They would get on plane and run a short distance on dry ground if they had enough speed up to begin with. I know the person that built almost all of them up here so if you pursue this and need more info let me know. As for your 4' X 10' 20hp it may be as simple as changing the prop to get what you want. For this info I would suggest getting ahold of the prows in small airboats
http://www.mosquitoairboats.com
You give them all the specs on what you have and they can tell you what prop to use.
Good luck --Have fun and Be Safe
 
Great advice, Ron .... another prop might make all the difference, and he could probably hot rod that Kohler a little for a few bucks and turn an even bigger wheel.

BF
 
Thanks---- now that you said that --?????-(idea)-- He could also build a reduction belt drive like my hovercraft friends do and turn a bigger prop slower with more thrust and less sound.
 
When I was growing up in the 70's I had several friends that had Corvair powered Airboats and they preformed very well they are all most like a 6 cyclinder Aircraft engine and you can get a lot of hp out of one if you get one of the 1965 or later engines I think they were 164 ci and they use a cut down 327 crank and pistons I was very much into hot roding Corvair engines when I was in High School they had a turbo model that put out 180 hp and the hot set up was to get the Corsa 140 hp heads and then put the turbo on it you got close to 300 hp with that set up and the engines are very easy to work on to.
 
Sure, U guys told me 100 hp wouldnt do it. But yeah it would be pretty easy to get more out of that 20 and simple belt drive would be really easy!
 
Sniper, do the cylinders slip into the crankcase on a Corvair engine like they do on an aircraft or VW engine? I always liked them, but never had a chance to work on one.
Carrol Shelby, the Daddy of the Cobra, once said that GM missed a chance to build a Porsche beater by not continuing to develop that engine.

BF
 
BF Yes the cylinders come off and one nice thing that chevy did on the 164 ci engine is they used 327 rods and pistons and a cut down 327 crank so the engine is very strong and can take a lot of HP added to it I am surprised that more people don't use them the parts are cheap and the engine is very reliable and not very heavy and there was a corvair race car that was very successful called a Yenko Stinger and they used to beat Porsche very regular in there day
 
Cool. I remeber that they had kind of a bad reputation for oil leaks, but that was in the days before Blue Silicone ..... you could probably build one today that would hold up pretty nice.

That was also in the days before electronic ignition, which would probably be good for a few horsepower by itself, and a lot more reliable.
I remember the Stinger ..... Don Yenko built some fast ones.

What years were the best if a guy was interested in one ....... :wink: .

BF
 
I have had 2 corvair powered airboats. 10x4 ft is too small for a corvair guarranteed. I reccomend a boat that is atleast 5ft on the bottom. We still run alot of corvair boats in this area. It depends what you want to use the boat for but a 15x5 or 16x5 works well if not running dry. the 5ft is on the bottom 6ft accross the top of hull. if you want a shorter boat I recomend a wider hull 5.5 on bottom 6ft is a bit much the boat corvair I currently have will run 36mph turning a 60x28 wood prop direct drive. There are modifications that must be done to the engine to put on the boat. you will need a ford 390flywheel and a vw starter mounted on a plate under the rear of the engine stand. and you must make baffles to cover the holes that will be there after the engine is removed from the case it sits in to mount it in the car or it will overheat very easy no big deal.... If you have any further questions please ask I will try to help you. I also can not see any reason why on a 10x4 your 20hp kohler should not plane with one person unless you engine is not mounted at the right location such as how far from rear of boat and angle on engine or correct propeller lenghth and pitch... we use alot of kohler and briggs engines as well here and have a local builder who uses alot of these engines on his boats.

...Mike...
 
BF

The 164 ci engines are from 1965 and up any thing below that is a 145 ci and the problem with them leaking oil was that GM used the wrong type ruber for the O rings that went on the push rod tubes the later modeles they cured that with Aircraft type o Rings I did see one time what the 1970 model was going to be if they would have built it but Ralph Nader took care of that it was going to be a little more ci and single over head cam and if I remember right four valves per cyclinder and best I can remember it was going to be right at 300 hp amd the car it self was totaly redun and looked something like a Deno Ferrari it would have out sold the corvet I think.
 
A 327 SBC Chevy has a 3.25 stroke so if a Corvair is a 6 cylinder and it’s a 164 C.U.I motor that means it has a 3.25 bore that’s what us engine builders call a square motor YUK no wonder why that design of a motor never caught on. They might be cool motors but not a power house that's for sure.
 
Thanks Sniper, I'm gonna do a little homework on 'em. Could be a fun motor for the right, light two person boat. Let's see .... roller cam and rockers, throttle body injection, MSD ignition, ...... :wink: .

Thunder, I might be needin one of those gearboxes after all ...... !

BF
 
164 cubic inch engines were also made in 1964 I know because I have one 1964 was the first year for 164 cid engines
 
Thanks ABMike. I'd nearly forgotten about the old Corvair engine, but when Sniper mentioned 327 rods and pistons, some lights started to come on .....

BF
 
Mike you are right about the 164 ci in 64 it was 65 when they made the body change it 's been a long time since I any dealing with corvair power plants so I have had to do some thinking and remembering.but it is not unheard of to get 300 hp out of one they are still real popular in Calafornia in sand rails and buggys.
 
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