argo engine swap

[Dustin]

Hi everybody im new to the site. I own a 1980 s argo 6x6 with a 16 hp briggs and stratton engine in it. I want to swap this engine to a 700 rotax but im wondering if this is too big of an engine for the running gear or if the 700 will overheat because it is air cooled? Any input at all will greatly be appreciated , thanks everyone!

[6X6]

Rotax 700 Air cooled?
What engine is this? Twin or tripple? opposed twin?
What year? Can't think of an Air cooled 700 Rotax.

[number1cas]

Are you refering to an ultralight engine ? They are the only 700 I can think of from Rotax ?

[Dustin]

i havent picked the engine up from the guy i bought it from yet but im sure its a twin. He says its a 700 but he could be wrong , he told me its out of a 1980s snowmobile. I tried to google search a 1980s 700 rotax and found nothing and im guessing from the responses on here that there is no such motor. Any ideas what size of rotax engine this could be????????

[number1cas]

My guess is that it is a Rotax 670, if it is you probably have around 60-70 hp, maybe more, I can't remember what the hp ratings were back then, however it will be LOTS!! You will need a good rad and fan to keep it cool though. Rotax did not make a 700 until just recently, however they did make the 670 for a long time and I used to have a full Mod one in an ice racing chassis, made around 180 hp. (Normally aspirated) We used to hill climb it in the spring too and had no cooling system to save weight (closed loop) It would blow the antifreeze out at the end of the run while taxiing back to the start line, but it lived forever (as Mod engines go) and we ran her a lot harder than we should have.

[Dustin]

thanks alot for the information its very helpfull . apparently this engine is air cooled though so i think i will have a hard time cooling it maybe an electric fan running off of a sensor would be an idea? i like the sound of 60-70 hp in my argo though , i hope the running gear will stand up to it.

[number1cas]

Hmmmm, you got me if it is 700 AND air cooled, I don;t know of a Rotax like that. Could still be an ultralight engine, if it has dual spark plugs and dual ignition that will tell ya if it's aviation or not, most of those are air cooled. Post some pics when you get it if you can, I would like to see it.

[6X6]

Well, an air cooled engine has a fan, driven off a belt from the crankshaft, singles usually have the fan built into the flywheel as in lawnmower engines. If it's a FREE AIR then it relies solely on air flowing over it, and you'll have issues, I wouldn't recommend it. Free Air motors are usually all out race motors (hence no fan to not rob HP) and usually the highest HP for the Displacement/MFG/Time. Is it a Rotax 776? That was a Free Air engine, but older than you're stating.
If it's fan cooled, you just need a duct directing fresh air to the intake of the fan and/or hot air from the outlet side OUT of the engine compartment. The closer the opening is to the engine, the more efficient your cooling will be (It will recycle less hot air) Directing hot air out also helps power as the hotter air is less dense, less O2, less power. Without knowing the specific engine/HP ratings, it's tough to answer if the Argo will handle it, although I would expect so. But Bear in mind while I'm a big Rotax fan, I know near squat about Argos.
#1, do you know the year the 670 was introduced? I can't think of a 670 that was pre-90's.

[Dustin]

thanks for the advice i will have to take some pictures of the engine and post them as soon as i get it , i do know that it has a starter on it if that helps at all?

[number1cas]

6x6... yeah you're right on the year thing, I am stumped on this engine, will wait for some pics and maybe we can figure it out. I am very curious now !!

[garbie]

Is it perhaps a 640? The 640 is a twin air cooled, electric start engine found in skidoo alpines. Not sure what years they were available, but my 1980 alpine has one, I would guess around 30 hp.

[Ozzy]

In 89 the biggest thing ski doo had was a 583 in their Formula Mach. It was a liquid. I don't know of anything that was a 700 until the Mach's got them in the 90's & they were liquids. I agree with Garbie on the 640 but I have never seen anything in a 700. If it's a sled motor it might be a special race motor. I use to have a bunch of Merc Twister sleds & I know from some of my research on them in the late 70's racing that there were a few triples that were put together that got near the 700 mark. There are some early 70's sleds that had big twins in them. They were usually in that 600 to 640 range. I have a 2000 Arctic Cat 800 with over 140hp I thought about shoehorning into my Conquest (just to see if I could). It is a liquid cooled motor so the cooling wouldn't be a problem. You could certainly do the same thing with a fan cooled motor (they have a cooling fan built onto the motor). I wouldn't try to run a F/A motor (free air=air cooled, non fan). There is a reason that during the time of F/A motors in sleds the manufactures put huge air vents in the hoods. In fact some of them had the tops of the engines sticking out of the hoods. They require a lot of cold air to cool them down & I would think you would melt one down in an Argo. -Ozzy

[curtisbyrne]

My uncle has a bush plane with a rotax engine in forget what size but is a good engine overall easy to work and and stuff, that's aviation talk now but might be just a good as an Argo!

[john swenson]

yea, i'm curious what rotax it is. in the powered parachute i fly now is a rotax 582, dual carb, dual ignition. 65 h.p. water cooled. flying at 25 to 28 m.p.h. the water temp runs around 160 deg. egt's around 900. johnboy

[curtisbyrne]

Engine oil temp is usually 90-100 degrees Celsius but that's in plane with the wind blowing through the louvers in the cowling