Hello everyone,

I built a Model II and put a 670 in it. Twin 38mm mikuni carbs, C box with 3:1 ratio, 72" power fin prop, green sky altitude compensation system, Custom exhaust by CPI racing in Morgan, Utah.

It made a great mountain airplane out of the fox. Plenty of power. I weighed my 582 befor I sold it and the 670 is 14lbs heavier. The engine is producing 98 hp. The engine is capable of much more if the exhaust was tuned a little better. A project for this summer if I find some time. I would definitely do the 670 again. My field elevation is 5,000. I flew it to Oklahoma once and it jumped off the ground at lower elevation. I have had it up to 13,000 and I was still climbing at 500 fpm even that high.

I cruise at 85, rpm is 5,900 to 6,100 at a little less than half throttle. If you push it up in level flight it will Vne the plane in a couple seconds.

Words of advise and wishes.

There are two versions of the 670. The pre 1991 version has the same crank case bolt pattern as the 582. Makes it nice that you can just bolt it on with no mods to the engine mount. Newer models don't have the same bolt pattern. Same engine, different crank case casting.

If I were to do it again I would get mine bored to 740 to get started. They will crank up to 150 hp. You don't have to use all that but it is nice to have if you need it.

A tuned exhaust is important. Tough to fit it under the cowl but it is critical to get the horsepower and efficiency.

I have over 300 hrs on mine, engine inspections look good so I'm going to press. I talked to CPI about rebuilding my engine and he told me he has rebuilt several 582's at 300 hours and it was not necessary. Rotax will recommend it to cover themselves and to sell parts to you and me. Thorough inspections will let you know when it's time to rebuild.

If you want more info give me a call. 801-388-7753