The International Cessna^® 170 Association

I have been laboring under the impression that the Lygoming O-390 series of engines were still for experimental use only. Can anyone enlighten me as to whether or not they have been certificated and are now useable on certificated airplanes?
I have been told that an acquaintance is planning to install one on a C-170B, but I was under tie impression that they were for homebuilts only.

http://www.stootsaviation.com/New_STC_I ... _210HP.php


It's a real thing.

The new IO-390 lycoming engine is a certified engine and is STC,d for the Cardinal RG and it's now fitted as a standard engine for the Super Decathlon . I have flown both Decathlons ( 180 and the 210 HP ) basically there isn't much difference in performance . The super decathlon also had a MT prop on the front . I found the 390 lycoming a lot more thirsty on the fuel . The 390 lycoming in the decathlon isn't the best for cruising , it vibrates too much . It's not the smoothest engine around . I have flown a number of hours in a citrabia (similar airframe to the decathlon ) which was fitted (standard fitment ) with Superior 180hp. It had the same sort of performance as the Decathlon but didn't drink the fuel so excessively . The citrabia also had a Sensenich fixed pitch prop on it also . The superior engined aircraft was a LOT smoother also . There are a lot better choices out there for the Cessna 170 to be re engined .

ghostflyer wrote:There are a lot better choices out there for the Cessna 170 to be re engined .

Like a TCM IO-360

A couple of weeks ago I flew an experimental Super Cub with the IO-390 and a MT 3-blade prop from Spearfish, SD to Dallas, TX. It averaged 12.2gph at 24" and 2400rpm. Any leaner caused CHT to approach 400°F. It ran nice and smooth.

That's downhill, Big tires ?

Richard,
If you found that further leaning on the IO-390 engine increased the CHT, you apparently were running on the rich dide of peak. Once you lean over the top, the Cht will cool down. If you were down to 65% or less, there is no way to cook the engine by leaning.
On the old TCM O-300 if you were cruising at about 7,000' MSL or above, it was common to lean down to where the engine started to stumble and then just enrichen enough to smooth it out, Under those circumstances you would be running lean of peak.
Naturally aspirated engines will very seldom be able to develop more than 65% power above about 7,000' MSL

What kind of a TAS were you getting in that Cub at 12.2 GPH fuel burn?

Well 12.2 gals per hour equals to 46 litres a hour , in the super decathlon we will pull about 12.7 gals a hour at 2400rpm. Or about 50 litres a hour. BUT with the superior engine (180 HP) cruising at 2500rpm we are getting 36 litres a hour . TAS is 110 knots . With only 1 person on board.

blueldr wrote:........What kind of a TAS were you getting in that Cub at 12.2 GPH fuel burn?

Dick- The TAS was around 100mph at 75%. I never knew anybody who bought a Cub to go fast.

Richard,
It wasn't the speed I was thinking about. It was the miles per gallon. Not so hot, was it.

blueldr wrote:Richard,
It wasn't the speed I was thinking about. It was the miles per gallon. Not so hot, was it.

Miles per gallon is determined more by the airplane and speed than the engine. When I flew to Alaska in 2000 alongside two 180hp B-models, they ran at 19" MP to my 24-25". All three airplanes took about the same amount of gas at every stop.

Where you win the most with more hp is takeoff distance and rate of climb. Every horsepower you add to a 2200 lb airplane gains you 15fpm climb.

c170b53 wrote:That's downhill, Big tires ?

Yes, it had 31" Bushwheels. It was a very nice plane but with $260,000 invested, it was not my kind of Cub. I would be afraid to fly it really hard in the bush. I was just the ferry pilot on that trip.

The 390 is a great engine. Very torquey. IO-360's are 200 hp downhill on a good day. The IO-390 is 210hp everyday all day (in fact they all dyno closer to 216-218 hp). And they do all this at basically the same weight as a 360. We have one in our RV-8 and it's an animal. Barrett built it and it's pretty smooth. Not sure if the Lycoming ones are that smooth. We have no problem leaning it down to 9-10 gph.

Would I put one in my 170? Only if I won the lottery. It's an expensive engine (face it, any new engine is ridiculously expensive), and it's relatively young so there aren't a lot of used ones out on the market.

DEM

Miles,
What I was thinking about was the approximately eight (8) miles per gallon at a fuel burn of 12,2 GPH vs. 100 MPH