912 maximum continous power setting

[Dusty]

A few questions from a 912 newbie
I am having trouble getting my head around operating limits.
5-5500rpm continous (52-5300feels best, only a few hundred below my screaming 2 stroke!)
I run an ivo ifa and am waiting for a manifold pressure guage so engine load is a guess.
What determines the maximum load on an 80 hp?assuming temperatures are within limits.
As a rough example a 80 hp at full throttle=80hp
a 100 hp at 80%=80 hp so assuming apart from capacity all else is similar the engine load is the same?
The same goes for the zipper kit (95hp?)
Should I run as much throttle as I want if the revs are at 5500?
It is an early magnesium case engine and the prop is 72"3 blade if that makes a difference

[jiott]

I have the 100 hp uls and I agree, 5000-5300 feels best; 5150-5200 is my sweet spot for cruise at 4 gph. I believe max load on either the 80 or 100 hp is 5500 rpm and WOT continuous, although I would never run that way-too much fuel consumption and max strain on the engine.

Since the 80 hp and the 100 hp are different compression ratios, I would not assume that a 100 hp run at 80% is exactly the same engine load as an 80 hp run at 100%, but it is probably approximately the same. My 2 cents.

[Slyfox]

I have the 912 uls, medium Ivo in flight. On take off I let it go into the yellow, I think 5600, for I think it's 3-5 minutes. then I bring it back, full throttle to 5300, runs it's best there. If I want to play around, you know, 20ft off. I back off the throttle to 4400 and then raise the prop rpm to 5300. then I go play down low and have fun, then it does right at 84kts. a nice speed for fun. I also do the same exact setting for 3 miles out setting up to land. then it's all set up for take off the next time. I was told if you keep the rpms at the 5300 area the gear set last longer. washers and junk in there.

when I had the 912 ul with the patriot ivo in flight I did the same exact thing.

Oh, don't waste your money on the vacuum gauges and stuff. rpm guage is all that's needed for correct settings. I have 3000+ hrs on my plane with doing this.

[av8rps]

I fly a 4-1200 912ul on amphib floats with the IVO ULTRALIGHT 3 blade prop and agree the manifold pressure gauge isn't really needed. I also have a Lake Amibian with a constant speed prop, and there the mp guage is absolutely needed. But for some reason or other, the Rotax mp gauge doesn't move as much, so I pretty much never use it.

Rather, I listen to the engine to know if I am overloading or underloading it. I find 5,000 rpm to be a nice speed for my engine overall and find it runs smoothest there. But I believe every 912 has its "sweet spot", so just play around until you determine that with your Kitfox.

I think the 912 and the 4 were a match made in heaven...it's that good. I keep thinking I should replace my 80 hp 912ul with a 100 hp 912s, or maybe just Zipper kit my UL? But even though I'm on heavy amphib floats it does really good with that 80 hp 912 assisted by the IVO IFA. . I even have a spare 100 hp 912s laying around, but just don't know if it will make my plane that much better? So I haven't got real serious about changing it out.

Can anyone that changed their 912ul Model 4 to a 912uls comment on that? Maybe I'm not knowing what I'm missing?

[Av8r3400]

No, you don't know what you're missing... ;)

We'll go for a ride sometime in the Mangy.

[Dusty]

Thanks for the advice,it sounds like a manifold pressure guage is irrelevant.
So running wot or slightly below for an extended climb is not stressing the engine, that is good news, as one of the trips i do involves a steep climb from sea level to 8500 ft.
I see a zipper kit in the future.
Magnesium case, good or bad or indifferent?
It seems from researching this forum 1440 egt is ok?
Cheers