912 Big Bore

[mr bill]

Some years ago I installed an O-320 in a C-150. When flown at the same cruise airspeed, fuel consumption was about the same as the original O-200 (specific fuel consumption being roughly the same for both engines), but if I flew at the same rpm, fuel consumption increased significantly. Take off distance shortened and climb performance increased dramatically. Of coarse I flew faster and lived with the increased fuel burn--but it sure was fun!!

[SkyPirate]

eventually I plan on either getting another kitfox and mount floats on it,..or get floats for my 5 ..I'd prefer the best of both worlds,..and have 2 fox's keep the 5 as a TD and another 5 or up with floats,.. if I got my hands on a 912UL with high time for a decent price..the big bore kit might be the answer if my funds aren't up to par for a ULS purchase, allot of untold "IF's"

[cubtractor]

On the subject of hotrod 912's, I just noticed in a link (see below) posted by Snowpaw in the Oratex covering thread, has an article on a turbo system to take the 80hp up to 120hp.

http://experimenter.epubxp.com/i/247918

[SkyPirate]

That looks very interesting Mike, i know the turbo's work well for power, my ecoboost F150 has 2 of them , a v-6 pumping 365 hp , although its said a turbo isnt as responsive as a supercharger, i get instant response when eccelerating

[Av8r3400]

I've often thought of a big bore with a turbo normalizer instead of a turbo charger. Maybe 30-32" of manifold pressure to keep rated sea level hp all the way up.

A lot less stressful to the engine.

[jiott]

I agree with AV8R3400 that it is important to not overstress the engine. I really am leery of all these big bore and turbo aftermarket mods. It is well known that the 912 80 hp engine is longer lived than the 912s 100hp with its bigger bore. Rotax deliberately used the 80 hp bore when they added the 914 turbo, rather than the 912s bore to keep engine stresses down with the added pressures of the turbo. When I was taking my flight training at Stick & Rudder in Boise in their 914 powered plane, Paul Leadabrand kept emphasizing not to use the full turbo boost any more than necessary because "it was hard on the engine".

Now I see poeple talking about aftermarket big bores (bigger than the 912uls) and aftermarket turbos delivering more boost than the 914, and then the combination of the two. All without any basic strenghtening of the engine itself! I really have my doubts about the longevity of these mods. I know this is "experimental aviation", but I believe it should be entered into with eyes wide open as to the consequences of possible short life and higher costs. Has anyone heard of these mods running trouble free for anywhere near 2000 hours? OK, I admit I am a stick-in-the-mud (probably due to my engineering background).

[n85ae]

This is making me think about my own engine (IO-240B), actually for a 20%
power boost I'd be willing to live with a 50% reduced overhaul time considering
the amount I fly this would be a good number of years before the overhaul
was actually due ...

Yeah a 150 hp IO-240B with 1000 hour TBO, I'd be fine with that

YES I would be Happy to fly with a 150 Hp engine in my plane, so before you
say this is too much power ...

Regards,
Jeff