Now a days there seems to be Tuned Exhaust for all types of motorized people movers. They all claim to give your engine more horsepower, better fuel milage etc, etc.

Which has got me to wondering, why not a tuned exhaust for the Rotax 912, namely the 80 hp version? On looking at the exhaust on my 701 I think improvements can be made. Wouldn't it be great if a tune exhaust could give you 5-10 hp improvement maybe more?

Maybe there is all ready a tuned exhaust for the 701, if so could you point me in the right direction. Is there anyone else interested in this subject.

Views: 2259


You need to be a member of Zenith Aircraft Builders and Flyers to add comments!

Join Zenith Aircraft Builders and Flyers

Comment by Chris Aysen on July 8, 2010 at 7:33am
Pat - I have talked to a couple of racecar engine specialist. They said the cheapest way to make your engine more efficient is port polishing; exhaust and intake. Their reasoning is your exhaust manifold (and/or intake) may not match up exactly with their perspective mating parts. Therefore, you may have some flat spots in, for instance,the exhaust tube that create turbulence somewhat restricting exhaust flow. I believe gaining 5 - 10 HP is somewhat obtimistic. It would be more probable that any particular factory engine would have some flat spots restricting airflow and port polishing would bring you UP TO advertized hp.. So we may be running our engines up to rpm and not quite getting advertized hp. But I do believe port polishing would produce gain in engine efficiency not necessarily more than advertized hp.
Comment by Mike Ethridge on July 5, 2010 at 3:48am
Bob I'm seriously thinking about the Bully Hawk 914 conversion from LES for my 912ul since they reduced their price from over 12,500.00 to around 8,500.00 dollars a few months back. I like the extra horsepower, light weight and stable operating temps of this engine which make it a good option for the CH750 and I would think a good resale point for anyone looking at amfib floats. Still looking at options but keep coming back to the tried and true stuff. Mike
Comment by Bob McDonald on June 29, 2010 at 7:49am
Contact Bob Robertson of Light Engine Services in Salmon Arm B.C. 1-866-418-4164.
There is also another advertised (no experience with this one) google "Rotax 912 X-tra" its a power boost kit involving pistons and exhausts. Generally Rotax has enough expertise on their engines that your not going to gain anything over factory product. Remember if you change the probably need to adjust carburation or air intakes. More power usually results in reduced reliability...its a balancing act.
When it come to Rotax Bob Robertson's the go to guy...I strongly recommend his advice be followed.

New from Zenith:

Zenith Planes For Sale 

Classified listing for buying or selling your Zenith building or flying related stuff...

Custom Instrument Panels
for your Zenith

Custom instrument panels are now available directly from Zenith Aircraft Company exclusively for Zenith builders and owners. Pre-cut panel, Dynon and Garmin avionics, and more.

Custom Upholstery Kits for your Zenith Aircraft:

Zenith Vinyl Upholstery Kits

Zenith Apparel from EAA:

Zenair Floats

Flying On Your Own Wings:
A Complete Guide to Understanding Light Airplane Design, by Chris Heintz

Builder & Pilot Supplies:

How to videos from

Developed specifically for Zenith builders (by a builder) these videos on DVD are a great help in building your own kit plane by providing practical hands-on construction information. Visit for the latest DVD titles.

Aircraft Insurance:


West Coast USA:

Pro Builder Assistance:


Transition training:

Golden Eagle Aviation

Pianosa Flying Farm

Aircraft Spruce & Specialty for all your building and pilot supplies!

© 2021   Created by Zenith.Aero.   Powered by

Badges  |  Report an Issue  |  Terms of Service