Polishing intake manifolds

by Eugene Klimenko in General Tech Discussion 6 years ago

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Re: Polishing intake manifolds

by Alan Arnold » 6 years ago

Alan Arnold

20 188 145

I've been flying my 1" equalizer tube for several years now with absolutely no problems or complications. It could be that that Rotax, while designing the 912 series, reached a point where the engine worked well at the rpms at which it would be mostly operated and locked in the design. The small ID tube might have been added for a manifold pressure gauge because the fittings were already there to balance the carbs. Further research into the engine was directed towards the iS upgrade.

Yes, I know; mere speculation, but it's my speculation and I'm sticking to it.

Alan

Thank you said by: Eugene Klimenko

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Re: Polishing intake manifolds

by Eugene Klimenko » 6 years ago

Eugene Klimenko

12 74 1

Company this size, with so many engines flying, for so many years. Admitting something or issuing AD = is unbelievable amount of money. After all this - This improvement is not doing anything for you at 5000 RPM and this is what engine was designed for.

My airplane is 18 years old and I am on my third gearbox. Turns out that none of my previous owners ever ever deed carb. balancing or rebuilding them. I will try to post pictures off some bolts right below engine mount. I believe low RPM and high RPM vibration did this damage

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Re: Polishing intake manifolds

by Eugene Klimenko » 6 years ago

Eugene Klimenko

12 74 1

From Rainbow Aviation -
"The Rotax 912 is essentially two engines connected to a single crankshaft and gearbox with both the left and right sides of the engine having their own independent carburetor, ignition, and exhaust system Figure: 1. As you might well imagine, having two engines trying to run a single propeller requires a bit of choreography between the right and left side of the engine in order to make things run smoothly. Most of us, who have spent a considerable amount of time in the air, can remember a time when one of the cylinders on a four-cylinder engine just quit firing, maybe from fouled spark plugs, or a plugged fuel injector. Regardless of the source, if you have ever lost a cylinder, it likely got your attention. Now imagine losing two cylinders. This is nothing short of an all-out assault on your engine and airframe. The shaking can be so violent that the fear of the motor departing the airframe becomes a realistic concern. With an engine like the Rotax 912, which has the right and left side induction systems isolated from each other, you can see the potential hazard with having one throttle wide open and the other at idle. The resulting reaction of the engine would be similar to the scenario of losing two cylinders in our previous example. In fact, we now train pilots differently in a Rotax powered aircraft by teaching them to advance the throttle to full throttle in the event of a violently shaking engine. The reason for this is that on most Rotax powered aircraft the throttles are spring-loaded to the full throttle position. As a result, in the unlikely event of a throttle cable failure, pulling the one remaining throttle cable back to idle when the engine starts to shake just exacerbates the problem. By advancing the throttle to full throttle, it allows the throttle springs to bring both carburetors to the (same) full throttle position. This allows the engine to run smoothly and the aircraft to be flown to the nearest airport where the engine can be shut off for a dead stick landing, a better scenario than losing the engine power entirely. Theoretically, at full throttle the carburetors are perfectly synchronized by the throttle arms hitting the full throttle stops simultaneously."

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Re: Polishing intake manifolds

by Bill Hertzel » 6 years ago

Bill Hertzel

13 1.95k 7.97k

Let me break out my Crystal Ball...

The 80hp 912UL was introduced in 1989, the 100hp, 912ULS variant arrived in 1998. So we are asking Rotax to perform major mods on a 30-year-old design.

And major improvements they have done!
All the problems with dual carburetors have been solved.
The solution is in the form of the 100hp, 912is, and 135hp, 915is engines.
Welcome to the 21st Century!

I predict that in the near future the carburated variants will be discontinued.
The Fuel injected variants will be the Bread-and-Butter of the company.
The 80hp 912UL and the 2-stroke 582UL will remain for a while to supply the Single Seat and Ultralight Market that use the smaller engines.
The carb'd 912ULS and 914UL will be retired and not available for new construction.
Spare parts for the retired engines will remain available for as long as it is economically feasible.

So says my Crystal Ball. :)

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

Thank you said by: Eugene Klimenko

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Re: Polishing intake manifolds

by Eugene Klimenko » 6 years ago

Eugene Klimenko

12 74 1

https://drive.google.com/file/d/1PNyU9MNs_O6IDAH9VJ7iRCo5MNvC3t7d/view?usp=sharing

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Polishing intake manifolds

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