Rotax 914 power setting question

ckurz7000

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Hi Mike, I read through the French forum, but there isn't much more information there, either.

The little graph shown on the website of Gyroperfo suggests an increase in power from 4500 rpm onwards. That seems way too low for the 105% throttle position. So there are some questions which I would like to ask the person who sells this device.

I would like to get some testimonials, too, before installing it on my 914. I wonder how widely used they are. Will start to ask around to get a better idea.

Thanks a bunch for the pointer!

Greetings, -- Chris.
 

Mike G

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Chris
I think they just took the original Rotax curve and re drew the line, very few people actually understand the details within performance curves. Don't forget the Rotax curve (and hence the Gyroperfo one as well) are WOT curves. These curves assume that you are at WOT and you drag the speed back with a VP prop (or dynamometer) so you could quite conceivably drag the rpm down to 4500 at 105% throttle setting.

The two French guys (one of whom is selling them) who have fitted this device seem to confirm an increase in power "at the end of the acceleration" (This seems to confirm it kicks in after the throttle has passed 100%. One says there is a slight increase in "inlet pressure" (I presume he has a MAP gauge) and both confirm they've increased the pitch a little.

I'm still looking for the turbocharger manufacturer's model number/reference for the 914 turbo, any takers????

Mike G
 

Smack

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fuel injection

fuel injection

Chris,
Have you considered eliminating the carburetors and installing a fuel injection system?
That would get around any carburetor float bowl pressure change concerns.
Either a mechanical or electronic system would also likely allow fuel/air ratio changes more easily than the Bing mixers.
Brian
 

ckurz7000

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...These curves assume that you are at WOT and you drag the speed back with a VP prop (or dynamometer) so you could quite conceivably drag the rpm down to 4500 at 105% throttle setting.
But at WOT (i.e.m 40 inHG) and 4500 RPM you are lugging the engine and are almost certainly in a regime where you will encounter uncontrolled ignition, knocking or detonation.

The two French guys (one of whom is selling them) who have fitted this device seem to confirm an increase in power "at the end of the acceleration"
What I am wondering is that there don't seem to be too many people around having this gadget installed on their 914. And, it is only a modest 5 HP power increase, usable for 5 minutes max at a time.

Greetings, -- Chris.
 

Rick E

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Having had fitted these type of devices to motor vehicles over the years with mixed results I am of the opinion that if Rotax could increase the power so easily they would do it but have to weigh up the power gain against engine longevity. I think I would trust Rotax before someone else with a vested interest.
 

Mark Humbke

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Having had fitted these type of devices to motor vehicles over the years with mixed results I am of the opinion that if Rotax could increase the power so easily they would do it but have to weigh up the power gain against engine longevity. I think I would trust Rotax before someone else with a vested interest.

Well said Rick...I have contact with the guys who write for Rotaxowner.com here in Vernon, BC, Canada which is a valuable source of information on their engines. Highly recommend it.

I have taken a week course on the mechanics of the engine in Vernon(through them)on the 912/914 all the way to a complete strip down ..etc.

And as you say or I would say they are in charge ..research ...warranty..etc..why buck the system when it comes to the dependability/longevity of there engines..

Cheers
 

twistair

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Found this old thread while looking for any info/experience on that Gyroperfo device. Some days ago we installed similar (not from Gyroperfo but from other country, no signs at device at all) thing on a Cavalon and made some short flights to check if it works. First is that it adds ca. 30 lbs static thrust at WOT (MAP 41) and apparently makes a take-off roll shorter and rate of climb better. No exact numbers to the momemnt, hopefully will have next week. I wonder if anybody else uses such add-on. Any input would be greatly appreciated.
 
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