914 TURBO

[RickE]

Just wondering whether anyone knows what actually triggers the turbo on a 914. Is it the throttle position, engine revs or manifold pressure.The reason I ask is that I have an inflight adjustable prop and by adjusting blade pitch the engine revs and manifold pressure changes and I was wondering if I had the engine flat out at 56 to 5800rpm and on turbo and added pitch and the revs dropped to say 5200 rpm is the turbo still operating or not?Maybe I should stop wondering and just fly the bloody thing!

[t-bird]

Are you planning to break the sound barrier with your Gyro cruizing at 5800 rpm?The throttle position indicates that it needs more power from the Tcu. The Tcu then closes the waste gate if the airbox temperature is within limits and Rpm is above 5300 - I think. If your prop is too coarse then no turbo.You usually take off full fine and the dail the prop in for the cruise. You can do this with the Map and Rpm.I have found that a fuel flow meter could be very handy as your fuel consumption will increase after a certain degree of coarseness.

[RickE]

The turbo cuts in at around 53-5400 rpm, I am just trying to find out if it is the engine rpm or throttle position that initiates the turbo.I do take off on full fine and dial in pitch as required.Not that I ever would but if I had the prop pitched to full coarse with a wide open throttle it would probably be lucky to get to 5000rpm. Would the turbo be working or not????

[t-bird]

Not at 5000 rpm which gives 80 hp compared to 115 hp at 5800.Throttle position tells Tcu that you want the turbo.Tcu decides based on Rpm, temperatures and pressures if it is going to close the waste gate.The throttle positions are calibrated by hooking up a pc through a serial cable to the engine"s tcu.

[RickE]

Thanks T-bird.

[bones]

Not at 5000 rpm which gives 80 hp compared to 115 hp at 5800.Throttle position tells Tcu that you want the turbo.Tcu decides based on Rpm, temperatures and pressures if it is going to close the waste gate.The throttle positions are calibrated by hooking up a pc through a serial cable to the engine"s tcu.The 914 i had started to add boost from about 4600, about 4600 the motor was netrual ie not sucking, 4800 the pressure guage was just starting to go the "getting busy side" and yep full boost at about 52-5300.That being said, as stated before it is the throttle position not the rpm that tells the tcu to get to work, you could have the engine bogged back to, for eg, 4000 rpm then open the tap full, and every things will still work, ie the tcu tells the waqste gate to close and the turbo to start making heat, so yes if you had your prop on full coarse on full throttle the tcu will be closing the waste gate to try and get the rpm up.Nothing different to the ch7 choppers with the 914, they run constant rpm, but different throttle position to obtain the rpm, hence the waste gate opening and closing to be able to hold the rpms.If you really want to see some power come out of these engines, you just have to put a 1/4 turn tap in 1 air line, to shut it off, and the engine will develop about 180hp, dont ask how i know, but it is true

[RickE]

How long would the engine last if it was set up to produce 180hp do you reckon?

[birdy]

Just long enuff to start melting.

[Disco]

I"m walking round thinking what the hell 1 air line means...?

[bones]

the motors will easily develop 180 hp if the waste gate does not open, but the airline is just one of the sensor lines

[Disco]

ok gotcha, the airline for the sensor to the tcu