RPM 914turbo

Hi Seamus,

Could you please rephrase your question?

"Shoot into turbo" is not a term we are familiar with, so we want to make sure we fully understand what you're asking.

Thanks!

when flying at 4700rpm or 4800 rpm if I want to increase to 4900 rpm  it will not do so but will try to go into Turbo

Hi Seamus

The MAP for the 914 shows that this is a turbo "boosted" engine, not turbo normalised.  In looking at the data the engine is boosting to hit the setpoints shown in the data.  Even if you are at a low pressure day, or altitude ( up to 5000 meters) the TCU will hold the wastegate closed enough to hit the MAP to RPM value.  

Think of this, without a turbo this engine is a 1211 CC 80 HP engine.  

Cheers

To old school

Have you any idea what the values are that are set at default on the TCU for the rotax 914 turbo.

Or where we would  get them please.

We still have problems.

we can get it to 4750rpm at the 1st stop but when we move the throttle past the 1st stop it wants to go into turbo

Seamus Brennan

Hi Seamus

The load, prop pitch, is what allows the engine RPM to run in its range.  When you speak of stops I am not sure what that is in reference to. The TCU graphs are also in the installation manual and you can see what the performance is relative to the power curve.  The TCU has no stops built into it, the prop controls how much RPM you have.  At take-off you want max RPM, fixed pitch would be 5200 to say 5300 in climb after lift off.  At WOT level flight you should have enough load to control the engine RPM to 5500 to say 5600 RPM on a fixed pitch.  The balance of the numbers should then fall into line with the power curve shown and the MAP at a given RPM should then match closely with what you see in the manual.  

Constant speed is different in that you control the load in flight.  Again there are limits, 5800 max at take off cimb (limited to 5 mins) and WOT again at level flight at 5500 RPM.  Most people will then drop RPM and load to run at the 75% power level to get better fuel economy.  

Cheers