RPM

[Arnieb]

How do I check to make sure that the EIS is reading correctly? I have a Jabiru 3300A and a Grand Rapids EIS 4000. I have done some internet searches and can't find any information on how to do this.

[peter anson]

You can check RPM with an optical tachometer. I was able to borrow one from a friend but they are not fabulously expensive, some less than $100. You can probably get one from a model aircraft supplier but there are plenty listed on eBay. Just select the number of propeller blades and aim the meter at the rotating prop. The one I used could be check calibrated against a fluorescent light.

Peter

[Arnieb]

The reason I ask is my RPM"s are running high, Someone told me that perhaps the Propeller may not be too small for engine. The prop is a prince 60" P-Tip.

[sonex1374]

I had a similar issue early on with my RPM indication as well. My Jabiru 3300 and Sensenich prop was reading 3200 rpm static, and more in the air. I thought my prop might be pitched incorrectly, but it was simply the pulses per revolution setting in the Dynon EMS. I changed the pulses from the default 5?? pulses/rev to 6 (as the Jabiru Installation manual says, not the 4 stated in the EIS manual) and it started reading correctly. I confirmed this shortly after using an optical tachometer and it matched very closely.

The other thing you might need is a resistor in the tach signal line to prevent the voltage from floating and reading too high at the higher rpm's (2800+). 10k-20k ohm will do it.

http://grtavionics.com/media/User-Manua ... igures.pdf

https://wiki.dynonavionics.com/Common_EMS_Questions

Jeff

[peter anson]

The reason I ask is my RPM"s are running high, Someone told me that perhaps the Propeller may not be too small for engine. The prop is a prince 60" P-Tip.

How high? I used to have a Prince 54 x 60 P-tip and it was too fine for my 3300. Full throttle static was 3000 rpm and at full throttle straight and level it would run to over 3300 rpm. When I measured the pitch at several locations along the propeller blade, the maximum pitch was 59", going down to about 56" in some locations. OK, I'm not an expert on this so you can take my measurements with a big grain of salt, but it did explain the performance.

Peter

[Arnieb]

Jeff you were right I changed the setting to 6 and hooked up a tach and now it is reading exact. Thanks for the tip!