How to equip my GRT

I'm in the wiring stage of a fixed-pitch, day-vfr RV4 and am hoping to tap the collective expereince of the group to help decide what exactly I want on my engine monitor. Here are the options:

Outside Air Temp
Carb Temp
Manifold Pressure
Ammeter

Which, if any, of these should I go with and why?

Thanks,
Steve Zicree
RV4

Outside Air Temp
Carb Temp

would be my top two ... lets you keep an eye out for icing.

then

Manifold Pressure

nice to help figure power vs rpm.


We have all three

Where and how does the OAT probe mount?

Steve Zicree

OAT sensor on my -8 is in the underwing NACA scoop (don't know if you have one on the -4). One of the coolest things about the GRT EIS/EFIS so far is how it computes percent power using MP and RPM...you set power just like on a turbine - I use it all the time. Granted, with a fixed pitch, you get what you get with throttle setting, but if you have the MP sensor, you can tell exactly what that is!

Paul

A battery ammeter is also very useful for monitoring the health of the electric system. An alternator ammeter would be second, but if you only have one, I'd go for the battery ammeter.

I have an FP RV-6A with a GRT EIS. I use the manifold pressure readout all the time, especially when I was playing about with the prop pitch. I fitted a carb temp probe for peace of mind - so far (in a year) I've never seen carb temps get even close to freezing. I also have an OAT in the wing root (not glued on to the root fairing), seems to work well. I did not bother to fit an ammeter - I'm not sure it is a good value instrument as the voltmeter tells you if the charging system is working. So far I haven't needed it. I believe you could add it later if you really wanted - as long as your electrical system was set up to allow it.

Pete

If it were me, I'd just buy all of those options you'd mentioned. They are relatively cheap options after all, and all of them add a good bit of functionality to the system. Normally in all the GRT stuff we sell, those options are almost always the 4 main ones that are added. After selling over 60+ of these things (EFIS & EIS's) just this year alone, all of those have been the most popular by the majority of our customers. I'd also spring for fuel flow, whether even with the FP. That being said, MP is less important with a FP prop, but for the price it's still a really "nice to have". I'd also spring for the Fuel Flow on any airplane I'm building, regardless of engine and prop combos. With fuel prices the way they are, I now normally fly my engine my FF numbers instead of anything else. If you engine is injected, I'd add the fuel pressure sensor too.

Just my 2 cents as usual!

Cheers,
Stein.

I received mine a few weeks ago. I opted for all the options because in the relative scheme of things, those options were inexpensive and great to have. Mine is going to be FP but even so I have manifold pressure and fuel flow (I do plan on going C/S down the road).

So far GRT has been great to deal with.

mounted our OAT in the NACA scoop on the pass side.

I apologize if this is a dumb question, but if I have a carb temp gauge, what does OAT do for me?

Steve Zicree

You definitely want OAT. You'll use that to calculate TAS, if nothing else.
Carb Temp?? never had it myself. I guess you would use it to watch for carb ice, but I don't know what else you would need it for.

Oat?

szicree said:

I apologize if this is a dumb question, but if I have a carb temp gauge, what does OAT do for me?

Steve Zicree

Click to expand...

Your EFIS system will calculate TAS from using the OAT data. TAS is THE number you want to fly from.
And DO NOT mount the OAT off any fuse surface (NACA) pickup. It will be off by at least +8deg F.

Kahuna

I don't have an EFIS, just one of those ol' fashioned round deals. Where should the OAT be mounted?

Steve Zicree

Besides the obvious, tells you how cold it is outside.... It lets you know if you are flying in rain that is above freezing, about to freeze, or time to change altitudes or do a 180 asap! You can get strange carb temp readings in a lot of conditions, even up to 70 degree F if the humidity/conditions are right, but the OAT helps to know if the airfilter may be getting clogged with ice...if you haven't noticed it gathering on your wings/canopy etc.

A nice to have for sure VFR. I think mandatory IFR!

Jetj01