Which Engine analyzer?

[jrenwick]

Richard, when you installed the UBG-16, did you also mount the red LED alarm light? I like that feature of the EI unit. I mounted mine right below the altimeter, where it will always be in my scan. I added oil pressure and temperature sensors -- so I could be alerted as early as possible on low oil pressure, and so I could know my actual oil temperature (because the Cessna gauge has no numbers on it). The Cessna gauges are still in the panel, because those are the primary (legally required) ones.

A friend of mine installed the comparable JPI engine analyzer, so I've had a chance to make a few comparisons.

1. JPI uses a D-sub connector at the back of the unit. You can cut the wires from ahead of the firewall to the length you need. In contrast, the EI unit uses rather fat, stiff, shielded wires that come out of the back of the unit in three bundles, with round phenolic connectors that go to three similar bundles. Two of those go through the firewall, and one connects to other things behind the panel (power, alarm light, RS-232 data, etc.). I ended up with two sizeable loops of EI wiring tied off behind the instrument panel. For neatness of installation, I think I'd prefer the JPI unit.

2. When you wire the engine sensors to the unit, JPI has a fixed pin position for each sensor on the connector on the back of the unit. EI lets you use any wire pair you want for any sensor (with a few restrictions), and then you program the unit to tell it which sensors are installed and what connector pins they're on. The programming is all done with the two toggle switches on the front of the unit.

I haven't used the feature that lets you download engine history to a PC, so I can't comment on that. (Never saw a need to do it.) (One thing occurs to me though. The interface is RS-232, which connects directly into a serial port on a laptop. But can you still buy a laptop with a serial port? And if not, is there a way to connect an RS-232 device to a USB port? I think there is, but I don't know the details.)

I agree that these devices don't have much value for setting the mixture, as they would with a higher-performance, fuel-injected engine. But I do in fact use them to set the mixture, because I've learned what the resulting EGTs are when I set the mixture according to the owner's manual at a given cruise power setting. So I can use it as a reference while I'm adjusting the mixture by the book.

If you have one of these, you get used to a certain "picture," and any deviation from that can give you a clue that you need to look around and do something. That, and the programmable "idiot" light for high and low limits on all your sensors make it worthwhile to me. It was expensive, but I'd do it again.

[hilltop170]

John-
No, I did not mount the red indicator anywhere. Carb temp was added to position 7 but nothing else was added. I haven't used the download function, I just use real-time info.

Many of the EI gauges are STC'd as primary replacements so I had those original instruments replaced. I prefer exact values as opposed to ranges.

The EI oil temp/press gauge has green, yellow, and red indicator lights built-in.

I don't know anything about the wiring or harness layout as I did not install them myself but I did notice some tied-off bundles under the panel.

Having the UBG-16 has come in handy at times. It told me baffles were needed in front of cylinders 5 and 6 to increase CHT on those two. At the first annual after the engine major overhaul, the UBG-16 was used to locate and isolate a manifold vacuum leak to cylinder #3. It would have been difficult to find otherwise. I have also used them to locate stuck valves, fouled plugs, plugged injectors (on an IO-520) and one time a broken ring. Sure other means can be used to get the information, but it is good to be able to tell the mechanic there's a problem with cylinder number 1 or 3 instead of it's running rough.

Even back in the 1970's I had an old Westach analog EGT rigged up with a 6-position rotary switch to montior EGT on each cylinder. I knew which cylinder ran hottest and which peaked first, long before JPI, EI, or GEM "invented" analyzers. I located the broken ring with it. See picture below;

[Mark Harwood]

Ordered the EI through Sandhill aviation in Hampton NH. Thanks for all the feedback. Mark