I've had this Exhaust Gas Temp gauge sitting around for a couple months and while I had the car up on ramps getting a new fuel filter (and it needed it!) I decided to pop this guy in place.

I got the parts from Aircraft Spruce, this guage, this clamp-on probe, and this 15' extension cable. All told, I spend around $100. This gauge has the benefit of being semi-original looking, ambient temperature compensated, and matches my Micro1000 CHT gauge.

All I did to install it was drill a small hole in the exhaust tube, and insert the probe, tightened everything down, attached the cables and ran them to the cabin.

I drove the car around the block, which was very interesting. My car has been running very poorly ever since returning from the RRC, and I thought it was just the fuel filter. But it's not. It was very interesting to watch the needle moving as I opened and closed the throttle and it also helped me visualize the problem that I'm having. My car has been intermittently losing power, and I would be driving along at a nice EGT, and the car would lurch, and I would look over and the EGT was extremely low. And since it is my understanding that EGT is more affected by timing than AFR, I can be pretty confident that for some reason my timing is wonky. This may be the KitCarlson EFI dying or a bad wiring harness connection. It might be time to *GASP* install a spare set of carbs and a Mallory.

This was an affordable and easy upgrade. I expect that it will be a useful tool for tuning the motor and if anyone has an extra gauge slot to fill, I would recommend an EGT after you have a CHT.

Timing does affect EGT but not as drastically as you might think. It sounds like when " the car would lurch" you are experiencing a miss, or intermitent ignitoin failure.

The relationship between timing and AFR does show in your EGTs, in the end though tune with AFR.

This stuff is interesting to me. If for nothing else than the educational factor, I want to put both an EGT and AFR gauge in and learn how to optimally tune an engine - carbs and FI.

Thanks for sharing this Mark. Good to know about some parts options with ballpark pricing.

For those who have had experience with AFR gauges, what do you recommend? Clearly it should be wideband, but what kits exactly and what are good prices? Any thoughts on this NGK unit? -> http://www.powerdex.com/

I have an Innovate Motorsports LM-1 that will get installed sometime soon as well. That will round out my gauges and give me lots to look at while I'm driving.

Thanks for the tips Tim. I always appreciate your perspective. You have way more experience than I do.

Great! Then you will never see that deer you are about to hit!!!

Mark,

Is this the same CHT gauge you are using? CHT Micro 1000
If it is how do you like it?

I have absolutely no complaints about it. Installation was easy and straight forward and so far it has worked great. The numbers are a little hard to read, but realistically, you don't read the numbers after the first few drives, after that you are just used to it and just look at where the needle is.

What are your EGT temps.? What is good temps for EGT on these motors?

According to my reading on the RAT Forums, 1275 is a good temp for WOT, and at 1375 you should start looking for your motor to explode. But I have no real world experience at this point, my reading ranged from 900 to 1400 at various points and was changing rather quickly. I only took a quick trip around the block to test out the EGT and to see if my new fuel filter fixed my problem.

Hi Mark!
Glad to hear you got out of the new house for a bit. Did the EGT guage have a screw in sensor offered? I have the O2 sensor bung welded on my header and with the Dells it would be a waste to use an O2 sensor...

The EGT probe is very small. You would have to custom fab something to adapt and O2 bung to an EGT bung. Actually, it wouldn't be too bad, just drill a hole in an O2 bung plug, and weld the EGT bung onto the O2 plug...

Interesting info. How close to the head must the sensor be mounted to get an accurate read? Do you need to monitor all four cylinders or is one enough?

Not so quick, the Formula Vee and Formula First crowd use the Innovate LM-1 for tuning their motors. They only run a single carb.

SR Racing sells them. Here is what they said:

A high quality Wide Band 02 Sensor with Data Logging (44 minutes) and expandability. We use one here at the shop on our engine dyno.

The LM-1 can be expanded with the addition of the RPM Adapter and you have Wide Band 02 Sensing AND 4 additional inputs for anything else you want to data log (Temps, Pressures, RPM, Throttle position etc.) Fully programmable for mapping to any type of sensor you can think of.

So that bung might be useful after all.

Mark, thanks for the post and link to the site. The CHT dual gauges are affordable and two would allow you to moniter all four cylinders.

With all the talk of 'cold-junctions' and wire extensions compromising CHT readings, I never understood why putting a selector switch for the gauge was never a problem. Isn't extending the wires a big no-no?

Somebody talk thermocouples to me...

IIRC, the thermocoupler measures the difference in temperature between the end where the reading is taking place and opposite end. It assumes the ambient temperature for the end closest to the gauge to be some static temperature like 78 degrees. As long as you don't cut the thermocoupler then it is fairly accurate. You can add wire as long as it is under a certain gauge to reach the gauge if needed.

This is is based on the instructions received with my CHT.

I know *someone* who would just JB Weld it!!!

Don't poke a sleeping.... um.... well, regardless don't .

What??? What did I say???

a switch has resistance......

so your true CHT reading would be skewed going through a switch. You would have to find a switch with ZERO resistance....

extending wires is a no-no! (adds resistance!)

BUT!!!

you can shorten a CHT harness, if you know EXACTLY how much resistance it had in the full length harness, cut it to desired length, and add a resistor to let it reach its original resistance....

i think...

cuz yall know i dont know shiiiit

Aaron, Mark, you can extend an egt harness, you need the correct wire to do so

If you need to shorten the egt harness, dont cut it, just coil it up and store it neatly. Also you can add a four way switch if you like four way switch

Huh... Neat!

But that's a special switch, just throwing in any ol' two or four way switch will likely create false readings, right?

I've got an LM-1 with the aux box, it lets you log in the LM-1 box afr, rpm, 2 axis acceleration (backtrack out hp easily), map, cht or egt (long thermocouple wires included), and a number of other inputs that you choose. And if you have a laptop you can monitor it all real time (or you can buy gauges). Its very useful to have, especially when performing an inital tune on a new engine. I do feel a little fast and furious when I am crusing down the road with a laptop open in my passenger seat!

If you are considering buying the rpm box for the lm1, I suggest you save up the extra 150 bucks to get the aux box to get the extra features.

............Well aircraft spruce is a good source for the EGT guage and parts. THEIR products are FAA approved.....which means they are the highest quality you can find.....some of the other brands are NOT.........then with all the genius EGT users making comments NO ONE has said ANYTHING, at all about the required location of the temperature probes to achieve accuracy of the combustion temperature....the EGT....readings.........FINALLY ....reguardless of what you have heard or read or have been told here is the facts.....EGT readings of 1275 to 1375......THESE temperatures are suitable ONLY FOR FORGED PISTONS...read FORGED PISTONS ONLY..........heres why.....at 1400 degrees a (typical) forged piston has lost 1/2 ONE HALF of it,s strength./structural regidity......(this is why you see drag racers, replacing pistons after every run.)(in the higher classes)..(even tho they have overkill in piston design) the temperatures and fuels (nitromethane)..shatter..in small fractures...their pistons , forcing replacement or a lost engine.......SO consider this....a CAST PISTON is NOT as strong as a forged piston....this is why cast pistons in stock engines are heaver than a replacement forged piston....they are making up for, in total mass, their lack of strength, as compaired to forged.....also cast pistons do not expand as much as forged , therefore, tighter cylinder wall clearances work fine for stock engines....BUT a EGT of 1275 degrees is NOT , NOT suitable /safe/or smart to use with cast pistons.....................................hope this saves you an engine.murray.

If ind that the TIV engine is VERY responsive at WOT to timing adjustments in relation to EGT values.

There is a big difference in EGT values at cruise and WOT and the points of failure related to them. I only pay attention to EGT at WOT, at cruise and light load EGT can be 1500F with no adverse effects.

Don't even look at the EGT gauge if you are at anything less than WOT on an N/A engine.

I use Westach and SPA EGT gauges in the dyno cells and in my personal cars.

...westach...is available at aircraft spruce.....and is FAA rated. westach is installed in many O.E.M. aircraft, and they have many, many , variations of instrumentents, of all types and uses, including CHT, EGT. the EGT probes MUST be installed at a particular point in the exhaust system, or the combustion temperature reading will not be accurate. the location is furnished in the instructions.

Westach is cheap.
You get what you pay for.