Egt probe in downpipe?

[Tony Hanna]

I've got an egt guage and thermocouple that's been laying in my glovebox forever. The original plan was to pull the head to install a ported exhaust manifold, new turbo, new headgasket, and new timing belt all at once. I was planning to install the thermocouple in the ported manifold before it went back together. Unfortunately things are going a little slower than I'd originally planned and it's got me wondering would it be worthwhile to go ahead and install the thermocouple in the downpipe for now?
I can always move it to the manifold and weld the hole up in the downpipe when I finally get around to pulling the head. I know the guage will read colder than what it would if the thermocouple was mounted in the manifold but could it still be useful for tuning mounted like that? Also, does anybody have an idea of how to correct the temp reading for being downstream of the turbo?
Thanks,
Tony

[Frank]

Some EGT is better then none. EGT in down pipe means your high limit is around 1300. Downside to this location is the fact that they are slower to respond, but do take into account all cylinders.

[Tony Hanna]

Frank,
That's exactly what I needed to know.
Thanks

[Rattlesnake]

I got mine on the DP right after the turbo and my EGT temp. always agree with my wideband.

Reinaldo Moloon

[Tony Hanna]

I got mine on the DP right after the turbo and my EGT temp. always agree with my wideband.

Reinaldo Moloon

That's nice to know. I won't be running a wideband on mine at least for now, so I'm stuck with a narrowband a/f meter and an egt in the downpipe. Mostly I was curious about the high limit which Frank said is 1300. Another nice thing would be to know what a safe normal range would be. I'm going to be pushing around 18 psi worth of hot air out of the stock Mitsu until I pull it apart to swap turbos plus I have no idea how well the intercooler I'm going to use will perform. Taking that into consideration, I imagine the egt gauge will be a big help avoiding any engine damage.
Thanks,
Tony

[Rattlesnake]

When I didn't have the wideband I had the EGT probe on the DP, where I have it right now. My goal was 1300-1400 with the Dawes A/F meter on blue, anything lower or higher than that I could feel the car slightly loosing power.

Reinaldo Moloon

[Tony Hanna]

Thanks man. I'll probably tune for a little below 1300 to stay safe. Since this is my daily driver, I'd rather sacrifice a little power in favor of keeping the engine healthy.
Hopefully this will only be temporary. I'm really looking forward to a bigger turbo and methanol injection so I can run some decent boost. Hopefully by that point I'll have the extra cash to drop on a wideband.

[Rattlesnake]

Hey man, are you near Summit Point Raceway? I'll be there in the summer.

[Tony Hanna]

I'm kind of in the middle of the state. It looks like Summit Point is in the eastern panhandle. About 319 miles according to mapquest. Still, it might make for a fun roadtrip...

[WVRampage]

I was reading the instructions online about how to hook up the EGT and it says on a turbo engine it needs to go after the turbo,any explanation of this.

[Tony Hanna]

The idea is to put it in the exhaust runner for the hottest cylinder because it's likely to be the first to melt down if you go lean. With it reading the hottest cylinder, you know if you keep that one at a safe temp then the rest will also be at safe temps. That is if everything is functioning properly. If you mount it after the turbo like I'm going to do, theoretically you could go lean enough to damage the hot cylinder while the gauge is still telling you that you're safe. That's the way I understand it, somebody please correct me if I'm wrong.
In my case, with the engine together it'd be next to impossible to install a clamp style probe into the manifold runner, so I'm going to put it after the turbo and then move it when I pull the head to swap turbos.

[Frank]

They say after a turbo to help reduce the number of stupid trouble calls of people saying, they didnt detect any lean conditions because they were monitoring just one cylinder instead of all.


Frank

[Frank]

I would target 1200 as max if you are putting it in the downpipe. Keeps longevity up of things like the valves, etc.

[Tony Hanna]

Thanks again Frank.
1200 it is then.
Was I about right on the reason for running the probe in the runner for the hottest cylinder?
If I had the unlimited budget, I think I'd go for one of those digital aircraft egt's that can monitor 4 probes at once. I looked at one awhile back that you could set to either display the temp of 1 cylinder, cycle through all the cylinders, or automatically display the hottest cylinder. It even had a warning light that you could set to come on if any of the cylinders went over a certain temperature. That would be really handy to point out an injector that's on it's way out hopefully before it causes any damage.
I'll dig around and see if I can find a link for the thing. I think they were selling on ebay.

[Tony Hanna]

Found it.
4cyl aircraft egt
I'd really like to have one of these but I just can't justify installing a $435 gauge in a $200 car.

[Frank]

I have one and I am not confident that it is working properly. I need to call them up and find out what the deuce is going on.

[Rattlesnake]

Just make sure you put it as close to the turbo as possible. The further down on the DP the cooler is going to read.

[Mario]

If you're using a Wideband is an EGT still necessary?

[Tony Hanna]

I have one and I am not confident that it is working properly. I need to call them up and find out what the deuce is going on.

Frank,
How's it acting to make you think it's not working properly? For all my grousing about the price of the thing being more than twice what I paid for my car, I probably will still buy one eventually. You can bet if the Sundance finds a new home, the gauge will be kept to be put in the next TM that comes along though. So, yeah, I'd be really interested to hear what kind of problems you are having with it.

Rattlesnake,
I was planning to put it as high in the downpipe as possiable without interfering with the flange for just that reason.

Mario,
I guess if nothing else, it would be handy to have both because you could check them against each other. Your WB is going to give you en exact idea of your a/f ratio, and the EGT should be pretty close. If the two don't agree with each other then you know something screwy is going on.

[BARRON]

What about putting the probe in the swingvalve..just above the O2 sensor??