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EGT monitoring

 
Old 01-07-2019, 11:51 AM
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Light aircraft dont operate under the same conditions though, rpm ranges, swings of rpm, and engine load etc. Very different scenario. They almost operate at steady state a lot of the time with moderate loads.

And logging EGT's, the response is massively slower than lambda. Wouldnt matter gauge or other....thermocouple is just much much slower. But that's not overly surprising anyway, and lets face it, you should never ever be seeing huge swings or drops in EGT

Even if one cylinder does go down, it can easily take the sensor a full second or two to drop a few hundred degrees, whereas the lambda will show the change in milliseconds. ( ideally lambda per cylinder, but that does come with it's own range of problems on a turbo setup. )
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Old 01-11-2019, 07:18 AM
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There are factory twin turbo engines that simply put it right before the turbine inlet on each turbo where all the exhaust has already been merged for that bank.
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Old 01-11-2019, 04:33 PM
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I'd say most OEM setups would be more interested in EGT there more from a point of view of not destroying the catalytic converter though ( although not very many OEM's have it )
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Old 01-11-2019, 05:17 PM
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Originally Posted by stevieturbo View Post
I'd say most OEM setups would be more interested in EGT there more from a point of view of not destroying the catalytic converter though ( although not very many OEM's have it )
In the example I'm referring to , it's in the hot side not in the down pipe. If it was all about the cat they would have just put it before the primary cat to know exactly the cat temp. I think they use it for adaptive timing by cylinder and boost adjustment since the wastegate is electronically controlled.
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Old 01-12-2019, 06:51 AM
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In my situation I am looking to use them more for trouble shooting to see if there is an issue with a cylinder by reading the logs after a pass. I've spent 2 seasons now wasting a bunch of time trying to track down different issues that a set of these would have helped me at least narrow down in 1 log file.
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Old 01-12-2019, 07:11 AM
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Yep, still too many underestimate the value of good logging. Even many who do log, dont log enough, or often/long enough.

You dont just need a pass...you need before, during and after ! as all sorts are happening all the time.
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Old 01-13-2019, 04:53 PM
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Originally Posted by gametech View Post
EGT gauges have limited specific uses for tuning gasoline engines. For just driving around or for racing, they are useless.

I defy anyone on this site to say an EGT gauge saved their motor during a street driving or drag racing situation.
Back in the day, my friend Gary Donovan (in CT) used to race a 10-second 2.5L turbo K-car. Through much trial and error--especially error--he learned the stock cast pistons give up around 1700^ and start to melt/fail. With an EGT on board monitoring cylinder #1 (the hottest one on those engines, due to the head design and how coolant flows through it) he would be able to prevent meltdown if things went wrong as he was going down the track.

When I began seriously racing my 2.5L turbo Caravan, I decided to follow his lead and installed an EGT gauge in the #1 exhaust runner. I would aim to have my EGT level off in the 1550-1600^ range during my pass. If my temp climbed past 1600, I would abort the run, then raise my fuel pressure a few pounds and go again. (Our '80s speed density computers were extremely primitive compared to modern ECUs.) Thanks to his experience and my gauge, I never melted a piston in six years of racing.

Could a wideband O2 sensor have served the same function? I have no idea. He never ran one, and neither did I. But if I ever do rebuild my 5.3 and hang a hair dryer off it like I am planning to do, perhaps I'll find out.
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Old 01-13-2019, 04:59 PM
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High EGT, does not necessarily mean high chamber temps though.

And no, Lambda sensors do a different job. Both have their own pros and cons.

Although I do wonder that when people use the timing strap as an indicator of chamber temp.....why we cant just drill through the head and stick a thermocouple into the chamber and actually monitor chamber temp. On most heads there's bound to be a viable drill path. Although it may be difficult to get one into the middle of the chamber near the plug.

In fact, I've a fucked TFS head sitting here I might try lol.
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Old 01-13-2019, 05:12 PM
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Originally Posted by stevieturbo View Post
why we cant just drill through the head and stick a thermocouple into the chamber and actually monitor chamber temp.
Dude, that would be... incredible.

Originally Posted by stevieturbo View Post
In fact, I've a fucked TFS head sitting here I might try lol.

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Old 01-13-2019, 10:37 PM
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The only real problem I see is the slow response of the sensor. Too bad you can't use thermal imaging for real time temp data. Of course it is possible, but ridiculously cost prohibitive.
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Old 01-14-2019, 10:34 AM
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The plug electrode isnt so fast either.. A 3mm thermocouple would respond ok, and as a run will see WOT for a few seconds, it would still give good information.

But I'm guessing as it doesnt seem so common, even on test applications, there must be some reason for that
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Old 01-18-2019, 03:04 PM
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Steve, I’m pretty sure you CAN get in cylinder pressure sensors. This tells you even more about what’s happening inside the cylinder than O2 or temp sensors. You can actually see dept happening!

OEMs don’t care because they have already modled every eventuality and know exactly what the combustion profile (temp, pressure and o2) will be. So there is no need for monitoring as they already ‘know’ what it will be (or the range it will be in). Aftermarket don’t have that luxury obviously.

i wonder how much power could be made with a SBE and pump fuel with this extra ‘monitoring’?....
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Old 01-18-2019, 03:29 PM
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I know you can get in cylinder pressure transducers, but they all cost a fortune, and most common method is via a modified spark plug to get access to the cylinder, which again costs a huge sum of money.

And they are also very fragile, with a high risk of detonation shortening their lifespan by a lot.

Using them in head, with direct access to the chamber would reduce some cost....although to a degree it would kinda **** up a cylinder head. But there's bound to be several straight lines from chamber to outside space through solid metal that could be drilled.

But it does also need the ability to log extremely fast, far faster than pretty much any ecu currently offers, so all such things at present are via a scope..

it'd be nice to have it all in one package !
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