ky7

I'm posting here because I swear I found somebody posting on this very topic ages ago, but can't find it for the life of me..

I've tapped an O2 plug to take 1/8NPT thread for my Defi EGT probe. My idea is to remove the 02 sensor from the downpipe (because I don't use feedback), and place my EGT sensor there instead, using the plug "adapter". The car is a 96 Jspec, as such the stock downpipe does not have a cat..

Has anybody tried this with results? Thanks.

bobybeach

it needs to be in the manifold before the the turbo.

rx7veilside

after the turbo is fine u just need to adjust ur reading of the temp to account for the drop..its actually better as the thermocouple may break off at some point depending on heat and use and u dont want that entering the turbo

ky7

I have seen people place in the downpipe, beside the stock O2 sensor?

Boby, you don't explain your answer and preferrably I would like to know if anybody has tried this approach - replacing the stock O2 sensor with EGT probe..??

Bump!

ky7

Thanks rx7veilside.. so what sort of drop are we looking at (approx)?

bobybeach

before the manifold is standard practice. You can place the temp sensor anywhere you like i guess and it will read and show some level of temp but the information is then useless because you cannot use it has an accurate indication of ignition timing tuning.
Before the turbo is where exhaust pressure and temp is most consistant and accurate for exhaust temp ignition tuning.

Its like buying a boost gauge and installing it before the throtle bodies and intercooler..... It will still show preasure readings but none that are relevant to you.

books

iTrader: (8)

I have run an EGT probe in the O2 bung of a couple of downpipes for at least a year. I also have logged EGTs in this configuration with both the twin turbos and a single turbo setup. I do log this data as an aid to tuning for timing.

While it is probably true that a more accurate reading is at a preturbo location. I doubt if there are many individuals who tune exclusively using EGTs. Further I believe that the location/distance from the exhaust ports is relative along with the speed and accuracy of the probe.

mark57

Rotaries can hit 1800F. My EGT is located in the DP after the turbo; it reads way too inaccurately cold. Correct location for an EGT is the exhaust manifold before a turbo.

books

iTrader: (8)

Will 6" further away cause a 200F degree temp change? If so, when will that occur i.e. time delay? On a completely stock engine how much timing advance would cause a 200F degree increase at 5,200 rpms?

Does anyone have any recorded values for EGTs on the downpipe vs. the turbo manifold to illustrate the deltas?

mark57

Sorry for my vague post. My Dakota Digital EGT sensor is 3" after the turbo and it won't even reach 900F. It does react very quicky, but unfortunately is useless until I place it ahead of the turbo.

mark57

Dammit - I meant to say "1800F at peak torque".

ky7

Do you blame your EGT sensor for this?

I'm using the probe that came with the DEFI BF EGT gauge I've purchased.

I would like to tap it to my manifold (but not right now), because I can understand how the turbo itself would be a major contributor to fluctuations in EGT's compared to at the exhaust ports. I suspect, depending on factors like whether the turbo is operating or not would be a major factor.

It would be great if somebody datalogged with the sensor at the dp and then in the manifold under similar conditions. We could have some measurable reference for EGT's based on these two different locations. It would also be very interesting to see if the differences would be linear / relational.

Anybody have approx differences in EGT's I wonder..?

mark57

I blame me for the incorrect location - the sensor is fine. I don't see the point in doing a comparison test of correct v. improper EGT location. I doubt there is literature that supports placing EGT after the turbo - what I've recently read says EGT must be located before the turbo. The turbo is an erratic heat sink.

ky7

Indeed. I think I will test with a probe in the manifold and at the same time one in the o2 location.. I have modified my defi for 0-5v logging and I'm just curious too see in practice exactly how erratic the effects are post turbo.

rotarypower101

iTrader: (1)

Interesting, I have always thought about doing this, but haven’t gotten around to purchasing a good duel EGT setup yet.

Howard Coleman and Jeff48 has posted their recommendation for the TeamRip thermocouples.

I have wanted to get these and implement them, but haven’t as of yet.