# Exhaust Gas Temp



## Cashpoint (Jan 12, 2004)

What are considered high and normal exhaust gas temps as sat on the motorway last night doing at 70-80 my temp was showing 800oC.


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## kismetcapitan (Nov 25, 2005)

it entirely depends on where the EGT probe is mounted. Which leads me to this question - where to mount it? I got into this with my tuner today - I thought mounting in the rear turbo elbow would be the best location, but he wants to put it much further back, near the end of the downpipe or even in the decat pipe.

Being that far away from the rear turbos (and exhaust gas from cylinders #4,5,6), will I get accurate enough readings to react fast enough if something starts to go wrong?

Where is the EGT probe mounted on stock BNR34s?


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## Lamb (Sep 25, 2003)

Cashpoint said:


> What are considered high and normal exhaust gas temps as sat on the motorway last night doing at 70-80 my temp was showing 800oC.




If your cruising at those speeds the temps should be lower then that.........ideally 800-900 is probably the highest you wanna see when driving hard.

Best thing to do is get it booked in somewhere and get it checked......probably needs a few adjustments on the map.

Where are you located???

Harry


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## Cashpoint (Jan 12, 2004)

I had though 800 was a little high, i'll have a look tonight to see which exhaust outlet the probe is mounted. 

I'm in Berkhamsted, Herts


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## Eikichi (Jul 25, 2006)

Didn't know it was that hot!!!

BTW, Lamb, have you got a blue GTR & where you in North Watford last saturday? (around 1pm-ish)


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## Lamb (Sep 25, 2003)

Cashpoint.....you have pm mate.




Eikichi said:


> Didn't know it was that hot!!!
> 
> BTW, Lamb, have you got a blue GTR & where you in North Watford last saturday? (around 1pm-ish)



Yes i have got a Blue 34.....as seen in my little pic under my name.....but was'nt me out and about.......my car is off the road in hibernation for a while.


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## Eikichi (Jul 25, 2006)

ah ok thanks mate


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## ExScoobyT (Jan 6, 2004)

800C pre-turbine is fine.

800C post turbine may or may not be fine.

EGT sensor anywhere other than 5-10cm from the exhaust valve is useless.


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## kismetcapitan (Nov 25, 2005)

ExScoobyT said:


> 800C pre-turbine is fine.
> 
> 800C post turbine may or may not be fine.
> 
> EGT sensor anywhere other than 5-10cm from the exhaust valve is useless.


ergo, the best mounting location would be in the rear turbo elbow (as the rear runs hotter than the front)? That's more or less what I figured...sticking the probe in the decat pipe...how would that help me at all???


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## ExScoobyT (Jan 6, 2004)

`ergo, the best mounting location would be in the rear turbo elbow `

`EGT sensor anywhere other than 5-10cm from the exhaust valve is useless`

In case you`ve not figured it out, the elbow is AFTER the turbine.....

`sticking the probe in the decat pipe...how would that help me at all???` - Clearly it would not!!!!!


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## kismetcapitan (Nov 25, 2005)

oh really? I thought the turbo elbows were in the intake, after the intercooler, but before the air filter. Thank you for clarifying that.

Someone else suggested I stick the probe in the decat pipe. I thought that was crap, hence I brought up the topic in the first place.

I'll put mine in the rear turbo elbow, not in the manifold, and call it a day.


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## LAURENCE (Jan 4, 2005)

Depends of course on what piston material you're using really I guess.
I'd agree 800celcius before turbo is a max on stock pistons.
There are EGT kits that run 6 individual EGT Probes that you can put in each of the exhaust manifold runners so you can record the temp of each cylinder.
The concerns of running before the turbo's is what if the probe breaks off and damages the turbine.


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## kismetcapitan (Nov 25, 2005)

exactly, which is why I will run post-turbine, but just barely after. As #6 is the lean cylinder, it's most likely the hottest, which is why I chose the rear over the front.

The Tomei elbows are so shiny and beautiful - pity to drill and weld a bung in one of them 

oh, and the pistons I'm installing are HKS 87mm forged, with the nickel-plated tops that supposedly take higher temps. Not that I want to run higher, but more to increase the safety margin....


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## Floyd (Dec 15, 2004)

Most Tuners who use a wide band lambda sensor put it in the decat pipe (after both exhausts have siamesed together). As already said narrowband o2 sensor and exhaust temp sensor should be in the turbo elbow (just after turbine).


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## David (Apr 25, 2003)

I dissagree to get an accurate idea of port temperature the sensor must be mounted pre turbo as close to the port as possible.

The development engines I work with we have on automated shut down at 850 degrees port temp these run non forged internals and are boosted.


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## ExScoobyT (Jan 6, 2004)

Chaps - you are quite a confused bunch.

Kismet-enginedestroyer....EGT - Exhaust Gas Temperature - nothing to do with intake side of the engine.

EGT probe needs to be in the EXHAUST manifold BETWEEN the cylinder head and the turbine to be off any use what so ever. Putting it in the elbow is USELESS.

I would be happy with 900-920C on std pistons, a bit more on forged items.

David - I suspect you comment relating to development engines is when auto running perhaps? Or as a safety margin so as not to damage $$$$ proto engine? 850C port temp on any new gasoline turbo is about 200C below the benchmark temp.


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## David (Apr 25, 2003)

ExScoobyT said:


> Chaps - you are quite a confused bunch.
> 
> Kismet-enginedestroyer....EGT - Exhaust Gas Temperature - nothing to do with intake side of the engine.
> 
> ...


You are right very expensive development engines

We arnt allowed to get near the point of melting them :chuckle:


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## kismetcapitan (Nov 25, 2005)

ExScoobyT said:


> Chaps - you are quite a confused bunch.
> 
> Kismet-enginedestroyer....EGT - Exhaust Gas Temperature - nothing to do with intake side of the engine.
> 
> EGT probe needs to be in the EXHAUST manifold BETWEEN the cylinder head and the turbine to be off any use what so ever. Putting it in the elbow is USELESS.


apparently you can neither read nor understand subtle sarcasm. Tomei TURBO ELBOWS. They go BETWEEN the turbo and the downpipe. They're a good place to take EGT readings.:GrowUp:


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## David (Apr 25, 2003)

Thats because you are still talking about the wrong place. Give me a second and i'll mark where they should be


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## roadie (Feb 6, 2006)

The problem with placing the probes in the elbows is the temp will drop too much by then. The idea of an egt gauge is to measure the temp inside the cylinders. Between the engine and the turbo, there will not be alot of temp drop. After the turbo, how will you know ???


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## Asim R32GTR (Sep 24, 2003)

Exhaust temp is ALWAYS measured before the turbo!!!
This topic is not even up for discussion.
Temp after turbo can be as much as 200c lower.

Do not play with this, or else you will experience the whole thing with melted pistons etc over again... but hey... it you're engine... your money... 

Go Get`em kid! :squintdan


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## DaleHarrison (Nov 16, 2005)

From my own experience I would have to agree, I've always seen any EGT probes installed into the exhaust manifold.

This was the same for My Starlet GT Turbo, Pulsar GTiR and my R32 GTR - all of which I have had EGT guages installed purely because it saved my engine in the Starlet once.


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## David (Apr 25, 2003)

In the picture below I have marked with red the exhaust manifolds, this is where the EGT sensor should be fitted.










Ideally as close to the port as possible, but then you would only be measuring one cylinder. I would put it at the 1st point where all 3 meet on the rear bank, or one in both or in an ideal world 6 one for each cylinder.


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## kismetcapitan (Nov 25, 2005)

that's very, very useful information. Finally, a clear answer!! 

As I've only got one going in, would you agree that the rear manifold would be better, as #6 and sometimes #5 run a touch leaner?


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## DaleHarrison (Nov 16, 2005)

kismetcapitan said:


> that's very, very useful information. Finally, a clear answer!!
> 
> As I've only got one going in, would you agree that the rear manifold would be better, as #6 and sometimes #5 run a touch leaner?


You could be really geeky and have one guage for each manifold  give you a good comparison of temps


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## ExScoobyT (Jan 6, 2004)

The problem with your posts (Kis) is the (very)fine line between complete ignorance and sarcasm......

The reason for pre-turbine is not soo much the temperature drop as such, but the fact that the temperature drop is highly variable depending on running conditions.......Vmax running for 10miles will see elbow temps close to pre-turbine. A single mapping 4th gear run could see upto 2-300C difference.......

The EGT sensors you see installed after the turbine are almost exclusively to monitor EGT into the cataylst. The limit for cat entry gas is around 850C (R32/33/34 frop example).


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## Asim R32GTR (Sep 24, 2003)

kismetcapitan said:


> that's very, very useful information. Finally, a clear answer!!
> 
> As I've only got one going in, would you agree that the rear manifold would be better, as #6 and sometimes #5 run a touch leaner?


Yes, use the rear manifold where cyl 5+6 is 
In a ideal world you would use one in each cylinder... but thats just to ricy 

Asim...


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## ExScoobyT (Jan 6, 2004)

Putting the EGT in the collector of each turbine is just as valid (maybe more so) as the temperature here will be slightly hotter that in the individual runners due to the cycle average. EGT in each runner gives an idea of cylinder variations of both AFR and timing (combined). EGT inthe runners and UEGO in the downpipe allows you seperate (to some degree) AFR variations from timing variations...


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## kismetcapitan (Nov 25, 2005)

fair enough, although how hard is it to say straight up in simple english, "mate, you wanna stick the probe at *this spot*"

So, is there truth to the stereotype of the ignorant, shoot from the hip American, and the insufferably arrogant Briton? Perhaps we exemplify both


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## ExScoobyT (Jan 6, 2004)

`So, is there truth to the stereotype of the ignorant, shoot from the hip American` - taking out countless people / property / animals / birds / buldings / cars 

`and the insufferably arrogant Briton?` - sitting in his (my?) sandbagged shelter, slowly shaking his (my?) head...

Perhaps we exemplify both - surely not?????!!!!!!!!


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## Sayajin (May 30, 2006)

kismetcapitan said:


> fair enough, although how hard is it to say straight up in simple english, "mate, you wanna stick the probe at *this spot*"
> 
> *So, is there truth to the stereotype of the ignorant, shoot from the hip American, and the insufferably arrogant Briton? Perhaps we exemplify both *


ROTFLMAO.

Sorry guys, but I have to agree with Kisme here... Sure the man posts ALL the time, however it is not to be an ass. He truly just wants to know the best way to protect his investment. I am sure it gets annoying to some of the people on the board, but he doesnt do it with malicious intent. Personally I was just saying "damn these boys are hard on kisme." Oh well... just my .2. Then again I was always an objective person.


-Sayajin


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## ExScoobyT (Jan 6, 2004)

....yeah perhaps......but it is brought on himself a little bit......maybe....


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## tweenierob (Aug 5, 2003)

> Sorry guys, but I have to agree with Kisme here... Sure the man posts ALL the time, however it is not to be an ass


 Agreed



> He truly just wants to know the best way to protect his investment. I am sure it gets annoying to some of the people on the board, but he doesnt do it with malicious intent.


 Also agreed

However, Kisme.. when will you quit posting facts that are in fact not facts 

You post saying that the best place is in the elbows, then whe you are questioned on it you get all confused and post that it is after the intercooler.
Maybe it was in jest, but it doesnt come across like that.

Do you want to learn or teach? By teach, i dont mean teach us how to blow an engine up 

Just to finish my little speach  Kisme, post up your legendary Ignition map that you did and i'll let you know if it is truly worth keep posting that it is great  I'm not the god of mapping but i am sure you may learn something.

Rob


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## kismetcapitan (Nov 25, 2005)

I do ask a billion questions, some of them idiotic. This little quote was meant in pure acerbic sarcasm though:

"oh really? I thought the turbo elbows were in the intake, after the intercooler, _*but before the air filter*_. Thank you for clarifying that."

I was trying to clarify the 5-10cm statement that ExScoob posted - just trying to summarize engineering-ese into plain and stupid english I might have a chance of understanding. In addition, being American, I have very little sense of what a centimeter is by mental visualization. I can tell drill bits by feel to the 16th of an inch, I know without feeler gauges if the string height on one of my guitars is off by 1/128", but I know **** all about millimeters or whatever. So 10cm? How far is that from the exhaust valves? Without a ruler and not standing right next to my engine, I threw out a guess - turbo elbow?

If I came across as knowing anything on this thread, that was wrong - I needed to know exact EGT probe placement, I asked, and was just trying to ferret it out from the static in subsequent posts.

Once I can access my Power FC, I will, at risk of what little reputation I may have, post my ignition and my fueling maps, via excel so everyone, datalogit-equipped or not, can take a look and either laugh their asses off or say "well, that wasn't too far off the mark" (hopefully the latter). I don't claim for a second that either map were truly expert quality maps - hence the Jap I'm flying in for the mapping session.

I don't care how much of an ass I may look, so long as I do come away at least a bit more knowledgable. I don't want just a fast car. I want to know how to BUILD a fast car. Kind of the same thing, but not. For example, I'm a professional guitarist, but I refuse to hire techs to set up my guitars, and there is very little I can't do with a guitar or a guitar rig, electronic or woodworking wise. No one touches my guitars or amp rig when I'm setting up for a gig. To me, that's part of being a guitarist. Now that I've taken up driving, well, the mechanical part naturally follows by analogy - and a Skyline is rather more complex than an electric guitar or a rackful of amp gear.

questions like this: "at what AFR are in-cylinder temps maximized (measured indirectly through EGT), and wouldn't it be smart to avoid that AFR at highway cruising points on the fuelling map?" - are these sensible? I am aware that ignition timing is also a factor here, perhaps making a pat answer to said question difficult, if not impossible...


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## Rain (Apr 8, 2006)

I would have found it funnier if the original author of the post never even got an answer. glad he did. Kismet your a thread pirate ARRRGGG


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## roadie (Feb 6, 2006)

There is no denying the man loves his car.....:thumbsup: 
And that's what this website is all about.


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## r33 v-spec (May 24, 2002)

Sorry for the hijack, but still on topic; where is the EGT probe(s) mounted on the R34 for use by the MFD?


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## kismetcapitan (Nov 25, 2005)

r33 v-spec said:


> Sorry for the hijack, but still on topic; where is the EGT probe(s) mounted on the R34 for use by the MFD?


I think that's an incredibly germane question - where did Nissan see fit to stick their EGT? My original game plan was to install mine where the R34 takes its readings for the MFD. A friend with a R34 M-spec Nur says he backs off when the MFD reads 900 degrees. But 900 degrees where? Pre or post turbo??


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## r33 v-spec (May 24, 2002)

Well i've yet to see 900, but knowing where the sensor is located would put my mind at rest


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## kismetcapitan (Nov 25, 2005)

so this is where the EGT bung will be welded in - will it compromise structural integrity of the exhaust manifold? According to the Apexi install guide, the tip of the probe extends in a few millimeters. Boy, hope that tip doesn't ever break off....

ah, and with the head shield in place, the probe will have to go in sideways.


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## tweenierob (Aug 5, 2003)

Something else worth considering, what thickness is the EGT probe?

Turbines dont like stray EGT probes.

Rob


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## kismetcapitan (Nov 25, 2005)

tweenierob said:


> Something else worth considering, what thickness is the EGT probe?
> 
> Turbines dont like stray EGT probes.
> 
> Rob


It's very thin (Apexi probe) and the tip breaking off was a point of concern today. Spent a fair amount of time discussing with my builders on whether to weld the bung in the spot indicated above (for accurate - read: real-time readings), or immediately after the turbine at the top of the turbo elbow (for worry-free location). If I were absolutely sure the probe would never weaken and break off, then it'd go into the manifold. But nothing's ever 100% sure in this game, is it?

So for now...nothing drilled yet.


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## tweenierob (Aug 5, 2003)

1mm sensor?

Rob


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## ExScoobyT (Jan 6, 2004)

3mm sensor minimum for permanent install.

R33 has sensor in the cat-pipe, R34 just after turbo (I think)


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## tweenierob (Aug 5, 2003)

R33 sensor not Cat on fire sensor?

Rob


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## MIKEGTR (Jul 8, 2005)

I seem to be quoting lots of old proverbs today but has anyone ever heard this....


"A little bit of knowledge is a dangerous thing"


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## ExScoobyT (Jan 6, 2004)

Rob - yes R33 uses it for cat temp warning.


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## Neal (Dec 10, 2005)

sorry for digging this up but did anyone ever find out where the r34 places its probe? someone suggest just afetr the turbo... so there are 2 in the r34? does it take an avg or something when it displays a number in the cockpit?


I've got a seperate issue where my cat temp sensor warning light in my r32 is going off everytime when my egt approaches 500 yes mine is in the downpipe where they all meet up (wrong place according to some but i tend to believe in looking at the delta... normal op versus under boost as an indicator, and this way i dont miss any temp variance from any cylinder with the use of one sensor), the cat temp warning light in my R32 is consistently going off when my egt goes + 500... 

i may relocate the EGT, if i do id like to do it in the same spot as the R34...


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## kismetcapitan (Nov 25, 2005)

I'm pretty sure the R34 temp probe is immediately after the turbo. Mine is in the rear elbow - 4,5,6 run hotter and are more likely to fail than 1,2,3. Since my temp probe is a thin one, I decided not to risk putting it before the turbo in the exhaust manifold. If the turbo is cold, and your EGT is very hot, there could be as much as 200 degrees difference between pre and post turbo. EGT of 1100 degrees means bad things are happening. So my warning lamp is set to 900.

I've never seen an EGT over 750, but I don't hold sustained WOT for more than 10-15 seconds. In a Skyline in Seoul, you've run out of road at that point.


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## Neal (Dec 10, 2005)

so you're only running one sensor reading 4 5 and 6? ...

the only thing i fear with that is what if one of your injectors go on 1 2 or 3?

and is there anything else besides it being to hot that would trigger the "cat warning temp light"?.. at 500C even plus minus 300 degrees C that would be 800C that seems a little low for a temp warning... but then again running to hot = running lean so im not taking the warning light lightly... im thinking maybe injectors?


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## kismetcapitan (Nov 25, 2005)

if I lose an injector I'll hear the misfire, see my wideband go lean, and seeing fuel pressure being normal, I'll know it's an injector.

You don't have a Power FC, do you?


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## Neal (Dec 10, 2005)

no, no power fc yet *sniff*


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## canman (Jul 7, 2001)

R34's only got one sensor. Recently changed from twins to a big single turbo and we didn't hook the sensor up so no reading. If there was multiples i'd still have been getting a reading .........

We mounted mine just after the turbo as I think that was where the factory one came from.


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## turbo gav (May 26, 2007)

kismetcapitan said:


> if I lose an injector I'll hear the misfire, see my wideband go lean, and seeing fuel pressure being normal, I'll know it's an injector.


:smokin: :smokin: :smokin: Now that made me laugh!


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## kismetcapitan (Nov 25, 2005)

wideband's a godsend. if I misfire and see it go rich, it's either the ignition failing, or an airleak causing the cylinders to flood with fuel. My fuel pressure gauge also let me know a pump failed, although the symptoms were just like a lean misfire situation.


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## turbo gav (May 26, 2007)

kismetcapitan said:


> wideband's a godsend. if I misfire and see it go rich, it's either the ignition failing, or an airleak causing the cylinders to flood with fuel. My fuel pressure gauge also let me know a pump failed, although the symptoms were just like a lean misfire situation.


After some testing myself where do you take your w/b readings from? I use a uego in the decat for my dash gauge and use the LM1 with venturi clamp in tailpipe whilst tuning..... big differences! 
After mapping myself i was very pleased with the results and the nurburgring was a very good test for the car, i will look forward to future modifications so much more now:smokin:


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## kismetcapitan (Nov 25, 2005)

interesting - I have an NTK UEGO mounted just before the decat, and after calibration it read spot on with the tailpipe-mounted unit when I last dynoed in February. Anyhoo, I need to start up water injection, see if it cools my EGTs. I could always advance ignition, but I've got knock where I want it (non-existent) and don't want to have any pinking at all.


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## scoooby slayer (Jun 13, 2009)

ive just read all of this on my old cossie my egt probe was in the downpipe 5 inches after the turbo and i saw 950c dozens of times but never had an engine / turbo failure in 5k miles of hard abuse !


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