EGT probes Mounted post Turbo?

[Kieran]

...As the title suggests really.

Basically I want to get 1 (or two) EGT sensors hooked up in preparation for my MAP ECU. I know for best results one should place them on the Exhaust manifolds pre-turbo, however that involves drilling the manifolds and that's a bit too scary./pan

However, I can whip off the Pro-Shop downpipes relatively easily and put a sensor in there.... But will it be of any use? I'm thinking not as by the time the gas gets there it'll be difficult to tell if the exhaust valves are melting....

What say you guys? Any cunning plans for mounting the sensor if not there?

And also.... Ben/Gowf - Will one be adequate or is there a significant difference between the banks?

Thanks in advance!

[phosty]

I'm looking to install EGT's too to help the MAP2 tuning - hopefully using Wodjno's spare manifolds though to get upstream the turbos (I'm hoping it won't involve too much disassembly of the engine/exhaust system to fit them - wishfull thinking)

Which gauges/sensors are you considering?

[Turbo_Steve]

Not seen underneath: Is the lambda sensor in the manifolds or the downpipe on these?

If it's in the manifold, move it to the downpipe and put the EGT in the manifold :D

[Kieran]

It's in the downpipe Steve - Otherwise that would've been a very cunning plan!

However... The later V6 Sports had Lambdas in the manifolds.... I wonder how different they are from the VR4 ones?

[Eurospec]

Ideally, your egt probe should be pre turbo, as close to the collector as you can. That should be the hotest point.

The dissadvantage is exactly as you have realised, you have to drill the poxy manifold, which is a pita! Worse, you have to get all the drill swarf out before you start the car and it smashes into your turbine blades at the speed of light. (well maybe not quite that fast, but Mark has stolen my shark with frikin laser beams on it and i'm off on one!)

Realistically that means turbo and manifold off.

When presented with the options, all but the hardest bitten performance customers will pay to have the probes put into either the precat housings (turbo elbows) or into the downpipes as close as they can get to the precats, since is so much less work. Bit of drilling, sucky sucky $5 long time, from the hoover and if it has it remove the cat or decat pipe to blow any remaining crap out. The real nutters who want every last ounce the car can give and are prepared to roast it within 20 degrees of valve meltage will pay to get the turbos and manifolds off to put it in the right place.

When the probes are further back down the gas path, remeber they will read low, so you wont want to push the egt as high. In these circumstances you will use the guage of indicative of increase or decrease in egt, rather than out and out its 567degrees in there!

Cheers,

Ben.

[bradc]

I'm going to go with 2 egt sensors but that is because I will have two fuel pumps and it will be able to be used to see if one bank is leaning out more than the other (ie a fuel pump is dieing)

In a stock(ish) car like your one K, I'd just put a single EGT in the rear bank, it will most likely be running hotter than the front by quite a bit.

[Turbo_Steve]

brad....for lean fuelling an EGT is usually too late: the temperatures are less of a worry than the Det on cast internals. If you're worried about fuel pressure, I'd monitor AFR seperately for both sides, or fit a pair of fuel gauges with pressure warnings (I love Defi's!)


As ben has said, for ease of fitment, I'd put the EGT(s) post turbo. Then rent yourself an infrared thermometer, get the manifold hottish, and calibrate your EGT sensors accordingly.

[bradc]

Steve - my autronic measures the AFR in the stock location, about where the firewall is on the car but I was thinking that having a pair of them would help.

[Turbo_Steve]

If you're seperating out the fuel lines, I'd definitely have two: there will be discrepancies between the fuel regulators (unless they're sold as a matched pair, they never behave EXACTLY the same, the difference is usually trivial). With a pair of widebands, you could either:
Monitor both whilst mapping, and build in an injector correction map on the autronic
or
Monitor both, and feed back to the autronic for intelligent compensation, though I have to confess I have only ever done this on Motec before.

[fassi1]

I think that is the right thread to ask this question.
What EGT probe and gauge is worth buying and which ones are not worth spending a penny?
Thinking of fitting the prob post turbo for comparison purposes between petrol and LPG.

[swinks]

Defi are good ones.
The best point is no 1 cylinder exhaust manifold runner.

[fassi1]

Do you mean rear bank first cylinder from timing side?

[adaxo]

Closest to the 'hottest' one

[John TheAntique]

If you are just using it for comparison the R-Spec one is perfectly adequate.

[fassi1]

If you are just using it for comparison the R-Spec one is perfectly adequate.
Thanks John. Looks like they have plenty to choose from.

[swinks]

Do you mean rear bank first cylinder from timing side?
Cylinder #1 is... cylinder #1 if you know firing sequence :)

Cylinders in 6A13TT:
1 - 3 - 5
2 - 4 - 6
But you should know this ;)

[fassi1]

I don't get it. Fitted egt in the downpipe just after rear flange just to see the difference between lpg and petrol and needle won't move.
It's already 2 gauges and 2 sensors without success.
Probe sits 25mm in the exhaust gasses and gauge reads from 200degC.
Any idea? Im lost.
There should be at least 400degC.

[swinks]

Wrong place :)
Rear bank manifold sir.
Temperature drop post turbo is huge in vr4.

[fassi1]

Even under boost below 200deg C?

[fassi1]

Tested both sensors with gas torch (red hot) and gauge needle didn't move :o