Hi to all,

I'm driving a MY00, Sti panel air filter; downpipe; full de-cat exhaust system; Sti TMIC; VF28; Fuel pressure reg; std ecu (ae802) and running std boost ( 1 bar ). My country here has an ambient temp of not lower than 27 degrees C in the night, whole year round!

My question is: Does anyone know the delta T across the Turbocharger for the exhaust temp?
Reason: Unfortunately, the exhaust system on my car came along when i bought it 2nd hand and the EGT probe was installed at the downpipe which i believe is not the most representative place to be. I guess why they put it there is bcoz of the ease of installation.
I do see max of 670C on my gauge and presuming that the delta T is 100C across turbo than i would have peace of mind that I'm not running lean. ( optimum is said to be in region of 800-900C, right? )
Is anybody in the same shoe as me and has taken remedy action towards it?

Nology,

Temp drop across the turbo can be as much as 200deg C, on boost. 670 deg C is on the SAFE side, and if anything, you're probably a little "rich", not lean.

I'd aim for a max of 730deg C measured after the turbo. This will be on the safe side, although you should get a better idea if used in conjunction with an AFR meter.

Mark.

Nology

Mark as usual is correct in what he says. The temp drop across a turbo can be as much as 200 C, and it is safe to run 900 C at the turbo. However, on your boost and power output you will not be dropping this amount, 150 C max, so he is right you'll be running rich and hence safe.

Duncan

PS 27 C night temps all year round - any chance of a job so that I can emigrate! :D

Thanks for the info, Mark. You too.....Duncan.

Mark,

You were saying to use those EGT figures along with AFR....I truely agree with you but i do have a question here...

I believe the O2 sensor is of 2 or 3 wire type which means a narrow band one, right? and this type of sensor DO NOT give very accurate readings, is that true?
The reason i'm saying this is bcoz from past exp. i had a Pivot A/F ratio meter on my previous car and the signal light on the meter keeps moving from "Lean" to "Rich" all the time. I guessed the ecu is trying to achieve ideal A/F ratio of 14.7:1.

So what do you guys fix up to check on ur A/F ratio?

thanks

Any of you guys using a thermocouple as EGT sensor? If so, how are you mounting it and where? Thanks.

On cruise, or idle, you would expect to see an AFR meter hunting back and forth, as the ecu adjusts for stoich.

Narrow range lambda sensors aren't "that" bad, after all, most cars run them as standard. The main problem, is that when they get very hot, they do tend to read "lean", which is why a lot of OEM ecu's tend to switch to map, or AFM, on boost.

The less experienced tuners would tend to keep adding fuel, to compensate. Only to find that when things cool down, they're running very rich. Been there, done that :rolleyes:

The trick, is to warm the car up, and only do 2~3 test runs, before things get too hot. Then let the engine cool down, and repeat the runs.

If you had a Link, Motec, etc', you would datalog the runs, and see exactly what needed adjusting.

TRUE wide band sensors need some very trick electronics, that can compensate for temp changes. They are also BL*ODY expensive, my sensor cost about £400, on it's own :eek:

Apart from the WB sensor, that the Pectel reads, I also have a separate Bosch wide range sensor, that is much better than the stock sensor, but not much more to buy. This is read by a standard Lambda Link. Even the stock sensor works well with the LL, if used correctly.

Ideally, mount the EGT sensor just before the turbo. If it's impractical, then just after, but then you need to add circa 150~200deg C under WOT, to get a "safe" before turbo reading.

Mark.