EGT probe on RS2 manifold

[adam g]

Hi, has anyone fit an exhaust temp sensor on an RS2 manifold. I'm struggling to find anywhere to tap one in that won't make a nice week spot for crack propogation. I'm advised they should be fit before the turbo for a good reading.

[Jamo]

Be easier to put it after the turbo and then compensate your reading be 100c accordingly.

I wouldn't fancy tapping the manifold, most people have done the turbo hotside housing.

[A80Avant]

yes i have done the turbo hotside but i will put a new tap just after the turbo on the downpipe for 2 reasons.

1) safer(no probe particles can come into the turbine wheel in case that ever happens)
2) initially i will be able to see the EGT difference between the 2 logs so that i can actually see what is the '100C' . Is it actually that or is it less? more?

[GazzaG60]

if possible tap the runner farest from the throttle body. this is usually the leanest as airflow to here is greatest.

i did this on my 16vt but that was tubular. i have mine aqbout 2 inches after the turbo exit. i run wrap on the tubular and have a hotside jacket so the heat is carried through somewhat more than a non wrapped item.

i see no more than 730c or so. ive seen race engine subarus run upto the 900 or so mark. that was with the probe in the manifold just after the port exit on the manifold.

[Jamo]

yes i have done the turbo hotside but i will put a new tap just after the turbo on the downpipe for 2 reasons.

1) safer(no probe particles can come into the turbine wheel in case that ever happens)
2) initially i will be able to see the EGT difference between the 2 logs so that i can actually see what is the '100C' . Is it actually that or is it less? more?

After the turbo 100c less is measured is the rational of tuners.

[A80Avant]

yes i know.I go by that as well but since i will change my turbo at some point and will have the chance to test it...why not?

[GazzaG60]

i would have thought 100 degrees is a lot to dispurse in 2 inch of pipe. im not arguing though.
what needs to be taken into consideratino is how long the runners on the manifold are, whether it is wrapped or not. is a turbo blanket used and is the downpipe wrapped.

i feel what we are trying to do is.

1. keep the temps down inside the engine.
2. keep them from being too high in the turbo.

now the wrap keeps the temp up but helps speed the exit of the gases which in turn helps spool slightly and reduces pressure.

i have however seen it the oposite way where the wrap is replaced with gold foil to remove heat from the exhaust to keep egt at the turbo lower. thats on the super high ho apps though and im sure has other factors that influence.

i understand why they want to take the temp out but am unsure as to if we are robbing peter to give to paul so to speak. surely the engine is mighty hot to need to lower egt at the turbo.

is there a big margin between turbo heat limit and an alloy head?

[adam g]

Tapping it after the turbo and correcting by 100 degrees sounds a bit generic but could be a rule of thumb if its been tried and tested. I want it to assist with engine mapping my timing, rather than checking how quickly heat is dissipated so it needs to be pretty accurate. I might try and tap into the furtherst runner instead, that sound plausible for the worst case condition.

[GazzaG60]

either way you you should see a decrease in egt as you add timing.

EGT can be a pain to meansure accuratly. the incremements are tiny and a couple of mm extra in the exhaust can alter egt quite condsiderably.

the bast place is as close to the port as possible on the leanest pot. in practice the easiers place is after the turbo.

mine is after the turbo. its a slightly bigger probe designed for FI. if you put it there on a factory map you can use that as a rule of thumb. i try to keep temps below 750c on mine. expect high temps on crusie as you are running a lean burn, thats the idea. fuel is a good cooler but timing has the biggest affect.