I'm nothing more than an armchair/internet tuner-mechanic guy...but every serious person taps the manifold. All the first-gen uppipes had EGT bungs...now most of them don't.

And I also think tapping #4 is becoming more important (at least on the WRX) because it seems to be the hottest running cylinder.

I mean it's a heck of a lot easier to tap the uppipe if you just want a relative measurement....but I would guess from a tuning point of view...the temperature measured in the uppipe means less than the manifold temp.

 

Ya, you're right that under the most ideal circumstance you'd want it in the manifold as close to the cylinder as possible. I always thought that #3 was the hottest and tended to run the leanest but that seems to be under some debate lately. Unless you're running at the limits of your setup and internels though I don't think that the extra 18" of pipe from the passengerside manifold to the up-pipe is going to cause a significant enough cooling of the exhaust gases (this is of course if you're bunging the #3 port though not the #4) to make that big of a difference.

But like you I'm not a professional tuner or anything and if the big boys are saying that it really makes a big difference then it probably does. For me though unless I start pushing some very serious numbers I think the up-pipe will work fine.

I've actually even heard a few different people say that you should put the EGT just after the exhaust turbine (in the DP) on a turbo setup because of the heat caused by the turbo and not in your manifold. :/ I could see this if it was a second EGT and not your primary but not if it's your only one. Has anyone else ever heard that?

 

i'm with MP on this one... #4 seems to be the problem child. put it close to the most common failure.

no up pipe cat will reduce egts about 50-100 degrees farenheit. more effecient evacuation of exhaust gasses is to blame.

jm2c
ken