EGT thermocouple placement on a header

[truckinwagen]

hey all, I am planning on running a 4-2-1 header on my supercharged motor.
I want to keep track of EGT's, and even have a controller to turn on my water/meth sprayer when the EGT's get too high, but I have a question about where to put the thermocouple.

the header I will be using does not merge until under the car, behind where the Cat would be on a gas car.
should I put the thermocouple there or up next to the head in one of the primary tubes.

would it be better to wrap the header in heat wrap and measure EGT where the exhaust streams come together, or as close to the head as I can and only read one cylinder's temp.

-Owen

[rabbitman]

I think reading only one cylinder's temp will slow the gauge down a bit due to the time between firing, it may not make much difference though.

I've read on here that the "toilet bowl" stye of manifold actually flows better than the 4-2-1.
The restriction with the toilet style is in the downpipe, some people have modified the toilet part with a bigger pipe all the way back and got very good results. The exhaust is still devided until it gets to the DP though, but it comes together closer to the head than a 4-2-1.

[truckinwagen]

the 4-2-1 that I am using is a TT race designed one, it is supposed to flow much better than any stock exhaust.

I might just heatwrap it and put the thermocouple in the merge where the O2 sensor would go.

-Owen

[VelocityConservation]

How quickly are you merging the 4 into 2?

I think you would get better data from a sensor in the first 12-14 inches of the collector than downstream under the car.

If that means you put it in one header tube from a single cylinder then choose either #2 or #3 they tend to be hotter.

VelocityConservation

[truckinwagen]

they merge to two fairly quickly, within 8 inches of the head.

the merge to one is way under the car.
as for 2 and 3 being hotter, I am using a gasser manifold that should distribute boost better across all the cylinders, so that should be less of an issue.

[VelocityConservation]

With that being the case I would either put one EGT probe in each where they collect from singles into duals.   Or just put one EGT probe in which ever collector you had more space around.

VelocityConservation

[truckinwagen]

I would do one in each, but the build has a budget, will probably and up doing the drivers side one.

[Rabbit on Roids]

wrap it and put it down low where it merges into one. thats what i would do. or get it cer. coated then wrap it.