Pyro Location

[RSchwarzli]

How much of a differance in temperature is there between the front port and the rear port of the exhaust manifold?



My quation is in regards to the fact that I have my probe in the rear, but now that I am going to twins, that requires flipping the manifold upsidedown, thus putting my probe in the front port. I am just trying to see if it is worth re-drilling a new hole in the rear if the temps are that different, or to just leave it as is.



If it helps it is a ATS manifold.



Any thoughts?



Robert

 

[Makaio]

Robert,



The rear 3 cylinders run hotter, making rear placement of the probe a preference.



Aloha,

Matt

 

[JGrefenstette]

yea i agree with matt. if i were you i would go ahead a redrill/tap. because your rear 3 will run hotter, it would give you a more usefull reading to moniter their temps. that way you can know you wont need to add any degrees to estimate your actual average temp. you can just know your getting the hottest reading. you could leave the probe up front, but i would just add a few degrees to the reading... this is just off the top of my head, but i think the difference is somewhere between 50*-100*... . anybody else know otherwise?

 

[DValentine]

Not to jack the thread, but tell me more about the back three running hotter. I can see the first cylinder running cooler because of the water pump, as on a gas six banger. Are you saying that the back three are hotter because of the coolant water flow pattern?

DV

 

[JGrefenstette]

well actually, this is what i understand from people ive talked to and stuff ive read. that the #1 cylinder on the VE 12valves actually run the hottest! yea it didnt make sense to me either, but it has somthing to do with the fuel flow and it getting more than the rest, or somthing along those lines. but the back 3 as an average do run hotter still for other reasons. on the 2nd gens, its because they are under the firewall and have very restricted air flow... (im not 100% sure about the science behind all this, just what ive heard and read). but im honestly not really sure why the rear 3 run hotter on a 1st gen.

 

[cerberusiam]

Cylinder #1 tends to run hotter due to the fact the airflow to it is really choked so you getter hotter combustion temps. Cylinder #6 runs hot due to the distance from the water pump and the circulation of water is soaking heat all the way thru the engine. In addition, #6 has a slightly restricted coolant flow due to block design and being at the end and a tight turn on the air intake.



Due #6 having mutiple conditions contributing it tends to heat soak more and faster and that is what causes most of the scuffed cylinders and other problems.





Thats my sttttory and I'm stickin' to it! :-laf

 

[JGrefenstette]

ah yess! thank you... that is exactly what i didnt fully understand and was attempting to explain :-laf

 

[RSchwarzli]

About 100* huh?



I guess I will re-drill... .



Robert

 

[cerberusiam]

About 100* huh?



I guess I will re-drill... .



Robert

FYI, the tests I have seen say anywhere from 100-300 degree difference from front to rear depending on how hard you run it.