1badFB

iTrader: (1)

Ok, so as some of you may know I have been experimenting with the stock 12a intake manifold, over the winter I nixed all the emmissions junk, and while I was at it removed the shutter valve, and matched/scuffed the walls of the runners.

I definately noticed a difference, but lately Ive become a bit more concerned about it.

I dont have an wideband, or pyrometer...so basically I have no idea if everything is how it should be, but something told me to get out my infrared thermometer and check the header pipe temps.


I found that the front rotor is acheiving noticably higher temps than the rear rotor.

After a normal drive, the temps are as follows:

Front rotor- 1" from housing - 695 F Rear rotor- 1" from housing - 430 F


Then, after romping around a bit:

Front rotor - 1" from housing - 730 F Rear rotor - 1" from housing - 450 F


Now, since I removed the shutter valve the rear rotor has quite been opened up quite a bit. I am hoping that the rear rotor is running a bit rich, rather than the front rotor running lean.
Is there anyway short of getting a wideband that would let me know if my engine is fine?
If this is a sign of running lean, I would really like to know about it now before anything bad happens.


I have a feeling that the rear is just running a bit rich, but Id like to confirm that thought. Can anyone give me any insight into this matter?

Is 730 degrees F on the outside of a header a sign of running lean....(I really think its not, since people say they get their headers red hot).

Thanks in advance for any info you can provide.
-Alex Brett

David Dewhurst

iTrader: (2)

My 2 cents worth. If you don't have an EGT in each header tube or use a single EGT probe in one tube then the other you might never know. An o2 sensor may be fooled if one tube is high & the other tube is low. You'll get an average temp. For starters compare the leading plugs from each cylinder. I dought the shutter valve removal has had any impact.