Higher EGT with 4 inch exhaust?

[FBJR]

I installed the Recon gauge kit and my temps at idle were around 250* as the instructions said they would be.

This was with an MBRP cat back 4 inch SS cat back exhaust.

Added the turbo back pipe and temps are in the 350 range at idle now and the running temps seem to be just where they were or a little more.

I am totally confused with this as common sense and everything else said it would be lower with less back pressure. I do love the sound though!!!

Any ideas?

[Mark Rinker]

Hmmm. Interesting. Here is my theory...

Less back pressure = slower turbine RPMs at idle = lower flow of air in proportion to fuel at idle = slightly more unburned fuel in your exhaust at idle = slightly higher EGTs at idle.

Once you are into the power band, with the turbo spooled up, your burn is 'more normal'. Now you have the capacity to flow more exhaust, so turn up the boost levels in relation to fuel and watch the EGTs drop.

[FBJR]

At least it makes sense to someone. I do have more of a diesel smell now and like it :D

[More Power]

I've noticed a somewhat different exhaust temp, depending on conditions. For example, I see a little higher exhaust temps when the engine & trans are cold - while driving. Plus the newer engines with the VNT turbo see different turbo action with a cold engine - to produce faster warmups. This will also affect idle EGT.

Is the higher idle EGT present when the engine is both warm & cold, and is this temperature repeatable? How many times do you remember seeing 250 at idle?

Jim