Finally installed my 4" exhaust this weekend. EGT's still reach 1150 unloaded on 40 hp tow safe mode if I stand on it going up a slight grade. If I run the 80 hp economy mode I can definitely put it over 1200. Everything I've been reading says that I shouldn't be able to get these numbers unloaded with the mods I have. Is this because of the larger injectors on a CA truck or am I missing something? Any help is greatly appreciated, aloha.

 

Your pyrometer could be broke. Maybe?

jimbo

 

Hey thanks for the reply jimkidd. A couple of months ago I had a problem with my pyrometer. Had it replaced and verified readings on the new vs. old with a infrared temp gun, new gauge was reading approx. 50 degrees higher than gun. I have always been able to pull these kind of numbers when I had my 3.5" straight pipe, but I thought that maybe the reason for those numbers were because of the smaller exhaust. They have come down since the 4" (about a 100 degrees less), but not as much as expected. Thanks again, aloha.

 

Going to 4" won't stop the EGT from climbing thru the roof, just let's it take a couple seconds longer. I can still hit 1200, but I've noticed that on the same hill with the same load at the same speed, the temp is about 50-75 degrees less.

 

Yeah DaBigTow, I did notice that temps don't seem to climb up as quickly with the 4". I just thought, from reading various post here, that if you have a 4" you pretty much couldn't get those kind of numbers unloaded. It's OK, I still love my truck and the way it runs, and the 4" is much nicer sounding than the 3.5" straight pipe I had (I don't wake the neighbors), aloha.