Egt - Mpg

[jsmiracle]

I just returned from an approx. 1400 mi. trip from KY to SC and back. I averaged approx. 900F on the pyro and hand calculated an average of 11.1 mpg. I was pulling a ~9000 lb. Coachmen TT over the Appalachian Mts. BTW, I was seeing about 600F EGT downhill and about 1200F EGT up fairly steep grades. I kept speed fairly constant from 55 - 60 mph.

I hope this is helpful to MP's scatter plot.

[More Power]

A round trip last Friday of 450 miles on I-90 between MT & ID. Some legs were at 75-80 mph, and some were at 65-70. Averaged approximately 650-700 F EGT (900 going up, 300 going down, 700 on the flatter portions), and hand calculated 19.35 mpg for the trip.

Jim

[Philsauto]

I have found it is nearly impossible to maintain a constant exhaust temp unless the terrain is perfectly flat, and where do you find that?

I will try to see what exhaust temps are while not towing on the flat. Towing my trailer, I can't keep temps under 750 degrees unless I go 50-55, and even then, going up hills the temp always clears 1000 degrees. I do notice that as soon as the truck downshifts out of 5th gear, the temps start dropping even as rpm and turbo boost goes up. Does that mean I would use less fuel on a hill in a lower gear? Even in high gear my temps don't exceed 1250 degrees unless the hill is really long. I do wish I could manually select 4th gear somehow.

[DmaxMaverick]

......I do wish I could manually select 4th gear somehow.

You can. Either keep the speed under the threshold in T/H, or install an OD lockout. Just a momentary switch and a lead into the PCM connector. I think Kennedy still has the procedure on his site. If not, it's here in the forums, somewhere. If you are interested in the high idle, do them at the same time. Same procedure, different pin.

[D_R_C]

My question is did you`all install the probe pre-turbo or post turbo
Pre-turbo can/will be 200-500 + degrees higher,depending if you are empty or towing.
Compaired to post-turbo/after turbo when probe is installed on down pipe.

[jsmiracle]

I think most here have installed the pyrometer pre-turbo. Most people indicate their placement in their signatures. I know the guage faces were different depending the placement of the pyrometer. IIRC, the pre-turbo guage was color-coded about 300F higher than the post-turbo.

Jim M.

[D_R_C]

Yes I read that as well,the one`s that posted higher temps 900-1200 was pre-turbo but also several stated 600.
I have not installed a gauge on my GMC as of yet,but my last truck I monitored pre and post turbo.
Mainly to prove to a local shop that there can be more than 200 degrees difference between the two locations as most shops think.

[Basshopper]

What happens when you add a grill cover for the winter? if it adds 200 deg from lack of air flow does that raise it from 600-700 to 800-900 or do you have to slow down evenmore to achieve the same MPG without the cover. Inquiring minds just have to know

[mastertech]

it is not wise to add any covers to block air flow to the intercooler or the cooling system you can risk overheating and engine to trans damadge be careful. you can also get erratic maf sesnor reading causing injectors to not work correctly and or ses lights

[Stlheadake]

it is not wise to add any covers to block air flow to the intercooler or the cooling system you can risk overheating and engine to trans damadge be careful. you can also get erratic maf sesnor reading causing injectors to not work correctly and or ses lights

Maybe if you are driving in 'warmer' weather. Those of us that live in the areas that actually HAVE a winter, use them safely.

Adding the winter cover in cold weather shouldn't really change your egts... However I HAVE noticed that I get better fuel mileage with my cover on when the temps are in the 30s.