EGR Delete - Will I benefit?

[L31MaxExpress]

Don't forget less air for a box on wheels to cut through too. I25 from Colorado Springs to Denver and back is also a magical stretch of road. I averaged 31mpg there and back once in the Z06. Everything I drive there and back gets weirdly good mpgs.

I was definitely surprised. I went 285 and 160 across the mountains from Denver to Pagosa springs. It felt like the engine was really working hard, but evidently it was just from the torque loss of being in the thinner air. I filled up right as I was leaving Denver and did not have to get fuel again until I was in New Mexico on my way home. I managanged an almost freakishly good 25 mpg that tank. I thought the dash MPG display was lying its butt off, but hand calculating it, was nearly spot on. I filled up in northern New Mexico and made it almost to Lubock on that tank and even running 75-80 mph at times still managed 22.2 mpg.

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[L31MaxExpress]

I feel like air density is the biggest factor. At 10,000 ft, the air density is like 70% of sea level. Thus that 4.0L was only drawing in 2.8Ls worth of air. I do not see how lean cruise could possibly give the same effect on an engine that is already down on power because in effect it is way down on displacement. I also knew the air density was substantially lower and when I filled up in Amarillo on my way out of Texas, started using 85 octane rather than the normal 91+. On that trip I realized how you are able to get away with the advance curve you use on your L31 without spark knock.

 

[L31MaxExpress]

The interesting thing I found too, has to do with engine management systems based off torque demand for throttle by wire. Nissan uses a similar method of throttle mapping ro a newer E78 or E90 GM PCM. The throttle is mapped by driver driver torque demand. The ECU and TCU try to maintain torque delivery for a given throttle input. At altitude that meant the engine and transmission would rev willingly and hold gears longer as well as downshift more easily. At 1/2 pedal it would rev 3,500-4K with willingness to climb grades and pass. First time I have driven anything with torque demand throttle/transmission mapping at that kind of elevation. It was interesting not having the typical dead pedal throttle response something drive by cable has at elevation. Last time I was at that kind of elevation was in the 1997 Express when it still had the 350 in it. Felt like I needed a 102mm throttle body to give it any off-idle throttle response. Boost would be a necessary thing if I lived up there.