My wife and I decided to drive up to Aspen and go via the 12,095 foot Independance Pass on Route 82 in Colorado. Lots of winding turns on the steep climb up the pass and I found myself shifting at 7,000 rpm and cruising typically at 4,000 rpm in 2nd and 3rd gears. I did hit the 8000 rpm buzzer a couple of times passing slower cars but that is another story.

When it as all said and done, I averaged 23 mpg during the 320 mile round trip. What I don't get is that I never got this good mileage driving 55 mph for a 1000 mile trip from Minnesota last Februrary. I was amazed by the good fuel economy. I do run 8 oz of two stroke oil per tank (OMP is functional) and did not run A/C-not needed at the higher elevations.

The only problems I had during the trip were minor:

I got a check engine light when descending downhill from the 12,085 foot pass. I was in third gear with no throttle applied and the CEL came but disappeared as soon as I applied throttle. It never reappeared. Also, I think my charcoal canister is not working. We had to stop and loosen up the gas cap to let it vent because e smelled a lot of fuel (no, not the fuel dampener). The rise in altitude caused the air in the gas tank to expand and overwhelm the evaporative emission system on the car. I left it loose the entire way.

I did get smoked pretty bad climbing back up the pass. The first time a 1965 Shelby Cobra passed me and everything in sight. At first I thought it as a replica Shelby but changed my mine when soon after I was passed by 4 cars racing up the pass: A Lotus, A Lamborghini, A Ferrari, and a Porsche. Looks like the Aspen wealthy were doing their best to kill the many bikers on the road.

 

the higher the altitude the less gas you need.

 

The higher the altitude the less air there is, the AFR should stay the same with EFI.

 

Yes, the reduced O2 in the atmosphere means that the ECU compensates by injecting less fuel but still maintaining the same air/fuel ratio. That also means LESS POWER which required the higher RPMs. I doubt that there is a fuel economy savings when you consider that the altitude requires higher rev's to get and keep the car moving.

I can't wait for 2008 to come around. That is the year that my cherry Vert (25,000 miles on it) is getting a major engine upgrade. I'm thinking LS1 or maybe the new LS7 (7.0 Liters/427 cubic inches 700 hp at 6200 rpm. It also benches 475 lb.-ft. of torque at 4800 rpm.) I think my 13B would be perfect for my lawnmower. This upgrade should give me plenty of reserve power when climbing mountains without having to work the engine overly hard.

 

Yea thats exactly my point. If the there is less air,to keep same afr's you need less gas.

 

As hard as I was driving the car with of high throttle high rev driving, the engine ran great and the temperature guage didn't move one bit and stayed steady the entire time.

I did love taking some of those switchback turns at the faster than recommended speeds which allowed me to shake many tailgators. I almost forgot but I did have 5 gallons of contaminated fuel in her that was topped off with 85 octane fuel. A buddy of mine accidently fueled his diesel with gasoline and I drained the fuel and kept it for myself. I put 10 gallons of the gasoline/diesel mixture (about 10:1 ratio) in my wife's Ford and the remaining 5 gallons into my TDI. Ran like a champ with no detonation/preignition issues.

 

youre talking round trip.

going downhill you dont often need to use the accelerator. with no pressure on the pedal, the injectors are off, which means no fuel is being used. the downhill trip likely influedned your MPG rating for the better. I get the same result when going up to my local resort to go mountain biking.

 

Jono,
Are you saying that NO fuel is injected when coasting in gear? I find that interesting.

 

the engine wont start injecting fuel with your foot off the pedel until it returns back to idle speeds.

 

I always get better gas mileage when I drive a little more on the aggressive side. My best MPG yet was in the 3800-4500 range on my way from Ohio to NY.

 

hah, i got 9mph when i drove in the 4k-6k range. Damn secondaries.........

 

Hard to be out of boost in that range though with a TII.

 

haha....i have a heavy foot, and the secondaries dont have anything conrtolling them....

 

man that must have been awesome

 

That isnt bad at all. Right now im getting 18.75mpg (avg by tank, avg fill 12-12.5gal)

However that is in my 13b-re, t04s and wolf3d.. there are still alot of medium vac area's that see 12:1 < afrs, so i expect to make 20+mpg easliy