RPM and MPH

[Rico001]

we just did a 4 day round trip from Panama City FL to New Orleans LA the miles were about 330 both ways not including what we drove around town.

Without using calculators and math, I notice that on the way to New Orleans I used the cruise control on the way over when the truck approached a small incline the cruise control made the transmission down shift and what also seemed like a 3/4 throttle opening and it held these settings fro about 30 seconds or longer after cresting the hill. The engine had a load droning noise like it is under a heavy load while this is happening and it sounded the same when on level ground plus the trans temp stayed at 3/4 hot.
I noticed with cruise control the RPMs were at 3500 and the speed was 75mph. We only made it to Ocean Springs Mississippi. We filled up and went on to New Orleans, we left after 4 days of city driving and filled up and went back home but this time I did not use cruise control. even after driving in bumper to bumper rush hour traffic on the way home we were able to make it all the way home and with over 1/4 tank of gas. With me doing the "driving" the engine ran at 2500 RPM but we were going 82 MPH and I did not need 3/4 to full throttle shifts to go over a hill and the trans temp only went up 1/4 way up the gauge.

Just my thoughts here and nothing scientific here and wonder if others had noticed anything like this with there HUMMER too.~Richard

[jsbihn]

Richard,
Wish I would have known you were coming through.... could have stopped and had a coffee, you actually stopped in my town (Ocean Springs) to get gas.


Ok with that said, I have wondered the same about my rig. Many times there are little hills and what not I drive back and forth to work and when it tries to get up over then if shifts and drives hard and I am thinking damn there goes half a tank of gas to get up over that hill.

I might try seeing if I can get better results over the next week by not CC'ing it to work.

I will let you know

[PaHumBug]

cruise control is not fuel efficient at all. It tries to hold off on shifting for as long as possible, but also tries to maintain the exact speed. Driving with your foot allows you to gain momentum before you hit the hill, and you can keep it from shifting, and if you lose a MPH or two that's OK. But cruise will maintain the speed approaching the hill, then floor it to keep you at the exact speed, and it won't shift up until it's certain it's over the hill. Our 4 speeds have a lot of room between gears so it's a neck jerker when it down shifts with lots of RPM. I always wished I had the new 6 speed tranny with closer gears.

[jsbihn]

Did I read somewhere that for our 4 speeds just dropping in a 6 speed isnt an option.... the whole truck would have to be reworked and reprogrammed?

[Rico001]

Originally Posted by jsbihn

Richard,
Wish I would have known you were coming through.... could have stopped and had a coffee, you actually stopped in my town (Ocean Springs) to get gas.


Ok with that said, I have wondered the same about my rig. Many times there are little hills and what not I drive back and forth to work and when it tries to get up over then if shifts and drives hard and I am thinking damn there goes half a tank of gas to get up over that hill.

I might try seeing if I can get better results over the next week by not CC'ing it to work.

I will let you know

We never plan much for our vacations just make reservations and gas the truck up and go.
We actually ate at a BBQ place one town east of Ocean Spring and I wanted to kick my ass for not going to The Shed if I knew we were that close, it had to be better than the place I went to and as usual the gas was cheaper 1/2 mile down the road too.
If we go back any time soon I will drop you a line first ~Richard

[jsbihn]

Originally Posted by Rico001

We never plan much for our vacations just make reservations and gas the truck up and go.
We actually ate at a BBQ place one town east of Ocean Spring and I wanted to kick my ass for not going to The Shed if I knew we were that close, it had to be better than the place I went to and as usual the gas was cheaper 1/2 mile down the road too.
If we go back any time soon I will drop you a line first ~Richard

Ok you came to O.S. and didnt go to The Shed?

Bad Richard!

Where did you end up eatting at?

As for the gas.... well there are two places in O.S. that are about the cheapest... Funny thing is they are cheaper here then Sam's Club in Mobile.

And in regards to vacations.... well I tend to plan... the issue is that even though my vacations dont cost alot (usually go on cruises - which are AWESOME!!!).... its hard to commit or know that I can get away that far off. (I dont have a job where you can "put in" for vacation time)