RPM at freeway speed?

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Originally Posted By: A_Harman
My '02 Camaro turns 1400 rpm at 65 mph in 6th gear. I don't know what fuel economy it gets there because I've never had the patience to find out. My normal cruising speed is 77 mph, where it gets 26 mpg.

My '01 Dodge turns 1650 rpm at 65 mph in 5th+OD. Likewise, I don't know the fuel economy at 65 mph. It gets 20-21 at 77 mph.


thats about where my 97 SS Camaro was at but I got around 30mpg at 70ish mph
 
05 dodge ram diesel 2K rpm at 75mph
14 dodge durango 2k rpm at 75mph

15 Polaris RZR 8k rpm at 70mph.... top speed is 70mph, for now....
 
Which begs the question, is there any connection to rpms and engine life? Considering how long some of these high revving Honda's last it doesn't look that way. Although common sense could dictate otherwise.
 
Originally Posted By: demarpaint
Which begs the question, is there any connection to rpms and engine life? Considering how long some of these high revving Honda's last it doesn't look that way. Although common sense could dictate otherwise.


Cylinder pressure vs ring material/cylinder hardness and ring tension/thickness has more to do with bore wear than engine speed in my experience. A small engine with lower cylinder pressure at higher rpm with less load experiences less wear than the same engine at high load and cylinder pressure at lower rpm.
 
Originally Posted By: demarpaint
Which begs the question, is there any connection to rpms and engine life? Considering how long some of these high revving Honda's last it doesn't look that way. Although common sense could dictate otherwise.


I think rod angle. A longer rod, shorter stroke less rod angle and less side loading of the piston.
 
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My 2002 F-150 4.6 5 sp manual would get 13-16 mpg no matter how it was driven. My 1996 2.0L Zetec 5 sp manual Contour averages 34 mpg at speeds ranging between 70-85 mph. If I keep under 80 I usually get 35-37 mpg.

Whimsey
 
I don't regularly drive 65mph do don't know offhand, but do know the 70mph figures.

The MKZ is 2200rpms at 70
The LS is 1900 at 70
The MG is 3800. I know that number well as I drove it for over a year without a speedometer
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The LS is the heaviest of the three, but also has the largest displacement engine(and the most cylinders)

The MG is so high because 4th gear is 1:1 and I don't have O/D(I'm working on that). Also, as mentioned above, it's sort of "ideal" for sustained high RPM action since it's a typical small bore, long stroke British pushrod 4. It's happy to run at 4K all day.
 
Originally Posted By: bunnspecial

The MG is so high because 4th gear is 1:1 Also, as mentioned above, it's sort of "ideal" for sustained high RPM action since it's a typical small bore, long stroke British pushrod 4. It's happy to run at 4K all day.


This was universally normal...it's hard to tell with all indirect gearboxes, but in rear wheel drive boxes, 4th gear is normally direct, 5th overdrive. Motorcycles still run these sort of ratios, so like the MG, they are always ''in the zone'', and the higher rev limits give higher top speeds than cars.

My Volvo does about 2,400rpm, my motorcycle about 4,500rpm at those speeds.
 
Originally Posted By: bbhero
Look at that big ol whomping snorkel
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Primed and ready for the real deal outback adventure.

Oneyejack my Altima runs at 2400 rpm at 79 mph. This is my cruising speed on the interstate where 70 is posted. I pass many, many state troopers and they have all let me keep on rolling. In fact on July 4th weekend a couple of years ago I passed one state trooper in their car in the median. I was going my typical 79 mph. Less than two miles down the road another state trooper was out of his car holding a radar gun and I was going 78-79 mph. No problem noted.

I will say for all my friends on here... DO NOT go over 80 mph on Interstate 295 near Hopewell VA. The local police officers from Hopewell sit in that 1 mile stretch of I Interstate all the time. In fact that part of 295 has the nickname the "million dollar mile". Hopewell made 1 million dollars worth of tickets on that part of 295. They will let you go up to 80. If you go 81 and over then you will get a ticket. In fact yesterday I saw someone pulled over in that stretch of 295.


Virginia is notorious on every Interstate to be ticket happy for a fraction over the limit, the slowest pasrt of our yearly journey from CT to FL !

07 DMAX - 1600rpm @ 65 18-20 hwy, maybe 22 if the wind is right !
04 Aveo - 3000+ @ 65 not done often / 2000 rpm round town 28-33 mpg
 
At 65?
My GSW 5sp stick sits around 2k rpms and returns well over 40 mpg.
All of my previous rides were 4cyl stick shifts, but had much higher freeway rpms and didn't get as good of mileage. They were n/a though, and needed to rev for power.
 
Originally Posted By: Srt20
05 dodge ram diesel 2K rpm at 75mph


What transmission and rear gear do you have in that?
 
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