What is the "sweet spot" rpm for best mileage
08-14-2006, 09:50 PM
#11
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Originally Posted by It'llrun
5.3's getting 24 is hard enough to believe.
21mpg from a 6.0L? GM claims like 16 in 1/2 ton models and I don't believe 21 will happen UNLESS you're resetting the average once you get to highway speeds and only counting that. Taking into consideration the on ramps and traffic after refilling will ruin that average. I should point out, that's every bit as good as most diesels and we all know diesels are more efficient by far.
I just have to believe if these engines got anywhere near 21mpg, GM would be ALL OVER that in advertisement.
EDIT: Tuning can help and I know that. But I'm thinking of stock as opposed to modified. GM won't run it lean, fuel economy be damned. They don't wanna rebuild one on their own dime, ever.
21mpg from a 6.0L? GM claims like 16 in 1/2 ton models and I don't believe 21 will happen UNLESS you're resetting the average once you get to highway speeds and only counting that. Taking into consideration the on ramps and traffic after refilling will ruin that average. I should point out, that's every bit as good as most diesels and we all know diesels are more efficient by far.
I just have to believe if these engines got anywhere near 21mpg, GM would be ALL OVER that in advertisement.
EDIT: Tuning can help and I know that. But I'm thinking of stock as opposed to modified. GM won't run it lean, fuel economy be damned. They don't wanna rebuild one on their own dime, ever.
Since I've had it tuned back to stock, the best I can muster out is 19.0-19.5 doing the same thing.
I agree with you about once you enter traffic or exiting into the city, but I was just telling my hwy fuel mileage. I get an average of 16mpg between 40% hwy & 60% city driving.
I don't know about any of you other guys, but ever since they began placing ethanol in the gas, I've noticed an average of .5-1.0 mpg decrease in average fuel mileage. My 01' 3.8L Impala is showing similar results on it's DIC average MPG read out.
Maybe it's just me, but my driving habits have only gotten better not worse.
Jim
08-15-2006, 07:26 AM
#13
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The sweet spot for rpm isn't exactly related when you don't list a certain mph. Between 52mph and 60mph is going to be the best fuel milage the vehicle is going to get because the transmission will be in overdrive with the converter locked in, wind drag will be fairly low, and the engine rpm should be somewhat low. If you were going for actual highway speeds, the common best rpm is going to be 1800-2000rpm as long as your engine has enough nuts to push you along at that speed with that low of rpm.
08-15-2006, 02:08 PM
#14
Originally Posted by zippy
...be the best fuel milage the vehicle is going to get because the transmission will be in overdrive with the converter locked in,...
08-15-2006, 02:48 PM
#15
formerly silverbrick (changed 02/17/2013)
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are you positive about that? because what if the comverter will lock up failry low but you can stil go a little faster before you pass the threshold where your engine is spinning faster than the increased MPH is worth?
08-15-2006, 03:17 PM
#16
Originally Posted by Soon2bSpooled
are you positive about that? because what if the comverter will lock up failry low but you can stil go a little faster before you pass the threshold where your engine is spinning faster than the increased MPH is worth?
Once it locks, Any increase in speed will be an increase in rpms and therefor an increase in fuel demand. Engines run on fuel, more rpms will need more fuel.
08-15-2006, 04:46 PM
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Originally Posted by slowec
Once it locks, Any increase in speed will be an increase in rpms and therefor an increase in fuel demand. Engines run on fuel, more rpms will need more fuel.
This is pretty much what Zippy was getting at about your engine having nuts.
Jim
08-15-2006, 06:29 PM
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lol.....20mpg ill never see that...... i did get 13.5 mpg it was a 220 mile trip and i was hauling a pop-up camper and tryed to keep the speedo at about 63 mph whitch is about 1900 rpm in my truck.. 13.5 mpg is damn good i think in my truck......
08-15-2006, 06:34 PM
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Originally Posted by slowec
Once it locks, Any increase in speed will be an increase in rpms and therefor an increase in fuel demand. Engines run on fuel, more rpms will need more fuel.
