bigwillxj
NAXJA Forum User
- Location
- NC State/lexington, NC
Can anyone give me an rpm reading of a 4.0/5spd with 4.56s or 4.10's at 70mph as well as a mpg for both setups?
thanks
will
thanks
will
-
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Rpm's and mpg's
- Thread starter bigwillxj
- Start date
Without a consistent tire size those numbers arent gonna mean much. I dont have a tack but with my 38's and 4.10's and ax-15 I would say Im just under 2000 RPMs at 70. Problem is it doesnt have enough balls to stay there in 5th without lugging. So Im upgrading to 5.38's Ill have a much higher rpm but the motor will be much happier.
bigwillxj
NAXJA Forum User
- Location
- NC State/lexington, NC
yea im real sorry i meant to say with a 32" tire
sidriptide
nobody of any consequence
- Location
- western massachusetts
4.0L/ AX15/ 4.56s/33s runs me around 2700 rpm around 70mph, excellent drivability. highway mileage runs me around 18 mpg, around town it is fun but drops below 15 mpg because i have a heavy foot..
RPM alone doesnt dictate fuel economy...
RPM alone doesnt dictate fuel economy...
From my site:
You can use the above chart to work out what axle ratio is needed to return you to stock gearing by finding your stock gear tooth number under the new tyre size. Below is also a guide to what revs you will have with different combinations. This is about what you will have in overdrive or forth in a auto, ( 0.75 ). Pre '91 will be slightly slower at 0.70, Peugeot ( BA-5/10 ) had a 0.72 and faster for a AX-15 manual at 0.79 or a AX-5 with 0.85.
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 28's: 2,076 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 30's: 1,938 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 31's: 1,876 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 32's: 1,817 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 33's: 1,762 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 35's: 1,661 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 28's: 2,398 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 30's: 2,238 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 31's: 2,166 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 32's: 2,099 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 33's: 2,035 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 35's: 1,919 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 28's: 2,668 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 30's: 2,490 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 31's: 2,409 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 32's: 2,334 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 33's: 2,263 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 35's: 2,134 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 28's: 2,855 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 30's: 2,664 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 31's: 2,579 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 32's: 2,498 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 33's: 2,422 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 35's: 2,284 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 30's: 1,938 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 31's: 1,876 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 32's: 1,817 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 33's: 1,762 RPM
RPM's at 65 MPH/105 KPH w/ 3.55:1 axle gears running 35's: 1,661 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 28's: 2,398 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 30's: 2,238 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 31's: 2,166 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 32's: 2,099 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 33's: 2,035 RPM
RPM's at 65 MPH/105 KPH w/ 4.10:1 axle gears running 35's: 1,919 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 28's: 2,668 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 30's: 2,490 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 31's: 2,409 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 32's: 2,334 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 33's: 2,263 RPM
RPM's at 65 MPH/105 KPH w/ 4.56:1 axle gears running 35's: 2,134 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 28's: 2,855 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 30's: 2,664 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 31's: 2,579 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 32's: 2,498 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 33's: 2,422 RPM
RPM's at 65 MPH/105 KPH w/ 4.88:1 axle gears running 35's: 2,284 RPM
Gearing for best MPG
Most people think that less revs will equal better MPG. That is not always the case as less revs can also mean more strain on the engine which causes more fuel use. According to a engine design text‚ maximum fuel economy occurs with open throttle and at a piston speed of 1200 – 1500 ft/min. So if you know the stroke of your engine‚ you can calculate the rpm for best fuel economy. Usually comes out somewhere between 2000 – 3000 rpm. Dino provided me with the following numbers. The 4.0L has a stroke of 3.411" and a 4.5-4.8L stroker has a stroke of 3.895" so the numbers would be as follows: 1200-1500ft/min piston speed = 2110-2640rpm on a 4.0, 1848-2310rpm on a stroker. So use the table above to pick the right gears for your tyre size. Above gives the average cruising speed of 65 mph or 105 kph. The more weight you carry the more revs you need to stop the extra fuel use through engine strain. The extra revs is also better for the auto and even engine temperature with less strain and the water pump running faster to circulate the coolant.
Most people think that less revs will equal better MPG. That is not always the case as less revs can also mean more strain on the engine which causes more fuel use. According to a engine design text‚ maximum fuel economy occurs with open throttle and at a piston speed of 1200 – 1500 ft/min. So if you know the stroke of your engine‚ you can calculate the rpm for best fuel economy. Usually comes out somewhere between 2000 – 3000 rpm. Dino provided me with the following numbers. The 4.0L has a stroke of 3.411" and a 4.5-4.8L stroker has a stroke of 3.895" so the numbers would be as follows: 1200-1500ft/min piston speed = 2110-2640rpm on a 4.0, 1848-2310rpm on a stroker. So use the table above to pick the right gears for your tyre size. Above gives the average cruising speed of 65 mph or 105 kph. The more weight you carry the more revs you need to stop the extra fuel use through engine strain. The extra revs is also better for the auto and even engine temperature with less strain and the water pump running faster to circulate the coolant.
bigwillxj
NAXJA Forum User
- Location
- NC State/lexington, NC
yea im sorry i didnt really separate my questions very good. I was only concerned bout the rpm's for cabin noise.
