What is the optimal cruising RPM?

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Mar 2, 2004
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Kentucky
Over the years I have noticed the normal cruising RPM on modern vehicles going up and up. Somehow lower geared, high RPM driving is preferred. I remember my first vehicle, a 1978 F150 w/ the 400ci V8 would run 1500rpm at 65mph. A buddy's 1969 Ford Ranchero w/ the 302 V8 was similar. Even modern pickups with high torque OHV motors, the same trait shows. 65mph cruising often bring RPM's over 2600. What are the advantages to this? I see the same thing with cars. My old 2.5L '89 Dodge Daytona would run 2000 rpm @ 65. Most cars I drive nowadays will happily rev close to 3000rpm at 65mph. My "old" 2001 Jetta, a 2.8L VR6 (a torque monster for it's compact size) would run 3200rpm at 75mph, which had always seemed counterintuitive to me. I must be missing something..?
 
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Jun 24, 2004
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Maybe the Jetta was geared more toward performance. My 99SL2 is at 3,000 RPM's at 70. The single overhead cam S-Series was geared for highway driving and fuel economy and cruises at lower RPM's.
 
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My SOHC saturn cam profile makes it most efficient at 2300 RPM. Oddly, that's exactly what it spins at 65 MPH. ;\)
 

OVERKILL

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My Expedition is ~2,000RPM at 70MPH. Mustang was at about 1,500RPM. As engine sizes have decreased, the need to spin them higher has increased. A smaller engine will not make the same amount of torque down low, so it is not optimal to gear them so that they "lug" and need to downshift all the time. Their "optimal" RPM range for cruise is higher, and so that is what you are observing.
 
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My 05 f 150(5.4 3v) can chug along at 1500-1900 at 60-65 the 06 explorer (4.6 3v) seems about the same. my JK Wrangler likes to spin faster. If I want it to respons over 60 I need the rpms above 2200 prefereable 2500 to 3k. In the mountains with my 6 speed manual I will often use 4th to drive 60-65 to maintain a sense of authority below 2200 rpms going uphill at 9-12k feet the speedo starts sliding downhill.
 
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My Saab 93 2.0T is geared pretty tall. It'll do 65MPH in 2nd gear (it's a 5-speed). It is, in fact, geared taller than the 2.5L V6 Ford Contour I had before it. I forget what the cruising RPM at 65MPH in 5th is but I think it's around 2500RPM. It has NO TROUBLE going up mountain grades on I68 in 5th @ 75MPH.
 
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Jul 16, 2005
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Glendale
3000 RPM at 80 mph for both my cars. (3.0 SOHC V6 Mitsubishis) But I don't do it much anymore cuz they put traffic cameras EVERYWHERE on the I-10 in AZ! \:\(
 
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Nov 30, 2005
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Texas
My car is about 3k at 80mph, and about 2k at 60mph in 5th gear. Its a Ford Focus 2.3l.
 
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Oct 18, 2007
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GN is around 1,800rpm at 65. TL is around 1,900rpm at 65. My old Celica was at a solid 3,000rpm or more at 65. GN pulls plenty hard in top gear at that rpm. TL does nothing without unlocking the convertor or downshifting.
 
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 Originally Posted By: BuickGN
GN is around 1,800rpm at 65. GN pulls plenty hard in top gear at that rpm.
"84 Buick GN 602hp 620lbs Stock crank, rods, block." Oh I bet it does! lol ;\)
 
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Oct 18, 2007
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 Originally Posted By: jigen
 Originally Posted By: BuickGN
GN is around 1,800rpm at 65. GN pulls plenty hard in top gear at that rpm.
"84 Buick GN 602hp 620lbs Stock crank, rods, block." Oh I bet it does! lol ;\)
There was a time when it had a hard time pulling top gear because it made 0 boost at that rpm. Now I have an awesome turbo that will make decent boost down low. It was an expensive journey but the drivablity is excellent for the power it makes.
 
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