How many RPM's at 65 mph? Options

[blumontag]

Just wanting to compare...my 1994 ST manual transmission runs 3000 RPM at 65 mph. I've got the 1.8l 7AFE engine. Curious to hear what others' cars are like.

[Poonicus]

Just wanting to compare...my 1994 ST manual transmission runs 3000 RPM at 65 mph. I've got the 1.8l 7AFE engine. Curious to hear what others' cars are like.

Mine runs about 3k in 5th gear and in 4th about 35 or 4k. I have a 5sfe though.

[Box]

Through lots of complicated math the exact RPM's at 65 mph in fifth gear should be 2,984.74.

This post has been edited by Box: Apr 19, 2014 - 10:25 PM

[VavAlephVav]

the gt has a 4.17 final and will run about 3200 rpm at 70.

[blumontag]

Thanks for the replies...good to know. I was driving my wife's Corolla (1998, automatic 4 speed) and noted that I was at 2300 rpm at 65 mph. Different cars, for sure. The Corolla has 120hp, compared to the 1.8l in my Celica (110 hp).

[Box]

The Corolla is geared specifically for fuel economy. That and I want to say the auto has a stupid low final ratio, in the 2's I believe.

This post has been edited by Box: Apr 20, 2014 - 1:22 AM

[cardshark525]

I don't know about 65 but at 79-80 I'm at about 3200 with the 3s-gte and E153. Get to spend another 3 hours on I-80 today so I'm looking forward to the gas mileage figures I get when I have to fill up half way back.


EDIT: at 65mph I'm looking at 2900 rpm.

This post has been edited by cardshark525: Apr 20, 2014 - 7:40 PM

[Special_Edy]

Automatics always have a greater overdrive than manuals. The automatic only provides 4 forward gears but it has a torque converter which muliplies torque at various loads and rpms. So functionally a 4 speed automatic has more gear ratios available than a 5 speed manual.
Also, due to the fact that most automatics use orbital gearsets they are severely limited on the ratios of the 4 gears, if you change one gear you change all the gear ratios since all 4 gears are used at all times. The final drive has to be a compromise between a reasonable 1st gear and a economical 4th.

Finally, manuals are inherently more economical than automatics due to the fact that a manual uses a mechanical clutch which fully engages and disengages; while automatics use a torque converter which is a fluid coupling that always experiences parasitic drag. The automatic requires the steeper overdrive in order to compete with the fuel economy of a manual transmission.

[Box]

Yep, even the most efficient hydraulic automatic is up to an 80% transfer of energy. Why more hybrids don't come with a manual is beyond me, the first generation Honda Insight is pure genius and has yet to be surpassed.

[blumontag]

Great info...thank you. I'm a guy that's come to be interested in the mechanics of cars rather late in life, so I find this forum most helpful.

[VavAlephVav]

Yep, even the most efficient hydraulic automatic is up to an 80% transfer of energy. Why more hybrids don't come with a manual is beyond me, the first generation Honda Insight is pure genius and has yet to be surpassed.

At least with the Good electrics, like a Tesla, the motor has so much torque you don't need 'gears', it's Direct Drive.