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Could one of you with a 08 Civic MT tell me the eng RPM's at 60mph?
Also what size are the tires?
thanks

Hi Paul:

___Give me a few minutes...

___Good Luck

___Wayne

Hi Paul:

___This is what the calc’s show…

08 Civic LX/EX/EX-L

MT – Fifth ratio: 0.727, Final ratio: 4.294, Tires: P205/55 R16, RPM at 60 mph: 2,518 RPM.

AT – Fifth Ratio: 0.525, Final Ratio: 4.437, Tires: P205/55 R16, RPM at 60 mph: 1,879 RPM.

08 Civic DX

MT – Fifth ratio: 0.727, Final ratio: 4.294, Tires: P195/65 R15, RPM at 60 mph: 2,538 RPM.

AT – Fifth Ratio: 0.525, Final Ratio: 4.437, Tires: P205195/65 R15, RPM at 60 mph: 1,894 RPM.

___Good Luck

___Wayne

Wayne,

Thanks for the speedy response

Here's a cool link that does some fast compares.
http://www.1010tires.com/TireSizeCalculator.asp?action=submit

The DX tire, if on my Fit Sport, would lower my Rpm's. Using your rpm of 2811 @ 60mph and the calc reduction of about 6%, it would be 2640. I have to see how a 25" diameter tire would fit in the wheel well on mine comp to the 23.44" Sport. About 3/4" more radius. I know on race tires that diameter can vary a great deal. Know idea how that is on passenger tires.

Do you have any real live data to say I'd get a measurable FE change from this RPM change on a Fit? I ask as I hate being the Guinea Pig on expensive changes.

Hmm...wonder if I can swap in the Si 6 speed for a lower rpm at 60...

I doubt it'll help much. I think 6th is about the same as the EX 5th, with more gears closer together below that.

Update:
08 Civic LX/EX/EX-L
MT – Fifth ratio: 0.727, Final ratio: 4.294, Tires: P205/55 R16, RPM at 60 mph: 2,518 RPM.

08 Civic SI
MT - sixth ratio: 0.66, Final ratio: 4.77, tires: P215/45 R17, RPM at 60mph: 2579 RPM.

Nope. It's actually worse. :(


math:
215*.45 = 96.75 mm sidewall height
*2 = 193.5 mm for top and bottom sidewalls
/25.4 = 7.618 inches for both sidewalls
+17 = 24.618 inches total diameter
*3.1416 (pi) = 77.34 inches tire radius
/12 = 6.445 feet tire radius

5280 feet / 6.445 = 519.24 tire revolutions / mile
* 0.66 * 4.77 = 2579 engine revolutions / mile, which is the same as rpm at 60mph. 60mph = 1 mile / minute

Well thats crappy! Thanks for the info though!

I doubt it'll help much. I think 6th is about the same as the EX 5th, with more gears closer together below that.

Update:
08 Civic LX/EX/EX-L
MT – Fifth ratio: 0.727, Final ratio: 4.294, Tires: P205/55 R16, RPM at 60 mph: 2,518 RPM.

08 Civic SI
MT - sixth ratio: 0.66, Final ratio: 4.77, tires: P215/45 R17, RPM at 60mph: 2579 RPM.

Nope. It's actually worse. :(


math:
215*.45 = 96.75 mm sidewall height
*2 = 193.5 mm for top and bottom sidewalls
/25.4 = 7.618 inches for both sidewalls
+17 = 24.618 inches total diameter
*3.1416 (pi) = 77.34 inches tire radius
/12 = 6.445 feet tire radius

5280 feet / 6.445 = 519.24 tire revolutions / mile
* 0.66 * 4.77 = 2579 engine revolutions / mile, which is the same as rpm at 60mph. 60mph = 1 mile / minute

Missed this thread a couple days ago. The 6th gear from an SI would significantly lower your RPM.

Andrew, the final drive determines the total drive ratio from engine to wheels. The SI has a taller 6th gear, but a more aggressive final. It's the combination that makes the 6th about the same as his 5th.

The final drive ratio is the product of the gear and the final.

Civic 5th: .727*4.294 = 3.12 tire revolutions per engine revolution.
SI 6th: .66*4.77 = 3.14
SI 6th with Civic final: .66*4.294 = 2.83 = ~2300 RPM @ 60

That assumes that the SI 6th will mechanically replace the Civic 5th, which it most likely will not.

You can't put Civic wheels on a Fit as the 8th gen Civic is a 5 lug pattern and the Fit is a 4 lug.

Hi Paul:

___This is what the calc’s show…

08 Civic LX/EX/EX-L

MT – Fifth ratio: 0.727, Final ratio: 4.294, Tires: P205/55 R16, RPM at 60 mph: 2,518 RPM.

AT – Fifth Ratio: 0.525, Final Ratio: 4.437, Tires: P205/55 R16, RPM at 60 mph: 1,879 RPM.

08 Civic DX

MT – Fifth ratio: 0.727, Final ratio: 4.294, Tires: P195/65 R15, RPM at 60 mph: 2,538 RPM.

AT – Fifth Ratio: 0.525, Final Ratio: 4.437, Tires: P205195/65 R15, RPM at 60 mph: 1,894 RPM.

___Good Luck

___Wayne

I think that is wrong. I'm pretty sure my LX auto is at 2000 rpm at 60 mph. I'll check again when i go out for a drive.

I think that is wrong. I'm pretty sure my LX auto is at 2000 rpm at 60 mph. I'll check again when i go out for a drive.
The calculations are correct and those gear ratios were published by Honda, but I find my real world values are a bit greater than the calculations too. 2000 rpm at 60 mph sounds about right for real world numbers. Anyone know what would cause the difference?

The calculations are correct and those gear ratios were published by Honda, but I find my real world values are a bit greater than the calculations too. 2000 rpm at 60 mph sounds about right for real world numbers. Anyone know what would cause the difference?

Sorry, i was wrong lol. I just drove it today and it's a little under 2000

Missed this thread a couple days ago. The 6th gear from an SI would significantly lower your RPM.

Andrew, the final drive determines the total drive ratio from engine to wheels. The SI has a taller 6th gear, but a more aggressive final. It's the combination that makes the 6th about the same as his 5th.

The final drive ratio is the product of the gear and the final.

Civic 5th: .727*4.294 = 3.12 tire revolutions per engine revolution.
SI 6th: .66*4.77 = 3.14
SI 6th with Civic final: .66*4.294 = 2.83 = ~2300 RPM @ 60

That assumes that the SI 6th will mechanically replace the Civic 5th, which it most likely will not.

You can't put Civic wheels on a Fit as the 8th gen Civic is a 5 lug pattern and the Fit is a 4 lug.

You're right! :o I hadn't thought of just the 6th gear, without the final. You're probably also right about it not fitting as a replacement to the 5th. :(