Fuel economy loss with R&P or short gears, or both?

[Electro]

The grinding of when I shift from 2nd to 3rd is getting to be more annoying as time goes on, so it looks like i'll be saving up for the 90K mile service, along with the transmission to be dropped down to replaced the synchros... SO while i'm doing that, i want to find out which is it that takes away from fuel economy? i drive my NSX all the time, i just cant help it... so i can use all the fuel economy i can get! (i actually got 340 miles out of one tank full the other day doing just normal driving - mostly highway tho)

Is it both the R&P and the short gears that affect the fuel economy? I can imagine that the R&P would, but not sure about the short gears... what do u guys think? Thanks

 

[ChopsJazz]

The short gearset final drive (5th gear) is the same as the stock US final drive. Changing the R&P is what will most affect your RPM at cruising speeds. Since you seem to do most of your driving on the highway, you should see minimal mileage difference by changing to the short gears and 4.23 R&P. The trick is to keep from zinging it off the redline with every shift once those short gears are installed.
For more on this topic go to the FAQ in this site.
Also, I think my mileage has suffered from the shorties and 4.23 R&P because I'm ALWAYS on the throttle!

[This message has been edited by ChopsJazz (edited 22 September 2000).]

 

[David]

I saw a few mpg difference at 80mph with the 4.55:1 R&P. Enough to notice, not enough to cause me concern.

 

[ZABADNSX]

My buddy, TAMPABAYNSX-R, just had his 6spd, and 4.55's done this past week. While curising on 6th at 90mph he is at 4150 rpm, and with the stock 5spd setup, he was at 4000 rpm on 5th. Very little differnce when you figure mpg comparison, while getting a huge difference from 0-150mph. I am getting my new 6spd, and 4.55's installed right now. So I hope to experience the same turnout.

 

[TampaBayNSX-R]

Originally posted by ZABADNSX:
My buddy, TAMPABAYNSX-R, just had his 6spd, and 4.55's done this past week. While curising on 6th at 90mph he is at 4150 rpm, and with the stock 5spd setup, he was at 4000 rpm on 5th. Very little differnce when you figure mpg comparison, while getting a huge difference from 0-150mph. I am getting my new 6spd, and 4.55's installed right now. So I hope to experience the same turnout.

Now that I've put about 1,000 miles on my new 6 speed tranny w/4.55's I can say that my fuel economy has not suffered. In fact, I am getting about 18mpg with a combination of city and highway driving. This compares favorably to the 17mpg I had averaged before. The car is quicker, more fun to drive and sounds great!

 

[Electro]

What about the length of 1st gear - as the stock gears are pretty long..... best for when you're in stop and go traffic....

i like being able to leave it in 1st gear and reach about 30mph if i have to without taking it into 2nd.....

What are the max speeds u can get in each gear? Its getting closer and closer to the time that I'll be doing some work on my X...... so i want to do more than just repairs... THANKS!

 

[nsxtasy]

What are the max speeds u can get in each gear?
http://www.nsxprime.com/FAQ/Technical/gearratios.htm