Japanese R&P

[bambookid]

What does it mean to have Japanese R&P? What is the Stock R&P? What is the difference between the 4.23 and 4.55? What is the performance advantage to have either?

Thanks

 

[Larry Bastanza]

R&P = Ring and Pinion Gearset It includes the countershaft and ring gear inside the transmission. (plus a few other parts but these are the main parts).

Stock R&P ratio is 4.06

Japanese R&P is the 4.23 gear ratio used for Japanese models including the NSX-R.

4.55 is an even shorter R&P made by CompTechUSA.

HTH,
LarryB

 

[nsxtasy]

What does it mean to have Japanese R&P? What is the Stock R&P? What is the difference between the 4.23 and 4.55? What is the performance advantage to have either?

Larry described the R&P gear itself.

All gears (five forward gears in the five-speed, six in the you-know-what) run through the ring and pinion gear. If you change the R&P gear to one with a higher number for its ratio, that gives you "shorter" gearing - just like first gear is a "shorter" gear than second gear - meaning higher engine revs for a given road speed.

The advantage of a shorter gear (any shorter gear) is better acceleration. The disadvantage of a shorter gear is that you run out of that gear sooner, and as soon as you do, your acceleration is worse because your overall gearing is higher after you upshift than it otherwise would be. Shorter gears also give worse gas mileage.

How much difference does it make? Take a stock '91 NSX, and vary only the R&P gears. Here are the results you can expect for 1/4 mile acceleration:

4.062 (stock): 13.67 seconds
4.235: 13.57 seconds
4.55: 13.43 seconds