Rb20 and RB25, what rpm do you cruise at on the hwy???

[RB20s13coupe]

Im just wonderin how many RPM's you're at while cruizin aroun 70mph. My stock single cam KA/ 5spd is at like 3000-3500 at 60mph... and it sucks!! Im hopin the RB20 trans isnt gonna be like that.

[Cpt_Impossible]

My RB cruises about the same as the KAe did. 2900-3200 I was suprised as well, but when you think about it the final gear ratio is nearly the same. The thing with the RB though is that you get an additional RPM range over the KA, higher redline.

[DriftingisLame]

I believe the gear ratios are the same as the KA's.. But dude, 3500 rpm in an rb20 compared to a KA24... holy night and day difference! The rb20 is smooth as a baby's as5 compared to the KA.

Another idea - do you have the stock 4.11 open diff? If you're going to grab yourself a VLSD... get a 3.73.

I believe those rear end ratios are correct, if not.. they're close.

[RB20s13coupe]

I was just wonderin for road trips... From what I've read the J30 diffs are 3.90 and the Z32 diffs are 3.70 but the Z32 diffs dont just bolt in.

[HxC_Nismo]

the n/a 300zx z32 diffs bolt in but not the twin turbo diffs. check this link out it will answer all your questions about diffs.http://www.ka24development.com/vlsd.html

[SX APPEAL]

In response to the original question, the stock transmission in a KA is almost exactly 3K at 70mph, so if the RB transmission has the same ratios and rear end, then thats your answer.

[RB20s13coupe]

Well mine is at 3K at 60 mph.... so something is up. and I have 205 50 15's in the rear.

[Sil240]

Well mine is at 3K at 60 mph.... so something is up. and I have 205 50 15's in the rear.

What's the actual overall tire diameter?Different tires/sizes vary with overall diameter.

Plus sounds like you went smaller in tire diameter.I think i had 215-55-r15 when I changed my tires and went smaller also.

Whats the stock tire specs or diameter?

[RB20s13coupe]

I dont know, they are stock for all I know. Im not really that worried about it. I was just wondering if the RB20 will be ok for road trips, or if it will suck like my KA. Im going to be changing my rear soon and I will have 275/40/17's in the rear, so that should change my final drive also.