RB swap for the z31

Jan 19th, 2003, 01:04 AM

I was checking out a website a week ago about JDM Z31's and found out that there was a Z called the 200ZR and it's powerplant was a RB20det! So as you can well imagine i got curious and asked an importer and he said that not only would the RB20det would fit, but that the RB20 is the same size as the RB25 and RB26 motors, if that is all true, would a RB26dett fit or is this guy pulling my leg. Just to let you know, he suggested i use a R32 skyline front clip,because i could reuse the R32 mounts and all the more obvious reasons to use the front clip. Any answers or info would be great. You gotta admit that a RB-powered Z31 would be one bad ass Z !

Blackbob · Jan 25th, 2003, 10:34 PM

No he's not pulling your leg. There's actually a guy who was I don't know if he still is. But he's in the airforce and has a website about his Z31 and the RB32 swap I belive he did in his. He's stationed in japan(go figure) so the swap for him was very cheap and very easy.

~blackbob~

esyip · Jan 26th, 2003, 03:00 AM

here's a little FYI for you before you attempt this swap.

you'll be MUCH better off keeping the VG30ET (if you have one) or getting a VG30ET swapped into your N/A Z31 than going with either the RB20 or RB25 swap. why?

for one of the more obvious reasons, the displacement. it's not that much of a difference over the RB25, but it's a definite advantage over the RB20.

second, the RB20 only makes 215hp, i believe. i don't remember, but it's in that vicinty, maybe a little less. and the RB25 makes 250hp. now, the VG30ET makes about 240hp, that's only 10 less hp than the RB25, but the displacement makes up for some of that.

also, remember that the VG30ET is a SOHC, single turbo, SOHC engine compared to the RB20DET or RB25DET, which are DOHC, single turbo engines. the VG engines are very tough and rigid engines to work on, and with the Z31, you have a bit more room in the engine bay, compared to the Z32s.

also, the RB engines are pretty well-known for the #6 cylinder going out. it's pretty weak from what i understand, and usually needs to be replaced or the internals are recommended to be built up. that's what i've heard.

JZK316 · Jan 26th, 2003, 05:34 AM

Real HP #s:
RB20DET-180 hp(Z31 200ZR)

RB25DET-250hp(R33 GTS-T)

VG30ET-200hp(usdm300ZX)

With forced induction and motors altogether more displacement doesn't mean more power. Remember that hp to wieght ratio will affect how fast your times are on a track.