RB20 in an '85 300zx??

[CA-mazing]

crazy idea right? buddy of mine wants to start a new project car and that is his grand idea. he's built two decent 240's with a highly modded KA and basically stock SR. but he said he wants to swap an RB into a 300zx. i told him that some serious work would have to been done in order for that to happen. he said it wouldnt be too bad once he got the motor in cuz everything about the car is setup pretty well. he's looking at an '85 300zx w/turbo. makes sense cuz he would already have a boost guage and just install or swap a few other. and it comes stock with 5 bolt pattern, i dunno about an LSD, have to look into that.....but i still dont know about fitting that engine in there. what do you guys think? personally, i've never seen an RB of any sort in a 300zx

[sillyvia13]

dude rb20dets bolt right up in them...
They come with rb20's in japan...

I put a rb20 in a z32...

lmk if you need some help.

maybe custom shaft and things of that sort...
do it up...

[CA-mazing]

really?? well goes to show how much i know about Z's. SWEET! well since this will be his first 300 build mind if i could get a list of a couple things he might wanna go ahead get? cuz as soon as i tell him this he is definitely gonna buy it.

[sillyvia13]

lol...
get the engine swap and go...
you'll need a shaft but I fucking bet you the one from it will work, or some nissan one will, maybe swap the splines? be easy to tell when your looking at it.

I think it needs a auto tranny bracket too... for some reason? i got one you can have.
then intercooler... and go.
ionno pretty easy.
pm me if you need anything, I'll try to help.

[CA-mazing]

sweet man thanks. it might awhile before i can get down to specefics with ya, but i will definitely keep your name on file and holler back atcha. and i just looked it up and the Z31's of japan did have RB20's, that sucks they get all the cool stuff and we have to settle for sloppy seconds

[Flicktitty]

Yeap, some Z31's came with RB20's in Japan. i always thought of putting a RB25/26 in my Z31 when i had it.

[Jtuned_andy]

[CA-mazing]

^^^^^thats a 240, i can tell that by looking at the shock mounts. i'm not putting an RB in a 240, i'm putting in a 300/Z31. but yours looks nice also.

[sillyvia13]

Originally Posted by CA-mazing

^^^^^thats a 240, i can tell that by looking at the shock mounts. i'm not putting an RB in a 240, i'm putting in a 300/Z31. but yours looks nice also.

nah bro no 240 thurrrrrrrrr
Look at rad support. look at fire shit, how about battery!
lmao! its a z31 homie!

rb25 dont drop in I dont think, you'd need a new subframe, I think q45 are same as rb25? not too sure tho... need to try it out 1st.
Peace homie....

looks cool with top mount IC!

[CA-mazing]

.....i'm drunk at 11 o'clock in the morning. excuse my drunk "know it all" self. i and my other self apologize for the false accusations and would like to say.....i'm sorry, and i....we really would like to acknowledge fine craftsman ship.

[sillyvia13]

holy shit...........
LMAO!
too funny,...

what we enjoying for drinks this fine morning!?
coffee and brandy?

[soreballz]

Originally Posted by CA-mazing

^^^^^thats a 240, i can tell that by looking at the shock mounts. i'm not putting an RB in a 240, i'm putting in a 300/Z31. but yours looks nice also.

^^^^^You're an absolute moron; I can tell by reading that post of yours.

[sillyvia13]

Originally Posted by soreballz

^^^^^You're an absolute moron; I can tell by reading that post of yours.

^^^^^You're an absolute moron; I can tell by reading that post of yours.

interesting how well it works here too...

Your asshole is showing.

[Flicktitty]

Man, RB's look so much more at home then the VG in the Z31.

[d r i f t swift]

just buy a 200zr motorset. and bam. bolt in swap for your z31... or just buy the rear sump pan and pick up tube. i cant remember which mounts you use. go read hybridz.org pretty sure youll learn everything you want to know over there.

[Benedict]

rb25 z31 build
Z31Performance.com • View topic - Racinjitter's RB-Z31 project.

serious z31 suspension
Z31: Drop your flares and cut your heat signature.

[CA-mazing]

well went and look at a decent 300 today. guy told us the t-tops didnt leak, but there was definitely a leak somewhere....(its been raining a lot here in TN lately and today we had kinda a warm day) we pulled up and all the windows had condensation on them....on the inside. opened the door and got a huge whif of a moldy nasty smell. i use to have a wrangler and it leaked when it rained...this is what the carpet smelled like when it would mold. so unfortunately after that, we didnt feel like even negotiating cuz there was no way either one of us was gonna drive it back to his house. but now we're both psyched about this 300 build, so the search is on! details: looking for a '84-'87 300zx, manual, decent condition, no mold or leaks, reliable enough to another 3-4 months before we swap the engine and no more than $2500. and in the middle TN area.

[lazysk8er2]

not that easy to find 200zr crossmember...but someone did do it with the na crossmember and flipped 200zr around and it bolted up. your best bet would be to look at hybridz or z31performance.com. be ready to get bunred if you ask the question cuz there are no write ups but you can find the info there. and as for rb25's they require modifying to fit in.

[Racinjitter]

LOL, the RB anything does not "Bolt in" to any Z31 chassis. You will need the NLA 200ZR crossmember and engine mount brackets. You will also need the NLA 200ZR transmission mount. As Benedict said, take a look at my build up and you will see what needs to be done to make any RB fit into a Z31. Here is a link to my hybridZ writeup. Rb Z-31 - HybridZ

[Howlermonkey]

Whatever you do, don't start with a z31 turbo crossmember.

It has the driver side mount pad skewed way forward of the passenger side.

The N/A crossmember is a better starting point and you will definately have to move the tranny back since the vg30 bellhousing protrudes into the engine compartment much more than in an inline configuration..................but you wouldn't be using the z31 tranny anyway so fabrication is in order in light of NLA parts.

[shmiddy]

Originally Posted by CA-mazing

^^^^^thats a 240, i can tell that by looking at the shock mounts. i'm not putting an RB in a 240, i'm putting in a 300/Z31. but yours looks nice also.

dude thats not a 240.. look at the batterie location

[Racinjitter]

Originally Posted by Howlermonkey

Whatever you do, don't start with a z31 turbo crossmember.

It has the driver side mount pad skewed way forward of the passenger side.

The N/A crossmember is a better starting point and you will definately have to move the tranny back since the vg30 bellhousing protrudes into the engine compartment much more than in an inline configuration..................but you wouldn't be using the z31 tranny anyway so fabrication is in order in light of NLA parts.

The distance from the engine mount to the transmission mount is 39.5" on a vg30e, It is the same for a rb25/20 at 39.5".

[joeyz31]

If you ask around on z31 performance a majority of people will point you in the direction of avoiding the RB and building up the VG just to avoid a lot of headache getting a crossmember and all of that and a majority of z31 owners are pretty cheap with the exception of a few. As a z31 owner with a VG If i had the money and time for a swap id love to do an RB but if your doing it on a budget A vg can make decent power with not too much work done to it. IMO it just dosent sound nearly as good as any straight six. here are a few other swaps that might be rad
If i can in the future id love to do an LS1 swap I know plenty of V8s have been put in to ZS

[Howlermonkey]

Originally Posted by Racinjitter

The distance from the engine mount to the transmission mount is 39.5" on a vg30e, It is the same for a rb25/20 at 39.5".

My suggestion of using the N/A crossmember as the best starting place for this was because the turbo crossmember has the engine mount pad on the driver's side 6 inches further forward than on the N/A crossmember which has the mount pads even with each other..........unless you needed that extra room for the turbo hardware.

My mentioning moving the engine/tranny back as a unit nets you the ability to fit a radiator in the conventional location with the rb engine maintaining the 1 inch between the firewall and rear of engine that nissan uses in most every stock implementation of the RB or L series engine.

Moving it back is absolutely necessary on the M30 or you will find the front pulley hits the core support when the engine is even with the flange of the bellhousing while lowering in the inline engine.

The stock vg30 scheme in both the M30 and the z31 has the bellhousing of the tranny protruding 4 inches into the compartment while the stock implementations of the RB and L engines have it only protruding 1 inch in relation to the firewall.

If you look at the any Z car from 1970 to 1983, first generation maxima, and most RB equipped cars, you find the bellhousing only protrudes 1 inch into the engine compartment.

Of course.............moving it back would move the shifter location a bit too far back but that's why I use the shorty FS5R30 tranny out of the pathfinder and swap over the bellhousing from the RB to it when I put nissan inline engines in a car made for a v6.

It also helps combat push at turn in and I'd rather have the extra space in front of the engine than behind it

Luckily, the z31 engine compartment and radiator location allow more room for this but the extra space with moving the unit back allows a stand up radiator netting tons of room up front of the core support for intercooler, a/c condensor, and fans.

I guess I'm just splitting hairs here but I am guilty of leaving no stone unturned in my quests for the maximum performance.

[Racinjitter]

Are you really trying to argue? I am the one who blazed this trail. You cannot move the engine further back into the engine bay of a Z31, than what I did. I have 1/2" between the head and the firewall, using the factory (fore aft) locations. If you put a vertical radiator in like I did, you will have airflow problems along with overheating issues. Your best bet for radiators is wait until tomorrow, when I pick up the first batch of aftermarket direct fit rads for the z31.

You might want to look at my build thread again. Rb Z-31 - HybridZ

[Howlermonkey]

I think you are mistaking arguing with discussing.

Nissan blazed this trail when they put a rb into a z31 body over 20 years ago.

Now if you only have 1/2 inch between the firewall and the head, then the flange of your tranny as installed is indeed back further than in the stock implemention of the Z31's VG30.

The mating surface of the tranny in stock implementation of the VG30 protrudes at least 4 inches past the firewall into the engine compartment if not more.

It has to because the crossover pipe and stock plenum hang over the bellhousing.

I am well aware of your setup and your car is definately sweet but inches are inches and the tape measure does not lie.

I guess this discussion has now become an argument so I will provide pics of said engines including tape measure........not sure why I have to but I will.

Time passes............drives to junkyard.

Finds a Z31 with vg30 ready for measurements.



Next......a vg30 out of a Z31



I've circled (ellipse) around the head of the tape measure butted against the engine mating flange but it's tough to make a distinction since this engine is missing it's exhaust manifolds and crossover pipe.

Please ignore the L28et block/pan upside down as I needed a surface upon which to lay the tape measure so I could step back and take the pic.

Next a pic of the vg30 as installed in the car at the junkyard.

It is about 7 1/2 inches from the flange of the engine to the firewall......if you include the indentation.

Without the indentation, it is six inches so I was wrong about the 4 inches those two extra inches go even further to support my claims.

Sadly, I could not get my hands and the tape measure into that cavity but you can see a considerable distance the tranny bellhousing protrudes past the firewall.




Same area with tape measure against where throttle cables comes out of firewall......which is visible in the pic above.



And last........here's why it might be tough to fit a RB engine using the turbo crossmember.....unless you need the extra room to fit the turbo hardware but that requires a lot more engine mount bracket fabrication.

The N/A has both the left and right side even without the left side being moved way forward to clear the turbo in stock form. I still think nissan did z31s a big wrong by going this far and not going just a slight bit further so the turbo intake doesn't have to make that very sharp turn around the left engine mount.


Drives back from junkyard to snap pics of z31 turbo crossmember out of car.



Racinjitter, I fully respect you and covet your unique ride since it is sweeter than anything I have owned but arguing with someone who's been professionally working on Z31s as a Z car specialist starting at Z shop of miami in 1988 will always be an uphill battle rarely, if ever, won.

The last guy who proved me wrong was brewster at F31club.com in a discussion of FS5R30 tranny lengths when he proved to me the pathfinder version has the shifter location even shorter (27 inches from bellhousing flange to shifter stick center) than the version in the 1988 and 1989 z31 turbos.......which is shorter yet than the distance in the Z32 tranny.

I fully give props to anybody who proves me wrong but that's not why I frequent forums.

[Racinjitter]

Since we have this discussion...

Nissan blazed this trail when they put a rb into a z31 body over 20 years ago.

No. They did not use any USDM parts to fit the 200zr's rb20det into the Z31 chassis.

Now if you only have 1/2 inch between the firewall and the head, then the flange of your tranny as installed is indeed back further than in the stock implemention of the Z31's VG30.

See, I think you are getting a little confused. I have a rb25 in my car, mounted to the exact same transmission mount that it came with from the factory, and the engine mounts at the crossmember are at the exact same location fore/aft as the factory. Making it the same exact location as the factory vg30e. Now in relation to the rb mounting places, the vg mounts are in fact further back in than on the rb, bringing the vg closer to the front of the vehicle. Is that also what you are trying to say?





So as you can see the factory mounting postions have been utilized. With that being said, mounting the RB using the factory mounting positions of the VG, it will give you 1/2" clearance between the RB head and the firewall. There is no need to move the engine further back into the engine bay.

A factory turbo crossmember can be utilized, but we are both in agreement. It will be more difficult and require more fabrication. Here is a pic of the NA crossmember next to a Turbo crossmember.

but arguing with someone who's been professionally working on Z31s as a Z car specialist starting at Z shop of miami in 1988 will always be an uphill battle rarely, if ever, won.

Well, then we are pretty much equal. I have been working on the z31 chassis since 87. I agree, you have knowledge and I respect that. Which shop did/do you work at? Your screen name looks familiar, But I cannot place a name with your screen name.

[Howlermonkey]

I worked for Harry Gershenson at Z shop of miami and went on to datsun dynamics in Vienna Va.........then it was dealership after dealership and I last turned wrenches 3 years ago at lexus of orlando.

I am known as pooflinginmonkey on other forums but the name gets truncated so I HowlerMonkey it is.

Before that I was a rotary guy but I just cannot stand a loud car anymore.

I'll concede your points but I still cannot understand why nissan went with that scheme on the vg30 when the car in stock form would have performed a lot better with the engine 4 or 5 inches further back.

I'm sure all the touring, improved touring, production, and showroom stock racers would have appreciated it.

My current project is a L28et into a M30 but it seems that nissan never had US market or left hand drive in mind when they designed it because the steering shaft u-joint angles are almost to the point of binding in stock form because the rack is unbelievably close to the firewall. Tried laying down the rack like a Z31 but the steering got very notchy as this increased the angle until the u-joints bound..........not safe.

Luckily, the first generation maxima hardware allows it to be a bolt in solution with the stock crossmember but I will be running a built 3n71b until I have time to fit Austin Hoke's FS5R30 adapter.

Here's a pic of a M30 crossmember fitted for a front sump vg30. Both the sump and crossmember may be for sale soon if the vg30 that came out of the car isn't salvagable.

It might be useable on the Z31 to open up more engine options.



Mad props to your car and the clean install. If I had a ride like that, I would be a lot happier than I am driving the grandpa looking sleeper I now drive.

[Racinjitter]

I knew your name was too familiar! That sounds like a very interesting project! On the 07+ series chevy trucks there is a 90 degree bend in the steering I shaft. I haven't gotten to take one apart yet, but it could be fabricated into the I shaft easily.

LOL, I have been thinking about my next project after the black Z is done... Nothing good yet, but it will be off the wall. Maybe a TTLS7 in a 80's taurus station wagon, but I have no idea what it will be.

[racepar1]

Z-31 is trash, tell your "buddy" not to waste time and money with that pathetic chasis.