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HR31 drivetrain conversion.

-scooter-
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-scooter- Contributor

-scooter-

Posted
Posted

Hiya fellas, Dan here.

i have an R31 import with a NICS red top rb20 turbo motor which has just snaped a timing belt and is now useless.

i am now working 6 days a week to save for a R32 front cut to do a conversion into the R31. So of course i have a couple of questions and would like some answers please.

Q1: will the r32 motor and gearbox fit and bolt straight into the the R31?

Q2:can i use R31 tailshaft from the box to the diff without modification?

Q3 to also make it legal i need r32 brakes (rotors, calapiers, etc)all round, is this an easy convet aswell?

Q4:and what power can i expect from an r32 rb20 with air filter, 3inch full system exhaust, FMIC, 550cc injectors, power fc computer, heaps bigger turbo (but have to study futher), 12 psi ??????? just roughly please

and any other helpfull hints and trick for this convert will be muchly appreciated.

thanks guys

DAN

BTW: this is a photo of my 31 after the timing belt mishap.

Skyline.jpg

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Bluprint Veteran

Bluprint

Posted
Posted

1 - Yes pretty much.

2 - I think so, not sure though

3 - Because you're putting in an RB20 to replace an RB20 (albeit a different one) I reckon you'd probably get away with slotted standard sized brakes, decent pads and good fluid. Sorta a go bigger if you want to kinda thing

4 - Ermm.... 170-180rwkw? I could be way off? Maybe less? Maybe more?

-scooter- Contributor

-scooter-

Posted
  • Author
Posted

cheers mate. hopefully all goes well. will keep the convert posted as it prgresses.

i would like to know some more about turbo upgrades for the rb20 with about a $2500 budget for the turbo itseft. If people could let me know of there experiences or opion that would be great!!!!!!

I will c if i can get some decent pics up aswell.

thanks fellas and girls if there are any!

Dan

Col-GTSX Grand Master

Col-GTSX

Posted
Posted

I have done this conversion twice now to my old lines.

1. It needs a few little minor tweeks (like brackets to mount power steering pump bracket)

You will also have to swap over with a silver top wiring harness, all wires will be fine. You only have to splice into the a/c for the compressor.

2. NO you will need to custom fabricate a new tail shaft

3. Its perfectlly legal to use the brakes you already got

4. ???? Guessing 220rwkw

Bluprint Veteran

Bluprint

Posted
Posted

different lengths between the gearbox and the diff

I had the thought that because it's still an RB20 that's going to be in there, with the same gearbox (or will you get a different one?) it shouldn't need a new one.

Could be wrong, I haven't done the 20 conversion.

Col-GTSX Grand Master

Col-GTSX

Posted
Posted

So i thought you were changing from auto to manual at the same time... sorry...

I found that the r32 manual box was shorter than the r31 auto box so had to get a custom one made up for it.The brakes you have are legal however i found the 4 pot calipers were a vast improvement. The mod it self was not a problem as all. Just forgot about the 5 stud wheels... LOL I had the car up on stands after a few hours of work we realised we needed a set of r32 gts-t wheels.... Also then we had to upgrade the rear hubs also so i could run the same wheels front and rear....

I didnt budget a set of wheels into this mod and it pushed the bank account a little.

-scooter- Contributor

-scooter-

Posted
  • Author
Posted

thanks for the replys guys.

just to sum up a few questions, my skyline is a manual but i want to put in an r32 box that i get with the front cut as mine has done 197 k's and second gear is being stupid. so i asume that my tailshaft will be a good fit, fingers crossed.

I will read the RB20 250kw thread tonight, if i get time, Cheers for that.

I pulled the air con out 2 years ago to make way for a front mount that was never fitted (dont ask me why, just lazy i guess). so no wire splicing needed there.

Qustion: do u have to get a bracket made up for the power steering pump?????

Question: will i get brakes with the r32 front cut???

Question : with the tacho, oil pressure, temp, and stuff like that, will that all still work with the new motor??????

i know i have to use the 32 wiring harness and comp, just no quite sure how the dash components and that works, if someone could shed a little light on this for me that would be great. :-)

Question: If i change all the brakes over (rotors, calipers, stc) will i have to change the booster and master cylinder as well??????

Thanks for your help people will get some more pics up soon. Cheers

Dan

Bluprint Veteran

Bluprint

Posted
Posted
If youre getting an r32 front cut wont you get the brakes with it? May as well change them too, make sure you get a Type-M front cut though, with the 4 piston calipers.

I understand that it's quite rare to get a halfcut with the brakes & suspension still on it.

If you get one, you're very lucky.

GTS20X Enthusiast

GTS20X

Posted
Posted

Just buy a motor & ecu a lot cheaper when you have everything else. All the guages work perfectly in a HR31 with the R32 senders, except the tacho there is a small mod that will allow it to work. You will need a different top radiator hose (i used Datsun 1600/180B). If you car doesn't have ABS you may have clearance issues between the disc & lower control arm & have fun finding wheels with the right offset & enough caliper clearance (i am).

Carlos

-scooter- Contributor

-scooter-

Posted
  • Author
Posted

I had a friend give me a cd with non stop vids from full boost with a few r31's on there, one r31 had an RB25 with a gt2535 and many other mods and got 358rwkw. so i got to thinking, and decided that for around the same price as an r32 front cut i can get a rb25 motor, loom and ecu.

so the plans have changed and a couple more questions for u guys.

1: i know the 25 gearbox is longer the mine so tail shaft length will be a problem, does anyone know a rough price to get one made up? and will the 25 box fit in the tunnel with no mods?

2: how will my diff hold up to an RB25 with say around 250kw???

3: any mods needed to be done to the engine mounts for th 25???

thanks guys

Dan

Col-GTSX Grand Master

Col-GTSX

Posted
Posted

I have only seen theis mod once in real life and the guys was a nut. QLD transport would not give him a mod plate as they called it a frankenstein of a conversion.

It is legal to have this done, however when changing motors to a different type/size this is where you should include the pros man. Look im all for doing your own work. But if you botch this conversion then its gonna cost you more to fix it.

1. Custom tail shafts are around $200 with new uni joints. The 31 i saw with a 25 motor was using a rb20 gearbox. I believe he said it was too tight and mods were required to the tunnel to fit it.

2. You standard r31 diff will fall to pieces at the first sight of 250rwkw. Remember is over 15 years old and has had a flogging all its life and now you want it to handle twice the power it was designed for....

3. The 25 mounts slightly more forwrds than the 20. This is due to the 25 motor leaning on the gearbox more so than the 20. I do believe you will have to tinker a little however i think this is the least of you problems.

Just one more note, we talked about brakes eariler. If you want to make a 250rwkw beast you need to get better brakes. It is road worthy as is.... JUST..... You want bigger brakes trust me, last thing you want is to finish you ride and have a bash and not stop.

Cheers Col

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