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Bnr34 Rb26/30 Conversion

destrukshn

By destrukshn,
in Engines & Forced Induction

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destrukshn Rising Star

destrukshn

Posted
Posted (edited)

Hi All,

Just hoping for some input. We are currently doing a RB26/30 conversion for my BNR34 and we didn't want to run a sump adaptor so an extra piece was welded on and machined flat. Has anyone done this conversion or know anyone who has?

Looking for some input, will it work? Or will I run in to more problems? Cheers! Pictures below:

Before welded:

Before%20Weld.JPG

After welded:

One%20Side%20Welded.JPG

Both Sides welded:

Both%20Sides%20Welded.JPG

Machined:

Machined.JPG

Edited by destrukshn
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KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

Good luck with that! I have a steel sump adapter but will be interested to know if yours works out. Can't you just bolt the sump on without a gasket to see how it looks?

What's the plan at each end?

destrukshn Rising Star

destrukshn

Posted
  • Author
Posted

It is not a problem of fitting the sump, it will fit the sump as it was already put on and those pieces were cut to fit the RB26 sump. We just need to tap the holes.

It's about the strength, will it crack? Just curious to see if anyone else has attempted this modification to avoid a sump adaptor?

  • Like 1
XKLABA Grand Master

XKLABA

Posted
Posted

did you weld the top too for strength, I would also try and weld some tabs on top to help.

The idea is good but you are trying to weld to cast, was something I thought of doing but was advised against and brought the platinum adapter instead, so am very interested how this turns out

destrukshn Rising Star

destrukshn

Posted
  • Author
Posted (edited)

did you weld the top too for strength, I would also try and weld some tabs on top to help.

The idea is good but you are trying to weld to cast, was something I thought of doing but was advised against and brought the platinum adapter instead, so am very interested how this turns out

Well it was welded both on top and the bottom for strength. Yeah i was told that youre trying weld on to cast it is hard but apparently with the right welding tools you should be able to do it. We'll see if it is strong enough! :)

Whats the plan for the oil pickup, its tight enough with an adapter plate

Oilpickup? It will use the same spot as the RB26 dipstick. :)

Edited by destrukshn
GTRNUR Grand Master

GTRNUR

Posted
Posted

I would have thought the only approach to do this would have been to build up the sides of the block gradually, so that discimilar metal thermal expansion variations are minimised. Thereby minimising the creation of stresses in the added material. It would have to be oven heated to do the welding to do this as well.

It doesn't look like there is a taper on the mild steel plate where it was welded to the block too. A thicker fillet weld between the block and the plate will increase the chances of this working if you couldn't get the metalurgy 100% correct. Welding it with a lot of current/heat to get complete penetration into the join might complete the weld, but it creates stresses all through the cast and added materials.

Weather it holds up is anyone's guess. You won't know till you try it.

destrukshn Rising Star

destrukshn

Posted
  • Author
Posted

what material is the extra piece?

What material weld was it?

If neither are cast iron it won't work

How was it welded?

If an oven was not used then it will crack and split

Though A for effort and trying something different

Not too sure of the exact material, but i am guessing it was some sort of steel.

Well it has been machined and hasnt cracked yet so it looks a bit promising. As it retains a few original holes on the RB30 from the RB26 Sump, will tap out using larger studs to ensure it doesn't move.

Whats the reason for not using an adaptor plate? Sounds like an awful lot of effort for something that would worth with a plate?

Well the reason for not using it was probably due to extra 10mm which person working on it didnt want for sump adaptor. Possible oil peaks too.. Well cutting was done in house, welding was done free & machining was done free. We'll see if it works otherwise if it cracks, can always take motor out and fix it! :)

I would have thought the only approach to do this would have been to build up the sides of the block gradually, so that discimilar metal thermal expansion variations are minimised. Thereby minimising the creation of stresses in the added material. It would have to be oven heated to do the welding to do this as well.

It doesn't look like there is a taper on the mild steel plate where it was welded to the block too. A thicker fillet weld between the block and the plate will increase the chances of this working if you couldn't get the metalurgy 100% correct. Welding it with a lot of current/heat to get complete penetration into the join might complete the weld, but it creates stresses all through the cast and added materials.

Weather it holds up is anyone's guess. You won't know till you try it.

Haha yeah guess we'll just have to wait and see once it is done and if it holds up! Thanks for the input!

  • 2 weeks later...
GTRNUR Grand Master

GTRNUR

Posted
Posted

I like it! Nearly looks like an RB26.

The only suggestion I'd make would make would be to haven an align bore done on the mains. Shave 1 thou off your cradle, install your main studs, and then re-align bore the main bearing saddles to make sure everything is straight. Then do the rest of your block machining.

destrukshn Rising Star

destrukshn

Posted
  • Author
Posted

I like it! Nearly looks like an RB26.

The only suggestion I'd make would make would be to haven an align bore done on the mains. Shave 1 thou off your cradle, install your main studs, and then re-align bore the main bearing saddles to make sure everything is straight. Then do the rest of your block machining.

It does look like an RB26 indeed, just letting everyone know the welds are so hard that our drill is having problems drilling the holes and it is getting done by someone external and not in-house!

There is no reason to align bore done on the mains. There is nothing wrong with the mains and so there is no need to realign them. It is factory aligned.

Gerg_R31 Mentor

Gerg_R31

Posted
Posted

heat from welding may have distorted the block, so if there is the slightest twist then the tunnel may not be in line, which is why a line bore/ hone is done, if it is not, and the alignment is out then the crank may rotate at an awkward angle and force it to flex and vibrate, and or seize

material hardness effecting the drilling... to make it easier get a drill bit guage and then sharpen the drill head to match the angle recommended for the material your drilling into

destrukshn Rising Star

destrukshn

Posted
  • Author
Posted

heat from welding may have distorted the block, so if there is the slightest twist then the tunnel may not be in line, which is why a line bore/ hone is done, if it is not, and the alignment is out then the crank may rotate at an awkward angle and force it to flex and vibrate, and or seize

material hardness effecting the drilling... to make it easier get a drill bit guage and then sharpen the drill head to match the angle recommended for the material your drilling into

Heating was only done on the top of the block, the whole block wasnt heated just to weld the sump extension pieces on and so there is no twist in the tunnel. It is definitely aligned. Work is done by professionals and there is no need to worry about it being out of alignment, but thanks for the input :)

The holes are drilled now, will update with pictures once short motor has been assembled!

GTRNUR Grand Master

GTRNUR

Posted
Posted

You are crazy... as if you would not go through the trouble just to be 100% sure. I know plenty of "professionals".

+1

I've not measured a standard block and seen all the mains measure up the same, let alone a welded one. For the extra few hundred dollars its worth the piece of mind. Personally I hate the idea of pulling an engine out of a car to fix something I could have done better if I'd just paid a tiny bit more.

While you might 'get away' with it in a lowish power situation combined with big 2.8+ thou clearences, why would you set an engine up like that if you can do better. Especially in a GTR.

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