Re-sleeving RB26 block

[GDZ1LA]

96od dont u mean? 86+5+5 each side? or 2.5 each side? i am forking out for custom pistons so wana get biggest i can without justifing strength, if 96 idd say it removes the whole casted lining? if 91 idd say it will leave .5mm or so each side to seal it?

[Sydneykid]

96od dont u mean? 86+5+5 each side? or 2.5 each side? i am forking out for custom pistons so wana get biggest i can without justifing strength, if 96 idd say it removes the whole casted lining? if 91 idd say it will leave .5mm or so each side to seal it?

Yep 96 mm, I was editing the post while you posted. I have some picures of an OS Giken kit around somewhere, I can use the CAD to get approximate dimensions. If I get time over the weekend, I will do a bit of a search.

[GDZ1LA]

96 they would do a full hone (no bore walls) i wonder whats the most meat you need on bore walls with new performance sleeves? 3mm idd say? (90mm pistons)

[discopotato03]

Out of curiosity what do OS do about the cooland water passages (block and or head) if the liners have 5mm wall thickness ?

Cheers A .

[Duncan]

my sleve was about 2mm OD so 4mm all up, over standard 86mm bores.

I have heard stories of the standard blocks cracking over 86mm, and Nissan went to the trouble of reinforcing the block on the N1s.....I wouldn't bore it out futher than 88 personally unless you are ready to take the chance

[proengines]

I've just been reading this thread and it got me wondering. I went up to the workshop and measured up a 26 block, measuring between cylinders 1 & 2 there is 10.65mm. If the sleeve was 5mm wall thickness there would only be .65mm between the 2 sleeves and the entire cylinder between the deck surface and the base of the water jackets would be removed boring out for the sleeves as the bores look to be around the 4-4.5mm mark thick which makes no sense the block would lose a lot of its stability.

I did a search on google image search and the only photo is the stock photo that the resellers use to advertise the kits. I enlarged the photo and the sleeves look as though they have a flange on the top. The spacer plate also looks to have a counterbore in it to accept the flange. It would make sense if this flange was 5mm wall thickness and the rest of the sleeve a 2-3mm wall thickness. this would leave the parent bore pretty much in place and the flange would locate the sleeve and stop it pulling through. I'd say the sleeve is a press fit at least in the original block to locate it properly and enable heat transfer to the cooling system. It also means the flanges would not overlap when the counterbores are machined.

I'm not sure about cooling, maybe the bottom of the plate has a cooling channel cast or machined into it to let some coolant run around the top of the bores. I'm also not sure what seals the spacer plate to the block, maybe a viton coated shim gasket or maybe a chemical sealant.

This is really a lot of guessing without any hard facts to base it on but it might help. Does anyone have photos of a finished OS Giken block that they could upload?

[mark99]

The OS engine that ive worked on looked a little different from the photos of the kit that ive seen. The sleeves were stepped, being very thick at the top then stepping back to more like a conventional sleeve where it goes into the block. They were thicker than 5mm on the bit that hangs out the top of the block though. I would have guessed more toward 10mm. From memory they had flats machined on the front and back so they keyed together. Then the spacer plate had flats on it that keyed to the front and back liners. The plate then just goes arond the outside of the block just protruding back in to catch the head bolt holes and the oil galleries. then the water jackets are just free to flow into the open space left between the outside of the sleeves and the inside of the plate. Sorry dont have any photos. Hope that makes sense. Oh the plate is sealed underneath with a big one piece o ring that goes all around the outside of the block and cicles the oil galleries.

[Sydneykid]

Following are a number of pictures I have accumulated over the years of OS Giken 3 litres;

The first is the original kit, take note of the liners and the spacer plate;

This is the spacer plate between the head and the block, it is 26mm thick;

This is a picture of the liners sticking out of the block, note the clearance between them;

This is a picture of the liner being filed slightly/gently at the top to clear the spacer plate;

This is a new style of spacer plate used with the liners above, it appears OS have changed the design of the spacer plate. At the same time they have gone to a open deck design, ie; the spacer plate doesn't fit directly/tight around the liners. This may indicate a change in liners (from the original kit shown in the first picture) with a large step at the top for better head gasket sealing.

That should provide for some interesting discussion:cheers:

[Sumo]

So people who usually rebuild engines are of the fitter/machinist trades?

I would think that this would over the top for the old mechanic down the road.

Cheers

Sumo

[proengines]

Those pictures make sense, thats a similar setup towhat some of the Cat diesels use, a flanged sleeve that sits on the surface of the block and a spacer plate.

I just looked at otomoto.com.au and these kits are $26,000? Now the machining to fit the sleeves is fairly basic if you have the equipment. We do it regularly to all type of engines. The spacer could quite easily be CNC machined from a slab of cast iron, we have a guy who does our torque plates and all we need to do it supply a cad drawing. We can have sleeves made in almost any size or shape, crankshaft rebuilders can make a billet couterweighted crank or you could use an RB30 crank to save some money. Argo or PAR can make custom rods any size and length and you could use an off the shelf RB26 piston. Head studs could be ARP 22R toyota or similar which are the same thread as an RB26 but longer and ARP make main studs for the 26. A cometic MLS head gasket isn't too dear either. Either powerbond or romac make a billet steel harmonic balancer for the 26 now. All in all it would make an interesting project.

[proengines]

So people who usually rebuild engines are of the fitter/machinist trades?

I would think that this would over the top for the old mechanic down the road.

Cheers

Sumo

Yep Sumo, there is actually an engine reconditioning trade certificate now but you will find most people working in engine machine shops are fitter/machinists or mechanics who have learnt on the job. The fitting and machining course doesn't teach anything about engines but the machining principles are the same for any piece of metal.

[GDZ1LA]

i think for a 4wd gtr, that conversion (open deck block space (cheaper to machine) will be much cheaper than doing the sump conversion in the end (and less rangi), i might get a qoute on one, ill make it as tall as the deck height of the rb30e block to enable the 1.7l 323 diesel belt,

if i master it it may be a better alternative than the rb30e option (4 4wd only tho)

althought open deck blocks are not as strong but i am sure os did it for a reason?

will the required head bolts be easy to source? rb30e ones are alot longer than twin cam heads they may do m10 tho?

[mark99]

I think Kakimoto make a sleeve and plate kit called a high block kit. Dont think it is too badly priced either. And just for a little extra capacity why not offset grind your RB 30 cranks con rod journals down to sr20/ rb 26 dimensions, use an off the shelf SR 20 Eagle rod (great value for money vs strength), narrow the big end slightly if memory serves me correctly. Then custom piston to achieve the correct comp height and take advantage of the SR 20's bigger diam gudgeon pin 22mm instead of 21 mm.... and you get all most 2mm of extra stroke, all adds to capacity

[GDZ1LA]

sr 20 is 86x86 rb30e is 86x85 (bxs)

offset grinding a factory nitrated crank? has any one done this? does it have to be re nitirted?

[Cubes]

Calcs for the 6cyl RB.

86 bore x 85 stroke in 2962.49cc

87 bore x 85 stroke is 3031.79cc

89 bore x 85 stroke is 3172.78cc

85 bore x 87 stroke is 3032.20cc

87 bore x 87 stroke is 3103.12cc

89 bore x 87 stroke is 3247.43cc

Is 69.71cc's really worth fiddling with the stock crank for?

[MattSR]

I love open deck engines....

[mark99]

Calcs for the 6cyl RB.

86 bore x 85 stroke in 2962.49cc

87 bore x 85 stroke is 3031.79cc

89 bore x 85 stroke is 3172.78cc

85 bore x 87 stroke is 3032.20cc

87 bore x 87 stroke is 3103.12cc

89 bore x 87 stroke is 3247.43cc

Is 69.71cc's really worth fiddling with the stock crank for?

Its not so much the extra capacity, thats just another benefit. The main advantage is going to the smaller journal size so that SR 20 rods fit. Smaller journal size equals slower surface speed on the jounal wich gives the bearing and the oil an easier time. An SR rod has the larger 22mm pin wich is better for higher stress application. If you compare the price of a set of aftermarket RB 26 rods, or for custom rods as in the spacer plate application being discussed here, to using Eagle SR 20 rods, normalising, offset grinding and re-nitriding the crankshaft, it probabley comes out line ball on cost but with all those added benefits. Plus i think the Kakimoto high block kit uses a 20mm spacer plate so if you use the SR 20 rod, at a guess you'd still have both a reasonable comp height piston, half decent rod / stroke ratio. With yet a little more capcity (im a sucker for capacity)

[Cubes]

Interestering..

Slower surface speed.

My concern would be a smaller surface area the greater the load on that surface area.

Is that a concern?

[RPMGTR]

We have built a couple of 3 litre RB26 using the spacer plate method, similiar to the original OS or Kakimoto style. First one used std 85mm stroke RB 30 crank with custom rods and pistons and was 25mm taller than RB26. More recently, we favour destroking to 84mm and reducing crankpin to RB26/SR20 dia. Then using off the shelf SR20 rods (Carillo) and off the shelf 87mm Jap pistons with 22mm pin (Tomei/HKS). 87mmx84mm gives 2996cc, only 20mm overall height increase and turns reliably to 8500rpm. Nissan should have called it the RB29 :aroused:

[mark99]

Interestering..

Slower surface speed.

 

My concern would be a smaller surface area the greater the load on that surface area.

 

Is that a concern?

Yes, but only if the load is too great for the surface area. 1.888" journal diam is roughly the diam of RB 26/ SR 20. This is also what the Americans refer to as Honda journal size when using this size journal in small block v8's. They run this size in a lot of high revving small block applications. But as with everything its always a trade off.... smaller journal size equals slower surface speed , physicaly lighter and smaller components, but less journal overlap so a weaker crank, and yes a smaller surface to bear the load.