Tomei Rb26 Piston And Ring Specs

[Stoney85]

I'm in the process of rebuilding my RB26, and will be using the good bits from my last built motor that dropped a valve, but need to find out the specs of these pistons for the machine shop, as they are a second hand set of 87mm cooling channel Tomei forged pistons.

From what I've found, the Tomei website mentions their motor has a 0.055mm piston to bore clearance, and i've also read to set the clearance between 1.9-2.2thou, which backs that up.

Can anyone confirm this, I tried sending an email to Tomei USA, but haven't heard back from them yet.

Also, I'm looking at what options I have for a set of rings, there is the two Tomei options, one being the standard ring set at $400 US, or the set with titanium coated top rings at $800 US, I'm not building this motor to make 1000hp, nor was this a planned rebuild, so funds aren't exactly unlimited, so I figured the stock ones would suffice, BUT before I go and spend $600 Australian on a set of rings by the time they arrive, what other options are available.

Do Total Seal do a set to suit? 1.2mm, 1.2mm and 2.5mm are the ring thickness'

I also got recommended to try wholesale performance as they can make custom ring sets for $250, or advanced ring sets for $400, but I need to have all the required specs to give them.

What about ring bedding in procedure? Will whatever ring set I get have a recommended honing pattern and grit coarseness to hone to?

[GTRPSI]

Hone finish should be based on the ring manufacturers recommendations.

Bore to piston clearance should be based on the piston manufacturer.

Seal pro do make 1.2 comp and 2.5 oil rings.

Most off the shelf packages are 1, 1.2 comp and 2.8 oil, some are 1.2 1.5 and 2.5 or 3mm oil.

They can put together whatever you need, give them your ring thickness package and bore and bobs your uncle.....

Last time i needed a set of 1, 1.2, 2.8 seal pro rings the were around $150-$200 to my door for a RB26.

[Stoney85]

I've sourced a set of Tomei rings, went with the original ones, but the info I have found available is all in Japanese, was $500 sourced from the states, not cheap, but I know these are exactly what is needed, rather than guessing and hoping a custom set is correct, would rather not have to rebuild the motor due to an incorrect sizing issue.

Still awaiting a response from Tomei, hopefully I can get the manufacturers specs on the honing procedure and ring/bore clearances.

[Ben C34]

Why can't other ring manufactures make rings?

[Stoney85]

Never said they couldn't, but I couldn't find too much information, and going to a third party ring supplier, I wanted to have all the information, plus I didn't have the old rings on hand as comparisons

[djr81]

http://www.tomei-p.co.jp/manuals/pdf/piston.pdf

See page 13 - .05mm to .055mm

[Stoney85]

Legend, I had already seen that, and saved it, but had only glanced at the first half seeing it in Japanese.

[GTRsean]

Got mine honed to 2.5 thou, tomei pistons, torque plate hone.

[Stoney85]

Is there a reason you went with a bigger clearance than recommended?

I went with about 2though in the end, it's definitely a tight motor, yet to drain the first run in oil, as i've only just done about 250kms, will do a compression test out of curiosity soon.

[GTRsean]

2 thou is good, as the tomei (jap brand) pistons seem to have a higher silicon content than the US counterparts, so they won't expand as much..

My machinist thought 2 thou was a little tight lol.

I'll find out what it looks like when I pull mine apart for a birthday. I built it a few years back.

I want to remove the L19 rod bolts and put in some new ARP 625's

[STATUS]

keep em tight ours lasted years of abuse at the middle range.

[GTRsean]

^

Agreed.

The way these pistons are made go with that

[SilverECR33]

With ACL gone belly up I'm wondering what choices are we left with for rb30/26/26