Nicoseal

[rob82]

Any one tryed nicosealing the cylinder walls in a RB motor, more specifically RB26? Its just that I want to try and use 87mm pistons as probably going to be a little over 87mm + clearences, so I need to build up the walls. I know they use it in some porche motors and a shitload of bikes but never really heard of it anywhere else. Also does anybody know where I could get it done?

[MattSR]

Dont you mean Nikasil?

[SteveL]

I think you mean 'Nikasil', and I believe it can only be used on aluminium alloy cylinders (RB blocks are cast iron).

Not sure what you mean by 'build up the walls' since you have to bore the engine for 87mm pistons. If the block is already bored out but worn, you could have it sleeved to recover it.

[rob82]

Yep wasn't sure on the spelling. The bores are already accepting the largest standard oversize piston. The average bore diameter measuring thrust side is between 86.7 and 86.8 with little to no runout however there is some rather large scores on cylinders 4 and 5. I was looking at using 87mm CP pistons that I think run a 3.5 though clearence. I think by the time I bore the cyclinders to remove scour and allow for honing I will be just out side the 3.5 thou clearences. So I was wondering what thickness and if it was possible to nickasil the bores to allow me to run the 87mm pistons. However I wasn't aware that aluminium alloy cylinders was a needed.

I could re sleeve but dont want to go to those lengths.

[N I B]

Jap companys have 87.5 and 88mm pistons.

[The Dan]

You don't want to go to the lengths of resleave but you will go to the trouble of getting Nikasil done. IMHO why don't you get a set of custom ROSS pistons. The ones for my 20 only cost me $1250 including freight, pins, retainers and moly rings. You can get them to make them whatever diameter you want and then hone the block to suit the pistons....that would be the best way to do it plus more durable.

[ylwgtr2]

i get nikasil done all the time on bike cylinders.....its quite expensive and as someone else said for alluminium only.....kawasaki started it and now most if not all manufactures use it..the early kawasaki's had drama's with it coming adrift from the cylinders in two strokes....sr20's have it

[discopotato03]

I though SR20's used cast in iron liners . Cosworth alloy block 2L BDG's used it .

[Denver]

AFAIK there arn't many companies in aus that do it, atleast reliably, i know of a porche 928 race car in perth, that had the bores re-done when it was rebuilt, 928 motors are an all alloy v8, which have the sealing done at the factory, but when are rebuilt, need it re-done..

After the motor was running for a few race meets, the sealing started to break down, and after a lot of research by the owner, he came to the conclusion he'd have to send the block back to a german company to get it done correctly as the various shops in aus didn't seem to have the right gear/know how to perform the job correctly..

[proengines]

Wiseco make an off the shelf 87.5mm piston. HKS makes them in 88mm. There is plenty of thickness in the bores of an RB26 so going to these oversizes isn't a problem.

As for the Nikasil, you can buy Nikasil coated sleeves but they are very, very expensive and you need to machine the block to fit them, you also need diamond honing equpment to hone them succesfuly, some of the Nextel cup teams run them in cast iron V8 blocks. As far as I know, no one coats cast iron bores. You could sleeve your block back to standard for around $800 using regular cast iron sleeves. Ninasil coating is only .002-.003" thick so you need a very straight, round bore before it is applied as there isn't much there to hone out to true the bore up.