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Discussion Starter · #1 ·
Guys,
Still quite a newbie regarding internals of my RB. See, I just have installed a Nismo oil pump, and since the engine was going out, might as well check the whole engine..

Unfortunately we found out that one of the block's cylinder has a scratch, so the next thing to do is bore the block to 87mm from an already big from stock 86.5mm.

Now my problem is choosing the right piston for the engine, I am now looking at Tomei forged piston, OEM 87mm piston, or N1 piston. The car is not a race car but me and my friends sometimes have some weekend spirited driving and track days. By the way the car was 520hp...

So guys hope you can help me the "light" on my little problem.

Thanks in advance!!! :)
 

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I have used HKS, Wiseco, CP, JE and Tomei pistons with good results, for your needs I'd see go with whichever can be had at the best price. IMO the main concern is gapping the rings correctly. I see LOADS, and I mean LOADS of recently rebuilt engines that have oil usgae or compression issues, and on strip down the aftermarket ring packs have had anything fro 40 thou gaps to no gaps at all.... It is ESSENTIAL to take the time to get them spot on. Currently I find I can buy JE ones at a great price.
 

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Discussion Starter · #3 · (Edited)
I have used HKS, Wiseco, CP, JE and Tomei pistons with good results, for your needs I'd see go with whichever can be had at the best price. IMO the main concern is gapping the rings correctly. I see LOADS, and I mean LOADS of recently rebuilt engines that have oil usgae or compression issues, and on strip down the aftermarket ring packs have had anything fro 40 thou gaps to no gaps at all.... It is ESSENTIAL to take the time to get them spot on. Currently I find I can buy JE ones at a great price.
Thanks for replying/helping bro... :) that is what I thought also, the gap issue. Currently the oversized oem ones is the cheapest, but do you think is it ok for my situation (the car being just a weekend fun car, seldom friendly track days) that I only use oem ones instead or should I go straight to forged ones?

Thanks again mate!
 

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I have used HKS, Wiseco, CP, JE and Tomei pistons with good results, for your needs I'd see go with whichever can be had at the best price. IMO the main concern is gapping the rings correctly. I see LOADS, and I mean LOADS of recently rebuilt engines that have oil usgae or compression issues, and on strip down the aftermarket ring packs have had anything fro 40 thou gaps to no gaps at all.... It is ESSENTIAL to take the time to get them spot on. Currently I find I can buy JE ones at a great price.
Sorry to rob the thread....

Question for Chris Wilson, What do you recommend for a starting gap on a set of JE pistons? I have them in my engine with the JE rings, And it took ages to bed in, and breathes a little heavy. Also I have had a lot of people say I should have used Nissan rings, as they suit the block better? What do you run?
 

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Have used wiseco on a previous build which seemed ok.
Used cp on my latest eng. chose these over je based on having heard
of bedding in issues with je rings.
Used the manufacturers specs on ring gaps which from memory
is around 15 thou. But check with the data sheet with rings to
confirm.
 

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Also forgot to say am sure tomei v good. But wildly expensive
compared to cp etc from states.
Unfortunately exchange rate has slipped quite badly last couple of weeks
so stuff from U S will be a little more at the mo.
 

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The stock RB26DETT pistons have the hollow cooling void in the crown that the oil squirters agitate cooling oil around, which offsets the fact they are cast. The only aftermarket forged pistons I have seen and used that retain this feature are the very expensive Tomei ones. If the budget permits I would go forged, but a lot of people seem to get big power from the cast, stock pistons. Another thing I see all the time on piston engines is huge valve guide and bore wear issues, plus turbo wear on supercharged engines, through the usage of terrible air filters. HKS seem about the worst for this, I had an ultra low mileage R33 GTR that was factory stock save for HKS filters, that went from 3 / 4 % leakdown to 28% leakdown in about 10 track days. On stripping the text book signs of wear through grit inhalation wear evident everywhere. I was told to get rid of them, especially on track days where sand from gravel traps litters circuits, but i was too busy / too idle / too stupid to bother. The costs were huge...

You can put Omega pistons in one, Cosworth, whatever you like, they'll all be *uggered by inhalation of dirt :)

As for ring gaps follow the piston makers recommendations for a boosted engine. If you are putting new rings in old bores you MUST have the bores honed firts, otherwise they may never bed properly. Honing can be good or bad, it needs doing correctly whether on new or used bores.
 

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Discussion Starter · #9 ·
The stock RB26DETT pistons have the hollow cooling void in the crown that the oil squirters agitate cooling oil around, which offsets the fact they are cast. The only aftermarket forged pistons I have seen and used that retain this feature are the very expensive Tomei ones. If the budget permits I would go forged, but a lot of people seem to get big power from the cast, stock pistons. Another thing I see all the time on piston engines is huge valve guide and bore wear issues, plus turbo wear on supercharged engines, through the usage of terrible air filters. HKS seem about the worst for this, I had an ultra low mileage R33 GTR that was factory stock save for HKS filters, that went from 3 / 4 % leakdown to 28% leakdown in about 10 track days. On stripping the text book signs of wear through grit inhalation wear evident everywhere. I was told to get rid of them, especially on track days where sand from gravel traps litters circuits, but i was too busy / too idle / too stupid to bother. The costs were huge...

You can put Omega pistons in one, Cosworth, whatever you like, they'll all be *uggered by inhalation of dirt :)

As for ring gaps follow the piston makers recommendations for a boosted engine. If you are putting new rings in old bores you MUST have the bores honed firts, otherwise they may never bed properly. Honing can be good or bad, it needs doing correctly whether on new or used bores.
Ah ok, are you talking about the foam filter by HKS? I currently have them, the racing type ones. :(
I also saw the Tomei pistons w/ cooling channel, yeah they are really expensive!!! Almost twice as much!
And dude, does the stock oem pistons of RB26 are the only ones having cooling channels vs. the likes of RB25 and SR20?

Thanks!!
 

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Yes, the foam filter elements from HKS, they are total junk in my opinion. There are very few foam filter elements I trust, two examples being Pipercross and ITG. You are far safer with a paper element filter, a modded stock air box with the stock paper element filter should be fine for all but the most radical of engines, it pulls cold air, seals the filter element properly, is light, comes free with a stock car and the element is designed to last X tens of thousands of miles in dry and dusty countries. Change it regularly and it should be fine. I am 90% sure the RB25 pistons do not have the cooling channel crowns, I am in the workshop later, I'll look at some.
 

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Discussion Starter · #11 ·
Yes, the foam filter elements from HKS, they are total junk in my opinion. There are very few foam filter elements I trust, two examples being Pipercross and ITG. You are far safer with a paper element filter, a modded stock air box with the stock paper element filter should be fine for all but the most radical of engines, it pulls cold air, seals the filter element properly, is light, comes free with a stock car and the element is designed to last X tens of thousands of miles in dry and dusty countries. Change it regularly and it should be fine. I am 90% sure the RB25 pistons do not have the cooling channel crowns, I am in the workshop later, I'll look at some.
Ok pls. sir!! :thumbsup: And was wondering if all RB26 generations from 32-34 had this cooling channel crown?
 

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Could you not get custom pistons made by CP with the coolings channels in them perhaps by copying the OEM piston design? I am sure that would be cheaper than a set of Tomei's?
 

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I know Tomei products...and also how expensive they are.

I'm currently rebuilding my RB26 and wonder if Cosworth or CP Pistons wouldn't be as good as Tomei...

Any opinions?

(not talking of Tomei pistons with cooling chanel BTW)
 

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Mate of mine is running Wiseco pistons.
Seem pretty good.
I have wossner pistons in mine. They are a good piston also.
You have loads to choose from.
 

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If you want to know every single make of piston, read the "Who amkes the best pistion" thread ...
Theres so many options and tbh engines dont usually fail because of who made the piston...
I use Arias , which are also fine.
 

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I m thinking of buying Tomei piston kit 86.5mm with no recess. Can i just change that kit without changing stock crank shaft and con rods?
Or
Do i have to buy stroker kit which includes crank and con rods.
thanks
 
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