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Rb25Det Forged Pistons

t304vkcalais

By t304vkcalais,
in Engines & Forced Induction

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t304vkcalais Enthusiast

t304vkcalais

Posted
Posted

well just got a heap of detonation on my 25 and have decided to pull the motor down and rebuild it.......again, the only things im going to need to change will be pistons,headgaskeet and new bearings.

i have done the n1 pump,oil pump drive gear,oil restrictors,26 rods,arp studs everywhere blah blah blah.

chasing 400hp and i know a standard 25 will do it but im wanting a bit of safety so decided of forged pistons and cometic headgasket, what brand pistons are doing well in 25's at the moment and what ones to stay away from, going to be boring it out 40 thou aswell.

tim

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https://www.sau.com.au/forums/topic/388464-rb25det-forged-pistons/
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SargeRX8 Grand Master

SargeRX8

Posted
Posted

Sounds too far fine to even bother comp testing if you are getting oil ontop of the piston...

Its kind of hard to say. I do know you can get drop in forged pistons which fit the standard bore but do you know if your bores are good? Is the crack still fine? Lots of things to check. If you were upgrading a healthy motor it would be fine, buy if you got a heap of detonation, you need to sus it out. Even head valves, are they still good?

Hyper gear on here has replacement pistons, I think cp make direct replacements.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

going to be boring it out 40 thou aswell.

Why?

Only go as far as you require.

Get a set of Weisco/CP/Mahle from the states. All are good, little issues with any really. More about getting the numbers/build right.

JonnoHR31 Grand Master

JonnoHR31

Posted
Posted

My engine builder said to avoid mahle, they are apparently very loud and the way they are made you have to bend the oil squirters. I just got a set of 86.5mm cp for $800 delivered.

everyone who doesnt have mahles seams to say that yet i've never heard any complaints from people actually using them

lilcrash Veteran

lilcrash

Posted
Posted (edited)

If squirters squirt oil through a gallery in the bottom of the pistons into the rings then yes my 25 does.

My new cp pistons don't have the gallery. I just hope that isn't going to cause too many problems.

Edited by lilcrash
lilcrash Veteran

lilcrash

Posted
Posted

The issue is the pistons are solid across the pin supports?? There is no cut out for the squirters in mahle pistons.

I can tell you 100% certain that my block is stock rb25 and it has squirters.

The Mafia Grand Master

The Mafia

Posted
Posted

Rb26 and rd28s have the block mounted squirters,

Rb25de/t don't so your most likely using rb26 squirters

lilcrash might suggest another machinist if he is having issues with a basic piston like mahle

je and cp are what id recommend

Dude no offense but you are 100% wrong.

Rb25 definitely have squirters.

Every rb25 I have had the sump off has had more squirters than a Asian porno

W0rp3D Grand Master

W0rp3D

Posted
Posted

well just got a heap of detonation on my 25 and have decided to pull the motor down and rebuild it.......again, the only things im going to need to change will be pistons,headgaskeet and new bearings.

i have done the n1 pump,oil pump drive gear,oil restrictors,26 rods,arp studs everywhere blah blah blah.

chasing 400hp and i know a standard 25 will do it but im wanting a bit of safety so decided of forged pistons and cometic headgasket, what brand pistons are doing well in 25's at the moment and what ones to stay away from, going to be boring it out 40 thou aswell.

tim

valves?

25 valves are knowing to be soft and get worse with age, may not need them but i would change them to be safe.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Valve float you mean...? Not the actual valves...

It's very hit and miss debate that one. Lots of people are fine, lots of people aren't.

If the head is in good condition it shouldn't really be a problem as the aim is very moderate, so there won't be a big huffer going onto it. One of the things you don't really need to "do" unless it is actually a problem.

Plenty have made 350-400rwkw on stock heads without changing the springs.

Ye some get to 300rwkw and get valve float. Suck it an see i say.

Gerg_R31 Mentor

Gerg_R31

Posted
Posted

http://ipg-supertech.com/cart.php?target=product&product_id=1300&category_id=853

take advantage of the aus to american dollar (but thats if you want to go all out nuts with the head) then you'd prob want cams, then solid lifters, then porting next thing you've spent around 4k in parts and labour on just the head

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