Jump to content
SAU Community

Recommended Posts

been looking at cp alot,and want to have that little more displacment but yer depends on what the bores look like, head was serviced less then 8000km ago, thinking bout throwing some springs and a high lift cam in to get more mid range/top end. but once again depends on condition of valves etc to see how far i go there.

I have done something similar i used CP +40 8.5.1 comp pistons and Manley con rods arp2000 bolt set and found no problems with them. All RB25DET engines have block mounted oil squirters.CP pistons dont interfere with them

when getting your motor bored you also might want to get the block decked crank tunnels honed and final hone in yor bores done with a torque plate

I would recomend at least replaceing the valve springs with new standard ones and get the head decked as i think the pistons from usa are slightly lower comp and get the valve seats done

I was told that i would lose performance and later turbo spooling beause of the lower comp pistons but i had the head and block decked and fitted a greddy manifold and got rid of about 4 feet of turbo pipe work

and found if anything turbo spools faster{hi-flow}.

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

That is correct, springs not valves, the thing is tho how much does it cost? The engine is out and head is off if it is not that expensive may as well do it for piece of mind

Yes the head is off... Realistically though it does not need touching at all.

It's just a case of sort the bottom end, bolt the head back on, away you go.

I have 9.0 compression CP pistons. They can do custom jobs but they cost more as they are not off the shelf.

Pity they are only 8.5 compression, I would be interested in 9-9.5. My car only runs E85 so I would look at ~9.5.

i got another head sitting here that i can get somework done on and allways bolt it up later, kind of interested in doing a oil drain from the head aswell while its out.mayby a decent set of springs and get some sure cams for it as well with about 9mm lift

You don't need an external drain if you put proper sized restrictors in that match against the oil flow you will have.

It's funny people haven't needed them at all really before, and the last 18 months they are the latest rage... And are basically a band-aid type solution.

  • 3 weeks later...

25s don't have squirters

Hey buddy, sorry to burst your bubble, but the RB25DET does have oil squirters. They are in the bore and are used for lubrication and for crown cooling.

By the way, I would have gone with JE Pro Series Pistons if you had the dosh. I am using them in my current rebuild as they come standard with Nitrite coated rings and tool steel gugeon pins. I chose Manley H-Beam rods with ARP 2000 rod bolts.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • You very likely need to get it on a dyno and tune it. My assumption is, you've got an RB25DET tune in it, which has a different manifold, different injectors, and different cams as a minimum. What O2 sensor are you running?   When you say it runs extremely rich from idle all the way to redline, is this just free revving it you see that?
    • I seem to the be only person that is using a Haltech 2500 on an NA motor, I've installed a Bosch DBW throttle body to the OEM intake manifold and am having problems maintaining AFR even with the wideband o2.  It will run extremely rich at idle and up to redline, but under load it will go extremely lean in the 20s and i'm essentially having to rev it over 4k and feather the clutch to get it up to speed.  I've read a few other threads of about the butterfly, it seems removing the vacuum to it is supposed to have it remain open, i've noticed no difference under 4k with the vacuum line to it plugged.  I'm hoping someone here has had luck using the NA manifold with Haltech, and if they happen to have a tune for it.  
    • I don't know any details, but I really wouldn't be surprised if they do it as a LHD only version, at least initially.
    • Thanks for the replies everyone. Definitely a coolant push. Oil catch can is empty and always has been. As the engine is out now I'll be having a good look over things. I do have some detonation on the piston tops from a trigger issue back about 5 years ago. I felt it and shut off then bought a new ecu and changed the trigger. Never been an issue since. It never hurt the power, its made almost 80hp more since that incident but I will pull the bearing caps to take a look. If the bearings are damaged I will do a bottom end refresh. Head is being re conditioned at the moment and the block will be cleaned and checked to ensure it's flat. I'll go with a kameari gasket and see how it ends up. The other thing I'm not super keen on is the cylinder colours. I suspect this is from the inlet manifold. The plan will be to put it back together, retune and then stick a plazmaman billet inlet on it and retune. I'm happy with the power, if it makes a little more, then great, but I would rather just make everything more efficient at this stage.
    • Maybe they'll look to do a bunch of presales to help inject some cash fast for their financial issues...
×
×
  • Create New...