Jump to content
SAU Community

Recommended Posts

hi all ive been doing a fair bit off research on forged pistons but can not make my mind up on size.?

A: Should i go for standard forged size for rb25det,.?

OR

B: Get 20thou oversize forged pistons,.?

option A sounds easy thats if the bores are ok.

But then i can get it bored out the same size as the oversize pistons then i will have a nice smooth bore.?

if you can give me some advice that would be great.

Cheers

Allan.M

Link to comment
https://www.sau.com.au/forums/topic/213876-acl-forged-pistons/
Share on other sites

well the motor with standard pistons and rods is fine has not been boosted more than 8psi since i have had it so you think go with the standard size forged pistons then get my machinist to check out the bore then he will let me know if i need more clearance encase of scrubbing from the piston.

but wouldn't it be better to go that tad little bit bigger so there is a fresh new bore to work with.?

cheers

Allan.M

Now i need a rb25det block anyone got one in Adelaide.?

take my time and build it right.

yeah true so do you think its still worth going the 20tho oversize pistons or stick to standard size.?

any advice will help me with this decision.

cheers

Allan.M

Edited by R334door(s2)

get bores checked for roundness. if they are still perfectly round (which isnt uncommon) then stick with std size. but u will still need to get the bores machined out to suit the new forged pistons (even if its just .001 thou)

the bores on my rb26 where still showing the factory cross hatching. perfect round and no machining nessacary for a standard sized set of forged pistons.

well the front 5 where. number 6 had a broken ring land and ever so slight scoring because of it. a slight hone might have gotten ridden of the mark but decided not to take the chance.

Its not so much the roundness, its the taper, as 99% bore wear occurs in the top 15mm. Anyone who has rehoned a second hand bore can tell you that its obvioius as the hone does the whole bore except the top 15mm. IMO if you are having to buy another block, then machine it out, its really not a lot of extra $$$, in the unlikely event that in the future you need to bore it out again twice, then buy another block then.

Edited by Adriano

just get the machinist to check the block first, then get the smallest pistons you can to allow for future use.

no point buying 20 thou over pistons and then finding out you needed 40 thou oversize due to some problem

ok so ive decided to go standard size by what every one has said.I am looking at a block that a friend has and ill get it checked out to make certain the bore is all fine.

cheers guys keep the info coming.

cheers

Allan.M

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

    • Stock ECU (or more accurately stock tune) absolutely refuses to go over 10psi and behaves like you have seen. The Nistune is the same if it is the stock tune. If the Nistune chip has been tuned, the resulting tune could be literally anything for any combination of parts. The Nistune just makes the stock ECU Tunable.
    • So stock ECU does not like anything above 10 psi?  That Nistune one is just for "try" if it will be any different, I know it need to be tune for that. I know but YOU may know about these problem but i/we dont. They few little Skylines here let alone people who know anything about tham so that is why iam asking here  
    • So now we have a radiator with no attachments whatsoever. It lifts up with a particularly tight spot between the drivers side air box mount and the lower radiator outlet, but if you've got this far you will sort that too. This is the lower mounts with the rad out so you can see where the rubber bushes go, it is a straight shot upwards Done! Assembly is the reverse of disassembly, with blood less likely to be shed.
    • Right, onto the second last trick. The Air Con condenser is mounted to the front of the radiator and stays in the car when the radiator is removed. There are 2x 10mm headed self tappers holding the top of the condenser to the radiator, remove those The bottom of the condenser is attached to the radiator with clips. You need to lift the condenser out of those clips and clear (up, then forward). f**ked if  could work out how to do that last bit with the front bumper on. I hope you can, and you share the trick.  Bumper removal probably deserves its own thread one day once I've recovered the will to live, but basically you need to remove the wheels, front inner guard liners (clips and 10mm headed bolts), the self tapper between the guard and the bumper at the rearmost point of the bumper (same as an R32 that bit), any remaining clips at the top/front of the grill, an absolute bastard design with a plate that holds the top of the bumper above the headlight each side (only 1 bolt which is tricky to get to, but the plate catches 2 places on the bumper and must be removed....carefully!) and push clips between the bumper and guard under the headlight. If you've done all that you will be faced with wiring for the fog lights on both sides and in ADM Q50 RS at least, 4 nasty tight plugs on the driver's side for the ADAS stuff. So, the clips at the bottom look like this on drivers side (looking from the front) And on the passenger side (also from the front), you can see this one is already out Clearance on both of these are super tight; the condenser needs to move up but the upper rad support mount prevents that, and the radiator can't move down far because it is (rubber) mounted. Once you achieve the impossible and drop the condenser off those mounts so it does not stop the rad moving, you are good to go
    • OK, next the shroud needs to come off and there are a couple of tricks. Firstly, there is a loom from near the passenger side headlight to the fans, coolant temp sensor etc and there is no plug to undo.  In my case I was OK to leave the shroud on top of the engine so I just undid the passenger side fan plug and about 10 of the clips which gave enough free wire to put it aside. The fan plugs were super tight, the trick I used was a small falt screwdriver to push down on the release tab, then a larger flat screwdriver to lever the plug out of the fan unit....be careful with how much force you apply! If you need to remove the shroud altogether for some reason you will have to deal with all the plugs (tight) and clips (brittle)....good luck. I removed all of the clips and replaced them with cable ties that I will just cut next time. Also, in the Red Sport / 400R at least, the intake heat exchanger reservoir hose is bolted to the shroud in 2 places with 10mm headed bolts; so remove them (the hose stays in the car; no need to undo it at the t fittings down at the radiator lower mount. Once you've dealt with the HX hose and the wiring loom, there are 3x 10mm headed self tappers holding the top of the shroud to the radiator; remove those.   The shroud then lifts out of the bottom mounts where it sits on the radiator, up and onto the engine out of the way. Simples
×
×
  • Create New...