RS225 OEM pistons and forged rods?

Discussion in 'Mechanical - Engine, Gearbox, Exhaust etc' started by maece82, Jan 19, 2021.

  1. I would like to rebuild a spare F4R-774 engine for my daily Megane 225. A used mid-mileaged engine in good looking condition, is already at hand and now I'm trying to source all the parts, needed for this rebuild job.

    This would be my first build, hence, sorry for my maybe "stupid" questions.

    I don't like to gain much power at all, as the car should stay a trouble free daily and not become a unicorn garage queen. Due to this, I think the forged piston, even in 4032 alloy, might need a piston clearance, that's not really recommended for an every morning cold start-up. Due to this and not needing the additional "robustness" of forged pistons, I think staying on OEM cast pistons would be a proper way. Or in other words, the potentially quicker wearing rate of forged pistons not being worth it at a near OEM power level...

    Getting everything nicely balanced and all the parts renewed, which have to be, would result in a proper healthy engine.

    Having fully floating piston pins, combined with moderate forged rods (PEC) would be nice as well. Does anybody already have modified OEM pistons, to accept the floating pin wire clips? And where could I source new OEM pistons? I'm not sure if this is really possible at all. But I know of older engines, where modifying pistons to accept fully floating pins, wasn't a big task...

    Any hint really appreciated!

    Many thanks and cheers
  2. Hey

    i Drive my with forged piston daily and the only issue is that mornings if it’s could the pistons could make a sound like a Diesel because the tolerance they should / must have.

    but that ist gone after a mile. but because of that I decide to make my car a sessional and get myself a wintercar to reduce stress / wear of the pistons.

    I think the best option for you would maybe just Megan’s 3 pistons and Conrods if you doesn’t need to bore the block.

    they can handle 400/400lbft as i found out.

    BTW to say I’m totally happy with my forged engine it burns not a single drop of oil and have no issues at all. I drive Woessner pistons
  3. @Jukidam
    Cool, many thanks!
    What kind of forged conrods did you choose?

    Nice to know, that there don't have to be a huge oil consumption caused by the Wössner pistons at all. I think Wössner pistons are made of 4032 alloy, right?

    As far as I've seen on pictures in other threads here, OEM pistons on both 225 and 250 cars are already equipped with fully floating piston least, there are visible wire rings to keep the piston pin positioned...

    Are the OEM 250 pistons suitable to install in a 225 block, without having problems with valve clearence? So, no modification might be needed on these pistons?
  4. Hey

    i have some Chinese one from a German distributor which are like the 250 at the top eye not flat they are pointed like a trapezoid for better pin cooling. (Made by the German distributor)

    mounted on flat woessner piston. Don’t know which material. But yeah oil consumption like zero and have a good quality.

    As I know yes they fit without issues to the 225 block but for sure @ianplymouth can answer that. They have another compression ratio as I know but I’m not sure.
  5. I have built a couple of forged engines now, the first was with Wossners, it didn't last long in my ownership as the turbo exploded.
    The next was my 265 i was told not to use Wossners due to the quality and shrinkage issues, so i went for Iasa pistons, or i could have gone for CP pistons but they are difficult to find.

    So on my build that in progress atm i have used Iasa pistons again, my 265 is so quite from cold unlike a few i have heard using Wossners.

    The first two builds i used PEC rods, but on this one i could not get them as there was a supply problem, so these ones are Catcam rods, they look so similar to the PEC rods.

    Both sets of rods are rated at 1000ftlb of torque, the pistons are rated at 600hp a set, Arthur (Tuttur) on here ran standard pistons and forged rods and i'm sure he was running 400hp with his GT220 estate.

    OEM pistons will fit the 225 block, there aren't any differences between them, the compression ratios are different but thats down to the cylinder heads.

    You can use 250/265 pistons and rods in a 225 and that would give you the option to run 350 hp and 350 ftlbs pretty safely, i am building an engine with the pistons and rods out of my 265 as a spare :laughing::laughing:
  6. If you are using flat top pistons then that going to be putting your compression ratio up a good amount, was that your intention ????
    Or are you compensating by removing material from the head ???
  7. The same questions interest me. I don’t even like the thought of my car running like diesel in the morning. :fearscream:
    Can be purchased factory mk3 oem pistons 83mm ?
    Are there other pistons that do not have that diesel effect. With less tolerance. For a car for everyday use I don't need more than 280 hp.
    Where to buy ?
  8. @ianplymouth
    Great, many thanks for sharing all your knowledge and lessons learnt!

    Nice to know the difference in forged pistons and to know 250 pistons being a tad more stable than the 225 ones.

    Yes, quite complicated to find a source for new 225 / 250 pistons...could one buy these pistons at a Renault dealer only?
    Having 250 pistons in its first oversize dimension 83 mm, would be great!!!

    I did some online research and neither of the "normal" known piston manufacturer like Mahle, Kolbenschmidt and Nüral have these pistons listed:-(

    Does anybody know which company is manufacturing OEM 225 / 250 cast pistons?
  9. Some numbers for complete OEM pistons (piston / pin / clips / rings):

    Megane 225:
    Diameter 82.70 mm
    82 00 264 972
    82 00 264 983

    Megane 250:
    Diameter 82.70 mm ??? (should be)
    82 00 899 268
    82 00 899 270
  10. Hi Mate
    I feel that's what the forum is for,
    1, its to help people that don't have the confidence to have a go themselves
    2, for others to learn from my and others mistakes
    3, and to tell you when things work out :laughing::laughing::laughing:

    To be honest, if you are looking for pistons, new ones from Renault will be more money than forged piston if you can find anyone selling pistons that they took out of there 250/265/275 to forge it would be the second option.

    The price of the pistons and rods are a part of the cost, if your doing a full build, the price of the likes of gaskets, oil pump, valves, valve springs, head bolts etc etc etc, that price will still be there.

    Its the conrods that are really the problem with theses engines and not the pistons, the 225 and R26 also suffer with fuel supply issues if you are pushing the horsepower up from standard, there isn't a set limit the conrods go, some have managed a good bit over 300ftlb of torque and then some have let go at a lot lower level.

    Piston problems are with the fuel supply limits of the fuel rail.
    Brigsy and manugtt like this.
  11. Hi mats,

    Forgiving my asking, why the forged pistons wear quickly than cast one?
  12. As far as i'm aware they don't wear, they shrink over time with the heat cycles.
    In my 265 i had Iasa pistons, even from cold the engine is very quite and still is when hot.

    A friend has Wossners fitted in his and it sounds a bit like a diesel on first start up it does quieten down when hot but you can still here piston slap.
  13. oh I see. I have JE Pistons in my 205 for more than a decade and it stills sounds ok, lucky me.
  14. autronix

    autronix RSM Club Member

    sorry to resurrect such old thread ,

    the Megane N4 rally spec is (was) using stock internals by regulations.
    the Pectel/Cosworth management was set to around 330 bhp but yet the cars were using turbo restrictors to limit around 270 bhp.

    the oem pistons proved to be resilient with all that race conditions + a lot of ALS :smile:

    so like some users here stated oem pistons + forged conrods seems to be a good setup if crazy power figures are not on the menu.

    on the other hand ,for the forged pistons vs bores clereances , needs to be measured by proper tehnician with pro tools and machined on Haas , Rotller , DMG Mori , etc .
    Filo likes this.
  15. autronix

    autronix RSM Club Member

    what brand to use for forged conrods? at this moment I found on the market , wossner , catcams and italianRP.

    (in the wossner listings pec conrods are also included , so I wonder is there any real difference between pec and wossner , or the wossner ones are pec rods with wossner laser stamps on it)

    many thanks
  16. I use Catcam rods, even ktec (so i have been told) don't use PEC rods anymore, think they had some issues with them.
    Mine is running 404 hp and a mates is running 500 hp and we track them all the time.
    autronix likes this.
  17. autronix

    autronix RSM Club Member

    there are also a lot of china rebranded conrods. I think I will go for italianRP platinum series as I have them in EU. import any other brand from UK is almost impossible due to infinite delay times. (I waited 50 days on hold at ktec for an scorpion catback, then I asked for refund. got the same item in Portugal at all stars, next day delivery....)
  18. I ordered a pair of track rod ends from Ktec on the 16th July and i still have not received them, better call them again :rage::rage:
  19. Just called them, still no stock :rage::rage:
    Got some aftermarket ones for the same price, how's that, i guess they don't want to give any money back
  20. autronix

    autronix RSM Club Member

    they will refund no worry
  21. autronix

    autronix RSM Club Member

    anyone knows please what brand/type of forged con rods can be used with the standard MK3 pistons? many thanks

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