Ive got a slapper
04 June 2009, 08:04 PM
#2
If you have forged pistons inside, then totally normal... So long as the noise totally goes away when up to temp!
The metal properties of forged pistons mean that they're in tolerence when up to normal operating temp i.e. expanded, therefore physically larger diameter. So when cold/below normal op. temp., the metal contracts a minute amount making them slightly undersize, hence the 'slapping noise' as the piston rings hit-come away-hit-etc... the cylinders' walls.
The metal properties of forged pistons mean that they're in tolerence when up to normal operating temp i.e. expanded, therefore physically larger diameter. So when cold/below normal op. temp., the metal contracts a minute amount making them slightly undersize, hence the 'slapping noise' as the piston rings hit-come away-hit-etc... the cylinders' walls.
Last edited by joz8968; 04 June 2009 at 08:09 PM.
04 June 2009, 08:13 PM
#4
If it makes you feel any better, I have a ZEN-built refreshed WRX v.1 ODB block with forged STi v.3/4 pistons in, and have exactly the same symptoms. When it had the original OEM non-forged WRX v.1 pistons in, no noise from cold whatsoever.
Last edited by joz8968; 04 June 2009 at 08:16 PM.
04 June 2009, 08:31 PM
#5
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FEEL ALOT BETER I HAV EXACTLY THE SAME IT WAS A WRX BLOCK NOW STI SPEC YOU DONT KNOW HOW MUCH YOU HAVE MADE ME CHILL. SORRY BOUT THE CAPS GOT 1/2 WAY AND CBB TO GO BACK. WT BHP R YOU RUNNIN
04 June 2009, 08:57 PM
#7
It's running 1.15bar (as mapped by JGM) on a Power FC, Walbro, Green panel, PFR7s, decat, etc. for about 280bhp.
This new engine has just finished running in, and am at ZEN's tomoz for oil/filter, and its remap. Still got the 380s and TMIC (silver STi v.2) on, but have the A'PEXi 3bar MAP sensor, so will bring that along to see if Paul agrees on fitting it, so as to map at 1.2bar (or more?). If so, hopefully will see 300!
This new engine has just finished running in, and am at ZEN's tomoz for oil/filter, and its remap. Still got the 380s and TMIC (silver STi v.2) on, but have the A'PEXi 3bar MAP sensor, so will bring that along to see if Paul agrees on fitting it, so as to map at 1.2bar (or more?). If so, hopefully will see 300!
Last edited by joz8968; 04 June 2009 at 09:02 PM.
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04 June 2009, 09:53 PM
#8
piston slap here. sounds like a bag of spanners in the morning but perrs like a kitten when warm. doesnt bother me anymore. no ill effects. forget about it mate and enjoy the car.
05 June 2009, 06:02 PM
#10
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im having mine mapped by jgm wednesday its wrx spec with an sti block want to go 1bar of boost ive been told i can expect betweet 280 and 313 bhp. im thinking of getting a front mount and injectors next
06 June 2009, 02:09 PM
#11
https://www.scoobynet.com/general-te...ml#post8748684
Last edited by joz8968; 06 June 2009 at 02:34 PM.
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