yellowturbo

Hi ! last night I was reading somes old magazines and I found something really important :

SRP pistons contain silicon in the aluminium... so they dont expand as much as JE piston who contain almost no silicon...

So they said that the SRP will be better for a street use because the could be fit tighter so less noise when the engine is cold for a better seal and they will not expand as much as JE ... and the JE are supposed to be used only for racing application when the engine is build to be always really hot...

When building an engine you have to keep in mind the expansion of the piston when the engine is hot... to get the good clearance when the engine is cold...

So im rebuilding my engine and I have SRP pistons ... so were I could find the good clearance to use...

So GOOD engine builders I need advice and opinion..... because my last engine builder built my last engine with SRP and he didnt ( and I didnt ) know this ..... My engine was really noisy and didnt last really long... now he leaks like a bitch on a leak down test and dont seal right and burns oil like... so I rebuilt the engine and I want it tight like a virgin lol ...

Thank

Mat

yellowturbo

anyone could help me ???

99B16Si

kim assuming youre referring to piston to wall clearance and mayeb ring gap also.

piston to wall...i would say around .004-.005
and ring gap around .016

i would just close up the piston to wall a bit to compensate for less expansion compared to a fully forged piston.
the ring gap doesnt really matter too much on the type of piston, mainly just the applicationa dn how much heat they will see.

yellowturbo

thank ! anymore opinon on this ???

Sonny

Piston to wall clearance in the .004 to .005 range will have you sounding like a diesel even after the thing is warm. My forged Endyn/Wiseco pistons were installed with .0025" of clearance and they are a little noisy at startup.

I think your best bet is to call JE themselves and ask. You should definitely run the clearances tighter than you would with a forged low-silicon piston, but I don't know if you can go as tight as a stock cast piston. (usually from .0004" to .0016")

There's a guy named Randy at JE that has helped me out in the past. Ask for him.


Sonny

yellowturbo

thank ! but anyone have SRP piston... how you set the wall clearance ????

Adi Radoncic

I had my sidewall clearance set at .002 for my srp's if you give them too much play the motor will sound like crap and sence they don't expand staying with a low clearance will give you the perfect combination for power and reliability..

Adi

99B16Si

i got .005 on my JE's and they make pratically no noise after full warm up

99B16Si

also, the machine shop needs to set the piston to wall clearance. u need to give them your block and your pistons and tell them what u want the walls bored to.

yellowturbo

thank you !!! oh ... and is it bad to use my old piston ?? I have a block that could be bored the right size for them ....

or I have to change them ???

yellowturbo

http://www.jepistons.com/pdf/2...h.pdf

look at the second page... the clearance are there... !!! : )

99B16Si

depends on the condition, also, measure the piston to ring clearance and bore diameter.

yellowturbo

newgsr you probably mean 0.0002 not 0.0020 ... look at my link...

99B16Si

.002 is right but a very tight clearance for forged pistons

Adi Radoncic

Yep you are right i meant 2 thousands not 20, you got to keep it tight with the srp's

Adi

Cyber ITR

i thought if a piston contains silicon , it will expand more ?

yellowturbo

no read the link... silicon mean LESS expansion ...

30psi Teg

What I hear is that pistons that dont contain silicon need an extra .001 to expand so... I set my pistons Wiseco, Ross to ~.004-.005 runs real smooth no noise at all. So for you a piston to wall clearance of .003 would be good.

Dont run to tight of a clearance like .002 or less you need to let the boost get by the rings so they seal up tight.

If you are that concerned about it just call SRP

RyanEJ8

My D16Y8 SRP pistons recommended "that all import piston clearance should be measured at .0015 to .002, however some applications such as marine, drag race, nitrous and forced induction may require additional clearance (.001-.003)." I had my machinest set mine to .003. This was done since I am building for forced induction. It sounds a little louder when its cold, but it is not bad at all once warmed up.

My rings were also set to SRP spec for forced induction. Bore 2.972 x .006 = 0.018" for the top ring, Bore 2.972 x .0045 = 0.013" for the second ring. These I file fit myself.

turbo sol

i have .0030 for my srp's and they work fine. When it is below freezing its noisy untill it warms up but most cars are noisy in the cold. CALL SRP/JE and talk to them, they will be more than happy to help you out.

I agree that .0040-.0050 is too much

Adi Radoncic

Noise Noise Noise, is what you get if they are too loose.

Just call srp and see what they say and than report back to us please!!

Thanks,

Adi