I'm building a stroked ls-v with custom JE pistons, its my first build with aftermarket parts and i was wondering if anyone who has used these pistons before had too much piston to cylinder wall clearance? would the piston, since its aluminum alloy, expand a bit during the break-in period? or should the piston fit snug like oem pistons from the get go? right now the piston to cylinder wall clearance is no where near .0025-.0035" as the instructions on JE's website states. The clearance as of now measures .035". Any information will help, Thanks in Advance.

 

send those pistons back and get a set that will fit a little snugger

 

Forged pistons expand more so require more clearance.

0.0035" sounds about right to me.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pomansouth01 &raquo;</TD></TR><TR><TD CLASS="quote">send those pistons back and get a set that will fit a little snugger</TD></TR></TABLE>

Edited: for decimal place.


Modified by Furyof4 at 12:59 PM 4/5/2007

 

you forgot a "zero". 0.0035 sounds about right, or what ever CP says it should be.

 

Woops, your right.

Changed it.

 

haha hopefully slowferio forgot a zero too.

 

Hopefully. CP recomends .0035 for turbo apps, .003 for NA. Its designed into the skirt. If they sell you an NA style forging thats marketed for an 4" bore, the piston will measure 3.997 in the area you would measure for p2w.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">Hopefully. CP recomends .0035 for turbo apps, .003 for NA. Its designed into the skirt. If they sell you an NA style forging thats marketed for an 4" bore, the piston will measure 3.997 in the area you would measure for p2w.</TD></TR></TABLE>

do allpiston manufacturers follow this practice?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Suck my DX &raquo;</TD></TR><TR><TD CLASS="quote">

do allpiston manufacturers follow this practice?</TD></TR></TABLE>

Most, but some are more accurate than others. This is why you should bring your pistons to your machinist when getting your final hone on your block. So he can take indiv. measurements on each piston and size each bore accorindingly.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">

Most, but some are more accurate than others. This is why you should bring your pistons to your machinist when getting your final hone on your block. So he can take indiv. measurements on each piston and size each bore accorindingly.</TD></TR></TABLE>
that makes sense....thanks

 

yeah mine measured .035, no missing "0" here.. so i should really send the pistons back?

 

Absolutely. Thats a ridiculous amount of clearance.

 

How are you measuring piston to wall clearance? The piston will measure quite a bit smaller at the top.

 

the measurement i took was from the top.. i'm not sure how to measure this. would the piston expand .01''

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slowferio714 &raquo;</TD></TR><TR><TD CLASS="quote">the measurement i took was from the top.. i'm not sure how to measure this. would the piston expand .01''</TD></TR></TABLE>

i dont know either, but i would assume to take the measurment from the bottom of the bore, because the circumference of the piston skirt is larger than the circumference of the top area where the rings are ... i hope an experienced builder can verify

 

Each manufacterer reco's a diff. place to mic the skirt. Usually an inch or two from the bottom. You would get extreme excessive clearance if you measured at the top.

 

Thanks guys! i'll have to post up my dyno when i'm done!

 

so I guess they fit!!