It's now been over 10K miles since the rebuild and boosting 15-17 daily, I'm noticing that the piston slap sound seemed to have gotten louder. I know it's also colder out now, but have you guys with JE pistons noticed this? It's pretty noticeable when the car is at idle.

I have the same thing. It is really loud when the car is cold. Then after driving it for a while it is not that loud, but it is still there. I have JE pistons too. If you ever take the head off check out the clearance between the pistons and the cylinder walls. Just to be sure they are within specs.

But overall, it is kinda normal.

I'm also running JE pistons, and I get the same thing. The colder it is outside, the louder the knocking until the engine warms up.

That's what I thought, too, but I wanted to know if this was normal or not. Thanks!

The dragcar has no piston slap. i have 20 over Arias pistons. Your clearances must be out of spec.

The called for clearances for my arias, are .030 - .040

i had him set me at .033 to be on the tighter side, But then again i have all my machining done by people who build 100,000 dollar engines. mine goes on all the same super expensive equipment, which is nice :-)

piston slap is a bad thing, because it eventually wears out your cylinder walls, and can cause them to be out of round. But once your engine is built, there really isn't anything you can do unless you tear it all apart, bore it over, and re-set the clearances with new pistons.

piston slap is normal on cold forged aluminum pistons. Even with perfectly within spec clearnaces, you'll still hear piston slap with a cold motor.

Tell that to my engine, not me :-)

Piston slap should go away after the engine has ran for 30 seconds - minute or so...

Piston slap when warmed up isn't normal.

Piston slap is NOT normal. I thought the same (slap is normal until it warms up blah blah) until i got my engine rebuilt with new JE pistons and got them installed with the RIGHT specs. My engine now is QUIETER than my turbo compressor at idle!!!!!

Before when my engine had the previous je's as well, it would clank and slap all over the place until it warmed up. Then my rings shattered (they kept binding against the cyl wall) because my je pistons were waaaay out of spec for piston-to-cylwall specs.

Long term out-of-clearance piston installs end up binding your piston rings and they eventually just shatter.

My .02 cents. if you dont believe me, come by and put your ear close to my engine.

I have my old bad je pistons right next to my monitor as paper weight now ;) I'll try to get you guys some pictures of what happens with long term out-of-clearance pistons...
_________________
Vinnie Lima
vinnie.lima@jvllogistics.com
AIM: Kiku888
1997 Chrysler Sebring "Silver XTC"
I4 420a w/ HRC Stage 2.45 w/ FMIC
14.7@97 mph@6psi
Proud member of the
ASOG BoOsT JuNkIe Crew

So how does one go about getting correct sized pistons, if everyone is buying from the same couple of places?
Did you buy the pistions then have your cylinders bored?

Just asking because soon I too will be rebuilding my botom end.

I've measured clearances on motors that slap, and they're within spec by JE's spec sheets.

Mine slaps when it's cold, and it was in spec when it was assembled.

*shrug*

Say what you want.. I've got 20,000 miles on my motor, it's always slapped when cold, and the compression has always been good for 8.8:1 and it isn't getting any lower. I think those results pretty well speak for themselves.

I have read that piston slap is normal. building a motor too tight can cause the engine to make too much friction, and then you're just fried. You have to meet in the middle.

I've also read that "piston slap" is due to the fact the the two dissimilar metals used in the block and the pistons (cast Iron vs. Aluminum) expand at different rates....

Current Mods:
Flowmaster Muffler
Ghettofied PVC intake w/K&N Filter
Platinum +4 Plugs
MSD Super Conductor Wires
1 Heavy Right Foot!!!!!

I also heard that slight piston slap is normal for forged internals. I was just wondering how many other people experience this phenomena. Oh, and I live in Ohio, so it's cold out. Supposedly, forged piston slap is normal and that it isn't the best when you car is driven on a daily basis. I've heard that it could wear down the engine over a period of time.

I also notice some my engine is loud with forged Wiseco pistons. It dose sound louder than when I first rebuilt the engine. That could have to do with the fact that I did the rebuild when it was warmer out. Have you heard Chad's car Kon? Smooth as butter on a fat man's belly. What?

Jay, you guys are really getting good with this engine building stuff! No, I haven't heard or seen Chad's car since it's been done. Hopefully I could find time to meet up with you guys sometimes. My work schedule is killing me. I miss everything at night.

I guess the cold weather does affect engine sound a bit. During the summer months, I can hear the engine, but it's not bad. Now, I can hear the ticking and slapping more.

I just had my machine shop mic and properly measure each piston to determine the bore size for the engine. No piston slap noises here....

I mention that it is not normal because my engine has been rebuilt twice by separate machine shops...first one was with crower rods and je pistons. Second was built by another (much better) shop and with also crower rods and je pistons. First one slapped all over the place like you guys have mentioned specially when it is cold. My seconde rebuilt it is so quiet that the turbo compressor is louder than the engine itself.

Not saying that slap is bad but if you have out-of-wack piston-to-wall clearances, you may run into reliability issues in the future (took my engine 3 years and a boat load of abuse to have the rings take a dump)
_________________
Vinnie Lima
vinnie.lima@jvllogistics.com
AIM: Kiku888
1997 Chrysler Sebring "Silver XTC"
I4 420a w/ HRC Stage 2.45 w/ FMIC
14.7@97 mph@6psi
Proud member of the
ASOG BoOsT JuNkIe Crew

JE pistons slap. That is why nobody in their right mind in the 4g63 world use JE pistons. They destroy motors. When I rebuild I will be going with Ross pistons most likely. One person has a website somewhere of what happened to his cylinder walls after driving on JE pistons for 500 miles. Not only was the cross hatching gone, but there were groves cut in the walls and metal shavings everywhere.

I would reconsider going with JE pistons in the future. Ross, Weisco, and Arias all have much better reliability. There are virtually no complaints of piston slapping with those brands of pistons. JE has nothing but problems.

Hey Kiku, what were the bore and piston size specs of your 1st, then 2nd rebuild?


>>>I would reconsider going with JE pistons in the future. Ross, Weisco, and Arias all have much better reliability. There are virtually no complaints of piston slapping with those brands of pistons.

Hmmm... I wonder if the JE, weisco and ross differences are due to the silicon content differences. The more silicon in the piston, the stronger the piston, but also greater heat expansion (so they will slap pretty badly when cold)

I know the site you are refering to Jeff. I beleive it is actually vfaq of 100q.dsm.org .. the motor in question overheated, which caused the pistons to expand beyond the bore clearance, destroying the cylinder walls. Solution: don't overheat your car and try to keep driving.

Arias uses high silicone pistons.

the Piston to bore clearance is set to expand close once warmed up more... and as it's been stated, overheat it and the pistons will continue expanding untill they melt themselves to the cylinder walls... lol

The main factors that contribute to "piston slap" are as follows:

- Piston-to-wall clearance(dictated by forging design, alloy, and skirt cam shape)
- Wrist pin offset
- Cam shape of the skirt

Wiseco does have a good reputation for little piston noise, mostly because of the skirt shapes we use. Another MAJOR advantage is being able to make our own forgings in house. Every other popular forged piston manufacturer(JE, Arias, Venolia, Ross, BME, Diamond, CP) orders their forgings from a company named Aluminum Precision Products, or APP(Except Probe Racing Industries. They make their own). I know our shelf stock 420A pistons are made of 2618 alloy, and I'm pretty sure we also use it the majority of the time for custom applications. 4032 is the high silicone alloy. It is used in naturally aspirated applications the majority of the time. It's lighter and expands less than 2618. Offset wrist pins are a nice little trick used for quieting down slap. By moving the wrist pin closer to the thrust side of the piston, it creates a sharper angle of the connecting rod relative to the bore, creating more leverage on the piston and in a sense "forcing" the piston against the cylinder wall. We put offset pins on quite a few sport compact/international pistons.

My pistons slap...my girlfriend says it sounds like a diesel..but it does go away after a minute or so.
It's been like 10 degrees here when i get up.


Jon

1997 Eclipse RS

14.21@101mph 10/4/02

MODS: 8.8:1 JE Pistons / Eagle rods / Stage 1 Hahn turbocharger / Melling Oil Pump / Autometer 5" tach / 4 JL 12" W0 subwoofers / Clarion 230w amp / short shifter mod / GReddy EVO exhaust / custom 2 1/2" downpipe / no cat con / CM Stage 1 / 30lb Mustang injectors / TurboXS MBC / 1G SMIC / Eibach Sportline springs / KYB GR-2 struts / GReddy 52mm EGT / A'PEXi Super AFC

:P :D

Ok, so if Je pistons slap and it isn't good for the engine. What pistons are the best for a turbo setup? I am going to building an engine soon and want to do it right the first time. What pistons have been the most successful, reliable, quiet, ect?
thanks

So everyone, what pistons would be the best and most reliable to go with? People seam to have great success with wiesco and JE's are stronger then hell...



Nick
97RS
Custom IHI Stage2
Obx exhaust, Limo Tint,
Custom interior, Upper Strut Bar, Kenwood/pioneer stereo.

At 0.004" piston to wall clearance, you should hear minimal slap when cold, NONE when at operating temperature.

I run my race motors at .010" pw to wall, and they slap a bit when cold, none under power.

Those of you that say your motor sounds like a diesel....your machine shop screwed up.

You buy pistins first, then the block is bored and precision honed to fit the pistons. That is the ONLY way to do it.

I Couldnt have said it better.
_________________
Vinnie Lima
vinnie.lima@jvllogistics.com
AIM: Kiku888
1997 Chrysler Sebring "Silver XTC"
I4 420a w/ HRC Stage 2.45 w/ FMIC
14.7@97 mph@6psi
Proud member of the
ASOG BoOsT JuNkIe Crew