The JE Piston thread

[Turbo Shogun]

As per the title, I wanted to make a thread and find out the truth about JE's (notably their 2618 forgings). So I only have about two questions to ask:

1. Who's run them and had them WORK? How? What were your piston/wall clearances? Anything special to note?

2. Who's run them and had them FAIL? Once again, how and why? "? "?

Yes, I've read all the threads about JE pistons on this forum, and the general consensus seems to be "they suck", but there's a handful out there that had them run flawlessly, and without the notorious piston slap they're known for. Yes, I know they need to be run wide, and yes, I know people swear on Wisecos, but can that truly explain the handful of people that run JE's without a hitch? And why does JE recommend a Piston/Wall clearance of .0035, when so many people have had their motors seize? Bad tech dept?

I really want to hear from you people who've run them successfully!

Thanks for your time and advice in advance.

 

[95blackGsTurbo]

Basically it all come's down to the machining. Some guys are too cheap to get the proper machining done and just throw pistons in a still grooved or non honed block at the least. Too many people think rebuilding a motor is just slapping some new parts in. I think on average I took 26 measurements on a 4 cylinder motor.Most people don't realize when you go from aluminum to steel rods or visa versa you have to change the deck clearance as well. Other measurements include the exhaustvalve margin. A narrow margin cannot dissipate heat fast enough. The result is often a series of hot spots that shorten the life of the valve and result in pre-ignition problems. Another common theory is that tension from the cylinder wall seats the rings. Not entirely true. Pressure from the combusion does most of the work. Only time is gets tension from the walls is on the intake stroke. I have built almost 200 motor's now and have used JE Pistons in some VERY high HP high revving engine's. I have never actually had one fail due to something defective or wrong with the pistons. Have used then in 4 cyl. turbo's, 6 cylinder supercharged, 8 cylinder high compression, turbo and supercharged and haven't had one fail due to stress or cracking. Wiseco are definatly good pistons too but I have no problem with either. Pistons slap is not a terrible issue and won't cause your motor to sieze usually. A lot of late model GM trucks that are back in Iowa have it when it get's below zero and the Aluminum pistons shrinks until it get's warm. I will post some more info later if I find anything out. Hope this helps.

 

[Turbo Shogun]

It does, thank you.

I just wanted to debunk the reputation JE's had. From what I've read about piston slap is too much can destroy your bores. They need to be warmed up well before they can be run hard, etc. Seems like it's the machine work and noise that are the subjects of contention.

I was told that JE's can be run, but the nature of the 2618 requires a piston/wall clearance that is inherently high (considering how little our stock pistons have).

To combat the issue of forged piston slap wiseco uses an offset wrist pin like our OEM pistons, but I understand not much can be done ...

Anyone (those who've used JE's) care to chime in with more input?

 

[Precision]

I have had nothing but good luck with JE pistons. Plus they are thus far the only piston manutature that machine there pistons to the same size. Too many times have I opend a set of Aries, wiseco's, ect. and the pistons be 1/2 to a full thousandth of an inch away from each other. Not to mention that I have seen JE's live though things that on othere piston ever has, such as heat, and detonation.

JE all the way man.

 

[steel_3d]

Another very important thing is to measure the width of the piston where the manufacturer specifies. The profile of most pistons is tapered to allow for greater heat expansion at the crown, meaning they're quite a bit narrower right below the rings than at the bottom of the skirt. Obviously if you measure in the wrong spot your clearance will be either too tight and seize or too loose and slap. Ex: .0035 at the top is definitely too tight, .005 at the bottom is probably too loose. This might be where some people trip up.

 

[JohnTSI]

We have had nothing but great sucess with JEs in both cars we run, the 5 speed car runs 10.4@140 and the auto car running 9.6@141. Like said before you have to have a good machine shop, first engine we built with JEs slapped like a SOB because the machinist was a moron. The 2 motors we run now have no slap whatsoever and one has been in the 5 speed car for almost 3 years now.

 

[Turbo Shogun]

We have had nothing but great sucess with JEs in both cars we run, the 5 speed car runs 10.4@140 and the auto car running 9.6@141. Like said before you have to have a good machine shop, first engine we built with JEs slapped like a SOB because the machinist was a moron. The 2 motors we run now have no slap whatsoever and one has been in the 5 speed car for almost 3 years now.

That indeed sounds very encouraging.

Would you mind divulging a bit of information on the "secrets" needed to make them run smoothly? Did your machinist have any experience with JE's, or was he just that damn good?

 

[95blackGsTurbo]

It is a big help if you have the piston prior to machining the block. Make's our job a lot easier in machining plus we can match each piston to each cylinder so they have the exact same side clearance. Because not all pistons are the same diameter.

 

[Wicked96GS-T]

I also run JE's in my built engine. Everything was balanced and blueprinted, and the bores were matched to the pistons. I have no slap at all. Just remember, always get your motor up to operating temps before beating on it.

 

[Turbo Shogun]

I also run JE's in my built engine. Everything was balanced and blueprinted, and the bores were matched to the pistons. I have no slap at all. Just remember, always get your motor up to operating temps before beating on it.

Ah ... I figured that since they needed to be run wide (some people have told me as much as .0045~.0050), they slap alot before the engine gets to operating temperature. It makes sense to me.

So you don't have ANY slap whatsoever? Even during a cold startup in the winter? WTF

When I send my block in I do plan on including everything (pistons, rods, head, headgasket, and ARP studs, even). Hopefully this will eliminate slap. :/

 

[4SFED4]

I had two fully built and balanced motors with uncoated JEs. I had no piston slap problems. One is still running in good shape. The other suffered a failure due to poor tuning--excessive timing/boost and an unforgiving lead foot. The pistons in cylinders 1 + 2 melted the top two ring landings on the intake side. The engine still ran suprisinly well and I didn't realize any signifigant damage until removing the head. I though it was going to be a routine h/g change until noticing the severe cylinder wall damage.

I have no complaints about them. As mentioned above it requires proper machining or any quality part can make noise and/or turn into junk relativly quick. I would stick to a reputable shop or machinist.

 

[JohnTSI]

My machinist has been building race engines for 20 years for everything from top fuel and lamas cars to weekend warriors. No good machinist would bore a block without the pistons there already. I have never asked him or rechecked clearances. I just pic it up file the rings and assemble the bottom end.

 

[Turbo Shogun]

Well, I'll be taking my engine to a very reputable DSM machinist in the area. He did ask for my pistons and rods, so I guess that's a good sign, right?

I was thinking about selling the JE's for a set of Wisecos, but we'll see ...

 

[Wicked96GS-T]

Ah ... I figured that since they needed to be run wide (some people have told me as much as .0045~.0050), they slap alot before the engine gets to operating temperature. It makes sense to me.

So you don't have ANY slap whatsoever? Even during a cold startup in the winter? WTF

When I send my block in I do plan on including everything (pistons, rods, head, headgasket, and ARP studs, even). Hopefully this will eliminate slap. :/

Nope, ZERO slap, even on cold start ups. I have had the car running in january temperatures with no problems at all.

 

[Turbo Shogun]

Nope, ZERO slap, even on cold start ups. I have had the car running in january temperatures with no problems at all.

Wow, well, that's contrary to everything that's been said about JE's. Did you run the so-called recommended tolerance of .0035" or did you go wider?

 

[pjules]

I have used JE pistons in two type of motors. One was a 420A block, and a 4g63t block. Machinig was done by NAPA, and the pistons had to have been present before the machinist would even touch the block. Both engines with the JE pistons had slap. I had 2 other motors built with Ross in one, and Wiseco in another and my friends 0 slap in these motors. Since then i have been a non beleiver in JE

 

[Turbo Shogun]

I went ahead and used my JE 9:1 +.020 for my engine build. I'm having Custom Engine and Machine down in Aurora, IL do the machine work (they have been working with Hahn Racecraft in the past and have told me they have always had their JE motors running strong).

I suppose I'll post my own story when I get the motor back in a week. The apprehension/anticipation is here alright ...

 

[groundPork]

Anyone personally measure their piston to wall with correct instruments, and notice or not notice slap? If so/or not with who's pistons did you notice this with?

I would alos like to reiderate what an earlier post stated. Piston slap is not the end of your motor, it is mearly an anoyance MOST of the time. Although piston slap can be a simptom of something far worse, it does not cause failure in itself. You may have not had enough clearance or may have run so lean the piston gauled.... if you ran it long enough cause you didn't know better, it could eventually start slapping very badly on startup.

Again, anyone acually measure their stuff? I gotta say when you assemble the motor you take responsability to check everything. This doesn't mean you are assed out totally if YOU find something wrong or defective, in fact it means you have saved your own ass. But don't ever not check, then assemble, then blow something, then blame someone else.... Emphasis on the not blaming, but you do need to investigate thuroughly if you have a problem no doubt.... If you want a boosted 4G piston to make any power, it is going to be made of 2618 period. Unless some of us can afford a foundry to make ONE measily set of aluminum-berillium pistons (which I don't even know if they can with stand 30+ psi boost, they're only used in F1)... there is nothing else stronger for what we subject our pistons to.

 

[94awdcoupe]

I have used JE with good success. I prefer to run pistons on the loose side. With a stock ECU running pistons with slap will likely be a problem. But this problem can be solved with a jester tuning chip. Knock can be ignored at throttle below 30%. On AEM the slap is not an issue at all.

Clearances should be at least .005. And this is with using a torque plate. Machine shop measured .001 bore distortion so that makes using a torque plate pretty significant. If you dont use a torque plate I would add .001 to your clearance. I tried running the recommended .0035 on four motors. And all four of those motors scuffed pistons when boost was turned up. After that I went the other direction. I then ran .0065. This clearance will produce bore slap for the first 1-2 minutes of run time. Then they quiet down. It is no worse than the sound of factory ls1 forged pistons.

If you want to have no piston noise set your clearance at .005. But at this level you will need to break the motor in real good before running high boost. .0055 is a nice safe clearance and should still be quiet. It might get a very small amout of slap after a lot of hard miles . As far as running loose clearance is concernerd, I put 15000 very hard miles on the block that was set at .0065. Every time the head was removed the bores looked very, very good. leak down was done at 10000 miles and had 4% on all four. I never needed a valve cover vent. I just let the stock hose dangle on top of the tranny. Very little oil was ever seen. This engine was beat on from day one. Eventually tuned to 565whp at 34psi on 93 octane/alky.

 

[nightspeed87]

im going to be running 2g pistons in a 6bolt engine going in next month, and I was goin to run JE rings with my 2g pistons , should I do this or stick with the oem rings on oem pistons... ( By the way I can get the JE rings for like 50 dollars cheaper than the JE. )

( also just to verify I was getting 2g rings since im getting 2g pistons... Because it wouldnt make sense to go with 1g rings on 2g pistons correct. )

Is there a perticular year I should ask for in the 2g yrs when i order the piston rings ( i.e , 95, 96, 97 ) or whatever or will it not matter.? Thanks

 

[Turbo Shogun]

I have used JE with good success. I prefer to run pistons on the loose side. With a stock ECU running pistons with slap will likely be a problem. But this problem can be solved with a jester tuning chip.

Oh? How so? If it's got something to do with the ECU I assume it can be tuned out ... I'm running a Greddy e-Manage as of the moment.

If you want to have no piston noise set your clearance at .005. But at this level you will need to break the motor in real good before running high boost.

I plan to do the standard 500 mile babying at 6-8 PSI, then another 500 miles of turning the boost up to 12 PSI, and another 500 miles at 18-20 PSI.

I ... ran .0065. This clearance will produce bore slap for the first 1-2 minutes of run time. Then they quiet down. It is no worse than the sound of factory ls1 forged pistons.

That seems like alot though. I'm going to ask the machine shop what clearances they'll be running tomorrow. As I previously stated before, they've built motors for HRC using JE's and the people at HRC have told me they haven't had ANY problems with JE's, and they've been using them since the mid 90's or so.

 

[Turbo Shogun]

I just got off the phone with Tim from Custom Engine and he tells me he's going to run the piston/wall clearance at .0040. Seems pretty interesting to me that he'd run them close, but I mentioned that I was going to be running 23-24 PSI max on the motor. As I previously stated from other threads, I'm not building a drag car. It's going to be a street/road course/auto-x car.

He's told me that I should expect no slap whatsoever at .004 with my boost/power goals in mind. All that's left now is to bore out the block for my JE's, polish my crank and balance/blueprint everything and wait for my motor at the end of the week.

 

[nightspeed87]

so like i was asking in a previous post, any input on the JE rings ... I can get some for 1 hundred over buying oem rings for 150, and supposeably there stronger and better than oem anyway... I was going to be putting them on stock (2g) pistons for my 6bolt rebuild set up.... I am going to order them tomarow but I would like some input on putting those rings on stock pistons before I do it.

 

[steel_3d]

If you don't get an answer here, just call up one of the dsm shops that build engines every day. They'll know.

 

[MrPikolo]

I don't know if anyone knows this, but John Shepard still uses JE as well.