Anyone else having problems with wiseco pistons? I Recently found the skirt on the exhaust side completely broken off of one piston and the rest cracked and on thier way out. Looks like the skirt cracks at the cut out for the oil squirter, then just before the wrist pin and eventually the whole side comes off. It's the last thing I expected, but it happened.

I've been away from NAM for awhile so I thought I'd see what you guys have experienced before I deal with wiseco or find replacements. I'll post some pics after I prepare a presentation for wiseco.

 

one broken completely and 3 cracked ? Thats insane.

 

If I was the person handling your claim and you came at me with a powerpoint presentation I would give you whatever you wanted. Well done.

 

Thanks. I'm not planning on powerpoint, but clear photos with notes pointing out the cracks and showing the consistancy between cyclinders should be helpful and set a good tone. We'll see how they respond.

 

That's what I thought. After looking at the stock pistons, my guess is that there just isn't enough support at the circumference of the skirt. Stock is much beefier there. Thankfully my shopmates pushed me to check the other 3 pistons. I almost replaced just the one. That would have been ugly and very disappointing. Not to mention the mystery of what the hell happened. Having them all out I can now see the stages as the piston fails. That is one positive aspect. Not knowing why would have really bothered me.

 

Stock Mahle Forged MINI pistons are handling a LOT of power.. thru Boost and/or Nitrous!! The after market pistons should have the beefer skirts knowing the engine is going to be beat on with a lot of boost!! But it is hard to beat the European made Mahle pistons!! There are more than a few stock bottom ends making a lot of solid power. Usually if the piston fails.. it is a TUNE ( A/F) issue!! Or a build issue. Do you know the piston to wall clearance?? just a thought..

Just me...........................

Thumper

 

I don't have the measurements with me now, but these are stock size replacements and wiseco's email said to finish hone, size the rings and drop them in. I was sure to get as much info as possible before installing them. I'm not sure there was much I could do in terms of sizing. They certainly were not loose. Detination, maybe, but it wasn't audible. The tops of the pistons don't show any signs of it. Should have some pics up tonight. I think it comes down to the material they had to remove for the oil squiter clearance. I think it weakens the skirt and is why they are all cracked at that radius and only on the exhaust (squirter) skirt. The intake side has more support and does not show any damage.

I have to get back to work, more later.

 

Boken skirt of #1 exhaust side

Missing pieces

#4 cracks at oil sprayer cut out. Similar on all the cylinders.

Same crack from the inside and showing the 2nd crack at the wrist pin

3rd crack at opposite end of wrist pin. #4

Same crack, outside view.

Compare intake side skirt (left) to ehaust side skirt (right). I think that overhang resulting from the oil sprayer cutout gives just enough leverage to crack at that radius. Then once the skirt is week it cracks at the edge of the wrist pins until the entire skirt come off.

All the pistons had the same pattern and there was no issue on the intake side. That makes me a little suspect of the design. Detonation may have played a role, but all the pistons in the same way and no noticeable knocking while driving. The car is not high power either. Cam, 15%, intake, header and mth tuner "rich". This is approximately 15k miles after install.

Let me know what you think, especially those with piston failures. Basicall I want to resolve why, so that I can rebuild with confidence. If it's the pistons, fine I"ll try another brand. Same with tuning. This just seems excessive for a low power car.

 

Welll...... that HAS to be a modified piston for the MINI... NOT a piston made for the MINI!! Did you buy them FROM Wisco... or from a supplier?? If the piston was made for us.. they would NOT have modified the skirt for the oil sprayer by removing the skirt... as shown!! Also the marking on the piston skirt shows the piston was rocking in the bore!! again too much piston to cylinder clearance..

I have a picture of a stock piston .. 40K and the ring land were broken do to detonation.. looking at the piston ( with 40K of 17% pulley and running the dog mess out of it )... you can see no abuse skirt wear or signs of the piston rocking .. ( from too much clearance) I would have yourself or friends Mic a good piston and then the bore... the piston should NOT have failed at any matter.. just a guess here!! Also I would make sure you got "For application" pistons... as like I said modifying the skirt for the sprayer.. isn't the way!! yes??

Just a thought..

Thumper

 

I don't have any "good" pistons to measure. They were all cracked and worn. Only one fell apart. I won't be able to measure them until saturday, but when installing them I remember thinking "these are much tighter than stock", at least the tops were. Honestly, my concern was that they were going to be too tight. I thought, they're wiseco, the right part numbers and my cylinders are perfect, so...

These were purchased directly from wiseco and had part numbers specific for the "S". I did not mean to imply that the skirts were modified. I was refering to how they delt with leaving a place for the sprayer.

The more I've looked at them today, the more I realize that they aren't a good design and I just need to find another brand that has more practical experience with MINI.

I did get in touch with wiseco today, but only for a minute. Basically they said I detinated them, too bad. When I told him that I thought it may be the thin skirt design, he said they are forged and don't need to be thick and hundreds of sets have been sold so... That may be true, but I wouldn't be suprised if mine were the only one's that actually made it into a car. I can't seem to find another poster that used them.

Then he refered me to someone that could test my pistons to see if they hadn't been heat treated. I haven't heard back yet and doubt I'll waste my time. The funny thing is I was really calling just to give feed back, buy another set if there had been design changes or even help them by letting them study my pistons.

So if someone has actual longterm experience with pistons in thier own car, I'd love to hear about it. Especially if they are wiseco.

 

Just because it is forged doesnt mean it is strong. The FSAE car I worked on had part of its hub snap off as we were pressing one of the lug studs in, and that was milled from a solid block of AL. Surprise... the part was designed poorly.

 

Here's a comparison of wiseco vs. stock

That's not the lens, the stock piston is narrower across the skirt and much more reinforced. It's becoming obvious wiseco wasn't prepared fore the load on the skirts. The irony is that the barrells/skirts are underbuilt, but the wristpins are so over built they negate the weight savings. I was originally suprised by the lack of weight savings, but thought it was worth it for the peace of mind.

 

The stock is oval for a reason... the pressure points on the piston skirts are reinforced.. this is a power builder that allows the piston to remain stable and frees up parasitic losses.. Mahle are used in almost all the performance engines over seas.. they are there for a reason, yes?? sorry for the issue you are having..

Just me..................

Thumper

 

Yeah, as I was putting this thread together I figured that out. I noticed the difference when installing them, but figured wiseco knew what they doing. I have a feeling they will see alot of failures. So far they haven't been to helpful or receptive, but they will have to deal with it sometime.

 

I measured the cylinders today. They all came up 76.99mm. Wiseco shows them for 77mm. I think I'm good there.

I'll try to measure the pistons tomarrow.

 

This is a known issue with the pistons Wiseco "designed" for the MINI... I had a set in my TC'd setup and was getting piston slap. But even still I was not seeing any cracking along the skirts. It did however make my cylinders oblong. I'd recommend going .020 over and getting a set from CP. They are actually designed and custom fit for the MINI's application. About $50 or so dollars more than wiseco I believe but well worth it... Also the top ringland of the CP is wider to prevent from detonation issues. If you get small detonation with your Wiseco's, your gonna loose the cylinder and possibly the block....

 

I'm looking at CP or set from Hubie Fuh, I think those are JE. Definitely not going to use wiseco again. Of course I will measure the cylinder roundness, but I would like to stay at standard size.

Do you know of other Wiseco failures? Who "knows" of this as an issue? I think it's an obvious design flaw, but they say they have never had a failure. The engineer has yet to call me back, so the conversation hasn't gone any further than this.

Thanks,
Jeremy

 

$599 for CP
Best pistons out there

 

What's the compression ratio?
Flat top?
Does that include rings and pins?
Any notable features? Are yours different from those sold elsewhere?
Do you mind posting pics, particularly a view of the bottom (wrist pin and skirt structure)?

I need to make a decision soon (CP or JE), but I don't want to rush in after my last experience. I'm not going for crazy power. I want it to be strong and have a little extra if decide to add some nitrous or another boost option (unlikely though).

My setup,
15%
Intake Exhaust header
Camshaft
Mildly ported head (matched exhaust ports to header and clean up)
light flywheel
MTH tuner
Plan to retune and add injectors.

I appreciate any advise as there is very little info available on this subject.

 

I'm still stuck in Denver
Shoot me an email
Jan@revolutionmini.com

 

Great support on these skirts.

 

Aren't those made by Wiseco too?

 

I've been running the CP's for close to two year's making big HP.

I highly recommend them.

Longboard

 

Don't you mean billet, not forged. Forged means it was beaten to a pulp or some other very large force was used to get the shape. We mushroomed the area around one of the holes in our hubs when we pressed a stud in. It was an oversized hole too .

Still catching up on sleep after MIS...

 

I believe so. The skirt struts look good and I like the reduced quench area, but... One bitten twice shy.

I should send a picture of those with my complaint pack to wiseco. It's hard to argue that the standard wiseco design is "strong" when tuners request strengthened versions to be made.

RMW I'll send you and email for more info soon.