| subject of the infamous Wiseco piston rattle fiasco.. Ah, who do I think I'm kidding - there's no 'little' to this clarification (hee hee). =) The other day a member asked about the Z1 wiseco pistons and was wondering if they are holding up and if there have been any problems with them. That post is here. He appeared to have gotten the answers he was looking for from several members who are using that piston, but there seems to be a bit of confusion about 'who done what' and the history of that piston. I'll be brief (tee heee) with the story: When Wiseco produced their forged piston for the VG30DETT there apparently wasn't a lot of testing done before it was put out on the open market - I have reason to believe that there was actually no testing done. Shortly after its release, several Z1 engines built with these pistons had an unusual rattle to them at certain RPM and certain loads which sounded like aggressive lifter tick. I recall hearing it on the red convertible that Z1 built about 8 months prior to moving up to work with them and it was not known at that time what the cause of the noise was, but the car continued to run without any apparent issues. A few other engines were built with those pistons and they too had this unusual rattle to them. The engine in the convertible was dismantled and carefully inspected - a lot of focus was put into the heads to find the noise, but nothing was apparent after hours and hours of measuring and speaking with other professional sources in the industry to try and find the problem. Meanwhile, Wiseco and Polydyne were already taking a beating as every piston set installed was making noise and everyone was complaining. It was becoming a very big problem for both of those companies. It was found that Wiseco was not marking the pistons for having a pin offset and some pistons were being installed properly, while others were not - that just became a crapshoot as to whether or not the piston got put in one way or the other. Just a brief rundown on piston design, but I'm not going to cover every single base, just the major design parameters:
1) Pistons are not perfectly "round". They are intentionally machined with a bit of oval (they call this "cam"). This is done because the sides of the piston where the wrist pin passes through, there is significantly more aluminum on those two sides which will expand more than the thinner skirts that are at the other two sides (the sides that run parallel to the wrist pin). When the piston is up to operating temperature, its shape becomes 'round', or the idea is that it should be 'round' when up to temp. 2) Pistons are not totally cylindrical. They are actually machined with a bit of a cone shape to them, with the crown being of lesser diameter than the bottom edge of the skirts. This is done because the top of the piston is subjected to greater heat which is going to make the aluminum piston expand more at the top. The idea here is that when the piston is up to operating temperature, it becomes less conically shaped and closer to a cylindrical shape so as to fit the cylinder bore more consistently. 3) The wrist pin is not always centered in the piston. They are very often slightly offset from center. This is the case with factory pistons (~0.030 offset) as well as the Wiseco pistons. This is done to reduce the rocking of the piston in the bore as the connecting rod swings back and forth while the crank turns. We contacted Wiseco to discuss the issue of the noise, the lack of markings to indicate pin offset, and the tens of thousands of dollars out of pocket that we endured to fix this problem in our customers' vehicles. When a piston has a pin offset, it is imperative that it is installed with that offset in a particular orientation to the rotation of the crankshaft otherwise the attempt to minimize piston rocking by offsetting the pin will make the piston rock significantly more when installed improperly than it would if it didn't have any offset at all. Because the pistons weren't marked and the datasheet that came with the pistons didn't have data on pin offset, these pistons were probably being installed improperly for a huge majority of the people using them. Our old engine builder didn't think to measure for offset when he built the engines; a big oversight on his part, but the pistons not being marked and lack of indication of offset on the datasheet was his excuse for not doing so. This is also one of many reasons we are no longer using that engine builder. Regardless, engines were rattling and Z1 was enduring a very big financial burden because of this. When I came up to Z1, my car had issues. An EGT probe burned up on the driver's side, which put a large piece of it into the driver's turbine, destroying it. It also blew a lot of smaller particles back into the combustion chambers (exhaust pressure reversion) which pitted the pistons, primarily #6. I was due for a rebuild. Having used in the neighborhood of a dozen or so wiseco pistons in my earlier days of moto-x, I heavily favored their product and was planning to use their piston in my build, that was, until the noise issue. I spent a lot of time with Brian Nutter on the problem with these pistons and did a lot of my own homework to find the source of the problem. He knew I was in the process of a rebuild and I told him I have no problem R&Ding this piston on my own car since that's what I do with my car anyway - test new stuff. By this time, Wiseco had pulled their shelf stock piston for the VG30DETT from the shelf and were no longer selling them, but they had began marking the pistons for directionality shortly before pulling them. This was mainly due to the fact that we disassembled an engine and remounted the pistons in the proper orientation and with Wiseco's suggested piston-bore clearance, they still rattled - not as much, but they still were too noisy. At this point it was clear that there were bigger problems with the piston. All of these results were being brought to Brian's attention as we progressed. In my findings, Wiseco was using a bit more offset than the stock pistons, 0.040" to be exact, which is 0.010" or so more than factory. They were also using 0.008" worth of taper in the piston from the oil ring land to the break point (1.3" below the oil ring). After a good bit of research, the taper was excessive and the offset wasn't quite right, I felt. So I then came up with a modification to Wiseco's original design and we dropped the taper to 0.004" and the offset to 0.030". They produced the pistons and sent them to us. I installed them with a bore clearance of 0.0035" (since I was planning to be making into the 500RWHP level with the prototype turbo I was also using - which became the Z1 stage2 turbo) and put 1500 miles on them. The design was tits and only at cold startup would the pistons make any noise - of which subsided after reaching operating temp. At that point, we had Wiseco produce several sets of this modified version for use in the customers' vehicles that we were having issues with. Those cars were taken care of and at the time, we were the only source for the Wiseco VG30DETT piston. Because of the financial losses Z1 went through because of this, Z1 was granted a special pricing break on any Wiseco piston, of which we passed directly to our customers. Then Polydyne got word of what we were doing at Z1 with these pistons and they contacted me. We were offered by them a full two years of FREE coatings to our pistons. Keep in mind, Polydyne was purchasing pistons from Wiseco, applying their coatings, and then selling direct to customers. When customers were installing the original pistons and they were making noise, a lot of those people blamed polydyne on the grounds that the coatings were wearing off and creating excessive piston-cylinder clearance and allowing the pistons to rock around and make noise. Unfortunately those people were ill-guided in their reasoning, but regardless, Polydyne was taking blows over it. Their approach to us was to try and mend their reputation in our community. We offer our pistons either coated or not, and we do not charge anything more for the coated pistons - we just pass that on to the customer. So that pretty much spells it out as quickly as I can without leaving out important details to support my next few statements. It is not an uncommon practice in any industry for a company to buy a product from another company, and then simply rebadge it and sell it as their own. Stillen is a prime example of this, but it happens everywhere. The only bug I personally have with that is if the company has had nothing to do with the production of said item and are ONLY rebadging it as their own. They can't really call it "theirs" if they are doing this IMO, just putting your sticker on someone elses' product doesn't cut it, but that's just my opinion. In the case of these pistons we sell, we had not only participated in the design of the piston AND tested it, but we also suffered a good deal of financial loss because of it. We fixed a problem that a major piston manufacturer had with their design and tested to ensure its operation, and then savings off to our customers. It ended up turning into a win-win situation for everyone, although there was still some damage to a few of our customers' confidence because of it. Regardless, we sacked up to it and took care of them despite the fact it cost the company several tens of thousands of dollars and lost time to do it all. We feel no shame in saying that we sell Z1/Wiseco pistons - we are pretty proud of the work we do although most of it goes unnoticed. The same idea applies to other things we put our name on such as our intercoolers, which are built by Bell Intercoolers, but they are built to our design specifications. Our radiators are built by Howe, but again, to our specifications. Our BigBrake kit uses rotors manufactured by Baer, but they are built to EradiSpeed's specifications and are for the Ford Cobra - we manufactured a kit of components that allow the use of this rotor on the Z and they too were built to our specifications. I'm pretty sure that Russell shares the same feelings on putting our name on products and we work together to assemble our website and special attention is given to this area when putting new product up. In closing - since this new design was a success and we had developed a strategic financial position with Wiseco that allowed us to freely play with the design of the pistons, we didn't stop with the refinement of the piston there. About two months ago, Wiseco re-stocked their shelves with the new VG30DETT piston that was built to the parameters that I came up with. There was still some refinement I wanted to do with the pistons to lighten them up a bit more, which included a modified skirt design, elimination of the second profile ring (just below the wrist pin) a very small reduction of the diameter of the 1st ringland (this was done preventatively to further reduce the risk of siezure in high horsepower and/or N2O applications) and a modification of the piston crown to cater to the asymetries of the combustion chamber. I have a box of pistons built to these specifications sitting on my machinists shelf which are going to be installed and tested in my personal engine once again. They have been polymer coated on the skirts to reduce friction and the chance of piston galling, and they also have been ceramic coated on the crown to reduce piston crown temperatures; coatings provided free by PolyDyne. Here's a CAD rendering of what that piston looks like: 
If this design is successful upon thorough testing of this piston, it will very likely become a shelf-stock piston available through Z1 as well for the same price as our other pistons so keep your eyes open for results on these puppies. I know this has been a long read and thanks for taking the time to hear this story. I hope it is not recieved as me or Z1 being boastful about all the great things we do or that we are the gods of the Z, blah blah, we know we aren't perfect but we do try =) - just felt like sharing the history of this piston with everyone and I hope to have entertained as well as enlightened you with it.
[ ashleypowers.com ]
[ agpowers@bellsouth.net ] [ Zemulator Information Sheet ] [ Z1 Motorsports Website ]
.JPG) Enthusiasts soon understand each other. --W. Irving.
Are you an enthusiast? If you are out to describe the truth, leave elegance to the tailor.
Albert Einstein
|
Z1/Wiseco forged pistons: A little clarification on the - 
