Concerns about Supertech pistons
 

Well, looks like my 'expensive' built motor is coming BACK out of the car :vash:

Long story short, I cracked the #1 piston. No pictures yet as I have not removed the head yet. But it damage was confirmed with a VERY NICE $6000 borescope, by a knowledgeable technician, and seen by me first-hand. Motor still runs, but the piston is a time bomb and has to come out.

The damage is right at the edge of the piston, where the recessed pocket for one of the intake valves intersects the flat portion right at the edge of the piston (at the bore). See the yellow circle area on the image below.

So here is my question/concern. Do I replace this piston (or all of them) with ANOTHER set of Supertechs (maybe even lower compression) or go with Wiseco?

So as some of you probably know the Wiseco is made with 2618 Aluminum, and the Supertech is made with 4032. The advantage of 4032 is it has a lower CTE, about 15% less than the 2618. So, the bore clearance can be a little tighter, and/or there is less chance of overexpansion and seizure/scuffing.

BUT, there is a downside. The 4032 is less ductile, much less. Its elongation is only 4% elongation at break, versus 10% at break for 2618. This is significant, given that I have had a piston failure due to what looks like a fracture, and not due to a melt-through for example, from overheating.

The other differences are that the 2618 has a higher tensile strength and ultimate strength than the 4032 does:
Yield (Mpa) Ultimate (MPa)
2618 372 441
4032 331 359

2618 is 12% stronger in yield, and 22% stronger in ultimate.

I have now seen some anecdotal warnings against Supertech pistons on the interwebz due to problems with cracking. This is consistent with my experience. Though who is to say that the wiseco would not have suffered the same fate under the same conditions? But, being prone to cracking would be consistent with lower ductility. This is the classic tradeoff normally present with metallurgy in general.

Now, my best guess is the crack was due to detonation. I did think I heard some recently when under acceleration, though I got off the throttle when I thought I heard it, and immediately backed the timing down (via the tuning laptop) by 3 degs across the board just to be safe. But, the other pistons, though not also borescoped, were showing no signs of problems, and, all of the plugs, including the plug in this one, did not show the usual signs of heavy detonation, like damaged electrodes. The bore, cylinder head and valves all look OK in the damaged piston cylinder as well.

So... I am hoping this will spur some additional discussion and bring in some experienced voices on the matter. I need to decide very quickly what I am going to do on the pistons as I need to get the motor out of the car, repaired, reinstalled, and tuned, in less than a month. I want to buy the pistons by the end of the week at the latest.

I also want to give you guys a heads-up so you would be informed. I am NOT saying at this point to stay away from Supertechs, rather just sharing what I know so far for further discussion.

By the way, this is supposedly a common area for pistons to fail in. The area over the top compression ring is basically cantilevered and therefore can break off when subjected to extreme pressure, like with detonation. Plus, if you look at the area where it failed, there is not a lot of material in that spot due to the valve pocket, not to mention the stress risers due to all of the intersecting geometry features.

Why did you investigate? What made you think something was wrong? Just curious.
Here in Europe not many have heard of Supertech and it sounds a bit like Wachiwucchi or your average China brand. The Wiseco, J-E, et. al pistons are much more well know.

Good question, meant to mention that... So the car was acting like it had some spark plug blowout at 20 psi. I had the plugs gapped at 0.035" so I decided to drop the gap to 0.030". When I removed the plugs, I noticed something was wrong with #1. See below (#1 to #4 from left to right). These are NGK Iridium IX plugs, two steps cooler than stock. Notice how much darker the #1 plug is. The rest look perfect.

http://lh6.ggpht.com/_jh2HiMm4nKQ/So...0/P8080144.JPG

Here is a closer look at #1. No signs of detonation damage I can see, just the dark coloring.

http://lh5.ggpht.com/_jh2HiMm4nKQ/So...0/P8080145.JPG

The rest of the plugs all looked like this one
http://lh6.ggpht.com/_jh2HiMm4nKQ/So...0/P8080148.JPG

So, wondering WTF, I began some diagnostic work:
Compression test showed #1 at 165 psi. The rest were all at 190-195 psi. Uh oh...
Then I did a leak-down test. #1 was at 10-15%. The rest were all at about 5% or less. Shit..
Then I did the borescope check, first with a cheap Chinese one, then the nice one, and that is when I saw, then confirmed the damage. FUCK!!! :vash: :vash: :vash:

I'll post up more pictures when I get the head off and look at the damage. The camera for the borescope was not available.

It could be just me, but I see pepper all over the first plug. Definitely detonation.

did you use det-cans to rule out detonation? Plug one looks like its blasted by detonation. #1 electrode looks rough, the other looks smooth.
edit: look at the insulator...its covered in metal. Lets see a picture of that piston. I'm sorry to see this misfortune.


If I didn't score the crazy deal I would go with Ross, Wiseco, or JE.

Who tuned this car? Do you have a knock sensor (as if they even work)?

This thread really drives home why I'm tuning on 91-octane then running 93 for headroom, running low compression, and running the large turbine housing.

I should also note that I do not like the valve relief that close to the quench ring.

I agree... something was going on that caused a lot more detonation in #1. Theories:
- Though they were rebuilt and tested by Witch Hunter about a year ago, I may pull the injectors and have them tested just to be sure #1 is not running leaner.
- Though this is a guess, is that the WI charge is not getting to the #1 cylinder as well as the rest (not sure about that). Makes me seriously think about going to port WI and adding more water/meth.
- Somehow the reroute is causing #1 to run hotter, not sure how it would though. If anything cooling would be more even.
- The fuel rail is not up to the task (feeds from #4 forward to #1) so maybe I need to go to a return-style system. I know this has been debated at great length.
- I am pushing the margin with the 550cc injectors. They are above 85% at 20 psi, 7500 RPM (14+ ms of duration). Might be time to go bigger.
And, the top reason is...
- Hustler scares me with his awesome manliness, so I had to blow up something on the motor to have an excuse to avoid getting ass-raped by him at the track.

Nope, neither do I. The wiseco looks like it has a little more material in that area. Hard to tell from pictures though.
http://flyinmiata.com/Store/images/04-69100a.jpg

are the cylinder walls smooth?

Do you mean new, or now? New, yes, see top photo. Now, no idea.
Or, do you mean the cylinder walls in the block? No idea yet either, engine is still in the car.

nomenclature phale. Check the edit.

No idea. The wall in #1 looked OK on the borescope, except for some scuffing where the piston damage was. The honing marks are still clearly visible. I am going to have all of that checked when I have the motor fixed by the local badass machine shop.

Yeah, I was thinking about the wall scraping, but judging from the spark plug, we know why it died. I bet you're not getting water to that cylinder.

get a lower compresion and say that your pistons were flat, without marks.

I have been guilty of subjective reasoning before, but I am thinking the same thing about the water. Inertia would tend to carry it past the #1 cylinder since it has to turn pretty sharply once it enters the plenum to get to the #1 cylinder, especially with all of the VICS related geometry in the way. After all, it was designed as a dry-flow manifold.

In fact, I think I am going to go with port WI, and might even gut the upper intake (get rid of VICS). No matter how you slice it, I am pushing the motor pretty hard at 300+ rwhp (guesstimate), and the WI system needs to work well in order to restore some knock margin.

Huh?
But on that note, Supertech goes no lower than 8.6:1. Wiseco goes no lower than 9.0:1. Plus, if compression ratio was the cause, why didn't the other three cylinders get ass-raped as well? Current pistons are 9.0:1. Compression test shows about 190-195 psi.

If you do end up wanting wiseco's, they supposedly have to be custom ordered for 1999+ head's because of the valve angle.

Maybe, but Flyin' Miata has them on-the-shelf. I called them this afternoon.

have fun on the high-compression junior boy's club. Don't worry, I make more than enough torque for both of us.

Just for that, I am going to ass-rape you reeal nice in turn one. Squeal like a pig boy!

The distance from the top of the ring to the top of the piston is 0.2800" on our 9:1 pistons.

There's a potential difference in the alloy as well. Supertechs use 4032 alloy, ours are the stronger 2618.

I can only comment on the Wisecos that we carry. They're made to our specs and design, other shops will have different pistons. Ours will work with all Miata engines other than a +1 intake valve on a VVT engine. No need to special order for 1999 engines, that's a rumor I hadn't come across before. Personally, I like having at least a 9:1 compression ratio as any lower gets doggy off boost. I used to have a 323 GTX, if you got caught off boost in that thing in front of a truck you were dead meat.

As far as I know, none have suffered the same failure as these Supertechs did.

Thanks for the measurement Keith. I'll check it on one of the Supertech pistons when I get one out of the motor. Unless, someone around here has a set sitting around that they have not installed, and are willing to take a quick measurement.

To paraphrase 'The Wolf' (ninja edit for correctness)
"If I'm curt with you it's because time is a factor. I think fast, I talk fast and I need you guys to act fast if I wanna get out of this. So, pretty please... with sugar on top. Measure the fucking Supertech piston..."
http://theare.files.wordpress.com/20...el-sr-lobo.jpg
:bowrofl::bowrofl::bowrofl:
That is one of my favorite movie lines, had to use it eventually.


So Keith I just want to be sure I understand this correctly... A +1mm oversized valve is only a problem with the Wiseco piston on a VVT motor, correct? I am non-VVT so I should be OK then.

It's a rumor straight from wiseco.com:
http://www.wiseco.com/Catalogs/Sport...undaiMazda.pdf

my 1.6 weiscos looked just liek your pic above man no idea on the 1.8s though gl with the rebuild.

What sign do you have in your yard?

Dead Miata storage.

OK well this concerns me too because the used engine I bought with supertech pistons was all messed up. The mechanic said that the engine looked like it was detonating and the tops of the pistons were eaten away. The belfab rods are apparently just fine though. I will try to post some good pictures of the pistons but now I will probably replace them with fm wisecos.

chokeasphyxia, then that's a good reason to buy the FM Wisecos. They fit the 99 heads no problem :)

Remember that we don't sell the same Wiseco pistons that Wiseco does. They've been modifying their own design and moving closer to our specs over the years, but it's not the same piston and you can only get ours from us. So when I say that our Wisecos will work with every Miata head except a VVT setup with +1 valves, that may or may not apply to Wisecos available anywhere else. I don't know.

Again, this is true for the FM pistons. Not necessarily all Wisecos. But yes, it is true for the FMs. All of our built motors go out the door with +1mm valves, it would be a little foolish for us to build pistons that wouldn't fit with them :D

By the way, I just updated the picture on the FM site to show the current 1.8 9:1 design, as it's our most popular piston.

Keith, I have a VVT head with +1mm valves. Am I SOL? No FM pistons for me?

you fail at reading :noob: :fawk:

That would be Winston Wolf.

I have been thinking about WI and after talking with some OG tuners, there's no way I'm NOT doing direct port, espicially on our shitty intake manifolds.

Hope everything works out man.

Yes, you are correct. I am an idiot. Referred to as 'The Wolf', not 'The Fox'.

OK I pulled the trigger on the FM pistons. Let's see if I can break them (like many other items that have gone into my engine bay).

Good thing you asked a third time - because I double-checked with some of my coworkers. Turns out we increased the valve pocket size a bit, so they do fit now. The current FM pistons do work with a +1 VVT. It's an interference engine so keep that in mind if you decide to break a timing belt.

I'd recommend checking clearances with any VVT head with +1 intake valves.

Wolf I always liked that one.

Joy!

Witness the power of reading faeflora style!

sux! i have wiseco's in mine. only they are LOW compression - 8.2 ccr if i remember correctly. anyway's why are you running 20psi? you goin' to the drag strip? i usually run 12psi daily. 15psi is all that i've tuned up to, but it's maxing out my 550cc injectors at that boost. only ran that a few times to play around with some friends. at the track i only run 9 psi. sometimes 10psi. and that's pretty fast if your turning like you should. dogged many porsche and vettes at that boost, especially on smaller tracks.

If you have to ask... :giggle:
Seriously though it is a lot of power, but manageable in 3rd gear and up. I am a speed junkie, that is all there is to it.

What the fuck is wrong with you? Isn't your username "spoolin2bars"? Did you know 2 bars is almost 30psi?

it's spoolin2bars is because of my galant vr4. and i wouldn't run that much at a trackday in it either. just seems like alot of abuse for not a big difference in lap times on most tracks. on the street or drag track, with sticky ass tires it makes sense. i would rather keep it safe/simple and run a trackday event, than be working on my car or spending money on replacement parts.

Attachment 204012

Attachment 204013

To each his own. I like having the power myself, and it is a lot of fun on the track too.
Fixing broken motors does suck though, but I am working on adding margin back. I suspect in this case the problem was caused by bad WI distribution into the #1 cylinder due to the manifold design. I am switching to port injection and better flow regulation.

i would love to have that much power too. but i can't sacrifice reliability for it. especially since i drive my car to all events still. hopefully i'll have a tow rig soon so i can push it harder. i think i will be running a little more boost for tws though. 11psi is 238whp so 12psi should get me to 250whp or so.
what about race gas? if your WI isn't flowing evenly throw some motorsport 104 or higher in there. then you don't have to count on the WI to save your motor. anyway's good luck with the new pistons. i'm dying to see what 300hp does out there.

Its fucking ridiculous. Reeling-in C6Z's, porsches, and just about anything under the sun is hilarious. When you make that kind of power, with decent suspension like Flex, and R-comps...there are no more excuses. FTD or tuck your tail.

I'm working on failsafe schemes, with some redundancy, for the WI in case it fails. But at the track, yeah using some higher octane fuel as a safeguard is probably a good idea.

I am also shopping for a cheap car trailer and when I get one will start towing with my truck to track events. That is what I do with the race bike now. It is nice knowing that no matter what happens, short of injury (a risk with motorcycle racing) that you can still get home. If I ever seriously got into car racing, I would build a track car. Ugly but fast, just like the race bike.

That being said, I would have driven home from MSR-C with no problems after running the motor HARD (at 14-20 psi) in several sessions with no problem had it not been for that piece of teflon tape. That was the root cause, not the track time. And I still got home even with a trashed turbo.

I know what you mean. On that track day I realized that my car isn't one you want to screw up in. With the new set-up I plan on running it at 10psi because I enjoy life. I need a cage for the way i drive out there.


I'm going to tune on 91-octane and run 93. Safety is win.

So, by chance are we ever going to see pics of these failed pistons...

FWIW my JE pistons are about 4.5mm from the valve pocket to the end of the piston. Will post pictures in a few min.

Attachment 203969
http://i6.photobucket.com/albums/y23...boarder/-2.jpg

Dear Lord, are those plastic calipers? :giggle: +/-.005?!?

yea they are crap, but its better than nothing. I'm not measuring oil clearances with them :giggle:

What bore piston is that?

again, who tuned this car on the dyno? Did you use det-cans?

84mm

My car? Sav, yes det-cans were used and there was no knock. Rod failure.
Attachment 203901

Same thing happened to me with my stock motor.

Dropped the motor off at the machine shop this morning. I should have pictures of the pistons in about a week.

BTW, we just took apart a race motor with similar piston damage in a very short timeframe, and I took another look at the 11:1 "Spec Miata" piston on my desk. It's just how a piston gets hurt from detonation. The rod bearings on the race motor were also hammered badly, so you might want to check those out. And definitely get the car tuned.

Yep, agreed. I asked the engine builder to check out the motor including the bearings. Definitely going to get it tuned too, and am adding port injection on the WI, and some failsafes.

This is what happens when you think a motor has forged rods, so you tune to 17psi, and then find out it has stock rods. :loser:

OK, finally, the moment you have all been waiting for...
Click here for pictures of the damaged piston

A preview...
http://lh4.ggpht.com/_jh2HiMm4nKQ/Sr...2/P9160209.JPG

The machine shop finished reassembling the motor and I picked it up today, along with the old pistons. There are definitely signs of detonation. Check out that bent up chunklet that is barely hanging on, with the crack running through the cantilever end. I saw that in the borescope, and it was clear it was time to park it and pull the motor :D

The rod bearings were also damaged, specifically the top portion (where the rod presses the bearing into the crank during the power stroke). Everything else was OK, including the head. The rest of the pistons look fine, just some carbon buildup. Amazing how well it was still running despite this damage. No oil smoke, no noise, nothing. If I had not pulled the plugs out to regap them I would have never known, at least not until that chunk broke loose.

On a positive note, one of the head guys at the engine shop, Donald Duffin (Duffin Engine, one of three brothers that owns/runs the shop) had a great story about a trip he took to Barber Motorsports Park; I was out there last week. We were talking about how incredible the museum is (if you are in Alabama, you MUST go). He had a great story about getting to meet George Barber himself, and getting a tour from him of some of the otherwise restricted areas of the museum. Great stuff.

We need to have a Miata Challenge at Barber. A Miata would be a blast on that track, even better than Hallett.