4032 Alloy Pistons for 500whp?

Sounds about right. A local guy is pushing like 490whp on his HTA3076 with a CM14 nozzle. I don't know what his IDCs are, though. He was FREEKTUNED, so I'm sure they're not too high for safety's sake, etc.

I know what you're talking about regarding descaling though. Since I switched to my CM10, I was only seeing 85 IDC @ ~365whp (summertime power levels suck), and I'm scaled so low it only showed 310 grams/second. When cooler weather rolls around, I'll be back in the 380-390whp range. When I put down that power level before methanol/MAF scaling, I was pushing ~380 grams/second.

 

Shit I'm pushing >100 IDC's on the S3.

Yeah I agree that climate is a factor too. I've seen built motors up here on cold starts on a subfreezing day literally throw liquid oil out the tailpipe(s) until the 2618's warm up.

edit: BTW you guys know you can cross reference your MAF voltage with a known good MAF cal to get your "unscaled" g/s reading from the MAF sensor, right?

 

Once you get that WMI going, it'll be a different story I was in the same boat regarding IDCs, being the 105 or so range in cold temps. Once I hit 107-108, my Pu doesn't like it. Even with fresh NGK IXs gapped to 0.026", that's when I start getting blowout. That was one of the main reasons I added methanol, and the CM7 on 100% dropped my IDCs on average maybe 7 points. I'm assuming the CM10 will have me down a full 10 points in cold weather. Time will tell.

Regarding great base MAF calibrations, I always reference this:
http://www.mazdaspeedforums.org/forum/f600/maf-calibrations-bigger-intakes-124734/

I'm at ~4.19v in the summer, which translates to ~365whp and ~335 grams/second unscaled. Not bad for a 100-degree day. In the winter, we'll see what the voltage is when I'm in the ~385whp or so range again. But even with the known good "base" calibrations, we have to be aware that with our Pu O/L fuel trims, we can still be +/- ~10% and still hit AFR targets. Gram/sec is educated guesswork on a Pu much more than on a Won.

 

Not entirely sure what you are saying but i quoted the relevant post for you

 

I'm seeing IDC's peak around 80 during 4th gear datalogs and showing 430WHP in the summer heat but when running up through the gears I'll see 95% in 3rd and then it drops to high 70's while running out 4th gear. Spraying 100% with a D14 nozzle.

 

My S3 was reaching ~120% when it got cold - yours will too. When you sacrifice that specific gravity and injector scaling for alcohol, it gets chewed up quick. Napkin math says you get ~5% IDC for every 250ml/min 100% meth you are spraying if you're at / near 100% IDC.

 

I don't think he's hitting 105 IDC in the summertime; I think he meant the highest he's seen, which would be wintertime. But I could be totally wrong regarding how @VTMongoose 's tune is setup.

Justin would've never tuned me to 105 IDC in the summer, knowing full well where I'd end up in the wintertime with 105 summertime IDCs. That would've been a bad tune, and he doesn't push those out.

 

Well.. I cheated. I got tuned by Justin, and then swapped to a catless DP, made an additional 24whp 30wtq and almost 26psi on the colder days. I knew I was taking a risk.. but that extra power is sooo hard to turn down. Pretty much why I opted to build before I blew it up.

 

Good idea. He probably had you optimized for power/safety. And going full catless after that can definitely affect boost/power levels enough to take you into an unwise zone, especially in wintertime, haha.

 

IDC's are easily manipulated by careless mixing. Highest I've seen is somewhere around 115 which is where my car starts to break up a little bit. That's at probably closer to a 2:8 mix or even a hair higher methanol ratio. The methanol injection will help when I finally get off my ass and install it.

 

That's true. Fortunately, I never have an issue with this. I use the exact same ethanol pump every time, travel to the exact same distance to get the 93, and add the fuel amounts accurately down to the hundredth of a gallon (yes, I bust out a calculator and everything, LOL). So far so good. In over two years of doing so, my fuel trims are on point every single time. The only FT drift I see is the appropriate amount commensurate with average ambient temperatures changing.

I'm 100% certain that my IDCs going up in the winter is directly proportionate to increased oxygen density/volume of air. I observed this phenomenon consistently (and to the same degree) for years of self-tuning, and see the same thing now, on my FREEKTUNE.

 

I just watch my fuel trims and if they're outside -5% or +7.5% consistently I just add methanol or gas. It's rare that I have to though.

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@Redline; thank you for this thread I've been asking this question about 4032s to multiple people and no one could give me a definite answer. This is what I wanted to know. My goal is 500 whp with PI or upgraded injectors (if that pipe dream ever comes true). Don't even want to mess with methanol.


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Heard back from Mahle. This guy is actually one of the piston engineers who was directly involved in the development of the 4032s for SP63 for our platform:

"Zack,

I worked with Speed Performance on the design of these parts. The 425whp rating is conservative. I would recommend the 4032 for your application at 500whp and using methanol / alcohol. The 2618 would give you a higher safety factor but as you stated the life span of the part is less.

The 2618 part should be approximately 10g heavier at the same bore size.

Kind regards,
Justin Dossett
MAHLE Engine Components USA, Inc.
MAHLE Motorsports (IMO7)"

So in other words, he's saying exactly what I was saying and @Realgib3 was saying: since I'll be using so much alky, the 4032s would be perfectly fine for me, and offer numerous other benefits as well, including longer service life, lighter weight, tighter PWC (so less chance of ovaling), faster warming up/ready to drive, more DD-friendly, less chance of burning oil, etc.

This is the final word on the matter for me. The 4032s for us, after all, are from Mahle; they're from the very guy who emailed me back, LOL. I'll be taking his advice.

 

So has anyone built with these pistons? I know data is going to be slow coming, but do we have a car for some preliminary feedback?

 

They look to be top-notch offering. Mahle makes excellent products (tons of fleet stuff, as well) and knows their stuff. I'd be totally comfortable being the guinea pig on these. But, alas, my build is still a couple years away...
[doublepost=1483633046][/doublepost]More info from our Mahle 4032 Piston engineer:

"Zack,

Piston to wall clearance should be 0.0020" for the 4032.

Top ring gap 0.021"-0.024"
2nd ring gap 0.017"-0.024"

Kind regards,
Justin Dossett

MAHLE Engine Components USA, Inc.

MAHLE Motorsports (IMO7)"

Since we normally run a smaller top gap, and slightly larger bottom, I asked him if 0.021" (top) and 0.023" (bottom) would be good for my goals. We'll see what's what. The general Mazdaspeed practice is to have smaller/larger top/bottom gaps. These 4032s may be game-changers in this regard. Any engine builders on here want to speculate/reason about how this would apply with these pistons?
[doublepost=1483638545][/doublepost]Response

Me:
"Justin,

Gotcha. You've been so kind to entertain my responses. Just one more quick question: is there a certain specific ring-end gap you'd recommend for 500whp and ~40% fueling from ethanol / methanol? Folks with my platform have had a TON of luck running a slightly smaller top end-gap. I think it had something to do with combustion gasses not getting trapped, but I don't remember for sure. Anyways, what about maybe:

0.021" top
0.023" bottom?

Does that sound about right for me?"

Justin @ Mahle:
"That will work yes and will be safe.

There are several thoughts behind staggering top and second ring gap. You will see conflicting arguments but piston design and application are the two largest drivers.

On the piston design side, the driver is whether is has an accumulator groove on the land between the top and second ring. The groove acts as a reservoir for gasses that get past the top ring. Having the extra volume between the rings reduces the pressure that could potentially unseat the top ring. The majority of our pistons have an accumulator groove (The ones you are selecting do). Without the groove, the second ring gap needs to be larger so that gasses escaping past the top ring have a leak path so pressure will not build between the top and second ring.

Heat is another factor in selecting ring gaps. The top ring sees significantly more heat than the second so the amount the running gap reduces will be less on the top due to the differential in heat. So if you run the same ring gap on top and second, while the engine is running, the second will have a larger gap.

Hope this helps."

 

This is all great info. Thanks @Redline for doing the leg work. Myself and @Chief Fabio are planning for about 500whp on both of our ms6 and were really torn between the two piston materials.

 

If you're going to run a lot of alky and therefore know you won't have any knock or cylinder temp issues, no reason not to go 4032, IMHO.

 

He is planning on the meths, I was leaning towards E and 6th port. I know they both provide cooling in cylinder in their own way, so I wonder if it's safe to assume that E would also be ok. Hopefully... If not I guess I can keep the meth kit I also have sitting in the garage.
The whole knock thing is intriguing to me, once again I assume that the "normal" knock people typically get during WOT (.35-.70 is what I see on occasion) isn't any issue, rather it would be longer durations of kr that would exceed the "acceptable" kr range. Aka, don't get a shitty tune?

 

The general rule of thumb is that WOT knock under 2.0 is of no consequence, and that's on stock pistons. Personally, I like staying below 1, but I'm just super-careful. Fortunately, with all the alky going through my engine, it's not at all an issue. All I have is the characteristic (and totally normal) throttle tip-in knock. The durability to knock would likely be higher on 4032s and especially 2618s. But with enough alky and a solid tune, it's a moot point. You won't have knock unless something mechanical is going on, and if that's the case, you've got potentially much bigger fish to fry.