MZR DISI Ringland Failures
 

Since the release of the MS3/MS6 platform, car enthusiasts have been pushing the envelope of what initially was a very difficult car to make power from. As a result, blowing a rod out the side of the block was not uncommon. Some members were proactive in dealing with the platform by leaving it altogether while others stuck around. Time passed, more knowledge was gained on the inner workings of the car, the engine and the tuning. Popping motors due to rod failure became less common.

Now a new problem has come to pass; cracked ringlands. Cracked ringlands generally arise from detonation (too much spark advance for instance) or excessive heat. Cracked ringlands caused by excessive heat generally occurs when the ring ends (the gap in the rings) butt up against one another, then exert vertical force between the piston ringlands causing the them to crack.

How do I know I have cracked ringlands?
The only way to really know for sure is to open up the motor and inspect. Generally, a telltale sign has to do with a marked loss in compression in one or more cylinders. For instance, if your compression numbers look like 180-180-150-180, it is highly likely that cylinder 3 has a cracked ringland. Shooting out dipsticks and pushing oil out of the valvecover vent can also be indicators.

Personally, I suspect that cracked ringlands have been around far longer than initially thought as some folks decide to part out their cars and sell them after discovering their engine is hurt. At this point, the car still operates and for the *most* part, its hard to tell something is wrong unless you have a keen sense of what is going on under the hood or feel a noticeable loss in power. The latter is sometimes less obvious than you think.

We should start documenting who HAS verified that they have cracked ringlands in their motor. Format is as follows:

Model/Year:
Mileage:
Compression Results:
Cylinders /w Cracked Ringlands:
Suspected Event Causing Failure, Condition of Affected Cylinder(s) and Other Info:
Pictures:

I'll start.
Model/Year: 2007 MS3
Mileage: ~85K KMs
Compression Results: 180-180-150-180
Cylinders /w Cracked Ringlands: Cylinder 3
Suspected Event Causing Failure, Condition of Affected Cylinder(s) and Other Info: Summer 2011 Time Attack. 35*C temps. 230-240*F coolant temps. GT3071R. Spraying meth. No KR as per AccessPORT. Cylinder bore was perfect.
Pictures:
http://farm7.static.flickr.com/6078/...619ef2b1_b.jpg
http://farm7.static.flickr.com/6180/...5675e17d_b.jpg

Database Listing

Are those factory pistons? How much power were you running?

Yep. Stock pistons.

Never dynoed/vdynoed so I'm kinda shooting from the hip. I'd say 330whp at the time.

@Lex; will be interested in this, I bet. Feel free to delete this post if you update the op with his mention.

I'll post up a few pictures later. I have over 100 pics from that teardown.

Model/Year: 2008 MS3
Mileage: ~110K KM's
Compression Results: 180-180-165(?)-180
Cylinders /w Cracked Ringlands: Cylinder 3
Suspected Event Causing Failure and Other Info: Logging since 2009, about 650 logs in. Time attack's through 2008 and 2009, along with testing, track days, and nightly logging on the closed-circuit Mexican test track.
Pictures: I will update with a couple of pics if I can find them.

https://lh4.googleusercontent.com/-3...0/IMG_1236.JPG

https://lh4.googleusercontent.com/-i...0/IMG_1238.JPG

Dave is right in that most will not notice the issue. The best way to notice through logging is that no matter what you do, you won't be making anymore power, and will slowly begin to creep downwards...you will notice this on VD, all else being equal.

I was making about 360whp on the GT3071R when it began to deteriorate.

may I suggest to also state how your bore looked after this? :)
also, how you noticed this.

also, just a side note, mine is also cylinder #3

Great point. I'll update OP when I get behind a computer again.


Sent from my iPhone using Tapatalk

I don't have pics, but the machine shop that did my tear-down and @Celestspeed3 confirmed that there were NO OTHER damage what so ever...bore was fine.

So here are my particulars

Model/Year: 2007 MS3 GT
Mileage: ~55K
Compression Results: 180-180-150-180
Cylinders /w Cracked Ringlands: Only #3
Suspected Event Causing Failure and Other Info: Aug 2012 - 100+* temps, GT2871/meth/E40 at ~380WHP- suspect that summer heat, a malfunctioning tstat, and numerous WOT tuning runs caused the failure due to top ring butting. No deto events noted. Probably put an additional 5K miles on the motor post failure.

Symptoms: loss of about 30WHP via VD graphs, tons of oil entering the intake via the VC vent. Enough to soak the maf after a while causing obvious driveability issues.

This was what she looked like immediately after being pulled from the cylinder, ring orientation unchanged. Looks like the rings had rotated in the cylinder from a 90* position to the pin. I guess the large lose section of ringland contributed to this. IDK

http://mail.netsecurenow.com/img/bui...wn/piston1.jpg

Hard to see here but you can see the shiny area on the ringland right where the ring butted, removing the carbon from the ringland. The shiny line is at a 90* angle from the land which was where the edge of the ring contacted it...IMO at least

http://mail.netsecurenow.com/img/bui...wn/piston4.jpg

top

http://mail.netsecurenow.com/img/bui...wn/piston3.jpg

cylinder wall

http://mail.netsecurenow.com/img/bui.../cylinder3.jpg

number 3 plug was getting a bit nasty looking and number 1 as well. Those of you who followed my threads will remember #1 had 1 valve that looked like a DI valve with 50k miles on it yet it was walnut blasted just a few thousand miles before this pic.

http://mail.netsecurenow.com/img/bui...down/plugs.jpg

4 out of 4 #3 ?

3 is likely the hottest cylinder of them all due to IM design coupled with how the coolant flows

My bores measured out fairly uniform on 1 & 2 yet 3 & 4 were more deformed.


Tappin

We have a local whose low-mileage Gen2 busted a cyl 4. But majority of issues we have seen is cyl 3...

Let's keep track of where the ringland cracks as well. Dave and Dan both you guys have the crack on the exhaust side of the piston correct? Interestingly this is the side of the bore that gets fuel soaked

Is this completely power-related or heat/knock related?

Fobio, were you spraying meth? I know Dano was spraying pre-throttle body and Bluestreak was spraying into the intake manifold runners.

Yes...I was spraying meth before going BT...which might've helped with the heat management for the tiny K04. My meth mix is usally 50/50, but for cleaning purposes I have ran up to 63 meth/37 water.

I hesitate to even post this because it will cause a ton of worrying for probably no reason, but there was a time when some of the evos were cracking pistons and ringlands from the drastic heating and cooling changes from meth injection.

damn you finkle!!

IDK thought in all cases. I was spraying meth for years before my piston broke. Now it could have been the extreme AMB heat along with broken tstat heated up the piston at that time last year more than any other and a shot of M10 100% meth at 26 PSI caused the damage.

no way to prove it one way or the other I suppose. Interesting that most failures to date are #3 which gets hotter and more airflow which = more meth :)

for now, I will continue to believe it was entirely heat related :)

I was honestly leaning toward meth for a power adder once the BNR was in, but after hearing that... I'm leaning toward E85.

By far the safer option in almost all aspects.

That being said, I do run a meth kit too.

http://www.injectordynamics.com/AlcoholArticle.html

Just cuz...

My perspective is that meth should NOT be used as a power-adder period...it's just there to give you a bit more head-room with regards to knock and act as a cleaning agent. Eth and NOS are likely more effective and less costly as a power adder.

We inject fuel directly on the top of the piston - hard to believe WMI injected prior to the throttle body cools the piston in a more dramatic fashion.

When E85 is not available WMI is the next "best" solution to allow more timing - especially in places with really poor fuel.

Mine would be cylinder 4 . Lol. I like to be different

Anxious to see what is found during tear down.

To add to the conversation, I highly doubt meth is at fault. The common thing I see here is very high coolant temps, very aggressive driving/racing and aggressive tunes. There is no doubt each of these cars went through hundreds, if not thousands of wot pulls.

After deleting a bunch of my logs, I started fresh and I'm already up over 500 datalogs on the AP. That is not including track runs, street racing in Mexico, or just spirited driving. Needless to say these cars take A LOT of abuse.

It was only speculation @ that time and a clear cut answer never evolved. I don't know how it can be said that methanol is not cooling the combustion chamber, but you are far more engineering minded than I.

FWIW, my care has never tracked, only few times of extensive spirited driving, otherwise, eager street drive.

The only thing I might have done wrong tune wise is aggressive low load/low rpm timing.

Very interesting and good shit. Though, my car never experienced this with having 93k on it. My buddy's turbo'd Mini Cooper S had the same thing, except his was the #4 cylinder. Ironic.

Now I'm worried about a cracked ringland... My compression test results were 190 - 165 - 150 - 175. :yikes: I guess that might explain why I'm making such little power at 18PSI. I just spent a couple minutes googling cracked ringland symptoms and it seems like a lot of people experience almost nothing besides a loss of power and find low compression on the cylinder with the cracked ringland. Some do experience a a rough idle, a lot of smoke and mis-fires though, so it seems like it's kind of hit or miss on what you should be looking out for.

I haven't taken the motor apart (and can't until I find a daily driver) so I can't confirm but I currently have low compression in cyl 2 and blowing oil out of the VC vent. I've been doing time attacks and track days for the past 3 summers. I know at Watkins Glen my coolant reached up into the 230's

^Picture within the quote

whats to stop this on a built motor?

Stronger materials and appropriate ring gaps for the intended application.

That, and a reasonable tune that doesn't risk getting into detonation. Knock will kill even the strongest parts if it happens often enough.

I think this whole cracked ring land issue is exclusive to Canadians and old people.
So if you are either, you are at high risk.
And if you are both, you might as well go buy a new engine.

:squintfinger:

Thing is, I doubt any of the ringland cracks were caused by deto.

lolololol. At least you are not too old not to recognize the reference.
Glad to see you are not completely senile - yet.

I went back to read what I had in the past and, as always, you are correct 100%. I re-read the many threads that were related to pistons cracking on different platforms and it all agrees with improper flow balance, not thermal expansion and contraction.

I cannot for the life of me find the thread I was looking for, but the common theme was 1 cylinder not getting the BENEFITS of WMI and over-tuning the remainder of the cylinders based on not seeing the detriment of improper flow on that 1 cylinder.

If someone could enlighten me on why there is speculation that the direct port injection manifold that is out now is a possible cause of a pooling issue, I would appreciate that, considering I bought one and am hesitant to install it until everything is hashed out.

When the initial talks of a IM being made by MSF'ers, a lot of designs were thrown around and discussed. Fluid-dynamic expert I'm not, but I did remember discussion on how certain designs, mostly OEM and due to packaging, does not allow balanced flow to all cylinders, esp under boost. The MR2 was one car that was notorious for doing this...this is from knowledge gleaned 20yrs ago, when my friend upped his boost without additional fueling and not first hand. In the MR2's case, it was the farthest cyl from the TB, and it makes sense from a NA/PI point of view. The interesting thing for us, is cyl 3 & 4 being closest to the TB...as such, I'd subscribe to the theory of imbalance flow, where cyl 3 & 4 are running consistently leaner than cyl 1 & 2...so who's gonna tap each EM runner with $1500 worth of gauges to check? =)

Regarding the tuning side of things and track work: I always run a detuned map for track...for example, on the GT3071, when I was running 22psi on the street, I'd run 20psi on the track...whereas I might pull fuel up top for the street, I richen up to 10.9AFR @ 7000 [linear taper from 11.8] for a track map. At the track, it's not that last 10whp that will win...it's finishing.

http://sphotos-b.ak.fbcdn.net/hphoto...60926703_o.jpg

The methanol related ring land failures are probably related to over advanced timing rather than anything else thermal expansion related.

This whole pooling on valves complaint stuff needs to be put to bed. Any port injector motor running more than a 30% duty cycle is going to spray and pool on a closed valve. If it caused any issues at all related to reliability there would be failures all over the place.

Zigatapatalka

Couldnt agree more about the fuel pooling behind the valves. With close to 100% idc that injector is a constant spray of fuel.

Now lex mentioned a good point about the cracked ringlands being on the exhaust side. Could this be related to poor piston top design and fuel washing the exhaust side of the cylinder wall.

Sent from your couch

:07: I just am hesitant to install it and run meth in the runners right now because I know 1 person in particular who is sketched by it.. and I trust his judgement.

I want to stop there because this is a ringland thread and I don't want to derail or bring in drama from another thread.

I guess it's worth pointing out that this issue being discussed is very likely related to the other thread made by Dano regarding heat management...specifically, break down of oil that many of us used, such as Pennzoil Platinum, which is more than fine for the street, but likely not sufficient for extended track work...a 20min stint is like 15+ laps of oil sloshing from side to side...being heated, without much chance to release that heat. Once that oil breaks down, even your "safe" tune will be too hot.

I'm inclined to think that even T6 may not be enough...we have shops here in Toronto, telling us to run a "proper track oil"...

When I would track my bike I would run 20w-50 oil then use 10w-40 for the street. Maybe we should consider something like that for track use.

I defintely feel heat is the major factor here. Curious to see the results of these next couple of motor tear downs.

Sent from your couch

it'll be interesting to see how my stock motor is if/when it is ever taken apart. I ran T6 during the track season in 2011 and 2012, including those 2 hot days in 2011 at Mosport big track (30+ C) where I was able to cook the power steering pump on day 1 and completely seize the power steering pump on day 2.

i haven't run a compression test yet (ignorance is bliss) but it still reads -12 psi vacuum when letting off at WOT, and reads -10 psi at idle.

on the built motor though, Motul 300v is what i'll run at the track.

FWIW, I'm pulling the same amount of vacuum and my compression numbers were 190 - 165 - 150 - 175. I haven't noticed any oil consumption, up until my most recent fill up and I had lost about a 1/4 of a quart. My idle is somewhat rough, but I've always attributed that to VVT/timing chain stretch problems.

I'm assuming that if I have a cracked ringland, it was probably caused by one of the previous owners running low octane fuel and detonating like a motherfucker. Detonation will fuck your ringlands, even with forged pistons.

To he honest. I don't even remember. I haven't handled a stock piston/rod combo in such a long time that I can't even infer the orientation of the one in my picture.

When I re ringed my forged motor not too long ago, I did notice that the exhaust side of the piston skirt coating was noticeably more worn than the intake side. This can be an indicator of where the majority of the stress lies in combustion given our motor layout.

If the oil was too thin for track use you will get spun bearings.

There are several possibilities here.

1. Heat in single event or over time deteriorating the piston or butting rings. Heat is the enemy of every turbo motor.

2. Detonation between the two rings due to heat and fuel washing down the cylinder wall. Might not take much and might happen outside the timing Window the ecu is listening for.

3. Luck of the draw. Some will fail and some won't. Especially if the car was assembled on a Friday, driven hard, put away wet and had slightly tighter ring gaps.

In the end tracked cars have failed as well as street ones. Heat management should extend the life of any engine and component so it's a good place to start.

This is an example of an engine that was run very hard for a long time. Iirc, it did suffer from somewhat high ECT's part of the time. This was a local guy's car that was tuned prior to him moving into the area.

Model/Year: 2007 MS3
Mileage: ~80k
Compression Results: Unk
Cylinders /w Cracked Ringlands: 2/3/4 shattered
Suspected Event Causing Failure and Other Info: Long term, WOT detonation with GT3076 and pump 93 (too aggressive of tune)
Pictures:

Pieces of piston 4 exploded into the intake manifold, and were sucked back into the other cylinders where they bounced around (you can still see the deto marks pretty well, though). The engine let go in the high revs, and had been experiencing boost spike issues with the GT3076/MBC/improperly adjusted preload on the IWG.

Cylinder1 - Cyl1 Photos by phate1985 | Photobucket

No cracked lands in cylinder 1
http://i64.photobucket.com/albums/h1...ps8deae3e7.jpg
http://i64.photobucket.com/albums/h1...ps71044397.jpg

Cylinder2 - Cyl2 Photos by phate1985 | Photobucket

http://i64.photobucket.com/albums/h1...ps14746efc.jpg
http://i64.photobucket.com/albums/h1...psd90834dc.jpg

http://i64.photobucket.com/albums/h1...psdedc4895.jpg
http://i64.photobucket.com/albums/h1...ps8de5c4fd.jpg
http://i64.photobucket.com/albums/h1...ps9eaac6dd.jpg

Cylinder3 - Cyl3 Photos by phate1985 | Photobucket

http://i64.photobucket.com/albums/h1...ps07eb2700.jpg
http://i64.photobucket.com/albums/h1...ps00dcc042.jpg

http://i64.photobucket.com/albums/h1...ps1fc2005c.jpg
http://i64.photobucket.com/albums/h1...psdd5b4223.jpg
http://i64.photobucket.com/albums/h1...ps4202e5b1.jpg


Cylinder4 (lol) - Cyl4 Photos by phate1985 | Photobucket

http://i64.photobucket.com/albums/h1...ps4b254ff6.jpg
http://i64.photobucket.com/albums/h1...ps3bdd340a.jpg

Each cylinder's albums are linked. I am not 100% confident the rings didn't get shifted a bit between pulling them and taking pics.






I will finally be getting my 4 EGT probes and logger hooked up after this weekend. Hopefully we can glean some info from it.

The fact that these failures are coming out 8 years after the car was released shows that it can also be age related and heat cycle related.

Holy crap @phate;! It's like silence of the lambs in there!

One of our Celestial Blue Pu's is under suspicion of a cracked ringland in cylinder 4 /w 35K KMs or so.

EDIT: I think we should also take into account that people have parted out their cars and ditched the platform when discovering less then ideal compression numbers as well as the genesis of most builds have been due to venting a rod. Not many people have gone the route of discovering low compression then building.

Ring orientation has nothing to do with cracked ringlands. The rings are always rotating as the piston moves up and down, so even if it was an orientation problem, there is nothing we can do.

Do our stock pistons have "anti-detonation grooves" in them? I know those are more theory than proven, but I'm just curious.

@phate; that's a lot of detonation on those crowns.
@BlueStreak; maybe so but not all low compression results necessarily mean a cracked ringland.

Absolutely, I agree. Has there been evidence of low compression due to rings?

After some debate with myself I've decided to take one for the team.

I will be running my car this year at Time Attack with no extra cooling aside from an intercooler. I will have the following gauges installed: EGT at the exhaust manifold turbo inlet, Oil temp in the pan, Oil pressure stock location, and water temp in the upper rad house. I will record the values I get from my abuse at the circuit this year. Before/after each event I will perform a compression and leakdown test to see if indeed I can cause a broken ring land. This will at least give us some data as to how much "heat", "load" and "time" it takes to crack a ringland. That is if I haven't cracked one already LOL. I have a spare forged motor ready to go, so why not take one for the team and see what we can find.

Temperatures, Loads, Time on track, and tune details will be put forth and reviewed by everyone here to see what we can find.

My car is fully bolted as they say so if anyone wants a complete list of modifications regarding the engine I will post it up. The most abuse this motor has currently seen is 85,000km of street driving and the worst I have put it though was 6 or 7 back to back logs to test of the track-ability of a tune. So it should be fairly healthy based on my current abuse.

If anyone wants to add anything or help me put together a way to organize the data please post up. Let's get stop talking about it and get it figured out. We worked around vented rods, we will work around cracked pistons.

Gdam

Out w wife at charity event and it looks
Like lots of fun
Going on in here. Must read when I get back

Lex do you not think cracked lands is less age related than the fact that we now blow fewer motors due to rod failure ?

I suppose one begets the other when u think about it.

BTW. I still love this place. Phate. U r Insane my brother!!

Can't wait to see pics on a PC.


Tappin

A ton of deto. I wasn't the one who tuned the car, and after getting to know the owner a bit, I suspect he turned up the boost controller some after the tune was done. By the time I ever saw the car, it had been running like that for thousands of miles :/ No bueno, I'm sure it just ate away at it, little by little.

You may be on to something hear Justin. Check out the failure posted most are gen1 piston design!!!!!!!!!!!! I would think If the coolant temps are high the cylinders with flow differences would be the first to go as det would likely happen hear first. And this brings a maintenance idem in the mix for the person that may track there car. Possible thermastat swap would be in order!!???

I don't think there's a smoking gun just yet with this. We'll track the failures and see if anything emerges. There can be a number of reasons for the failure. In any case, I am a strong believer in heat management and how it extends the life of mechanical components as a whole. These cars run hot so it's a good place to start.

I cant believe you managed to respond to that post. The only thing I read was HAY GUYZ, IM DRUNK!

Anyone have a contact @ i-MOTO? They abuse this engine more than anyone else, 24 hour races and 2.5 hour "sprints" in traffic. I would be interested in what they have setup for cooling and if that are using the stock internals(I think they have to), and if so what they are setting their ring gap to. Those cars are down on power, but certainly not on heat.

@Todd98SE;

Sorry Lex, different group (MotoIQ is not i-Moto racing team) but I will see what I can do.

http://i-moto-racing.myshopify.com/p...car-chassis-32

At a quick glance i-Moto is using a custom radiator. No details about oil and transmission cooling.

I think I just bought their race seat from last yr's car...when I get it in hand, maybe I can send them an email or something and get them to come on here to chat.

I think that @skeurton; has contacted them and received return e-mails from them.

I met them @ the Grand Am event in NJ and they are very easy going and easy to talk to.

I think if someone where to contact them, they'd have no problem responding.

Talking with out engine builder they told me this is nothing more than a heat issue. They said even if I upgrade the cooling it will still be a bandaid. The ring gap needs to be opened up as a start. If we are still getting cracked ringlands then we are running to much heat for the pistons. Although they believe just the ring gap will fix the issue.

Either way I'd like to see how much heat this motor can take.

Does anyone have any comparable data regarding EGT's? I know sensor placement as well as timing will affect the readings. Is there anything I can test for that will allow us to estimate cylinder combustion temperatures? If boost is fixed and I run 5* timing at RL, then up it in 2* increments to see theml temp change does that change in temp refer to the energy being added into the chamber, or is it more complicat d then that? Most things I have been reading suggest to keep EGT's at a most of 1650F when measured at 3" from the head.

@kritz; and I met Gareth Nixon up at an OCC meet last year, he was looking to sell this car which does lists both oil and tranny cooling as well as a 3 core radiator: Grand AM Continental Tires Mazda Speed 3 For Sale

He handed out business cards but I don't have it anymore. Steve do you still have his contact info? Just gives us another option to contact. iMOTO isn't the only ones racing these, they are just the only ones winning :P

EGTs and piston temperatures are not directly related. As you advance timing the EGTs will go down and piston temps will go up. Adding boost and/or leaning the afr will cause both EGTs and piston temps to go up.

The lower the ignition timing, the higher the EGT's will be until you get beyond MBT. Then they go through the roof. I would assume that 5* at redline would result in EGT's that are ridiculously high to start, then as you add the timing EGT's will gradually come down, and it moves the heat into the combustion chamber rather than the exhaust

EDIT: Ziggo beat me to it.

I would've thought the same exact thing ^^^(and I'm pretty sure this must be a common misconception because I've read that idea many times).

I ganked these (the below quotes) from a debate about egt behavior in another thread per djuosnteisn.

He also credits the author of a book that contains the info and the link is posted below.





quote from this post in another thread:
http://www.mazdaspeedforums.org/foru...ml#post1915217

Lets hammer out a testing proceedure then.

Boost and AFR will remain constant in this instance.
Lets say at 5* I see ~2000 egt as I advance timing it will go down. At what point do I know I have reached MBT? Also does advancing beyond MBT provide any gains?

I doubt anyone has really done this before. Most guys street tune and we just tune to the knock sensor. A few pulls on the street is not +20mins on track.

Yes, I fact I emailed him recently. I will shoot you over his info. I was looking to see if he wanted to part with a LSD.

You won't know you've hit mbt without a dyno.

This. It's the only reliable way to find mbt, and it's worth every penny.

They have a lot of used parts for sale on their site (for cheap).

How do I use the dyno to find MBT? What should I be looking for?

I don't mind renting a dyno for a few hours. I just don't want to go in it blind. Would this data then be used for my motor only? Or would it be engine dependant? Say at X AFR @ Y psi = Z timing. Does it work that way?

@Fobio; will know what to look for.
He's worth every penny.

It is engine and load specific, along with weather specific. As you walk up timing, gains decrease per 1* of timing. Then power plateaus, then power drops. That last point where you gained power is MBT. Back off a couple/few degrees to play it safe.

You have to be sure to keep things as consistent as possible between the runs. ect's and bat's are especially important to watch

Should MBT then be tuned cell by cell then ?

Should we then be looking for a plateau in load or torque?

The ideal setting is then to leave it at just before the plateau?

Does this hold true when using meth as well?

Cell by cell @ loads you hit per rpm.

Keeping the variables such as BAT and IAT as close as possible is important because you really want to quantify gains from spark advance only and not let other factors skew the power levels.

It is pretty clear to see where power has been increased by the changes you made on a map so choosing the points (rpm cells) that have made a positive difference in power is just an exercise in picking out those values and finalizing them.

I'm pretty comfortable saying that if you hit 2.5 load @ 6500 rpm and have a finalized timing value... e.g. 18*, 2.4 load @ 6500 rpm will also comfortably run 18* of timing (possibly more assuming you are commanding the same AFR).

I find that there is a bit of leeway before you start to lose power... sometimes as much as 2*, so I would let power plateau, use the lowest value in which that happens and back off a * or 2 for a case of a shitty tank of gas etc.

Okay did some calling around:

Yes, if must be tuned cell by cell to see the proper gains made at each RPM instance. As the computer interpolates which value to use between specific RPM ranges you want to see specific results for specific changes.

We are looking for peak torque output as the computer uses load as a reference calculation and its not directly related to torque output at the wheels.

Yes the tune should be left at the settling as close to the beginning of the plateau that the computer can command. This allows the most torque to be produced as well as the largest margin of safety.

Regardless of fuel the engine should be tuned the same way. Changes in the fuel mixture will require a different timing curve.

The last piece of the puzzle is then what are he EGT temps at MBT. Once we know this you use EGT as a monitor to verify the tune on the street and the track. EGT values higher or lower than what is expected given current weather conditions should be investigated as a possible mechanical issue.


Back to the ringland issue, how long can the pistons sustain the temps produced at MBT? This is where I will follow up with data and time logs from the track. Using ATR we can determine how much time and therefore heat it will take to crack a ringland. This data should allow all of us to tune safer depending on our intended use of the car.

After that is determined we can see if additional cooling will allow us any headroom. It may get to a point that we will just have to address the ring gap in order to continue. At least I see that being true for track applications.

I have a feeling though the coolant and water temps will be lower on the dyno than at the track. This is due to the "duty cycle" of the motor since it needs to be shut off to upload a new map. Where as at the track the motor is running WOT every few seconds. To this affect I wonder what the balance will be for cooling, will an oil and tranny cooler with an upgraded rad allow for enough safe track time to run out of tires and fuel. It should also be noted that at what temps is it time to pull off the track and allow for some cooling.

So you are going to tune to MBT then take that tune to the track? I don't know how much value there is in that, I would be Suprised if you didn't blow a ringland after the first afternoon session doing that.

Zigatapatalka

That's the idea, I want to see how much heat the motor can take before I crack one.

Or rather once MBT is found how much should one dail it back to be safe.

Example: tune for MBT, dial it back ~4* run a time attack weekend. Compression test. Increase timing do another weekend compression test. Rince and repeat until I crack it.

I will donate/lend you one of mine, if not 2 of my egt gauges [might need a new probe for my old pro-sport one] to do the testing...

hammer out a procedure here with the guys and we'll go from there.

Do you have a way to monitor oil temperatures as well as coolant temp? Those are as big a part of the equation as the timing.

I agree the ring gap is small, but I don't know that if it was my $ I would pull the stock pistons, regap the rings and reinstall. If I am pulling the pistons I am going to slap some 2816 pistons in as well and call it a day.

Zigatapatalka

Yes I have oil and water temperature gauges. I'm debating on a trans temp as well.

Does anyone suggest multiple EGT gauges? (Placement ?)

I think 1 at the collector should be enough or behind cylinder 3 as that one is know to be the hottest.

Ziggo I have a forged engine already. I just figure instead of just swapping out the stock one might as well learn something first.

Paul, I don't know you well enough to say this, but I'm going to anyhow. Don't sacrifice an engine / pistons like that on your own dime and time.

Hell, you may not even notice the exact point and temp that the ringland gives way and waste a great deal of $ and time.

I say that if we know this is an issue, @ the very least try to combat it and if that measure fails, we have an even better idea of how sensitive the engine really is to high heat.

If the water pump stops spinning, coolant stops flowing and becomes heat soaked.
You will still gain temps shutting the car off to load a new map at the dyno.

It's going to cost the same for me to machine a block with or without a cracked ringland.

I figure if we at least have an idea of what the safe limit is people can play within it. Building a motor is a big expense and not for everyone. I would hate to see people have to sell their car because they can't afford a build or to fix it. Especially with all the work the Nator community's put into modding the cars. I also don't want people to be scared of the track either. Adjusting the tune for the track is far easier then re-ringing the motor. Mind you re-ringing can be done in a day we have done that before but I would prefer not to have others go through that.

The way I see it other than some dyno time, it won't really cost me anything.

Would it be better for me to open the gap on the stock pistons then try to break them?

I'm open to doing that too.

105k, Stock K04, 33% E85 mix. Massive oil usage due to failed PCV and Turbo seals. 189, 70, 137, 188 compression

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I REALLY think opening up the OEM gaps , even if only the top, would solve the issue. At the least a very interesting experiment. That's just me though.

http://mail.netsecurenow.com/img/bui...oemringgap.jpg

Those are for the OEM application and we are generating 2x WHP and a lot more heat. I'll let ziggo do the maths for how much more heat is generated at 2xhp.

so typical forged piston ring gaps for turbo induction street are:

top .017
2nd .019

I wish I had measured my actual OEM gaps but assuming they were within spec opening them up to say .012 and .019 respectively would do wonders in allowing for thermal expansion. Really the OEM top gap is the issue more than likely. at .017, the oem 2nd gap isn't bad if it were at max spec.

But that is really a LOT of work for an experiment. lol

Provided my rings are good would you think I can reuse the current rings just open the gap or should I get new ones ?

I don't mind going the work. If it brings us closer to BMW smackdown so be it.

Hmm this has me all worried now cause this can happen regardless of what turbo/fuel we are running. If I get another beaner, I would like to run it on crappy gas with a tune that can handle 30+ minutes of canyon/track abuse. Should I go ahead and upgrade my radiator and oil cooler?

Sent via oil leak.

Looks like every cracked piston posted thus far has been cracked on the exhaust side.....

IDK man, again thats a ton of work no matter how you slice it. I do wonder if there is more chance of chipping the ring coating during a filing session after they have been used and heat cycled 1000s of times?

beyond that, I would just keep the rings in the same bore/location and file them down.

I suppose if your end goal is to always run OEM pistons this is a worthwhile endeavor.

and genwan pistons...right?

maybe mazda's design change was two fold. Better atomization of fuel for all the reasons implied, and better piston cooling/lubrication by removing wall wetting on the exhaust side.

If @breakfasteatre; ends up having a cracked one, he's a molestialpu.

well ban his ass if he ruins our genwan failure streak!