MZR DISI Ringland Failures

[Tokay444]

I don't think it's necessarily power related.
Kmac made 600whp on stock block. No chucked rod. No broken ring lands. LOTS of meth (while that doesn't eliminate meth as a factor, it does put one check in the no column), and just generally driving the car as hard as situationally possible. But he's just one case I suppose.

[Dano]

Originally Posted by Ziggo The point is, we were able to tune around a hardware limitation and continue to increase the ability to make power/go faster. At one point rods were bending at frequently at 300whp. Now cld12pk is running 500whp+ on the stock rods, and there are a bunch of us running around the 400whp level with the rods still in the block, which is what seems to be precipitating this new failure mode. I don't think this is going to be avoided in a similar fashion allowing the power to continue to increase without changing something internally.

Originally Posted by Lex Well it sounds like you have a good idea for the root cause. I know I personally can't say I do based on the few pieces of evidence provided. I don't think only 400+whp cars broke ringlands if we are to believe at least some of the other low compression K04 cases suffered this fate. On top of this not all high hp cars broke ringlands. There is always something that can be done to mitigate failure if we understand that root cause of that failure. Whether it's cooling, capping power output, or gapping rings but it's too early to tell. Let more data come forward.

I don't think the ringland failures are directly HP related either although more HP gens more heat. If a guy at 325WHP runs his car hot enough, long enough the ring land will likely break whether due to heat fatigue, ring butting, deto or all of the above. With the progress in eliminating rod failure we are now able to keep the same motor at a higher HP level for longer. This enhances the chance of other failure modes to crop up as we are now seeing.

What I think we want to do is push that time window out by cooling the motor off not decreasing power. That would be step 1 in my book. The next step for guys wanting to stay in an OEM configuration yet optimize it might need to alter the ring gaps to attain more headroom with ring butting. Could be the rings are not doing this in every instance of a failure but it is one thing to eliminate.

long term data my indeed show the gen2 piston design as already addressed this entire subject...lol

@Lex; do you, or anyone, have any data on a gen2 piston with the oil residue/burning on the exhaust side?? didn't ckmazdaspeed3 send you his PU pistons after he threw his rod?

[Lex]

Originally Posted by Dano I don't think the ringland failures are directly HP related either although more HP gens more heat. If a guy at 325WHP runs his car hot enough, long enough the ring land will likely break whether due to heat fatigue, ring butting, deto or all of the above. With the progress in eliminating rod failure we are now able to keep the same motor at a higher HP level for longer. This enhances the chance of other failure modes to crop up as we are now seeing. What I think we want to do is push that time window out by cooling the motor off not decreasing power. That would be step 1 in my book. The next step for guys wanting to stay in an OEM configuration yet optimize it might need to alter the ring gaps to attain more headroom with ring butting. Could be the rings are not doing this in every instance of a failure but it is one thing to eliminate. long term data my indeed show the gen2 piston design as already addressed this entire subject...lol @Lex; do you, or anyone, have any data on a gen2 piston with the oil residue/burning on the exhaust side?? didn't ckmazdaspeed3 send you his PU pistons after he threw his rod?

The one gen2 piston I have is a lot cleaner. However, through the many gen1 pistons I've seen, the buildup of oil residue and staining happens as mileage increases. So the gen2 probably just has fewer miles compared to the gen1. Gen 1 is on the left, gen2 on the right.

[Dano]

yes more mileage and data needed on the PU pistons.

[BlueStreak]

OP updated. Some info paraphrased to keep it short.

@taf0422;. Any news?

[breakfasteatre]

its a ton of labour hours even if I have guys helping me, and I wouldnt want to pull anyone away from the fun during the dyno runs, but would it be worthwhile to this discussion if we pulled my head and pulled the rods and pistons in april? If so, ill grab the one time use parts so we can put it back together.

For reference: I have a poo, now with 38k kms (23k miles) with low compression in cylinder 4. Me and my nader brothers did a leak down test, 20% past the rings.

Ran 4 time attack events, saw oil temps hit 260 after about 5 laps, did 5-15 laps at 260.
Off the shelf stage 2 map + maf cal. Dynoed at 270/310 ish
one event I blew couplers off multiple times due to faulty hose clamp

[taf0422]

Originally Posted by BlueStreak OP updated. Some info paraphrased to keep it short. @taf0422;. Any news?

I wish. I'm still waiting to hear from Pablo. I will try to find out from him tomorrow. I will let you guys know tomorrow night if I get anything. I'm just as curious as you guys are.
@SPEED6 KILLAH;

[cld12pk2go]

Great thread...

Anyone have a compression tester recommendation (and a good procedure)? I should probably check mine...

[802MS3]

Originally Posted by cld12pk2go Great thread... Anyone have a compression tester recommendation (and a good procedure)? I should probably check mine...

I bought the basic one from autozone. I forget how much, it was an impulse buy. Think around $30. Seems fine, produces consistent results.

As for the procedure, get car up to temp. Pull one spark plug at a time, attatch comp tester, pin accel pedal while cranking a few seconds, read pressure ASAP. Repeat for each cylinder.

[Todd98SE]

Originally Posted by cld12pk2go Great thread... Anyone have a compression tester recommendation (and a good procedure)? I should probably check mine...

OTC makes good testers. Bought mine on Amazon.

I pull all the plugs and crank for 10 revolutions on a warmed up motor.

[Lex]

Pull all plugs so the starter has an easier time turning the motor over.

[SPEED6 KILLAH]

I have a question for the people who had Ringland Failures how much boost are you guys running and what was you coolant temp at?

[BlueStreak]

Originally Posted by SPEED6 KILLAH I have a question for the people who had Ringland Failures how much boost are you guys running and what was you coolant temp at?

At the time, mine was 20-21 PSI on a GT3071. Coolant temps were in the 230F range coming off the road course on a 35*C day.

[mzr0818]

Mine was 22psi/ coolant temps 225 range after coming off the track 60degree day

[Dano]

I had just moved up from a 21-22PSI tune to a 26 PSI tune. The timeframe was around August last year and AMB temps were ~100*f. I don't know exactly when mine went nor the exact ECT but I routinely saw 217-220* last summer. My tstat must be broken b/c I see 217 now after a 10-15 minute drive around the city. AMP temps in the 40*f

[rfinkle2]

Originally Posted by Todd98SE OTC makes good testers. Bought mine on Amazon. I pull all the plugs and crank for 10 revolutions on a warmed up motor.

Just did the same thing with the same tester this weekend. $60.00 for what seems to be a really good piece of equipment.

http://www.amazon.com/gp/product/B004K2FSXI/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

http://www.amazon.com/gp/product/B004K2FSXI/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1
http://www.amazon.com/gp/product/B004K2FSXI/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

[Celestspeed3]

If you pull all the plugs and do the test sometimes the values come out lower. I've had this happen with my leakdown tester. I'm not sure why, just something I've noticed. So I just pull one plug at a time now.

[himurax13]

Originally Posted by Celestspeed3 If you pull all the plugs and do the test sometimes the values come out lower. I've had this happen with my leakdown tester. I'm not sure why, just something I've noticed. So I just pull one plug at a time now.

I have never done it without pulling all of the plugs.

Sent via smokey turbo.

[Celestspeed3]

Just something I've noticed with my leakdown tester.

When I did @breakfasteatre; motor I pulled all the plugs and the I didn't get proper values.

[himurax13]

Are you talking about doing a compression test or a leakdown test? In either case, you should pull all of the plugs. Maybe you need a new guage. My POS harbor freight setup reads 10 psi lower than other guages.

Sent via smokey turbo.

[mrQQ]

is it possible to diagnose ring/ringlands without pulling motor apart? something like like a camera or something?

[2.0t03speed]

Originally Posted by mrQQ is it possible to diagnose ring/ringlands without pulling motor apart? something like like a camera or something?

You can't. look at the pictures they crack on the sides of the pistons in between the rings. Compression/leakdown test is your best chance of diagnosis.

Edit: also have you ever seen a piston with rings seated in a bore? You can't really see the top ring at all.

heres a picture i borrowed from another thread. now imagine looking in there with a tiny camera trying to diagnose a cracked ringland with everything black and covered in carbon.


Sent from my Galaxy Nexus using Tapatalk 2

[phate]

A leakdown test will tell you what you need.

[Tokay444]

I just did a leak down.
It told me I need peepee touch.

[Lex]

A high leakdown percentage 15-20%+ tells you the motor needs something done internally and needs to come apart anyways.

[mrQQ]

got it.

edit: is high leak a definite for a crack? can it, in theory, be anything else (if it's leaking past the cylinder, not the valves)?

[Tokay444]

My leakdown tester has 40% at the far end of the "low" scale.

[atvfreek]

Originally Posted by mrQQ got it. edit: is high leak a definite for a crack? can it, in theory, be anything else (if it's leaking past the cylinder, not the valves)?

When you have high percentage of leak down, you have to listen for the air, if you hear it out the intake, it would be intake valves, exhaust-exhaust valve, out the oil fill cap then rings/ring land etc.

[Tokay444]

[Dano]

Originally Posted by Tokay444

but that's for normal cars not racecars...racecar rebuild occurs around 20%

[atvfreek]

I've never seen a spec for 40% leakdown. Is that from the 80's? lol

20% leakdown is the max spec I have always seen.

[Tokay444]

Fuck!
That was my anal seepage gauge.

[Dano]

haha well there's the answer then.

If you are leaking 40% its time for surgery.

[mrQQ]

Originally Posted by atvfreek When you have high percentage of leak down, you have to listen for the air, if you hear it out the intake, it would be intake valves, exhaust-exhaust valve, out the oil fill cap then rings/ring land etc.

yes, but does it have to be a crack? can it be something else?

[2.0t03speed]

Originally Posted by mrQQ yes, but does it have to be a crack? can it be something else?

It depends where the air is coming from. It could be cracked ringlands,valve seals,blown rings, etc.

[rfinkle2]

If the injector seals are leaking, could you get a shit compression / leakdown reading as well?

[2.0t03speed]

Originally Posted by rfinkle2 If the injector seals are leaking, could you get a shit compression / leakdown reading as well?

That's a good question. I guess it is possible, but iirc @Rokusek; did a comp test a few hundred miles into his built motor and compression was the same across the board. At the time we didn't know it but he had 2 blown injector seals.

[atvfreek]

Originally Posted by mrQQ yes, but does it have to be a crack? can it be something else?

Yes it can be something else, that's why I through in the etc. lol... Really the leakdown is confirming there is something wrong internally and it gives you an idea of where to look... Basically high percentage of leakdown means you need to open her up and see what has failed.

[atvfreek]

Originally Posted by mrQQ yes, but does it have to be a crack? can it be something else?

Originally Posted by rfinkle2 If the injector seals are leaking, could you get a shit compression / leakdown reading as well?

Unless the injector seal is totally fucked, the leakdown will likely be pretty minimal. Say 3 cylinders have 180psi for compression, then the 4th has 165psi, that is only about 8-9% difference between cylinders, so leakdown may only be 5-10% more than the others. One thing that will throw it off, is the compressor won't be able to put 180psi in the combustion chamber so the difference in leakdown may be even less.

[taf0422]

Still waiting for a diagnosis from pablo guys. Was supposed to get some pictures yesterday of her but nothing yet so as soon as I get some goodies of the possible failure I will update!!