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Help! 2JZ engine block and pistons failure

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Hello everyone!

I'm facing a recurring issue with cylinder block cracks in the 2JZ engine, which I believe falls under both engine construction and tuning aspects. I'm not entirely certain if this is the correct forum section to discuss this, but I hope to find some valuable insights and solutions here.

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Here's the configuration of our engine: we utilize an OEM 2JZ-GTE or 2JZ-FSE block with a standard crankshaft stroke. The Diamond Pistons HD-series 86.25 mm (CR=10.1:1) are installed, along with the stock head gasket and OEM 2JZ-GTE VVTi cylinder head and valves. We've incorporated BC Stage 3 (272) camshafts, and the turbocharger we use is the PT6466SP Gen 2 @ 170 kPa, delivering around 900 hp and 1000 Nm of torque. We rely on E85 fuel (an ethanol-based sports fuel using methyl alcohol) and employ the MoTeC M130 engine management system.

These vehicles are utilized in a professional drift racing series and undergo extreme loads. Throughout the season, we participate in seven races, with each car burning approximately 50-60 rear tires and consuming 250-300 liters of fuel per race. As a team, we have three identical cars, except for some experiments we conduct with different camshafts.

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During the previous racing season, we encountered the problem for the first time when one of the cars experienced a cracked cylinder block, causing coolant leakage and subsequent water ingress into the engine. Upon disassembling the engine, we noticed cracks on the piston skirts as well. At the end of the season, we disassembled the engines from the other two cars and the spare engine, only to find the same piston issues present in all of them. Three engines had Diamond Pistons, while the fourth one had CP Pistons. This led us to suspect that the problem might be systemic and potentially related to an incorrect rev limiter setup. Our drivers consistently push the engine to its limits, and it sometimes happens that a significant portion of the race is spent at the rev limit.

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Before the start of the new racing season, we assembled new engines with the same configuration and Diamond Pistons (DP HD 86.25 10.1:1). We worked on fine-tuning the rev limiter, aiming for a smoother cutoff, and limited the revs to 8500 RPM.

However, the problem resurfaced once again. After completing just one full race, one of the cars experienced another cracked block and the appearance of piston skirt cracks. Additionally, we observed unusual wear patterns on the connecting rod bearings across all six cylinders, indicating that the engine oil might not always be performing optimally. All engines employ a Dailey Engineering dry sump system, and we use Redline 50WT engine oil. We suspect that there might be an issue related to some other factors. Perhaps certain parameters in the engine calibration are not optimal, although I haven't noticed any high levels of detonation noise or other anomalies in the log file.

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Same wear for another 5 rod bearings also.

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And piston skirt crack again.

To provide more context, I've attached a screenshot from the log file, captured when the block crack occurred. At that moment, the engine temperature began to rise sharply due to the gas breakthrough into the cooling system.

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Furthermore, I've included a link to the complete log file for reference: MoTeC i2 log file

I would greatly appreciate your assistance in understanding and addressing this issue. If you have any insights or suggestions on how to prevent such problems in the future, please let me know!

Thank you in advance for your valuable input and support.

On the calibration side rev limiter settings and main fuel/timing values where you get into the rev limiter, as well as good old fashioned over advanced timing in other areas can cause that sort of damage.

In terms of mechanical, I've seen inadequate oil control rings allow oil up past it and fuel down below it which can disrupt combustion and cause burning down on the side of the piston. If CC pressure goes positive you're more likely to see oil going up, if not you're more likely to see fuel going down past rings.

Bore wash with ethanol is always a concern. Also some oils integrate with it better than others.

Dailey makes great stuff, but the tank, breathers, hoses have to be set up ideally to separate ethanol from oil well to reduce bore issues too. My car ends up with a good bit of ethanol in the dry sump tank breather cans, no oil, and the oil remains relatively uncontaminated over an event, but I change the oil every time the car finishes an event as well.

There are certainly other possibilities, but that's a few to get going on continued diagnosis.

Also I'd add a coolant pressure sensor and get CC pressure sensing working. CC pressure is key to monitoring dry sump behavior, and as a bonus helps see detonation and other issues.

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Thank you for your suggestions and insights. Regarding fuel quantity in the engine, how can we ensure that it is at an optimal level and not getting past the rings? We haven't noticed any other damage or wear on the piston besides the piston skirt crack.

We are concerned about the possibility of fuel leakage causing issues with combustion and piston damage. Do you have any specific recommendations or methods to verify and address this potential problem?

Additionally, if you have any further insights or suggestions after reviewing the log file and considering the other factors we've mentioned, we would greatly appreciate your input. Thank you once again for your interest and assistance in addressing this issue.

Not an 'expert' - I'll leave that to Mike, and others, who are - but some general comments.

Cracking is usually due to one or more of - excess boring, thin cylinder walls from core shift, short rod ratio, excessive combustion pressures increasing lateral loading from rod angle, excessive piston to wall clearance, something else.

The first shouldn't be a issue as it's 1st overbore size.

Core shift is rather unlikely as barely oversize and it's affecting multiple blocks.

Short rod ratio 'may' be a factor, but I'm unaware of it being a problem at those torque levels. I repeat, NOT an 'expert' on these engines.

Boost level, and timing, will affect where the peak pressure forces on the piston are in relationship to the crank and rod angles. The major thrust side, right from the flywheel end, is usually the side to fail as that's nortmally where peak pressures and rod angle load the wall most, if it's the minor thrust that may indicate too much ignition advance, but that would surprise me as other indications would already make that obvious.

Excess wall clearances, especially if driven hard before the pistons have heated and expanded, will allow the piston to 'rattle' in the bore and around TDC there can be a significant impact as the piston moves across the bore from minor to major thrust.

Something else? That's for others to suggest.

That's an unusual position for the cracks to form - first thing I'd suggest it talking to your piston supplier(s), as they should have the experience to know what that indicates. My first thought was a design and/or manufacturing fault such as a bad batch of alloy or machining, but not an expert.

Mike, good info' there regarding the breathers and separators - especially the crankcase pressure. I'm constantly amazed how some very experienced engine and car builders together engine and breather systems that manage to pump large volumes of fuel and/or oil into their breathers' catch tanks. IMO. "breathers" should ONLY have vapour/gas passing through them, ANY liquid means a screw up somewhere, usually resulting in oil being held in the heads and blown out the breathers - forward positioned engine outlets may not help, as under braking the liquid will be forced to the front of the heads...

Can I take it that part of your oil control is also ensuring the oil is hot enough to evaporate off some/most of the ethanol contamination?

Great stuff as usual Gord.

In my experience, contamination of oil has consistently significantly increased when running engines on alcohol fuels compared to gas, both stock and modified.

A recent example without the mystery of built engine quality is my current touring car. It's a swap of a stock low mile, low power, naturally aspirated engine which had great leakdown and no signficant blowby or fuel contamination on pump gas, but by checking the catch can during dyno tuning and after each session on track, I found it only spits fuel into the breather tank when I run it on e85. I've alternated back and forth, and it stops doing this when I swith back to gas.

All that to say, built or not, this seems to happen with alcohol, can be reduced somewhat with rather tight clearances, but what I've found has helped me the most is something you actually mentioned, carefully warming the engine up before putting it under load. If the oil isn't warmed up enough, you run the risk of putting a bunch of alcohol in the oil.

The look of the piston domes is very odd for ethanol. They're usually far cleaner than that, so that's of interest. Is it dry soot or does it feel kinda like tar (ethanol does this when oil contaminated)?

Dear Mike and Gord,

I would like to express my gratitude for the information and participation in resolving my issue. Regarding the oil, we regularly observe alcohol distillate inside the catch can connected to the upper port of the oil tank. Do you believe this should not be happening? We also notice a significant amount of vapor escaping from the catch can filter into the atmosphere, and we have always considered it normal since alcohol contains a high amount of water. However, the vapor and residue in the catch can decrease significantly after each oil change in the engine. Perhaps it would be a good idea to install a heater in our oil tanks to heat the oil to 100+ degrees Celsius at the end of each day and evaporate any remaining fuel from the oil.

As for temperatures, they heavily depend on the current weather conditions. For example, in the last race, we started with an oil temperature of around 80 degrees Celsius, and after two sessions, it reached approximately 105-110 degrees Celsius. Our drivers never start their sessions if the oil temperature is below 75 degrees Celsius.

Regarding the piston domes, yes, it is indeed strange, but we see this pattern every time we disassemble our engines. It resembles dry soot and can be easily cleaned off the engine components. We also notice similar soot deposits on the combustion chamber surfaces in the cylinder head. As for the fuel-air mixture, we use a lambda of 0.78 at a boost level of 170 kPa, which doesn't seem excessively rich for alcohol fuel.

As for the piston-to-cylinder clearance, we use 0.09 mm as recommended by the piston manufacturer. Considering the high loads on the engines, I don't think it would be wise to make these clearances smaller. Do you truly believe that reducing the clearance could solve the problem?

Honestly, I'm not entirely confident in the quality of the fuel we are using. It is a blend of alcohol and gasoline from a local producer. It's not easy to obtain ethanol in our country, and I know that the manufacturer uses methyl alcohol and isopropyl alcohol for this blend. Let's say it's not exactly regular E85, but it's the only available option, so we have to use it. According to the manufacturer, this fuel has a stoichiometric ratio of 9.2 and a molar mass of 38.95 g/mol. There might be something off with our fuel, but we have been using it for many years, and our SR20 engines have been running successfully on this fuel during previous seasons, producing over 750 hp.

Once again, thank you for your assistance and expertise.

There will be a significant amount of flow out of the breather at all times with a dry sump since it is constantly evacuating the crankcase of oil and gasses present, but the moisture gives more a of a visual cue, and with alcohol fuel, there will be more condensation, more steam during warmup.

The material on the piston seeming dry vs. sticky/tar-like is actually a good sign that oil isn't present.

Some pistons looking far dirtier than others would be of concern had the engine come apart prior to a failure, but once the engine has sustained significant damage, cylinders operating poorly often soot up quickly. The engine may be balanced until it's not, but that may be something to follow up on. Cylinder to cylinder disparities are often larger than you might think until you've monitored an engine per cylinder.

Using a heater is actually something that works great during the event, regardless of your oil temp on track. You're reducing time spent in warmup when a lot of the contamination occurs. You also avoid some of the moisture collection that occurs after sessions as the oil tank would cool off by using it between sessions.

Personally I still change the oil after each event, but to be honest if I was diligent enough with timed heating of the oil after each event, that may prove unnecessary.

A lambda target of 0.78 will cause more contamination than a leaner one, and it's richer than I generally run that fuel, at a modest boost level on a 2J. That said, there are many factors and without all the info I would not assume you could run leaner. Also remember a lot of the contamination may be occurring while you're not on power.

I just had a moment to take a quick look at the log and the target is a bit richer than you mentioned (0.76-0.77) with recorded lambda dipping to 0.73 at times. In my experience combustion suffers when you run ethanol that rich. You won't hear it like you do on gas, but if you review the RPM trace at high speed sometimes you can see it, and with a dyno that doesn't smooth over unclean combustion events, you can see it. This may actually be a significant part of your issue.

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PTW clearance has many factors so I couldn't give you an exact best value. You're in the ballpark I would expect, though I run that engine tighter for ethanol. I also go tighter on ring gaps than manufacturers tend to suggest, often by a lot with alcohol, but that's something to discuss with your engine builder and test carefully, as pinching the end gap causes instant damage. While engine build changes may help a little, I suspect it may be bandaiding less than ideal combustion from excess fueling.

If the fuel you're using has been successful in applications similarly used, with similar or greater HP per cylinder, it's probably not an issue as long as it is consistent.

Mike, thanks for you reply!

Regarding the lambda, I would really like to see a stable mixture at the target value of 0.77-0.78, and I will repeatedly ask my tuner to achieve this without any deviations. As for the dry soot on the pistons, I'm actually surprised when we disassembled the engine. Specifically on this engine, we used brand new ID1700-XDS injectors, which should not have any variation in their performance. Also, we never use individual cylinder fuel trim, so the mixture should be the same in all 6 cylinders. However, we can clearly see a noticeable difference. I suppose this could be due to uneven airflow distribution. By the way, we are using Plazmaman intake manifolds. It seems like it's time to consider using 6 oxygen sensors for maximum precision tuning.

Regarding the clearance between the cylinder and the piston, I would like to wait for a response from Diamond Pistons and see what they say about it. I have sent them several emails and even provided a link to this forum, but I haven't received a response from them yet. I believe the issue with piston cracking could be simply due to a flawed design of the pistons themselves. I did some investigation and learned from my colleagues that almost every team using Diamond Pistons HD-series has faced this problem, and most of them have switched to CP Pistons/Manley/JE/Wiseco... Well, let's see what the specialists from Diamond Pistons have to say.

In our recent race, we encountered the issue of our cars getting significantly hot after just one session under high ambient temperature (we always have enough rear tire sets for only 2 sessions, so after the second session, we have enough time to cool down during tire change and refueling). We start the session with coolant temperature around 78-80 degrees Celsius, and after two runs, we see around 105-108 degrees Celsius. It was really hot race, but... I suppose it's worth considering improving the cooling systems on our engines because I would like to see slightly lower numbers... In recent conditions, what temperature range do you believe engines should operate within?

There are two things at play.

One is hitting the target you request in the tune, which at full throttle looks pretty good, and is difficult to achieve in transients. Your tuner has done a good job of this. They might be able to make it a little better, but in talking to them I certainly wouldn't say it's not good now, and I don't expect that to significantly change the behavior you're seeing.

The other is the target itself, which is richer than you thought, richer than I'd expect, and easily changed if your tuner is comfortable doing so, but they likely have a reason for their choice so I would consider their perspective.

In terms of pistons, Diamond makes quality product, but I've not used them on a 2J so I don't have experience to mention there. I use Ross, CP, JE on 2Js myself.

2Js have lived more reliably for me when kept to 95 C, 100 C briefly. Are you hitting 105 after or during the run? I'd be most concerned with temps during the run vs. temp rise after the end of the run.

ID1700 have a lot of variation from unit to unit at low IPW despite ID's best efforts, so per cylinder tuning is important at low pulsewidths to avoid bore washing some cylinders during warmup and idle. Sets of 4 often have 12-15% difference across the set of 4 to give an idea.

The Plazman works great, but cylinder to cylinder variation at is going to happen on any setup.

Had the others having issues with the DP pistons reported cylinder wall cracking too?

Hi Mike,

One race in our competitions lasts about 60 seconds, and we typically have enough tire life for 2 races. There is usually not a significant break between the first and second race for the engine to cool down completely. Before the start of the first race, the engine temperature is around 78-80 degrees Celsius, and by the end of the first race, it reaches about 95 degrees Celsius. The second race starts at around 90-95 degrees Celsius, and by the end of the second race, it reaches approximately 105-110 degrees Celsius. Of course, these temperatures depend on tire pressure (lower pressure increases load and temperature) and are also influenced by ambient temperature and wind conditions. These temperature readings are from our previous race, where the weather was around 35 degrees Celsius and calm.

I'm curious about your experience with calibrating fuel injectors at low pulsewidths. Do you use exhaust gas temperature sensors or individual wideband lambda sensors on each cylinder for this purpose?

Hi Gord,

Certainly, other teams have reported experiencing the same issue with DP pistons, and it becomes evident that the problem is mostly related to the piston design itself. I would really appreciate it if representatives from DP could take note of this. At least six engines have encountered this problem, and they all used DP HD-series pistons. However, as I mentioned before, similar issues have also occurred with CP Pistons in the past year.

However, it's unlikely that the piston cracking issue is directly related to cylinder wall cracking. I carefully inspected all six pistons from our latest failed engine and didn't observe any further damage or anything else apart from small cracks on two of the pistons. Otherwise, they looked like new. Let's assume we address the piston problem by replacing them with pistons from another manufacturer, but it remains unclear how to address the cylinder wall cracking issue..

Personally I believe in adjusting per cylinder fueling on gas engines to achieve target lambda based on measured lambda, rather than temperature. Some may have success using EGT, but EGT is impacted by other factors.

All the pistons that have had failures have been on the bottom of the skirt and round on the side of the piston as opposed to the thrust face?

In every instance of a non major/minor thrust face skirt failure i have seen has been a result of the little end bushing (this failure mode usually takes a while to damage the piston) or on a few occasions it has been wrist pin/pin bore related.

The instances i have seen have been mainly in short track/rally applications where the cylinder pressure is high, and the little end bushing deforms/wears, causing the piston skirt to get exposed to side loading that the piston isnt really designed for.

This shows up as the wrist pin having play in the little end bushing, wear in the pin bore, uneven wear across the width of the rod bearing and cracked bores.

As you have had the issue with more than one brand of piston, it lends itself more to this. Are the rods replaced with the pistons? Have the same brand rods been used in all instances? Have the little end bushings been checked after the failures? Do the rods have forced little end oiling?

The same failure can be achieved by the block not being bored perfectly square, causing the same side loading on the piston, which i have not personally seen but have heard of it occuring.

The last piston picture you have in the original post looks almost like there is fatiguing/a crack in the inner edge of the wrist pin at the 3 o clock position

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