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Old 06-02-2003, 06:40 PM   #1
Blue02WRX
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Default What's causing ring lands to fail?

i have heard everything from crappy fuel rails, incorrect tuning, crappy pistons and rings, to heat from the turbo increasing block temp. is anyone convinced of anything? i am building a motor and want to avoid doing it again in the near future. btw, my motor is fine now, but i know i want more and this motor is not going to last forever.


ok here's a list of possibilities:
1. poor fuel rail design
2. bad tuning --causes breakage in even bullitproof motor
3. crappy pistons/rings ---probably not
4. heat from turbo being close to one half of motor (this one was from turbo mag or one of those mags)
5. poor cooling of cyinders --probable culprit
6. uneven airflow b/c of bad design of intake manifold
7. bad design of unequal length exhaust manifold

to add to the list post a suggestion and if you can think of a solution.
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Last edited by Blue02WRX; 06-02-2003 at 09:11 PM.
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Old 06-02-2003, 06:47 PM   #2
driggity
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You should add uneven airflow in the intake manifold and poor cooling to cylinders 3 and 4 to your list of possibilities. I don't think anyone know for sure what is happening though
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Old 06-02-2003, 07:11 PM   #3
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I'd nix the turbo being too close to one side of the motor.....every EJ series turbo motor has had the same configuration, and very few have ring issues.

I'd also nix the pistons and rings from being an issue...plenty of people have built/tuned dead on reliable US spec EJ20's without ever going inside the block. Timing (aka improper tuning) is definately a likely culprit, and at a certain point, fuel delivery is also critical (given your setup under your name, you're definately in that category)

Adam
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Old 06-02-2003, 07:11 PM   #4
hotrod
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Default detonation

Bottom line they are failing because of long term low grade detonation, or a few major detonation events.

NO high output engine can tolerate long term detonation. Some of the older NA engines would tolerate light detonation over a long period of time, but they were built like tanks, and due to the low power output were not very heavily stressed.

To resolve / prevent the problem, you need to avoid detonation. As you listed this can include sensible tuning, adequate fuel octane, avoiding boost spikes, avoiding fuel lean outs etc.

We have several good leads that the proximate cause is probably a characteristic of the cooling system on the EJ-20 engine.

We know that some people have found aftermarket fuel rails seem to help, but this may be a seconday effect due to more balanced fuel delivery and more uniform mixture.

There is some pretty good evidence that these engines are running hotter in the rear cylinders, and are most likely to detonate on the intake side of the cylinder near the rear most intake valve.

I suspect this is due to coolent flow stagnation on that part of the cylinder head.

For background you should note that the same sort of issue is common on American V-8 engines and many of the high power V-8 engine builders take special effort to equalize coolant flow to the rear of the engine by either modifying the coolent passages, or adding an external coolant line to the rear of the block/head. By adding this improved balanced cooling, they have significantly increased the maximum power out put possible from these engines. Builders with reputations like Smokey Yunnick and John Lingenfelter recommend these changes.

The coolant flow on the EJ-20 enters the front of the block and flows around the cylinders first then exits the block into the cylinder heads on the exhaust side of the head, passes over around the combustion chamber and exits the head on the intake side of the cylinder head back into the top of the block where the coolant goes into the coolant manifold on the top of the engine and returns to the radiator.


My theory is that the coolant takes the path of least resistance and a majority of it moves on the shorter paths near the front of the engine, and there is nearly stagnant flow on the area of the combustion chamber near the rear intake valve on the rear most cylinders. During long pulls in high gears this part of the head probably gets significantly warmer and may develop steam pockets in the the coolant due to inadequate flow to sweep the steam bubbles off the head surface. This leads to a hot spot in the chamber.

Every engine that has lost #4 and confirmed to me where the piston failed has to date without exception failed on the intake side of the piston slightly to the rear of the piston (ie. about 1:00 position.)

The coolant passages in the block and cylinder head are of adequate size, but the head gasket forms a restriction with the holes in the gasket only a couple mm in dia. I would recommend anyone building a high output engine should enlarge the coolant holes in the rear most coolant passages (or drill a second hole the same size in the gasket) to about double the hole area, this should equalize the coolant flow and more should move through that part of the head.

PDM turbos also has an external coolant line modification, that places an extra Aeroquip type line into the rear of the cylinder head. My understanding is that they have taken infrared thermometer readings of the head surface that indicate that part of the head is up to 40 degrees warmer than the front of the head.

Larry
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Old 06-02-2003, 07:16 PM   #5
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^ I must note this when I blueprint heads on a long block. I recall this now from my high compression small block days. Thanks Larry.
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Old 06-02-2003, 08:27 PM   #6
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Is convection working in any of this?
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Old 06-02-2003, 09:10 PM   #7
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would adding a external water pump or larger radiator help this cooling issue, or just buy the ra gears so you can only go 120some odd mph?
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Old 06-02-2003, 09:13 PM   #8
hotrod
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Default convection insignificant

Convective flow is insignificant. They did lay out the forced flow so it moves the fluid in the same direction convection does, so the engine may do a little self cooling when you park it.

To prevent hot spots you need pretty good forced flow to sweep any steam bubbles off the surface of the head. If enlarging the rear cooling holes does not provide enough relief, the next option would be to do the same thing the V-8 guys did and reduce the size of the front coolant passages slightly to move more coolant flow to the rear of the engine.

The other option would be a high capacity water pump, that would _NEED_ to push lots of coolant through all the passages to move its normal flow rate.

If we can equalize cylinder temperatures front to back there is probably another 50 - 80 hp available because you will no longer be tuning for the most detonation prone cylinder.

When you get up to maximum power output, cylinder balance becomes very important. Getting flow in the fuel rails, injectors, intake manifold equalized along with combustion chamber volume and cylinder head temp all the same allows you to tune closer to the edge safely as you no longer have one odd ball detonation limited cylinder that is holding you back.

Larry
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Old 06-02-2003, 09:19 PM   #9
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Default extra cooling

Blue02wrx:

Probably yes, AZscoobie told me that he saw an inprovement in allowable ignition advance when he up graded to an after market radiator. That is one of the pieces of evidence that makes me conclude this is largely a cooling issue.

(NOTE he's in Phoenix so would see more improvement than most with improved cooling capacity)

For the pump see my post above.

Larry
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Old 06-03-2003, 12:20 AM   #10
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got my car tuned two weeks later she died... My call, bad tunning but its my fault for pushing the tuner to over 300whp


-=melo <~guilty!
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Old 06-03-2003, 08:41 AM   #11
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in regards to the cooling issue, it sounds like it would probably help to have the higher pressure radiator cap too. but that would also mean going with an aftermarket radiator since the stock one can't handle the pressure. when AZscoobie did his radiator, did he also install a pressure cap?
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Old 06-03-2003, 09:23 AM   #12
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Just as a precaution I would look into refilling the cooling system with evan's npg plus. It has a much lower dynes rating and does alot better job of removing hot spots in the combustion chamber. This mod alone could cure the problem (If that is indeed the sole issue) It also boils at 400 plus degrees so there is no static pressue in the cooling system. You might even be able to get away with a few more PSI boost due to it's much better cooling capabilities. I suspect HOTROD is correct, and the #4 cylinder is evperiancing nucleate boiling causing a hot spot, and squeaking the ring lands
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Old 06-03-2003, 09:35 AM   #13
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Quote:
Originally posted by Baldturbofreak
Just as a precaution I would look into refilling the cooling system with evan's npg plus. It has a much lower dynes rating and does alot better job of removing hot spots in the combustion chamber. This mod alone could cure the problem (If that is indeed the sole issue) It also boils at 400 plus degrees so there is no static pressue in the cooling system. You might even be able to get away with a few more PSI boost due to it's much better cooling capabilities. I suspect HOTROD is correct, and the #4 cylinder is evperiancing nucleate boiling causing a hot spot, and squeaking the ring lands
Good info bro Ive heard of M people using that in the new gen, Know were I can pick some up?
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Old 06-03-2003, 09:37 AM   #14
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Default Re: extra cooling

Quote:
Originally posted by hotrod
Blue02wrx:

Probably yes, AZscoobie told me that he saw an inprovement in allowable ignition advance when he up graded to an after market radiator. That is one of the pieces of evidence that makes me conclude this is largely a cooling issue.

(NOTE he's in Phoenix so would see more improvement than most with improved cooling capacity)

For the pump see my post above.

Larry
To add to that, I noticed a much larger consistency in the timing I could run under heat soaked situations with a cooler thermostat, reprogrammed fans, and NPG+ as a cooling source.

3800 miles on the new motor and even under serious hot lapping the hottest I see on the temp gauge is 189F, averaging 175F. Proper cooling is key! I have a custom fuel rail system going in soon, after that we'll see what else can be done.

Jorge (RiftsWRX)
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Old 06-03-2003, 09:38 AM   #15
turboICE
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Water wetter = owned.

Amazing!
http://www.evanscooling.com/html/npgPls.htm

Quote:
In Evans' waterless systems, any locally generated vapor is immediately condensed back to liquid coolant and an insulating layer of vapor can't develop.
300*+ coolant temps and low pressure!

I had to stop before I qoted the entire linked page.

Considering your current 'vette project - I have no doubt that if you trust this stuff as coolant it works, thanks freak.

Now the question is how do you actually get all the water out of the system - have never needed to before.
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Old 06-03-2003, 09:49 AM   #16
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Quote:
Originally posted by jehcpa
Water wetter = owned.

Amazing!
http://www.evanscooling.com/html/npgPls.htm



300*+ coolant temps and low pressure!

I had to stop before I qoted the entire linked page.

Considering your current 'vette project - I have no doubt that if you trust this stuff as coolant it works, thanks freak.

Now the question is how do you actually get all the water out of the system - have never needed to before.
It was easy for me... it was a new radiator and new short block

There was nothing to take out.. hehe

But if not, you probobly have to pull the drain plugs in the head, get the radiator emptied as best you can, then fill it up... then after a few miles, repeat that process again. Expensive.... but works. Make sure to pull the heater core hoses and get as much out as you can (compressed air should help).

Jorge (RiftsWRX)
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Old 06-03-2003, 12:05 PM   #17
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NPG+ is denser than water - so if they do not mix then any remaining water should rise to the top of the system and be able to be siphoned out - theorectically.
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Old 08-17-2004, 09:09 PM   #18
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Old thread, but interesting. Whatever happened to this stuff? It only has 68% the Specific Heat of pure water, and only 83% the Specific Heat of 50/50 Water/Glycol.

Adrian~
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Old 08-25-2004, 05:27 PM   #19
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