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Old 02-25-2024, 04:37 PM   #1
JMlegacy
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Default race motor clearance theory

Good morning guys.
Been a while since i've posted here.

I have an engine setting up and I'm considering the clearance/oil/cooling combination to use. I've been plagued by spun bearings (550hp motor) every now and then.

I've asked a few people how they designed their motors and some may say use a larger clearance and thicker oil. Others rather a thinner oil (0W-X) and use adequate cooling.

I've noticed that the latest turbo Honda Type R uses 0w-20 oil in their motor. IT has a coolant based oil cooler. I can only imagine the clearances and tolerances in that motor.

Anyways, thanks for reading I'd love to hear your thoughts.
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Old 02-27-2024, 03:47 PM   #2
alexmartynyuk
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Adequate oil clearances that will promote flow to the rods and a good quality oil.

Also, the correct oil pump for your setup and not blindly slap a 12mm pump on everything.

The EJ shears oil more than other engines so I would say 40wt for daily/street car.

Dedicated track would stick to a 50wt if the oil gets really hot.

To be a bit more detailed:
One of the engines I have tuned that makes 600whp

Rods .0018Ē on all 4
Mains
1. .0015
2. .0017
3. .0016
4. .0017
5. .0015

Oil used is motul 5w40 300v

11mm factory pump, polished relief valve and shimmed as well. Ported on the inlet and outlet side.

This thing gets abused daily and revs to 8200.

This is also a single AVCs engine.
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Old 02-27-2024, 03:53 PM   #3
rtv900
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Quote:
Originally Posted by alexmartynyuk View Post

The EJ shears oil more than other engines
So you are saying that the EJ series reciprocating engine breaks oil down at a faster rate than other reciprocating engines?
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Old 02-27-2024, 04:06 PM   #4
alexmartynyuk
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Quote:
Originally Posted by rtv900 View Post
So you are saying that the EJ series reciprocating engine breaks oil down at a faster rate than other reciprocating engines?
Yes, oil galley design isnít the same in all other reciprocating engines and has a part in breaking down oil.
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Old 03-01-2024, 06:53 AM   #5
rtv900
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Quote:
Originally Posted by alexmartynyuk View Post
Yes, oil galley design isnít the same in all other reciprocating engines and has a part in breaking down oil.
guess my next question?

(what part in breaking down oil does the oil galley design have?)
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Old 03-01-2024, 05:19 PM   #6
alexmartynyuk
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Quote:
Originally Posted by rtv900 View Post
guess my next question?

(what part in breaking down oil does the oil galley design have?)
Why does oil even need to be changed? By the sound of it, you seem to believe that there is no such thing as oil shearing.
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Old 03-02-2024, 02:27 AM   #7
alexmartynyuk
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The point I was trying to make is the EJ has a much different oil galley design compared to say other 4 cylinder engines because itís a flat 4.

If you follow the oil galley path you can see there is one on each case half instead of just one going straight along the block like say a 4G63.

Resistance to flow will cause heat, heat is what shears oil. Many oil galleys with sharp bends, two separate cylinder heads, 2 or 4 cam gears for AVCs, 2 or 4 AVCs solenoids, 2 or 4 cams to feed the cam gears for cam control, plus the ej has a fairly skinny rod bearing design with a larger bore diameter compared to other 4 cylinder engines which also plays a role in heating up the oil.

This whole combo wears oil down faster than an inline 4. Not sure if Iím making any sense here, unfortunately Iím not the greatest at explaining things to people lol.
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Old 03-11-2024, 02:10 PM   #8
spoolinsti05
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Quote:
Originally Posted by alexmartynyuk View Post
The point I was trying to make is the EJ has a much different oil galley design compared to say other 4 cylinder engines because itís a flat 4.



If you follow the oil galley path you can see there is one on each case half instead of just one going straight along the block like say a 4G63.



Resistance to flow will cause heat, heat is what shears oil. Many oil galleys with sharp bends, two separate cylinder heads, 2 or 4 cam gears for AVCs, 2 or 4 AVCs solenoids, 2 or 4 cams to feed the cam gears for cam control, plus the ej has a fairly skinny rod bearing design with a larger bore diameter compared to other 4 cylinder engines which also plays a role in heating up the oil.



This whole combo wears oil down faster than an inline 4. Not sure if Iím making any sense here, unfortunately Iím not the greatest at explaining things to people lol.
No that just means the oil is traveling farther in the engines system. The flat 4 has one of the highest flowing oil pumps compared to most engines. The most the oil travels the cooler it gets. Vs a short path to the pan and reuse. It also makes a lesser chance of oil aeration.

The 4G63 has a large oil pan vs the EJ. Because the oil returns to the pan faster. The fact that the EJ has a PCV system that doesn't work so well is why the oil doesn't return as fast as it could. What they should've done was put drain back tubes from the valve covers with one way check valves. So the oil didn't sit in the valve covers.

The 4G63 also requires a balance shaft do to an imbalance of rotational assembly. Because the crankshaft through is so far off the centerline. Unlike the 4G61T that doesn't require a balance shaft.

The EJ is a very capable engine is modified correctly. All engine are technically once you find and address there faults.

Sent from my moto g 5G (2022) using Tapatalk
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Old 03-11-2024, 02:19 PM   #9
spoolinsti05
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Quote:
Originally Posted by JMlegacy View Post
Good morning guys.

Been a while since i've posted here.



I have an engine setting up and I'm considering the clearance/oil/cooling combination to use. I've been plagued by spun bearings (550hp motor) every now and then.



I've asked a few people how they designed their motors and some may say use a larger clearance and thicker oil. Others rather a thinner oil (0W-X) and use adequate cooling.



I've noticed that the latest turbo Honda Type R uses 0w-20 oil in their motor. IT has a coolant based oil cooler. I can only imagine the clearances and tolerances in that motor.



Anyways, thanks for reading I'd love to hear your thoughts.
First you should ask yourself why your bearings spun.

Was it from aftermarket bearings? Was it from overheating? Tune issues?

Who built that engine? You might want to consider checking into that it was built correctly and tuned correctly.

.017 on the rods is a clearance you should get targeting.

Sent from my moto g 5G (2022) using Tapatalk
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