Do thinner oils (SAE xW-20, xW-30) do better at high RPMs?

Okay, awesome.

My mechanic tells me I'm going to really enjoy the EJ20. Would you agree?

I was honestly thinking it was going to be revving higher because of smaller displacement. Never changed the type of engine before. Subaru yields a first.

Does it make more power than the engine that's coming out? That's going to be the determining factor.
 
It was also mentioned about flow equaling lubrication in this thread. so I maybe had some questions about how critical oil pressure would be at these higher RPMs.

Seems they would matter more at the higher RPMs than anything, the oil pressures, rather than at idle or easy driving... Correct?

I also thought I read somewhere that Subaru has some sort of low output oil pump that could put out a max of 42psi. Or am I off the mark there or does anybody know what I am talking about?
 
It was also mentioned about flow equaling lubrication in this thread. so I maybe had some questions about how critical oil pressure would be at these higher RPMs.

Seems they would matter more at the higher RPMs than anything, the oil pressures, rather than at idle or easy driving... Correct?

I also thought I read somewhere that Subaru has some sort of low output oil pump that could put out a max of 42psi. Or am I off the mark there or does anybody know what I am talking about?
No.
 
Does it make more power than the engine that's coming out? That's going to be the determining factor.
It very well may.. it's a 40,000 miles to max 60 or 70k miles (probably somewhere around 50,000 miles) JDM unit with a warranty.

This engine is going in on the cheap so I mentioned to my mechanic if I get a timing belt automatically to check the timing, he told me he would take off the timing cover and inspect the belt to see if it looks good and is pliable, or is all cracked. He told me that if the belt doesn't look good it's going to come off but if it looks good then it's fine. if I had the money I would of course tell him I'd pay to replace it but he probably looks at that as more work so a higher labor bill so since this is all going in as inexpensively as possible I'm going to be okay with that. Low miles engine. I know... Time. But that's where we're at.

All the stuff from the outside of the ej25 is going back on and all that is new...
 
It was also mentioned about flow equaling lubrication in this thread. so I maybe had some questions about how critical oil pressure would be at these higher RPMs.

Seems they would matter more at the higher RPMs than anything, the oil pressures, rather than at idle or easy driving... Correct?

I also thought I read somewhere that Subaru has some sort of low output oil pump that could put out a max of 42psi. Or am I off the mark there or does anybody know what I am talking about?

More volume has the potential to wick away more heat at a given RPM, but of course this is somewhat defeated by an increase in oil pressure as the increased resistance to pump it will also produce more heat. This would also require the fitment of a higher volume oil pump to achieve. By far, the biggest impact is engine RPM. User Shannow did a thermocouple test at the same speed, just using the gear selector to change engine RPM and the impact that increased RPM had on oil temperature was massive.

Also keep in mind that oil pumps are positive displacement, so going thinner doesn't mean more flow, you'd have to upgrade the pump, as I noted, to achieve that.

I have no knowledge of Subaru oil pumps being low volume or low pressure but pressure doesn't equal flow, it's quite possible they have a low relief pressure on their pump for whatever reason. You can have a very high volume pump with a low relief pressure and a low volume pump with a very high relief pressure, these things are not interdependent.
 
It very well may.. it's a 40,000 miles to max 60 or 70k miles (probably somewhere around 50,000 miles) JDM unit with a warranty.

This engine is going in on the cheap so I mentioned to my mechanic if I get a timing belt automatically to check the timing, he told me he would take off the timing cover and inspect the belt to see if it looks good and is pliable, or is all cracked. He told me that if the belt doesn't look good it's going to come off but if it looks good then it's fine. if I had the money I would of course tell him I'd pay to replace it but he probably looks at that as more work so a higher labor bill so since this is all going in as inexpensively as possible I'm going to be okay with that. Low miles engine. I know... Time. But that's where we're at.

All the stuff from the outside of the ej25 is going back on and all that is new...

I assume these designations denote displacement and so the EJ20 going in is 2.0L and the engine coming out is 2.5L? Are you getting the ECM reprogrammed or swapping it out for a JDM one or how is that being accounted for?
 
If you aren't changing tire size or gearing then RPM stays the same.
Except when it’s a V6 (my Jeep) in 7th gear at 70 mph instead of final gear at 70 mph like my V8 (GM) … which is ridiculous for 4.10 gears and an 8 speed …
 
I assume these designations denote displacement and so the EJ20 going in is 2.0L and the engine coming out is 2.5L? Are you getting the ECM reprogrammed or swapping it out for a JDM one or how is that being accounted for?
You are correct. EJ is engine family, a la EG and EZ (my stolen car was an EZ30D, an EZ30D first gen, the "H6-3.0" with badge that said as such. Great engine. An SVX is an EG33 I want one of those too but that's down the road.)

EJ201 = 2.0L
EJ251 = 2.5L
I have not memorized the bores and strokes but you are correct on displacement. I think 82mm or 92mm bore and 68mm stroke but don't quote me on that.

The ECU does not need to be reprogrammed or anything like that it's basically a direct replacement the ej25 is really just a half liter bigger ej20

And half the JDM slot videos I saw have them drilling a hole for the cam sensor in the block somewhere and half of them don't just have them checking the pulleys inside the engine (or something like that) and one shows an easy way to change the flexplate (Auto is flexplate, manual is flywheel, yes?) by taking one bolt off of the time because the USDM one is bigger than the JDM one and then the holes will line up

But since it's a EJ to a EJ I think the ECU doesn't need to be changed at all

Almost went with a cammed motor and my mechanic told me he guaranteed me it wouldn't run right.

Here is a link to the motor that did not go in.



and I do apologize but I don't have time to link the JDM motor that I bought at the moment because I'm switching charging stations on a forklift but it's from a JDM engine site.

EDIT: Only took short time. Here is engine.

It is a drop-in replacement.
 
I would expect the ECM programming to be different, as .5L of displacement is a fair bit. Interested in seeing how this turns out.
 
I would expect the ECM programming to be different, as .5L of displacement is a fair bit. Interested in seeing how this turns out.
So, we think alike and that's why I was asking all these questions.

Supposedly the ej20 is used in the rest of the world, has a smoother and wider Power band, of course I have no idea but I would imagine that it revs higher, that's what brought on this thread, and yeah apparently the ECU can stay the same since all that is happening is everything from the outside of the old motor is going on outside of the new motor and that's it.

looks like we're going to know the week after Christmas the way things are going.
 
You are correct. EJ is engine family, a la EG and EZ (my stolen car was an EZ30D, an EZ30D first gen, the "H6-3.0" with badge that said as such. Great engine. An SVX is an EG33 I want one of those too but that's down the road.)

EJ201 = 2.0L
EJ251 = 2.5L
I have not memorized the bores and strokes but you are correct on displacement. I think 82mm or 92mm bore and 68mm stroke but don't quote me on that.

The ECU does not need to be reprogrammed or anything like that it's basically a direct replacement the ej25 is really just a half liter bigger ej20

And half the JDM slot videos I saw have them drilling a hole for the cam sensor in the block somewhere and half of them don't just have them checking the pulleys inside the engine (or something like that) and one shows an easy way to change the flexplate (Auto is flexplate, manual is flywheel, yes?) by taking one bolt off of the time because the USDM one is bigger than the JDM one and then the holes will line up

But since it's a EJ to a EJ I think the ECU doesn't need to be changed at all

Almost went with a cammed motor and my mechanic told me he guaranteed me it wouldn't run right.

Here is a link to the motor that did not go in.



and I do apologize but I don't have time to link the JDM motor that I bought at the moment because I'm switching charging stations on a forklift but it's from a JDM engine site.

EDIT: Only took short time. Here is engine.

It is a drop-in replacement.
Wouldn't be interesting to read the fine print in that warranty concerning acceptable oil usage.
 
Wouldn't be interesting to read the fine print in that warranty concerning acceptable oil usage.
I'm wondering if a synthetic should be in there because who knows how long that engine has sat around before seeing new service.

I also would like Trav to chime in, he mentioned that one should avoid using group 4 or group 5 synthetic oils with its engine something about because of the valve covers?
 

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I do wonder if a 0W-20, 5W-20, 0W-30, 5W-30 oil lubricates "better" than anything heavier than that at higher RPMs, they can really increase once you get flying. 90MPH yields about 4K RPM on old engine and I'm sure many engines rev higher than that.
Motorcycles that rev to 10,000+ RPM use thicker oil (typically 10W-40 to 20W-50) for a reason.
 
Flow=lubrication. More flow, more cooling.
I go with the "thinnest" allowed by my owners manual.
Flow doesn't change with a positive displacement oil pump ... it's pretty much going to put out X gpm at Y RPM regardless of viscosity as long as the pump isn't in pressure relief.
 
What made you go with getting the 2.0?? Wouldn’t the 2.5 be a stronger engine according to your post above that the EJ25 is just a larger EJ20 that would tell me that the EJ25 would be the motor you want. When you first mentioned going to this smaller displacement engine I assumed it was one of those super hot screamers that would spank your current one.
 
The higher the rpm, the wider the clearances need to be to account for torsional vibration, and thus a higher viscosity is needed. This also depends on the use of the engine though.
Higher RPM also creates more MOFT in journal bearings because the journal want's to naturally center itself in the bearing bore.
 
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