that's a new one on me. I do remember all the backwards album playing,, listening for all the subliminal messaging from the dark side.. I would have enjoyed that book I'm sure.
Do thinner oils (SAE xW-20, xW-30) do better at high RPMs?
- Thread starter JT20
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OVERKILL
$100 Site Donor 2021
Well, it looks like he's giving up 40HP, which, in an application where the original engine was only 168HP, that's going to be significant.
That's why I was anticipating higher revving, engine has to do more work.
The H6 had either 212 or 232HP.
Will I see better gas mileage?
OVERKILL
$100 Site Donor 2021
Only time it may rev higher than it did previously is on hills if it has to downshift where it might not have before. Going down the road it is going to be spinning the same RPM. But it will have to work harder, overall, producing less power.
Curious, were you unaware of the power difference before this discussion?
I expect gas mileage will probably be similar or the same.
The simple presence of an adequate volume of oil does the lubrication. Pressure and flow by the pump just gets oil to where it's needed.
OVERKILL, I didn't know the power difference was that big, no.
And I am surprised. The 2.5 got better mileage than the 3.0.. even after I logic'ed out how it wouldn't. I was approaching 30MPGs... Usual baseline of 26 on the H6..
The H4 is a noticeably lighter car than the H6 which had a decent amount of weight due to its luxury package..
Dont know about subaru, but with other brands like toyota, they use the same gearbox between a 2.0 and 2.5, but the final ratio is different. For instance, a 1980s Japan Cressida with 4 spd auto has a 4.556 rear diff, but the 2.5 version has a 4.1 rear diff, both same tyres. So effectively the 2.5L spins lower in top gear than the 2.0. If you were to use your original gb from your 2.5 , to mate to your new JDM 2.0 engine, then you would get the same rpm as the 2.5L. The engine might struggle to pull at lower speeds though.
A smaller engine may rev-up quicker, if it has enough power to do the job easily.
But as already discussed revs and road speed are set by gearing.
Also, Sometimes with a smaller engine you may choose to use a lower gear at a given speed, to keep the revs up. This is often done on small capacity motorcycles.
Water cooled still leaves one with more tolerated heat in a bike as just one of many factors and therefore with somewhat different viscosity grade chosen. Not much sense in that whole reasoning wandering from rpm to bikes and back to the car's boxer, only noise to embed and cushion the usual preaching of more viscous oil even against the RPM creates MOFT further up.
In real heat the revs may be better off with a 0W-30 or 10W-30 instead of just some 0W-20 when imperfect balance e.g. aggravates loads unfavourably but likewise be badly off with a 5W-30 instead of the same 0W-20. Raised revs raise the question of shear thinning and more even more than usual.
Ain't Mobil1 0W-40 the answer anyway – totally unambitious as we are – even with the Subaru? Lugging and low revs love thick oil, high revs need more viscous grades,.. – and because not a motorcycle but motorcycle all is graphically clear.
Well, keeping the gearing could end in an imagination of a little bit of everything which in turn could justify the 15W-50 grade which is a classic bike grade. At some point I must have been wrong...
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I dont have any Subarus in the family anymore so I'm not so I'm no familiar with this, but unless this is a popular engine swap that many people on some forum can attest to working ok, I don't see this ending well. Smaller engine with significantly less power, running off the same gearbox ratios....and I have serious doubts the ECU runs the same tuning maps between the 2.0 and 2.5 liter version.
I was into the engine swap scene back in the 90's and early 2000's for Toyotas and Nissans and Mazdas and sometimes you could swap out a 1.6 for a 1.8, or a 1.8 for a 2.5 or whatever, but there were always some small, but significant details that had to be worked to make it all jive correctly, even if it all bolted up ok. You had to use the appropriate ECU, or manipulate the airflow meter readings with a piggyback, or.... something. It was never plug and play. Even if the wiring harness was the same, using the original ECU or airflow meter between different displacements of the same engine family made the the air/fuel ratios way off, cats were glowing and melting, the transmissions wouldn't shift right, idle would be all over the place, check engine lights galore, etc. It can be done and corrected, but you have to know which sensors carried over and which didn't, which ECU versions would run it ok and which didn't, etc etc.
I want this to work out, but its not sounding like all the homework has been done. Let us know how it goes, hopefully this turns out ok.
I was into the engine swap scene back in the 90's and early 2000's for Toyotas and Nissans and Mazdas and sometimes you could swap out a 1.6 for a 1.8, or a 1.8 for a 2.5 or whatever, but there were always some small, but significant details that had to be worked to make it all jive correctly, even if it all bolted up ok. You had to use the appropriate ECU, or manipulate the airflow meter readings with a piggyback, or.... something. It was never plug and play. Even if the wiring harness was the same, using the original ECU or airflow meter between different displacements of the same engine family made the the air/fuel ratios way off, cats were glowing and melting, the transmissions wouldn't shift right, idle would be all over the place, check engine lights galore, etc. It can be done and corrected, but you have to know which sensors carried over and which didn't, which ECU versions would run it ok and which didn't, etc etc.
I want this to work out, but its not sounding like all the homework has been done. Let us know how it goes, hopefully this turns out ok.
Most bike use thicker oil simply because sharing sump with the gearbox. Honda is the first one recommend 30weight oil on motorbike.
4WD
$50 site donor 2024
Maybe it’s just me … but I’m starting to worry this will become a thick vs thin debate on BITOG 
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What a trainwreck of a thread.
Car gearboxes use fluids that are on the thin side. 75w, 75w80, ATF etc. Most manual gearboxes run fluids that are similar to a Xw20 or Xw30 and even thinner if you compare data sheets.
I am curious myself. This is somewhat of an experiment, I will agree. Combine that with our fast roads the U.S. if RPM stays the same but load on the engine is increased. Sounds like a case for the best synthetic oil around, I'm thinking a thin 30, since 4k has been called "not high RPM" and someone mentioned the occasional fun blast won't hurt it..
I'm thinking a synthetic 0W-30, after the oil starts darkening. I hear these JDM engines sit around without oil in them?
I'm thinking a synthetic 0W-30, after the oil starts darkening. I hear these JDM engines sit around without oil in them?
4WD
$50 site donor 2024
C’mon man ! It’s a train with mud tires …
(a Bro-Lo) …
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I don't think an EJ20 is going to be any harder than an EJ20 on oil. They're timing belt, port injection engines.
From what I understand, you could swap 2.7 to 3.3 or 3.5 intrepids without changing the computer or anything. The computer can determine how much air is going in and coming out.
From what I understand, you could swap 2.7 to 3.3 or 3.5 intrepids without changing the computer or anything. The computer can determine how much air is going in and coming out.
OVERKILL
$100 Site Donor 2021
Just because they can adapt (and MAF is significantly better in that regard, I have no idea if those cars were MAF or MAP) doesn't mean the base table is correct and I'd be concerned about things like start-up enrichment and anything running out of base table.
Say for example it is MAP and calls for x amount of fuel at WOT so injector pulse-width is set to a value to achieve that in the table. You increase displacement by half a litre and power by 40HP, unless the injector sizing is different and just happens to perfectly match the same flow rate, you are either going to be either too rich or too lean relative to what's being expected. If it's MAF, its table will extend beyond stock values and so fuelling, provided the injector size is the same, should at least be close.
So, taking that the other way, if you've got an engine that's 2.5L and 40HP more and you swap in one that's smaller, I'd expect the base table to be overly rich if it is MAP based. MAF should be close.
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