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Engine, Exhaust, Transmission Discuss the FR-S | 86 | BRZ engine, exhaust and drivetrain. |
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11-21-2023, 12:30 PM | #71 | ||
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Quote:
Look at the chart I posted above. 0w20 at ~275F is ~5.5 psi/krpm (+/-), while 5w30 at same temp is ~7.5 psi/krpm (+/-). Implying that at 6k rpm, 275F, 0w20 is ~33psi and 5w30 is ~45psi. So *without* an oil cooler, 5w30 is running about +12psi higher oil pressure vs 0w20 in the medium/higher rpm range. I.e., going up in viscosity is *very* effective at increasing oil pressure, if that is the metric you are most concerned about. Meanwhile, the same 5w30 running -25F cooler at 250F, is at about the *same* 7.5 psi/krpm, so still ~45psi at 6000rpm, *zero* increase in oil pressure for the same 5w30 oil running -25F cooler with an oil cooler. So if oil pressure is what you're deciding to be obsessive over, going up in viscosity is a much more effective way to ensure higher pressures than going with an oil cooler. Quote:
To be taken with a grain of salt of course, but for sure that is what this data suggests. If I was as worried as you about oil pressure vs. temp, I'd be running 0w40 all track season instead of 5w30. But it seems to me the most critical thing is that oil is being supplied at all and not necessarily whether that oil is at 275F or 235F. IMO, RTV cloggage and pressure loss due to cornering g's and perhaps basic Subie flat-4 oil passages and tolerances are a thousand times more important. Oil pressure in the 30s at 275F isn't what kills these engines. Oil pressure in the teens and single-digits due to other issues is. IMO... |
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11-21-2023, 02:46 PM | #72 |
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I run 0w40 year round, in Canadian winters, and on track in Atlanta in the summer. 260,000 trouble free kms.
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11-23-2023, 11:36 AM | #73 |
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Based on the way Toyota "backs" their warranty for track usage I am not sure I would trust what the engineers deem safe applies to track usage LOL.
Also I recall the Toyota specing 10PSI per 1000 RPM for oil pressure which you're not hitting on track once the temps come up. Do you NEED that much oil pressure heck if I know
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11-23-2023, 03:48 PM | #74 | |
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That has been a rule of thumb for decades. |
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11-23-2023, 07:45 PM | #75 | |
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All I could find from the manual is this. Might not be much help as the temps are so low but mid to low 30s is way off 73psi. But again I have no clue how bad 30psi is for the motor. Personally for me at this stage and the type of track day format I am running. I just keep an eye on oil temp and pressure and pull off when I feel I need to. I have no real reason to push an extra few laps when I can just come in and go back out. I could also just do a cool down lap if I like. The session goes well beyond 20 mins.
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11-23-2023, 08:14 PM | #76 | |
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Are you seeing mid to low 30s at 6000rpm? What viscosity oil are you running? Ultimately you only need enough oil pressure to keep the bearings fed. Hydrodynamic wedge is what really carries the loads. Could be that 30psi is sufficient. Any case, if you want to see higher pressures at track temps, maybe consider going to higher viscosity. |
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11-23-2023, 08:46 PM | #77 | |
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Yes higher viscosity oil or lower the oil temps. Without doing a deep dive on my data he is what I shared in my build thread from my last track day. 5w-30 for oil weight. Seems like a good happy medium for street and track. UOA has been very good as well for me so I don't see myself changing. Again keeping temps under 260F is easy enough for me with the OEM cooler but if I was struggling to keep temps down and it caused a pressure drop I would get a better cooler before changing the viscosity. That is just what I preferer. To each their own. Max Coolant Temp: 194F/90C Max Oil Temp: 237.2F/114C Oil Pressure: 34.9PSI - 60.2PSI AVG 52.0 Seeing around 55psi at 7k
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11-23-2023, 09:17 PM | #78 |
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The spec is a single datum point good for a couple reasons. As Dan says, it specifies a reference point for pressure as a function of both temp, and engine speed. I also interpret it as a suggested minimum (normal?) operating temperature. Falls in line with most oil cooler thermostats at 180F.
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11-24-2023, 06:12 PM | #79 | |
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Is need of external oil cooler overblown
Quote:
For reference, those are about the same number I see with 0-20 Motul 300V though my pressure seems to peak about 5800-6k and drop off a bit after.
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11-26-2023, 09:25 AM | #80 | |
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11-26-2023, 03:18 PM | #81 |
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It doesn't need to ever. Just like how your bathroom mirror dries off after taking a shower. The internal environment of the engine is already at a high enough temperature and the crankcase atmosphere is at slightly below ambient pressure. What should be avoided is operation for short periods where the engine never reaches normal operating temp. My oil temp gauge never shows higher than the water temp.
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11-26-2023, 07:42 PM | #82 |
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Oil pressure gauge is on the Xmas list. I'm curious now.
Been running the JRDOC for years, 40ish track says and no issues. I run Mobil 0W-40 oil. My coolant temps are around 200ish and oil 235. I can stay out as long as I can handle it and it doesn't change. Seems to be working so far. I also change the oil every 2 outings. Overkill, I know. It's cheap compared to any other consumable and I'm under the car anyways doing a check. In my mind heat causes wear and keeping things a bit cooler should help. I'm not saying that you have to have a cooler but that's just my thought process. Knock on wood, another 12-15 tracks days next year. |
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11-27-2023, 06:06 AM | #83 |
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235f oil temp on track is pretty good I would say. Shouldn’t run into pressure issues at that temp.
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11-27-2023, 05:38 PM | #84 |
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