73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Performance => Topic started by: bd on December 28, 2011, 02:34:36 pm
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I plan to install a stacked-plate, thermally-controlled external oil cooler to my 87 R10 with a dedicated fan and ducting, plumbed with AN hose. I run 90+ PSI oil pressure (cold), dropping to ~25 PSI (hot), during the summer months, using Mobil 1 15w-50. The oil pressure is adequate for a clearanced engine, but not happy with the range of variation, cold-to-hot. I wish to narrow that range, if only 5 PSI. Any thoughts, before I commit?
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Are you in a very, very hot climate, or using your truck almost strictly for racing? If not you might consider just changing to a different oil. That 90 psi at startup is due to your oil being very thick and flowing like cold butter (engine wear). I know Mobil 1 15w50 is popular with racing and supercharged engines and all, but does that describe your motor and driving habits?
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I agree, I'd look into another viscosity
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Summers are commonly 109+ deg. The engine and powertrain are by no means stock. I'll experiment with other oil....
Thanks for your insight!
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Synthetic (Mobil 1) is known for having the best viscosity stability.
I am assuming you are running loose bearing clearance by design? May want to opt to a high volume oil pump to feed those clearances. Use the pressure spring from your old pump so that your oil pressure remains the same.......No need for radical high running oil pressures unless you have high combustion pressures. I.e. high static CR, or boosted induction.
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Thanks for your input. Running 'loose' by design. Oil pushed by Melling high volume pump with GM 75-lbs spring, driven by high-shear shaft. Static 10.1:1 moderate CR on premium pump gas, no extra additives. I failed to mention that oil pressure concern is at idle, only - above 1000 RPM, pressure is stable at 50 PSI (hot). Although 25 PSI at hot idle is easily acceptable, I would prefer slightly higher. So, it is simply a matter of personal preference.
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Looks like you have already done your homework. If you are getting 50psi above 1000rpm, I would be quite content with that.
A good rule of thumb for performance engines is 10psi/1000rpm. 25psi is well within that spec.
You have plenty of oil for your operating rpm range. I don't quite know how to add pressure to your idle without adding undue drag above 1000rpm
BTW, an oil cooler is a good idea for any application.
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I'm quoting from the Chevy Power book. I've never used this particular setup, I'm just throwing it out there as another possible option for you:
"An oil to water cooler was optional on late model Corvettes. This cooler assembly (pn10084369) circulates engine coolant through a heat exchanger mounted between the block's oil filter pad and the oil filter element. The benefits of this system include faster engine warm up, more consistent oil temperatures, and a reduction in normal oil operating temperature of approximately ten percent. This cooler assembly requires an adapter (14088848), gasket (326100), seal (10415353), and connector (3853870). For coolant lines, use 1985-86 Corvette service parts."
I don't have a scanner, or I'd include a copy of the page from the book.
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25 psi is more than adequate at idle for your engine. Sounds like you need to drop the cold temp viscosity. Why not start by going to a 10W-50 or even a 5W-50?