302 Hi Pro
Boss 302 - Racing Legend to Modern Muscle Car
I have been reading with interest about some of your reported engine oil temps and locations of temperature sending units. This started me thinking that matching the correct size oil cooler is most important to maintain proper oil temps. If the oil is running too cool, then the combustion by- products contaminants will not burn off, and if the oil bearing temps run too high, 375 plus degrees, bearing failure, overheated.
It made me begin to think (and this is only my thoughts on the matter), of the importance of selecting the proper size cooler for use in my Boss, which is used mostly on the street. Engine oil temps vary greatly through the engine and I believe two points are crankshaft bearing/journals and oil pan temps. These points represent the highest and lowest temp ranges on engines without coolers. Most critical temps are main and rod temps, and the relationship of these temps to oil pan oil temps. There could be a 75 degree (or more) temp difference between oil pan and bearing temps.
Look at this chart: http://performanceunlimited.com/documents/tempguide.html
Where to place oil temp sending unit? Before or after the external cooler?
Oil path comes up from the pan, through the pump, now pressurized, to the oil filter. Enters the outside circular row of holes on the filter and to the main oil galley from the center hole of the filter. Also Boss 302 water/oil cooler. Clean and cooled, (or heated oil, no joking) then enters the main oil galley and is first delivered to the crankshaft. After this, oil is directed, up to cylinder heads, cams, chain tensioners, rockers, etc. and the oil returns in each bank cylinder heads.
As oil moves through each lubrication point, a certain percent is subject to bleed off and returns to pan as well. Each oil galley off of the main galley will deliver oil to the above locations.
Stress point is the crankshaft and highest temp load is here. How hot is to hot? The chart suggest bearing destruction at oil temps above 375 degrees. Best oil temp sunset location is the oil pan readings, best operating temps 270 degrees. Or the range would be 250 to 270 degrees.
So if you are reading 250 to 270 degrees before the cooler, then keep in mind the oil is then directed from the sandwich plate through the filter then directly to the main oil galley, then crank bearings first, the secondary oil galleys and on to the Camshafts, etc. Also the oil pump will raise oil temps over oil pan temps and as oil is delivered to to the filter, the sandwich plate, directs it to the external, oil cooler then thru the filter.
Should I use a T-Stat?. The Boss OEM oil cooler actually acts as an oil heater when the engine is cold. Coolant temps raise to normal operating temps much quicker than oil temps, so when the coolant is at temp of 200 - 210 degrees, it does warm the cooler oil temps quicker. A good thing as the most stress on an engine is on cold start up and high loads on a cold engine. Do not rev a cold engine.
I have come to learn that a T-stat is very important when removing the Boss water/oil cooler and running a only the air/oil cooler.
So now after rethinking this and the importance of maintains proper oil temps, I will use the same size and spec components that FRPP offers in their optional external oil cooler. Now that is for my application as I am not a dedicated race car driver as many of you are, and your oil cooler decisions are based on a completely different conditions and application. But if your Boss is not a dedicated Race car, then we have a lot to think about before we install an external cooler. For street applications, bigger may not be better.
Sorry if I rambled on there, but I think this is a most important topic and it now believe that application/use is an important component of cooler size selection.
Thanks again for your consideration and I appreciate you comments and thoughts on my assessment of the engine lubrication system.
302 Hi Pro
It made me begin to think (and this is only my thoughts on the matter), of the importance of selecting the proper size cooler for use in my Boss, which is used mostly on the street. Engine oil temps vary greatly through the engine and I believe two points are crankshaft bearing/journals and oil pan temps. These points represent the highest and lowest temp ranges on engines without coolers. Most critical temps are main and rod temps, and the relationship of these temps to oil pan oil temps. There could be a 75 degree (or more) temp difference between oil pan and bearing temps.
Look at this chart: http://performanceunlimited.com/documents/tempguide.html
Where to place oil temp sending unit? Before or after the external cooler?
Oil path comes up from the pan, through the pump, now pressurized, to the oil filter. Enters the outside circular row of holes on the filter and to the main oil galley from the center hole of the filter. Also Boss 302 water/oil cooler. Clean and cooled, (or heated oil, no joking) then enters the main oil galley and is first delivered to the crankshaft. After this, oil is directed, up to cylinder heads, cams, chain tensioners, rockers, etc. and the oil returns in each bank cylinder heads.
As oil moves through each lubrication point, a certain percent is subject to bleed off and returns to pan as well. Each oil galley off of the main galley will deliver oil to the above locations.
Stress point is the crankshaft and highest temp load is here. How hot is to hot? The chart suggest bearing destruction at oil temps above 375 degrees. Best oil temp sunset location is the oil pan readings, best operating temps 270 degrees. Or the range would be 250 to 270 degrees.
So if you are reading 250 to 270 degrees before the cooler, then keep in mind the oil is then directed from the sandwich plate through the filter then directly to the main oil galley, then crank bearings first, the secondary oil galleys and on to the Camshafts, etc. Also the oil pump will raise oil temps over oil pan temps and as oil is delivered to to the filter, the sandwich plate, directs it to the external, oil cooler then thru the filter.
Should I use a T-Stat?. The Boss OEM oil cooler actually acts as an oil heater when the engine is cold. Coolant temps raise to normal operating temps much quicker than oil temps, so when the coolant is at temp of 200 - 210 degrees, it does warm the cooler oil temps quicker. A good thing as the most stress on an engine is on cold start up and high loads on a cold engine. Do not rev a cold engine.
I have come to learn that a T-stat is very important when removing the Boss water/oil cooler and running a only the air/oil cooler.
So now after rethinking this and the importance of maintains proper oil temps, I will use the same size and spec components that FRPP offers in their optional external oil cooler. Now that is for my application as I am not a dedicated race car driver as many of you are, and your oil cooler decisions are based on a completely different conditions and application. But if your Boss is not a dedicated Race car, then we have a lot to think about before we install an external cooler. For street applications, bigger may not be better.
Sorry if I rambled on there, but I think this is a most important topic and it now believe that application/use is an important component of cooler size selection.
Thanks again for your consideration and I appreciate you comments and thoughts on my assessment of the engine lubrication system.
302 Hi Pro