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Discussion Starter · #1 ·
coolant temps should IDEALLY be kept in the 190F-220F range,only ocasional OVER 230F coolant temps make me worry, OIL TEMP in the 215F-240F range for both the best power and the best lubracation, SYNTHETIC OIL DOES HAVE A WIDER AND HIGHER TEMP RANGE, if you use SYNTHETIC OIL, ocasional peak temps up to 260F are nothing to worry about, AIR TEMP entering the engine, should be routed from outside the engine compartment directly to the carb and fuel temp should be as low as you can manage
oil (especially synthetic)has improved dramatically over the last 15-20 years and thinner oil tends to BOTH absorb and carry away heat from the bearing surfaces quicker due to the faster movement thru those clearances, and those more modern formulas of thinner oils do protect your engine far better than the older oils did. keep in mind PRESSURE is a measure of the OILS RESISTANCE to being forced under pressure thru your engines clearances, and thinner oil reduces the resistance to both flow thru those clearances and pumping losses the moving parts have sliding over the oil films surface, remember the oil molicules are very small, and theres hundreds of layers stacked in that thousandth or so of bearing clearance.
a quick way to get an idea on your clearances is to look at your oil pressure AFTER the engine reaches the proper operating temps which should be about(between 215F and 240F...... OIL TEMP NOT COOLANT TEMP)
and use the thinnest QUALITY oil that maintains about a 20 psi at idle (700-900 rpm)
! keep in mind you want the OIL temp to reach a MINIMUM of 215F to burn off moisture, and that OIL FLOW does MUCH of the critical cooling in the ENGINE, so if your running hot, a larger baffled oil pan, with its far greater surface area and oil voluum can also aid in the total cooling process, just swapping from a stock 5 qt to a aftermarket 8 qt pan is usually worth about a 10-15 degree drop in engine temps
the oil temp is more critical than the coolant temp(with-in limits of course) but don,t allow the oil temp to fail to reach and stay in the 215F-240F range once the engines up to operating temp. or it can,t do its clean/lub job correctly
coolant temps in the 180f-210f range are about ideal according to G.M. test for HP and LONG ENGINE LIFE

Oil weight, or viscosity, refers to how thick or thin the oil is. The temperature requirements set for oil by the Society of Automotive Engineers (SAE) is 0 degrees F (low) and 210 degrees F (high).

Oils meeting the SAE's low temperature requirements have a "W" after the viscosity rating (example: 10W), and oils that meet the high ratings have no letter (example SAE 30). An oil is rated for viscosity by heating it to a specified temperature, and then allowing it to flow out of a specifically sized hole. Its viscosity rating is determined by the length of time it takes to flow out of the hole. If it flows quickly, it gets a low rating. If it flows slowly, it gets a high rating.

Engines need oil that is thin enough for cold starts, and thick enough when the engine is hot. Since oil gets thinner when heated, and thicker when cooled, most of us use what are called multi-grade, or multi-viscosity oils. These oils meet SAE specifications for the low temperature requirements of a light oil and the high temperature requirements of a heavy oil. You will hear them referred to as multi-viscosity, all-season and all-weather oils. An example is a 10W-30 which is commonly found in stores. When choosing oil, always follow the manufacturer's recommendation.


A. Mobil recommends that you follow your engine manufacturer's recommendations as indicated in the owner's manual. For maximum wear protection and maximum fuel economy, use the lightest oil viscosity that is recommended by the engine manufacturer for the temperature range expected. Heavier oils can lower fuel economy and rob horsepower. For normal driving conditions, 5W-30 and 10W-30 are the primary current recommendations of automotive manufacturers.


if your running a auto trans its important to keep that fluid UNDER 180F for long trans life

a trans fluid cooler helps immensly (I was forced to mount mine where the spare usually goes)

on a CORVETTE useing the TCI cast aluminum deep pan with the ribs ,it will lower the temp simply because it places the bottom 1.5" into the air flow under the corvette, rather than tucked up into the area behind the cross frame in the trans tunnel, BTW MY CORVETTES already have a trans fluid cooler factory installed,and I installed a larger one with its own electric fan also, and the pan still helped both slow the heat rise rate and lowered the max temp it reaches, in fact I have a hard time exceeding 180f now
and yeah your application may be differant, Im only running about 430 rear wheel hp off nitrous

heres an older, related post on oil pressure

first ID point out that the PRESSURE results from the RESISTANCE to the FLOW of oil thru the engines clearances ,....... and the oils viscosity and tempeture ,has a great deal to do with the results youll see .... it should ideally be about 20-25 PSI at IDLE, but if its at least 15 PSI at 215F its fine,IT MUST be MEASURED with the engine up to operating temp. which means the oil has reached at LEAST 215F.(if its to high reduce the oils viscosity as thats a sure way to get the oil presure to drop and get more oil flowing over the clearances faster on start up! YOU DON,T NEED THICK OIL,I.E. 20w 50 or similar viscosity in a modern engine, SNTHETIC oil quality has improved a significant amount from the oil used even 10 years ago and its totally differant fron the mineral oil gunk we used in the 1970s.

now IM well aware this old post, reposted below,.... below has to do with the earlier corvette gen 1 engines but a good deal of the info,fits the newer engines

read this over carefully

ok lets look at a few things, pressure is the result of a resistance to flow , no matter how much oil is put out by the oil pump there is almost no pressure unless there is a resistance to that oil flow and the main resistance is from oil trying to flow through the bearing surface clearances and once the pumps output pressure exceeds the engines ability to accept the oilflow at the max pressure the oil return system/bypass spring allows the oil circles back through the pump ,now the amount of oil flow necessary to reach the furthest parts in the engine from the oil pump does not go up in direct relation to rpm, but it instead increases with rpm at a steadly increaseing rate that increases faster than the engine rpm due to centrifugal force draining the oil from the rods as they swing faster and faster since energy increases with the square of the velocity the rate of oil use goes up quite a bit faster due to the greatly increased (G-FORCES) pulling oil from the rod bearings over 5000rpm going to 8000rpm than the rate of oil flow increases from 2000 rpm to 5000rpm (the same 3000rpm spread) and remember the often stated (10 lbs per 1000rpm)needs to be measured at the furthest rod and main bearing from the pump not at the pump itself, next lets look at the oil flow itself, you have about 5-6 quarts in an average small block now the valve covers never get and hold more than about 1/3 to 2/3 of a quart each even at 8000 rpm (high speed photography by SMOKEY YUNICK doing stock car engine research with clear plastic valve covers prove that from what Ive read) theres about 1 quart in the lifter gallery at max and theres about 1 quart in the filter and in the oil passages in the block, that leaves at least 2 quarts in the pan at all times and for those that want to tell me about oil wrapped around the crankshaft at high rpms try squirting oil on a spinning surface doing even 2000rpm (yes thats right its thrown off as fast as it hits by centrifugal force, yes its possiable for the crankshaft WITHOUT A WINDAGE SCREEN to keep acting like a propeler and pulling oil around with it in the crank case but thats what the wrap around style milodon type windage screen is designed to stop)the only way to run out of oil is to start with less than 4 quarts or to plug the oil return passages in the lifter gallery with sludge or gasket material! now add a good windage tray and a crank scrapper and almost all the oil is returned to the sump as it enters the area of the spinning crankshaft! forming a more or less endless supply to the oil pump, BTW almost all pro teams now use DRY SUMP SYSTEMS WITH POSITIVE DISPLACEMENT GERATOR PUMPS that are 3,4,or 5 stage pumps each section of which has more voluum than a standard voluum oil pump because its been found total oil control is necessary at high rpms to keep bearings cool and lubed

ok look at it this way,what your trying to do here is keep an pressureized oil film on the surface of all the bearings to lube and cool them and have enough oil spraying from the rod and main bearing clearances to lube the cam and cylinder walls/rings. now a standard pump does a good job up to 5000rpm and 400 hp but above 6000rpm and 400hp the bearings are under more stress and need more oilflow to cool and because the pressure on the bearings is greater you need higher pressures to maintain that oilfilm.lets look at the flow verus pressure curve. since oil is a liquid its non-compressable and flow will increase with rpm up to the point where the bypass circuit starts to re-route the excess flow at the point were the pressure exceeds the bypass spring pressure. but the voluum will be equal to the pumps sweep voluum times the rpm of the pump, since the high voluum pump has a sweep voluum 1.3-1.5 times the standard pump voluum it will push 1.3-1.5 times the voluum of oil up to the bypass cicuit cut in point,that means that since the engine bearings leakage rate increases faster as the rpms increase because the clearances don,t change but the bleed off rate does that the amount of oil and the pressure that it is under will increase faster and reach the bypass circuit pressure faster with the high voluum pump. the advantage here is that the metal parts MUST be floated on that oil film to keep the metal parts from touching/wearing and the more leakage points the oil flows by the less the voluum of oil thats available for each leakage point beyond it and as the oil heats up it becomes easier to push through the as the rpms and cylinder preasures increase in your goal to add power the loads trying to squeeze that oil out of those clearances also increase. ALL mods that increase power either increase rpms,cylinder preasures or reduce friction or mechanical losses. there are many oil leakage points(100) in a standard chevy engine.
16 lifter to push rod points
16 pushrod to rocker arm points
32 lifter bores 16 x 2 ends
10 main bearing edges
9 cam bearing edges
16 rod bearing edges
2 distributor shaft leaks
1 distributor shaft to shim above the cam gear(some engines that have an oil pressure feed distributor shaft bearing.)
chevy did an excelent job in the design but as the stresses increase the cooling voluum of the extra oil available from the larger pump helps to prevent lubracation delivery failure, do you need a better pump below 5000rpm or 400hp (no) above that level the extra oil will definitely help possiable deficient oil flow and bearing cooling and a simple increase in pressure does not provide a big increase in voluum that may be necessary to keep that oil film in the correct places at the correct voluum at all times.the stock system was designed for a 265cid engine in a passenger car turning a max of about 6000 rpm but only haveing the stress of under 300hp transmitted to the bearings, Im sure the orriginal designers never thought that the sbc or bbc would someday be asked to on occasion hold up to 450-800hp and 6000-8000 rpm.nore did they forsee valvesprings that placed 500lbs and up loads on the lifters and the use of over 9 to 1 compression ratios in the original design so the oil voluums and pressures necessary to cool those valve springs and bearings at those stress levels were never taken into account for that either.

Continued (oil Pan/pump)
the oil pump can only pump as much oil as the engine clearances allow at the max pressure that the oil pump bye -pass circuit will allow, and no more. for your idea to be correct (which it could be under some conditions)the oil flow through the engine clearances would need to be so great that the pump turning at 3500rpm,7000rpm engine speed(remember the pump spins 1/2 the speed the crank does)and most likely pumping at max pressure could lower the oil level to the point that the pick-up becomes uncovered or a vortex as you call it forms and the pump starts sucking air.

now under hard acceleration it is very possiable for the pickup on ANY oil pump to to become uncovered in a oil pan that has less than 5qt capacity and with no oil control baffles as the oil rushes to the rear of the oil pan if the pick-up is located in mid pan or under hard brakeing if the pick-up is located at the rear of the pan on a non- oil baffle controlled pan.

I will grant you that it is possiable for ANY oil pump to pump a good amount of oil into the lifter gallery at high rpms IF THE OIL RETURN PASSAGES IN THE HEADS AND LIFTER GALLERY ARE BLOCKED, preventing its normal return to the crankcase

, but running a high volume oil pump will have little or nothing to do with how much oil is in the pan if the engines drain back holes are clear and your useing a milodon style windage screen. I have several times had that same complaint about lack of oil pressure under acceleration but it is caused by a non-baffled pan or the pickup mounted so close to the pan bottom that the pump cant get a good intake flow, if you carefully check youll find that on a dyno runs it seldom happens,because the oil is constantly removed by the windage screen is returned to the sump, most of the oil pumped into the system exits at the rod and main bearing clearances or at the cam bearings and from the lifter bores lower ends, its not the constant oil flow or lack of oil into the rocker arms that has the big effect on total oil flow as SMOKEY YUNICKS PHOTOGRAPIC RESEARCH PROVED YEARS AGO,its the oil flowing from the bearings and lifters and that oil flow is quickly returned to the sump by a windage screen scrapeing it off the spinning crank and rods as the spinning assembly passes over the windage screen. in effect most of the oil in an engine works like your timeing chain in that it constantly cycles top to botton and back never getting higher than the cam bearing lifter area.

now what does quite frequently happen is that the guys installing a high volume oil pump just swap out the standard pump, reinstall the stock or simular pick-up and bolt on the pan with the pick-up in the stock possition on the oil pump. the stock pick-up is mounted about 3/8" off the pan bottom,the high volume pump is normally equiped with impeller gears about .3 inches longer than stock, the high volume pump body is that much lower in the pan, resultting in the pick-up being only about 1/8" from the pan bottom. the result is that on a normal chevy oil pump pick-up this leave a space of about 1/8" x 2.5" for oil to flow into the pump. at low rpms this works but as the rpms climb the pick-up that can,t get any oil to pump cavitates as it spins and fails to pump oil, result oil pressure drops untill rpms are lowered no matter how much oil is over the pick-up. simply checking to make sure that anout 1/2" of space is under the pick-up when the pan is installed cures that problem (a simple trick is to weld a 1/2" thick nut to the oil pump Pick-up base and test fitting the pan BEFORE WELDING THE PICK-UP TO THE PUMP BODY)

what it comes down too in every case that Ive looked into so far is a improperly positioned pick-up or a non- baffled oil pan without a windage screen or less than 5 qts of oil in the system, not a problem of all available oil being pumped into the lifter gallery and valve covers like some people would like you to think.


Most of the stock automobile engines are designed to operate from idle to 4500 RPM. The original volume and pressure oil pump will work fine in this type of application. As the demands on the engine increase so does the demands on the oiling system and pump.
The oil pump's most difficult task is to supply oil to the connecting rod bearing that is the farthest from the pump. To reach this bearing, the oil travels from three to four feet, turns numerous square corners thru small holes in the crankshaft to the rod bearing. The rod bearing doesn't help matters. It is traveling in a circle which means centrifugal force is pulling the oil out of the bearing.

A 350 Chevy has a 3.4811 stroke and a 2.111 rod journal. The outer edge of the journal travels 17.5311 every revolution. At 1000 RPM, the outer edge is traveling at 16.6 MPH and 74.7 MPH at 4500 RPM. If we take this engine to 6500 the outer edge is up to 107.9 and at 8500 it is 141.1 MPH. Now imagine driving a car around a curve at those speeds and you can feel the centrifugal force. Now imagine doing it around a circle with a 5.581, diameter.

The size of the gears or rotors determines the amount of oil a pump can move at any given RPM. Resistance to this movement creates the pressure. If a pump is not large enough to meet the demands of the engine, there will not be any pressure. Or if the demands of the engine are increased beyond the pumps capabilities there will be a loss of oil pressure. This is where high volume pumps come in; they take care of any increased demands of the engine.

Increases in the engine's oil requirements come from higher RPM, being able to rev faster, increased bearing clearances, remote oil cooler and/or filter and any combination of these. Most high volume pumps also have a increase in pressure to help get the oil out to the bearings faster.

That is what a high volume pump will do. Now let Is consider what it will not do.

It will not replace a rebuild in a worn-out engine. It may increase pressure but the engine is still worn-out.

It will not pump the oil pan dry. Both solid and hydraulic lifters have metering valves to limit flow of the oil to the top of the engine. If a pan is pumped dry, it is because the holes that drain oil back to the pan are plugged. If the high volume pump is also higher pressure, there will be a slight increase in flow to the top.

[/color] let me point out this chart
heres other info,

things to read carefully

braze the pick-up tube to the pump body so the pick up is 3/8" MINIMUM, 1/2" maximum from the oil pan floor and use a large lump of MODELING CLAY (every mechanic should have some its great for checking clearances)on the pickup then install the pan temp. with no gasket and remove to measure the thickness of the clay
your local arts/craft store sells it in 1 lb blocks I usually use brite blue or black but suit your self, a digital caliper or even a ruler will get you the thickness measurement your looking for)

once its correctly possitioned ,remove the bye pass spring and gears from the oil pump,and have the pick-up brazeD or welded to the pump body, then after it SLOWLY AIR cools (DON,T DROP IT IN WATER LET IT AIR COOL)replace the byepass spring and gears, lube the pump,with assembly lube on the gears, check the clearances, check clearances again! and install! just be damn sure its brazed or welded in the correct location as that 3/8"-1/2" is critical to good oil voluum feeding the pick-up

silver soldering is basically lower temp brazeing , the soldering metal flows over the surface and into micro cracks in the surace of the other metal forming a almost unremoveable bond to the other metals surface it allows you to stick iron to steel or brass to steel, it works more or less like normal solder does on copper but at higher temps and has a much stronger grip in addition too working on iron and steel

I vastly prefer the 5 BOLT BBC style pumps with the 12 tooth gears and thier larger 3/4" pick-up VS the small 4 bolt pumps with thier 5/8" pick-ups and 7 tooth gears. the oil flow is both higher pressure at low rpms and smoother in pulse presure spread,no! you don,t need it on a non-race combo, or even on some race combos but its nice to have and I willingly will loose a few hp pumping oil for better engine lubracation

56 Posts
Don't know about cavitating an oil pump. Cavitation as a definition is the formation and subsequent collapse of vapor bubbles as pressure falls below then rises above saturation pressure. Essentially like in a boat you "boil" the water b/c you create a lower pressure in front of the prop. An oil pump is positive displacement (gear type) but it has a relief. I can't imagine "boiling" oil by lowering pressure. I'd like to see a curve for that.

Super Moderator
8,547 Posts
Discussion Starter · #3 ·
in the oil pump,"cavitation" occures when the gears spin fast enought to break free from the liquid flowing around them and basically free wheel within a space around them, just like its possiable to install a prop on a boat,thats too small in dia, and/or spin it fast enought that it no longer pushes the boat effectively because its pushing froth vs hydrolically pumping liquid, its possiable to spin the pumps impeller gears fast enought too pump froth vs hydrolically pump oil,if the oil feeds restricted
the differance is the cause
on the boat its the props pitch and dia, allowing it to break free from an unlimited supply of liquid due to the rpm and torque exceeding the props ability to pump the liquid
on the oil pump its not the rpm or the pump itself,or the gear/impeller size, but the restriction of flow voluum on the feed side of the pump, if you can,t get enough flow into the pump feed side the out put side pressure drops rapidly usually the result of the pick-up mounted to close to the oil pan floor OR the oil pump pick-up design and internal diamensions or the debriss screen being partly clogged, but the result is the same, the impellers break free from the liquid surounding them and they pump froth vs solid liquid and efficiency drops off rapidly in either case.

ON the water pump its the same deal, restrict the feed flow and theres a loss in pressure and voluum on the pressure side of the pump,but the water pump impeller works on centrifical force throwing water off the surface of the impeller on a closed system with some expanion room for air in the liquid rather than possitive displacement sweep like the oil pump so its far easier to stall flow, now you should think that since the pump sucks from the radiator and pumps into the block theres no restriction, but if you restric the flow its possiable to cause the impeller to spinnwithout pumping fluid effectively

56 Posts
I do disagree with it "getting air". Cavitation is boiling of a liquid. Just like a pressure cooker boils water at a higher temperature, decreasing pressure lowers boiling temperature.. A water pump (such as an above ground well pump) can only pull 33' max of suction b/c at 33' pressure at the pump suction is < waters boiling point at near perfect vacuum (you can boil water at 32 degrees farenheit at a near perfect vacuum). So saying an oil pump breaks free means 1 of 2 things. Either you're sucking air from the suction or a gasket in the pump. Or 2 your boiling (turning it into a vapor) the oil b/c you fell below saturation pressure. Cavitation is bad b/c you are basically turning your liquid into a vapor "boiling" on the suction side and as soon as that bubble gets to the higher pressure discharge it collapses. That gives you that wonderful sound and also erodes the impeller/propellor/gears on the discharge side b/c it is a quite violent reaction. A cars oil pump is a positive displacement pump (gear types are) so you get a given amount of oil per revolution. If you stop the discharge flow you will destroy the pump or break the shaft. That's why there's a relief valve. A higher pressure oil pump has a different relief spring, where as a higher volume pump has different specs. A centrifugal pump can be dead headed (discharge shut) but you'll burn a pump up quick w/o a recycle to cool it off. So in water it's not pushing froth it's boiling on one side and colllapsing on the other. I was in the navy and operated as a throttleman on the enterprise and we could cavitate the hell out of the props if need be, but for one thing it's noisy (don't want to be heard too awful far) and 2 it's hard on the equipment including the prop (which was 30' in diameter). As a rule your engine needs <5 psi of oil pressure to operate. Now everyone is thinking !5! but in cars today there'd be something wrong at 5 psi. Your engine rides it's internals on oil so it's not a pressure thing. There are other variables at higher rpms such as heat removal requiring more flow. A Briggs engine doesn't have an oil pump. It uses "flingers" to cet the oil where it needs to be.
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