Fluid dyamics discussion - someone educate me.....

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Originally Posted By: BuickGN
You guys going back and forth has taught me a lot. I've always run a high volume pump even though the fast guys told me not to. This was in an attempt to raise my idle pressure which it didn't help much, it just put me on the pump bypass at 3,000rpm instead of 4,500rpm. Now it makes more sense to run my stock pump and save the front cam bearing.


What I've concluded about HV oil pumps is that they are only good IF your engine is modified to flow more oil.

Fact is, if you put a HV pump on a bone stock engine (stock flow resistance), and that HV has a relief pressure the same as the OEM pump (say 80 psi), then you are gaining nothing at all. The stock engine setup will flow the exact same oil volume (at some viscosity at X temp) at 80 psi REGARDLESS if the pump is HV or OEM, as long as the pump can supply adequate volume. With the HV, it just means MORE excess volume is shunted to the sump via the relief valve. The only time a HV pump will flow more on a stock engine is if the relief pressure is higher than the stock pump was.

The other alternative is to change the relief setting on the OEM pump. When doing that mod, this causes MORE flow volume at higher RPM because you are putting more pressure on the system, which makes more volume flow through the filter/engine. Of course, it you run the pressure too high, then you have other issues to address ... like filter strength, seal leakage, etc. The same would have to be considered if running a HV pump with a much higer pressure relief setting.
 
Originally Posted By: BuickGN
I still have a hard time accepting that school of thought. I can see how 40% of the cooling may come from oil. But I have a few problems with the theory, maybe you can poke some holes in it.


The only way to make cooling worth while through removeing heat from the oil is to have an effective oil cooler. Just increasing the flow in an engine without an oil cooler isn't gonna do much to keep the temps down.

Originally Posted By: BuickGN
Wouldn't that heat come mostly be from the piston crown bottoms and from flowing over the heads and not bearings??


Yes. On a side note, the rotary engines (Mazda) have hollow rotors that the oil flows through, and picks up a lot of heat from combustion ... of course they have two oil coolers on them.

Originally Posted By: BuickGN
Suppose a thicker oil flows slower through a bearing but there's always a continuous flow, wouldn't the thicker oil just get hotter but still carry away the same amount of heat?

BuickGN said:
If the pump pressure is just to deliver flow to the bearings and the hydrodynamic wedge motion takes over, wouldn't the same amount of oil "flow" thorough the bearing regardless of viscosity?


Same scenario ... if the oil pump in not in relief mode, then the same volume is flowing through the engine, which means the flow velocities will be the same with thick or thin oil through a fixed gap. But ONLY if the pump is not in relief.
 
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Wouldn't that heat come mostly be from the piston crown bottoms and from flowing over the heads and not bearings??


Maybe
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So?
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I'm not a race engine builder ..or even an engine builder of lawn mowers. This is just the current school of thought. The state of the art, if you will.

These engine builders who attend these Indy clinics (my buddy being one of them) says that these builders are now going back and redrilling their oil passages to accommodate higher flow. That may not mean any lower visc oil being used, just more oil flowing without reaching limits.


That's why I said that the use of a HV pump is questionable unless you can handle a visc that will fit through the engine. My 4.0 can only "demand" about 5gpm of oil max. I have that volume @ about (speculating) 1600 rpm ..maybe 2000rpm. To fit the full volume ..and get the added cooling aspects out of it, I have to go to a 20 grade. Even Bruce's 0w-10 will peak the relief limit at start up.
 
Quote:
The only way to make cooling worth while through removeing heat from the oil is to have an effective oil cooler. Just increasing the flow in an engine without an oil cooler isn't gonna do much to keep the temps down.



Much depends on your natural rejection rate. This can be variable. It will lower peak temps at the points of heat production. If you think of something like a Euro engine (even a VW) where you're at such high speed that the flow rate is the only thing stopping you from over heating. The throughput is JIT to keep things cool enough. For someone like GN, I doubt that sustained WOT or high speed (within the capability of the engine) is something that can be maintained.

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Fact is, if you put a HV pump on a bone stock engine (stock flow resistance), and that HV has a relief pressure the same as the OEM pump (say 80 psi), then you are gaining nothing at all.


Not necessarily true ..but usually true. Most stock oil pumps never reach relief limits at operating temps. Some do ..but most not. My oil pump had a peak of 42 cold ..24 at virtually any hot road speed ..and 12 pis hot idle. If bigger/longer vanes were installed, while the 42 still being peak ..the other pressures would be higher at all speeds. Only the cold flow would be the same using the same visc oil.
 
Originally Posted By: Gary Allan
Quote:
The only way to make cooling worth while through removeing heat from the oil is to have an effective oil cooler. Just increasing the flow in an engine without an oil cooler isn't gonna do much to keep the temps down.


Much depends on your natural rejection rate. This can be variable. It will lower peak temps at the points of heat production.


I agree that it would make some difference right where the heat is being produced. But fact remains that if you can't shed the heat you've picked up, then the oil will just keep get hotter and hotter regardless of the flow rate. X quarts of oil ran through the engine over and over can only hold so many BTUs for a given temperature. Anyone who's interested in running cooler oil and engine component temps needs an oil cooler for best effectiveness. Increased flow volume along with a cooler is optimum.

Originally Posted By: Gary Allan
Quote:
Fact is, if you put a HV pump on a bone stock engine (stock flow resistance), and that HV has a relief pressure the same as the OEM pump (say 80 psi), then you are gaining nothing at all.


Not necessarily true ..but usually true. Most stock oil pumps never reach relief limits at operating temps. Some do ..but most not. My oil pump had a peak of 42 cold ..24 at virtually any hot road speed ..and 12 pis hot idle. If bigger/longer vanes were installed, while the 42 still being peak ..the other pressures would be higher at all speeds. Only the cold flow would be the same using the same visc oil.


Yes, I see your point. This would be true ONLY if the HV oil pump could produce more volume at any given RPM below relief point. In essence, the "Flow Volume vs. Engine RPM" line in my graph (posted earlier) would be steeper - meaning it would put out more volume for a given RPM below relief point.

Here’s my view. Most guys use (and most HV pumps are sold for) racing purposes where the engine is near redline most of the time. My point was that if the HV pump has the same relief pressure as the OEM pump, then the HV pump isn't going to force any more oil volume down the fixed resistance filter/engine path unless that path is opened up (make less resistive) to take on more flow at the relief pressure. If the engine flow path is left stock, then that means it will flow the same X gpm at the same Y pressure (with constant oil viscosity) regardless of what pump is driving the oil down the path. The only thing a HV oil pump will give you on a stock engine is a steeper "Flow vs. RPM" curve below releif point - and you will see the oil pressure build up much faster and quicker then with a stock oil pump. In order to get noticably more flow volume in the higher RPM range you would need to a) use HV pump and open up the engine flow circuit, b) use HV pump with a higher relief pressure than the OEM pump, or c) ... both a) and b).

I don't think having a HV pump for idling and cruising to the grocery store makes much sense ... unless you're at least half way to redline the whole time.
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Absolutely (2nd point). Then again, one may not just grocery get with their engine. They may be mud slinging or climbing near straight up in low range while moving @ 3mph @ 4500 rpm ..or plowing snow ..or an number of things that involve higher combustion pulses over a given span of time.

It's probably a product of "more is better" notions that most seem to cling to. This is with anything ..viscosity ..whathaveyou. ..and the fact that Jeg's and Summit have 4 out of their 5 typical aftermarket performance oil pumps in HV. It's what reinforced intermediate shafts are for for your typical SBC upgrade.
 
Originally Posted By: Gary Allan
. ..and the fact that Jeg's and Summit have 4 out of their 5 typical aftermarket performance oil pumps in HV. It's what reinforced intermediate shafts are for for your typical SBC upgrade.


Absolutely ... it takes more power (torque x rpm) to pump more (and heavier) oil volume. If you have a wimpy shaft ... snap! ... your done.
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You're completely right, Gary. Mine would not come close to sustaining full power output for long. Oil temps get scary high very quickly, that's why it's limited to a full 1/4 pass at the track or a few seconds on the street. The only comfort I have is that if it got stolen and didn't get wrecked right away I would probably find it not too far away with a rod through the block. It already has a big oil cooler which doesn't seem to do much with the temperature spike at WOT but does reduce the average temp. I guess a 12 quart pan would be a good place to start to absorb the initial hit.
 
Originally Posted By: BuickGN
Oil temps get scary high very quickly, that's why it's limited to a full 1/4 pass at the track or a few seconds on the street.

I guess a 12 quart pan would be a good place to start to absorb the initial hit.


Yes, a large capacity oil sump would definitely help in the short 1/4 mile WOT scenarios. Oil coolers are really meant for track cars that are at sustained high RPM / high HP output / high speed conditions. An oil cooler on a 1/4 mile car isn't going to do much except soak up a little heat into its mass by the time you cross the line. Maybe if you spary some -320 F liquid nitrogen across the cooler it would help some ... j/k.
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Yes, you need more oil mass to soak up the heat. Dry sump with a 20 quart tank. Then it will take you 2 hours driving to the track to get the oil temp to a decent level
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Originally Posted By: SuperBusa
Originally Posted By: BuickGN
Oil temps get scary high very quickly, that's why it's limited to a full 1/4 pass at the track or a few seconds on the street.

I guess a 12 quart pan would be a good place to start to absorb the initial hit.


Yes, a large capacity oil sump would definitely help in the short 1/4 mile WOT scenarios. Oil coolers are really meant for track cars that are at sustained high RPM / high HP output / high speed conditions. An oil cooler on a 1/4 mile car isn't going to do much except soak up a little heat into its mass by the time you cross the line. Maybe if you spary some -320 F liquid nitrogen across the cooler it would help some ... j/k.
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I've been known to steal friends' nitrous bottles to chill my intercooler right before a run. Liquid nitrogen here I come...

The cooler is there because it's a street car and was daily driven from '94 to early '06. Believe it or not it seemed to take some of the load off the the cooling system. If it were a dedicated track car I wouldn't bother with a cooler. Sorry to get off topic once again.
 
Thanks for the info guys... SuperBusa... the oil cooler adapter block replaces the oem temp sensor housing and provides you with 2 AN fittings to run lines to a cooler of your choice. You are correct that it has a parallel flow path and not all of the oil goes through the cooler.

Now... the question is does the cooler's additional tubing and flow path etc. etc. make for more of a restriction (thus higher pressure) or less (lower pressure). Too bad I sold my cooler setup and it's a PITA to install or I could test back to back.

Here's some pics of the oil cooler adapter block etc.

Stock setup... the temp sensor housing is above the oil filter
Zoil1.jpg


LPE adapter block
Oil%20cooler%20block%20flow.jpg
 
There's no way that kind of setup can increase restriction. If it raised pressure, it was from cooler oil.
 
Well... here's the proof... it was the oil filter. I must have damaged the K&N internally when I hit the concrete.

Here's the oil pressure and temp when I got home from work today. It was moving from 39 to 40 and back again every few seconds. This is with a brand new Mobil 1 filter installed last weekend.
DSCF3242.jpg


Oil temp is 207
DSCF3243.jpg


Brand new K&N and some 5w30 to prime the filter
DSCF3244.jpg


After I did some yard work I swapped the filter and went for a drive to get the car good and hot. Here's the result:

Oil pressure was going back and foth from 49-50 psi... would not drop any lower than 49.
DSCF3245.jpg


Oil temp was 208
DSCF3246.jpg


So... as you can see... swapping from the M1 back to the K&N resulted in a 10 PSI gain at idle. So in my setup the oil filter clearly does matter and the K&N clearly has a different media than the M1 eventhough the M1 is also made by Champion Labs and looks the same when cut apart. The hot cruise and WOT presures were the same because in these cases the oil pump was in relief.
 
Glad you got it sorted out. The pressure sensor has to pick it up before the filter on your car.
 
The diagram I posted on the first page is how all LS series (LSXs) work... the oil is filtered then goes to the pressure sending unit.
 
Sure. You're in relief. You're above your threshold. The filter is restrictive in that state. If you had a 75lb relief ..you would not see a difference.

You're above your relief limit ..way down stream. You're seeing the filters true "free flowing" or "highly restrictive" properties. To 99% of the rolling population ..they're invisible.
 
How am I in relief? The relief spring begins to open at 52psi. The M1 filter held hot idle at 37-40 psi. With the K&N filter it won't drop below 49.
 
Hold on... I think I may have just "gotten it". Are you guys saying that my oil pump is making enough pressure to always be in relief? That at idle the pump is putting out 52psi, but that by the time in goes down the oil galley, through the filter, and makes it to the presssure sensor it's dropped 12psi for the M1 filter and 2psi for the K&N?

(also posted this in my oil filter thread)
 
I think you were right at first, your M1 filter was damaged and causing restriction.

You are at least near relief onset at hot idle with pressure that high.
 
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