'73 620 - Keeping it running, but still having fun

[G-Duax]

On the Toyota, I just put a solid spacer behind the relief piston, so it wouldn't move, then just plumbed the remote relief into the cooler/remote filter lines.

 

Oh, and thanks for the tip of making a dam in the coolant in port on the block.

I was just going to block the port out, and was hoping I could cut through the partially cured hardblok material to reform the coolant passage.

[distributorguy]

I didn't even think about that.  On the Datsun you can plumb a remote filter from the block and use the bypass hole as the return with a regulator in series.  Bingo.  Now I have to budget for a remote pressure regulator.  $$$$

[G-Duax]

I found mine on eBay under performance parts, an ex-naskar piece.

[datzenmike]

It will if I do a remote relief valve as I am doing on my Toyota.

Stock 'in the pump' relief valves generate a lot of heat.

Simple hydraulic tech, any oil that is pressurized, then released, without doing work, turns the power used to pressurize it directly into heat. (learned that 35 years ago, first simester of a fluid power degree).

By doing a remote, and plugging the stock relief, oil is routed out to a cooler, and then back to the pan.

So at 8k, the pump is flowing 4 times the oil than it does at 2K.

Engine gets cooler oil.

Also, aftermarket relief valves are adjustable, just turn the screw.  :)

 

Millions of these around and they work just fine. We're talking 70-80 PSI not 2,500 in a hydraulic system. Pressurizing an in-compressible fluid does not raise the temperature. You can get a rise in temp from friction of fluids forced at high speed around bends and through tubing. The relief valve on the L series just routes the excess oil right back to the inlet port on the pump. The only oil lifted from the pan is the oil going to the engine bearings, which is very little and does not increase with RPMs as the bleeding of oil past the bearings doesn't change. Routing the oil to a cooler and back to the oil pan will require the engine to pump harder and constantly to move it and will generate more heat than any saved. Better to just run one large oil cooler at the filter so the engine runs on cooled oil, not cooled oil mixed with hot pan oil.  

[G-Duax]

Pressurizing an in-compressible fluid does not raise the temperature.

 

Mike, do you have a degree in fluid power ?

Have you worked in the industry for 40 years ?

Are you cirtified by the National Fluid Power Society ?

 

I have all of those......

[datzenmike]

Of course not, I have a degree in common sense from the school of hard knocks. Yet you think that pressurizing oil to 65 PSI and releasing it through the bearings is going to significantly raise it's temperature? You'll heat it more from the friction of drawing 8Xs as much oil through the oil pick up and all the bends in the block to the pump and the cooler. The engine is going to work harder moving all that oil all the time, making even more heat and loosing some power doing it. Better to run the stock oil relief valve in closed loop control. The only oil being pumped is that used by the engine. Again a higher revving engine doesn't use more oil than one at 2K.

[G-Duax]

datzen, why don't you build your engines, and let me build mine.

 

You said

"You'll heat it more from the friction of drawing 8Xs as much oil through the oil pick up and all the bends in the block to the pump and the cooler. The engine is going to work harder moving all that oil all the time, making even more heat and loosing some power doing it"

 

For one, how in the world does oil run hotter, by going throug a cooler ?

 

Second, line loss (what you call friction) isn't squat.

 

Third, the engine isn't going to work harder moving 'all that oil all the time'.

The pump is a positive displacement design (all automotive pumps are).

So it moves the exact same amount of oil per revolution at idle, as it does at 10,000 rpm.

The flow is them the same through a pump with the stock set-up, at say 8000 rpm, as it does with my set up at 8000 rpm.

But in a stock pump, most of that oil stays in the pump, continually getting run over the relief, getting heated over and over again, before some of it gets to the bearings.

My set up, the oil gets a chance to cool, and what is going to the bearings is nearly the same temp as what it was in the pan before it entered through the pick up.

 

So like I say, if you don't understand it,

and you don't want to learn from someone who has way more experience in dealing with fluid dynamics than you,

keep it to your self.

[distributorguy]

Duax is right.  Your first assumption Mike, is that pan oil is hot, but it'll all be run through the cooler with the exception of the small amount that is discharged via the bearings and absorbs frictional heat.  The bulk will be passed through the filter and the cooler, then pressurized on the back side like fuel in an EFI system, which has no heat issues either.  In fact, look at it like an EFI system.  High pressure pump takes from the tank, feeds down the line, discharging a small amount of fuel at the injectors, the bulk hits the pressure regulator and returns to the tank at a reduced pressure via change in line size (more volume= faster, cooler return at a lower pressure), where its not hot. Very basic fluid dynamics.  The biggest difference here is that the engine won't burn the small amount of oil discharged, that's the hot oil in the pan, which is immediately blended in a 20:1 ratio (my guess) with cooled oil.  

 

You also can't look at oil like freon, because the boiling point is entirely different.  While there are similarities to an A/C system design, that's where that comparison ends.  Design similarities.  The engine makes a very poor evaporator coil, sheds very little of its heat (volume-wise) to the oil.  That's how you can maintain a 230 degree oil temp in a 325 degree block.  

 

You won't read any of this in repair manuals either.  This is all R&D based knowledge (think $$$$$$) that you're lucky enough to have someone like G-Duax sharing here, so absorb it and remember it, unless you are always going to run your motors bone stock.  Ever wish you got to work under one of those "old guys" in a machine shop that builds race motors and learn all their tricks?  Well here ya go.  Just watch and listen to this build.  

[datzenmike]

You are still movingvast quantities of oil, more and more as it revs up. The engine has to power all this. More sensible to run the stock pressure regulator and the engine only has to moves a tiny amount through an oil cooler and to the bearings, pretty much the same amount at any rev. 

 

Still wanting to know how much heat a liquid warms up from compressing it to 60 PSI and releasing it. Cold water comes out of my tap not warm or luke-warm. If there is some obscure theoretical value for this it must be vanishingly small. Certainly not worth putting an oil cooler on for. This is totally over thinking this.

[distributorguy]

When racing, oil has a heat saturation temp that you want to stay below to save your bearings.  Once you go past a theoretical point of no return, oil will not cool down.  An oil cooler buys you time before bearing failures.  My goal is to keep oil temps under 250.  If you hit 300, shut her down and wait.  Pressure has nothing to do with it.  Oil is a hydraulic fluid which does not compress, so virtually no heat is generated.  

 

Go find any race car or truck that doesn't run a cooler.  We're both on the fringes of running an external oil pump with dry sump.  This is the first step in doing so.  Since we already have an external oil pump, crank driven instead of belt driven, it makes sense to externally regulate and cool the oil as well.  The compression doesn't add heat.  Again, its not freon.  Heat comes from contact with the block, and what is absorbed from friction.  The oil cooler is not needed on the street, unless you are out of tune.  Its needed in severe duty conditions. 

[datzenmike]

It will if I do a remote relief valve as I am doing on my Toyota.

Stock 'in the pump' relief valves generate a lot of heat.

Simple hydraulic tech, any oil that is pressurized, then released, without doing work, turns the power used to pressurize it directly into heat. (learned that 35 years ago, first simester of a fluid power degree).

By doing a remote, and plugging the stock relief, oil is routed out to a cooler, and then back to the pan.

So at 8k, the pump is flowing 4 times the oil than it does at 2K.

Engine gets cooler oil.

Also, aftermarket relief valves are adjustable, just turn the screw.  :)

 

I was referring to this part about compressing and releasing pressure adding heat.

 

Agree on an oil cooler, it's needed.

[distributorguy]

I can tell you that the hop harvester we use every fall uses several hydraulic motors, and it generates a LOT of heat at the control valves.  Of course, that's 2000 psi, a little different animal.  My tractor operates at the same pressures, but not the same temps.  I actually think it has a lot to do with pressure duration, which is brief in an engine and a tractor, but still important.  In the end, it comes down to system design - line sizing, running minimally acceptable pressures, and using the right oil.   Personally, I don't know how a relief valve generates more heat when its in the pump versus out of the pump.   Probably a different style valve, in an aluminum housing, air cooled outside the engine?  Likely constant flow versus a trap door/check valve?  Too many proven ways to do this to doubt if it works.  

[datzenmike]

That's moving oil, forced through valves and restrictions doing work. Friction heat. Absorbed heat. My contention was that liquids placed under pressure, when released, do not heat up from absorbed energy.

 

As to the oil not cooling the engine much. Engine block 350F... oil 250F and coolant 200F. Seems like the oil is absorbing lots more heat. It goes to much hotter parts than the coolant or by design, allowed to get much hotter.

 

 

Yes oil cooler can be essential in a hot engine. As the heat can only come from that absorbed by the pressure side oil supply. Cooling the pan oil rather than the oil supplied to the engine seems like ..... six of one and half dozen of the other except more work and bother, and more work for the engine.. 

[distributorguy]

"Seems like" and real world are 2 different things.  Coolant carries more heat away by volume.  Period.  Think surface area.  Think temperature differential.  It surrounds the cylinder liners in volume.  Oil does not.  

[G-Duax]

Here is a little data:

 

http://hydraulicspneumatics.com/other-technologies/book-2-chapter-18-pressure-relief-valves

"At no time should the relief valve be used to pass excess pressure fluid to tank. When excess pump flow goes to tank, it generates heat."

 

http://www.womack-machine.com/pdf/rb365/47th/section10/sec10pg517-518heatxcoolingsystems.pdf

"BTU/Hr = psi x gpm x 1.5"

 

http://www.ehow.com/how_7725066_do-calculate-displacement-gerotor.html

 

L-series pump drive ratio = 2:1 or 1/2 crank speed

Stock L4 pump:

Rotor length: 34.87mm

Base circle: 18.6mm

Rotor center displacement: 9.474cc

 

Bore dia: 12.65mm

Bore volume: 4.382cc

Cross pln hole volume: .050cc

 

water volume displacement: 12cc

minus 5.042 = 6.958cc / 16.39 = .424 cu in

 

@ 2k rpm = 424.5 cu in / min

@ 8k rpm = 1698 cu in / min

gpm at 8k = 7.35

gpm @ 2k = 1.84

difference = 5.51 gpm

5.5 gpm = 660 btu/hr or 11 btu/min (if dumped externally through remote relies)

 

But because a stock pump dumps right back into the inlet of the pump, the oil gets reheated at a ratio of 4 minus 1 times, or 33 btu/min.

Since 1 hp = 42.4 btu/min, the HP on this hypothetical L4 engine is .778, or .78hp is turned directly into heat by going over the relief valve, back into the inlet of the pump, or 577 watts / minute.

 

So, running the stock relief valve is like heating the pump's discharge with an inline 577 what heater.

It is 1/3rd of that by running a remote relief.

[datzenmike]

There are about 115,000 BTUs in a gallon of gas.

 

Gas engines are about 30% efficient, likely the L series is much less but a race engine would be over 25% I would hope. 1/3 for movement,  1/3 for cooling and 1/3 heat out the exhaust.

 

My 710 at 60MPH and 30MPG that's two gallons per hour and at 70% is just over 160,000 BTUs an hour or 1/3 = 48000 BTUs a minute of waste heat to get rid of by the cooling system. Although water and oil are not mixed they share heat to a large extent. Raise one the other must absorb some. But lets just say (for argument sake) that the cooling system has to handle 47,500 BTUs of those 48,000 BTUs and the oil only 500 BTUs. About 1 part in 96 parts or just over 1.04%. That's 8,797 watts of heat absorbed by the oil per minute. Does saving 400 watts or allowing 400 watts more really matter that much???? That's just under 1/22nd added or removed. I wouldn't bother worrying about the oil heat even on a hot day but any oil cooler would be lots..

 

An engine run up to 8k WOT is surely going to use more than two gallons per hour. Lets say 10 MPG or 6 gallons an hour. You guys race, how much? More?? At 6 gallons that's 144000 BTUs to the cooling system. 1.04% to the oil is 2,016 BTUs now, or 35,470 watts heating the oil. Again... does saving 400 watts really matter when you are absorbing over 35,000???? Get an even larger oil cooler

[G-Duax]

Mike, go fuck yourself........

You may be great on stock things, maybe, but performance, you are a lost child.

Like another member said, 'mike has a closed head'.

Really, anyone who has a fictional drug dealer as a signature, must be using..........

[datzenmike]

What, there's something wrong with my figures? I'm willing to discuss it. You loosing your temper shows you find my position valid.

[Lockleaf]

For what purpose is this engine being built? Angry DD, hot street, 1/4 mile drag night at the local track? What performance are you expecting to see when all is said and done?

[distributorguy]

Back off Mike.  Its not good for anyone if you as a self appointed "king" chases people away from the forum.  Did you ever take into account air cooling?  Again, the only thing you are the king of is arguing semantics.  If we want to deal with that shit, we'll go home to our wives.  Play nice.  

 

Lockleaf, I believe Duax is putting together a pretty healthy drag motor.  

[datzenmike]

Air cooling? Knock 10% off the heat load on the oil and you will still have negligible heating of oil by the pump.

 

Semantics? There's no trickery of words here. I plugged in some numbers to the OPs previous reply to back my contention that the pump generates 'vanishingly small' amounts of heat. OK it does have a value (about 600 watts) but negligible is a better word.  True, I've assumed a gas engine is about 30% efficient and allocated the energy released by a gallon this way...1/3 to motion, 1/3 to exhaust heat and 1/3 to cooling system heating. In addition I assumed that the oil only receives just over 1% of all engine heat generated. Is there is a dispute over these assumptions? Maybe there is some wiggle room to move some values around. I maintain the 600 watts of heat generated by the oil pump does not significantly affect ....anything. For this I should go fuck myself, reference to a closed head and I'm using drugs?

[distributorguy]

What is it that makes you have to prove yourself right on every post Mike?  Why do you have to be a dick about it and push, push, push?  Too many "engineer types" assume that the "simple laws of physics" play out in an expected way in performance engines, but there are always other factors at play that always skew the results.  When building performance engines, there are a few things you learn by reading, but many more that you learn hands-on, and you clearly are not a hands-on engine builder, at least not the type that has done severe modifications beyond most peoples' imaginations.  Its one thing to ask questions about things you don't understand, and yet another to make assumptions and try to prove yourself right.  You are clearly the latter, unless you can say you HAVE used an external oil pressure regulator (as thousands have) and you know we are each about to make a mistake?  But you haven't.  And you are pushing your false assumptions.  Semantics really, because any percentage you have quoted is something you pulled out of your ass.  Even if your numbers were right, what is the oil coolers efficiency and capacity?  Radiator efficiency?  Your numbers are all bullshit so just let it go. If you want to argue with Duax or me, take it offline.  Its not helping Ratsun.net or any of its members.   

[datzenmike]

Hey I'm not a collage grad but when someone says compressing a liquid heats it, I say common sense says otherwise. But I'll take the OPs comments about him being a hydraulics engineer and the full page of proof about pump pressure, watts, HP, volume, and BTUs he supplied as true. I didn't call him names or suggest he's on drugs and I also said it must be truly a small amount of heat, and have shown this >600 watts compared to the total heat being dealt with in my following page of 'proof'. I said the 'assumptions' can be 'massaged' around a bit but they are probably close to real world. If there are false assumptions what are they? Does the oil get less than 1% of the total cooling system heat produced? I thought I was being conservative at 1%, is it less? Don't tell me it's bullshit, tell me a number.

 

The oil cooler and rad efficiency? How many watts of heat is being dumped by an oil cooler? by the rad? You race, so have probably some idea how much heat they dump. Any idea?

[distributorguy]

I'm not an engineer either, my BTU calculations are HVAC based.  I can tell you to the BTU what your house or business needs for your climate, both heating and A/C.  Racing, we use known quantities that are generally taken for granted (the same way most HVAC guys operate, but I actually know the math behind it).  But its been used for decades and it does work.  I'm just sick of members poking other members in the chest around here.  Its NOT necessary.  You have the option of being nice and asking questions or making assumptions and throwing it in someone's face.  For some reason you, Mike, seem to chose the latter and you've pissed off more than your fair share of new members.  If someone had the authority, I'd say you should get a warning or be banned temporarily for your recent (past few months) behavior on this site.  Just treat folks the way you would if you were face to face, where I'm sure you would be a little less aggressive.  And yes, pressure can create heat.  Just measure G-Duax's forehead temp when you raise his blood pressure and you'll see.  The color change should be significant enough that you don't need a thermometer.   :devil:

[Lockleaf]

I understand that this is to reduce heat in the oil, but it is hard for me to grasp just how much the pump heated oil affects overall oil temp. What time frame/harsh conditions make this kind of mod necessary as opposed to just neat useful and cool?

 

On a 1/4 mile drag motor, how much extra heat would the stock setup be adding? On a salt flats WOT motor, how much more? Or an endurance racer, is that even worse?

 

It's a very cool idea, and I love observing race builds like this (cuz I don't have what it takes to build stuff like this), but could one of you guys help me understand in what scenarios the juice is worth the squeeze?