Trans or steering cooler tech for 2020

[HYDRODYNAMIC]

as for power steering and transmission cooling, rather than running 1 gauge at the hot side output of the trans and then another at the cold outlet of the cooler, is there any compelling reason to not simply take the pan/reservoir temperature and be satisfied that it is below 180* ?

On a 4L80 the coolable flow is going through the torque converter spool valve and through the torque converter, then back to the valve, then to cooler, then to sump.
Putting the temp gauge and or switch in the line going to the cooler is the most reactive location as you will see the hottest oil coming out of the working TC. This will trigger the fan sooner. This will let you know the maximum oil temp in the system and when the TC is working. If you put it in the pan, the cooler will have done its work and you will not know the working temp only what you are feeding it. If you have a good cooler you might not know that the TC is working hard.
Whichever location you choose, the main point is to make sure that it stops climbing at some point and the cooler is keeping up.

 

[HYDRODYNAMIC]

I’d like to say the pressure will be much higher than 15 psi at pump’s discharge and it seem like most radiator caps are on cool side tank (after the pressure drop across the radiator)

People who race with Cummins purposely crippling their water pumps by clipping 2 of 5 fins off. Racing with unmodified oe water pump generate enough pressure to blow freeze plugs out, leaking out of head gasket, and such.

http://www.competitiondiesel.com/for...7&postcount=15

If you are running a surge tank with cap, then the cap should be on the high pressure side. The pump has to pump through the block which will drop the pressure down to a return pressure level that just needs to flow through the radiator and back to the suction of the pump.

The block restriction pressure is 25PSI at 4000RPM but a lot of that pressure should be gone once out of the block and only flowing through the radiator.
I found some testing I had done on the MA style cores running water. I was getting 5 PSI at 40 GPM through a 30" x 16" core. The 15 PSI I listed was for oil restriction based off of Thermal Transfers graphs and forgot about converting for water.

If you look at the Trophy truck radiators at 31'x31" with quad fans, they are lying down in the rear so the air flow at speed is not going to do much. Short course trucks are the same way and the fans are doing all the work.
Ultra 4 is not far behind on the HP levels but most are running half the radiator and half the fans.
When they sit and the intake air gets heat soaked by the 1/3 of the heat that does not go into the radiator, like the engine surface, exhaust, trans surface, torque converter, and trans cooler. The surrounding air is heated and the radiators are not bringing in cold fresh air even though the electric fans are pulling the same amount of air as at high speed.

Thought should be put into the air flow coming in and out of the radiators and coolers in a stopped situation. The inlet air should not be coming from something that can heat up. The hot air should be sent away from the vehicle so it does not heat soak something else. For example Spal fan blade profiles can change the discharge angle leaving the fan. The classic surface mount deep curved blade that many use dumps the air in a flood pattern. Where as the new brushless recessed blade design sends the air out in a spot pattern. The spot pattern is going to send the hot air away at a further distance if aimed correctly. My trans fan is the flood style which is fine because it is aiming at the ground and will send hot air more to the sides and out from under the vehicle. A spot discharge would bounce it off the ground , kick up dust and stay around. My rear engine radiator fans are the spot style and shoot all the air straight out the back into the face of the buggy riding my tail. The mid mounted radiators that send the hot air up at an angle is better than straight back which can heat soak the fuel cell or other coolers near by. The tilted front radiators that send the air down under the motor are better than sending it straight back into the engine where it heat soaks the motor.

 

[DMANbluesfreak]

Maybe I missed it, but any idea on how to determine the BTU/hr on a power steering system? That's where I struggle to properly size coolers for various rigs. It's 'easier' using rules of thumb based on engine horsepower to determine a radiator size than oil cooler from my perspective.

 

[Bebop]

The upside to the brushless is the one sensor controls off and on and ramp where the brushed would need a PWM controller and a low temp switch since hydraulics run cooler than most temp switches for engine temps.

You can run the PWM controler off an ECU that monitors trans temp and that supports a PWM output with custom programming (like my Holley). Works great for engine fans and whatever else.

For steering cooling, I think the Miller cars are winning KOH with a heatsink and a TT pump as the only cooler (correct me if I'm wrong). Therefore I don't think it's worth it to go any other direction, especially one that involves an extra fan (more failure points / complexity)

 

[HYDRODYNAMIC]

Maybe I missed it, but any idea on how to determine the BTU/hr on a power steering system? That's where I struggle to properly size coolers for various rigs. It's 'easier' using rules of thumb based on engine horsepower to determine a radiator size than oil cooler from my perspective.

Its varies like a trans cooler per application. Is it going to slip a lot and generate heat, is it going to be high RPM or low RPM most of the time, heavy rig or light rig. The steering is going to make heat based off of HP and PSI.
Rule of thumb is 1HP = 1Gal at 1500PSI
So 5 Gal at 1500 PSI is going to be 5 HP
So 10 Gal at 750 PSI is going to be 5 HP
If you are flowing 10 GPM at 250 PSI to drive around at speed then the cooler should be able to dump that 1.5 HP continuously. Even if the pump is regulated to 5 GPM outlet flow the total internal and external flow could be up to 10 depending on the size of the pump.
If all 10 GPM is at relief pressure 1550 PSI working in the rocks then you need to dump 9HP worth of heat.
For example my MA4 with fan can dump around 7HP at 17 GPM which my pump can flow unregulated. But the pump can generate 15HP at redline.
If the pump outlet is regulated then the 5GPM can only remove 5.5HP with the same cooler size due to reduced flow.
Most likely I will not be at redline and the relief but possibly at 50% generating 7.5HP of heat and that is back inline with what the cooler can keep up with. Either way you can not stay on the relief and have the cooler keep up. I have not seen numbers for the common inline aluminum tube coolers, but I don't see anything passive like this being able to keep up with much of a duty cycle. If your duty cycle is low then you will be fine with an inline like many others have done.
It all depends on how you want to drive.

 

[TrailTamer]

If you are running a surge tank with cap, then the cap should be on the high pressure side. The pump has to pump through the block which will drop the pressure down to a return pressure level that just needs to flow through the radiator and back to the suction of the pump.

The block restriction pressure is 25PSI at 4000RPM but a lot of that pressure should be gone once out of the block and only flowing through the radiator.
I found some testing I had done on the MA style cores running water. I was getting 5 PSI at 40 GPM through a 30" x 16" core. The 15 PSI I listed was for oil restriction based off of Thermal Transfers graphs and forgot about converting for water.

thank for adding more tech to this.

I want to add that there definitely is negative pressure on water pump's suction side, considering how a lot of OEM radiator hoses have springs inside them to stop from collapsing at high rpm, which can affect how you measure pressure drop across a radiator, cooler, etc, where it's inlet is pressurized and outlet is under vacuum, to calculate pressure drop more accurately if desired.

 

[HYDRODYNAMIC]

thank for adding more tech to this.

I want to add that there definitely is negative pressure on water pump's suction side, considering how a lot of OEM radiator hoses have springs inside them to stop from collapsing at high rpm, which can affect how you measure pressure drop across a radiator, cooler, etc, where it's inlet is pressurized and outlet is under vacuum, to calculate pressure drop more accurately if desired.

To be clear I was measuring the core restrictions not pressures.

Saying that the pump inlet is under suction brings me back to the supercharging concept. On a rear mounted radiator with a total of 15' of -20 =1" ID hose, the suction should be cavitating unless the pump is actually pushing the coolant through all of it right back to the pump. If you had air in the lines, radiator, and system that could compress then it cant supercharge by pushing everything through and could pull suction on the return side and close a soft hot OEM hose. Running a surge tank that pulls out air is very important to keeping the system running properly.

 

[DMANbluesfreak]

Its varies like a trans cooler per application. Is it going to slip a lot and generate heat, is it going to be high RPM or low RPM most of the time, heavy rig or light rig. The steering is going to make heat based off of HP and PSI.
Rule of thumb is 1HP = 1Gal at 1500PSI
So 5 Gal at 1500 PSI is going to be 5 HP
So 10 Gal at 750 PSI is going to be 5 HP
If you are flowing 10 GPM at 250 PSI to drive around at speed then the cooler should be able to dump that 1.5 HP continuously. Even if the pump is regulated to 5 GPM outlet flow the total internal and external flow could be up to 10 depending on the size of the pump.
If all 10 GPM is at relief pressure 1550 PSI working in the rocks then you need to dump 9HP worth of heat.
For example my MA4 with fan can dump around 7HP at 17 GPM which my pump can flow unregulated. But the pump can generate 15HP at redline.
If the pump outlet is regulated then the 5GPM can only remove 5.5HP with the same cooler size due to reduced flow.
Most likely I will not be at redline and the relief but possibly at 50% generating 7.5HP of heat and that is back inline with what the cooler can keep up with. Either way you can not stay on the relief and have the cooler keep up. I have not seen numbers for the common inline aluminum tube coolers, but I don't see anything passive like this being able to keep up with much of a duty cycle. If your duty cycle is low then you will be fine with an inline like many others have done.
It all depends on how you want to drive.

That makes total sense. I really needed a way to correlate the GPM/PSI to horsepower because there's no direct way for me to measure HP without the PS pump drawing that states the belt load information (touch and go with certain pumps). Fitting an enormous cooler won't allow the fluid to get to temp when it's cold outside and too small of a cooler will either run hot or have an e-fan running all the time, which is what I'm trying to avoid.

The comment before yours stating the heatsink cooler doesn't really apply to a full bodied rig that isn't going dozens of miles an hour in the desert but is still doing pretty hardcore rock crawling. What works in KOH isn't always going to work for vastly different rigs.

More than likely, a non-crazy PS pump will not be at max flow rate at relief pressure, so 9hp is probably overkill. I'll have to see if I can find a flow/pressure curve for my pump (or similar) and estimate the max heat output based on that. It is often with my rig that I can hear it hit relief pressure in the rocks when the front axle is locked, so I want to make sure I have appropriate cooling with only engine fans to draw air past the cooler on a hot day. Thanks!

 

[Provience]

On a 4L80 the coolable flow is going through the torque converter spool valve and through the torque converter, then back to the valve, then to cooler, then to sump.
Putting the temp gauge and or switch in the line going to the cooler is the most reactive location as you will see the hottest oil coming out of the working TC. This will trigger the fan sooner. This will let you know the maximum oil temp in the system and when the TC is working. If you put it in the pan, the cooler will have done its work and you will not know the working temp only what you are feeding it. If you have a good cooler you might not know that the TC is working hard.
Whichever location you choose, the main point is to make sure that it stops climbing at some point and the cooler is keeping up.

this makes me think triggering the fan on the trans out line and the in dash gauge measuring the pan temp would be a good compromise

 

[HYDRODYNAMIC]

this makes me think triggering the fan on the trans out line and the in dash gauge measuring the pan temp would be a good compromise

Normally you want the fan sensor to see the hottest source so it reacts as soon as possible and shuts off as soon as the heat has dropped. Eliminates cooling lag.
The temp sensor in the pan lets you know that the cooler is getting the oil to a temp that you want to feed the system with. It will not tell you how hot the torque converter is getting the oil up to though. If you took some measurements with a heat gun on the cooler infeed and remembered the sound of the fan speed or turn on speed you can use that as an audible gauge.

 

[arse_sidewards]

You can get cheapo electronic temp gauges for $20 these days. If you want to know your temp at various points get one of those, a bunch of replacement senders and a multi-position switch.

 

[Provience]

You can get cheapo electronic temp gauges for $20 these days. If you want to know your temp at various points get one of those, a bunch of replacement senders and a multi-position switch.

as nice as it would be to have ~10 inputs for temperature and a simple screen to flip around them all, engine coolant, trans fluid, power steering temp all reading on the "cool side" with fans kicking in on the "hot" side would probably be more than enough information to know if there is a problem and keep things happy without overcomplicating stuff.

 

[RadialDynamics]

For steering cooling, I think the Miller cars are winning KOH with a heatsink and a TT pump as the only cooler (correct me if I'm wrong). Therefore I don't think it's worth it to go any other direction, especially one that involves an extra fan (more failure points / complexity)

Yes, the Miller cars are running TT pumps (huge 1.22 in3 displacement, 20-30 HP consumed at high load) and "heatsink" style coolers. All of the Big B cars including Josh's that won last year are each running two of my finned tube coolers. Although these look similar externally to the Howe finned tube coolers, they hold about 6x the internal volume which means 6x longer residence time of fluid within the cooler (not to mention a very significantly thinner tube wall).

https://radial-dynamics.com/collect...cessories/products/finned-tube-cooler-3d-x-9l

I won't argue that a radiator style cooler is a more efficient heat exchanger than a finned tube but at the same time, finned tubes have the benefit of being compact, easy to mount, and able to take a beating with reduced risk of leaks/bent fins. Given that two of these are able to keep steering fluid temps in check during the most demanding possible race conditions with the largest and highest HP pumps available, I generally have little concern with being able to dissipate the energy from smaller TC and CB pumps, especially in non-race applications.

 

[DMANbluesfreak]

Even stagnant/stationary for long periods of time with lots of heat soak? That's the biggest thing I struggle with comparing non-race applications to race applications. I'm not denying your coolers working, I'm just looking for proof that on a stationary, full bodied rig that they'll indeed work better than a radiator style cooler.

 

[RadialDynamics]

Although the Ultra4's are rarely completely stationary, there are certainly slow rock sections with lower exposed air velocity and this is where some of the highest prolonged pressure demands (i.e. heat) are experienced. Also keep in mind that aside from KOH, most Ultra4 races have mud, sometimes lots of it, which adds another layer to heat transfer challenges. Unfortunately, I have not yet been able to devote resources to conducting any formal measure of exact heat transfer capacity of my coolers (sometime soon, hopefully) but on a relative scale, I know where they stand compared to all of the other finned tubes, aka heat sinks, that are on the market. How you decide which type of heat exchanger is "better" depends on what criteria is most important to you. BTU capacity, packaging constraints, reliability, these things all come into play.

I should also note that cooling requirements are affected by more than just the pump selection. Everything about steering system design from hose sizes to reservoir design will affect how much heat your cooler needs to transfer. Using too small of a hose results in heat generation through pressure loss. Cavitation and aeration of steering fluid produces heat due to the compressibility of gas. Reservoirs, meanwhile, transfer heat through their aluminum shell so if your reservoir has good circulation internally, this is another means to transfer heat to the surrounding air. Same goes for spin-on filters which typically have decent surface area.

When I began working with Big B, they were cooking their steering at extremely high temps and redesigning the coolers was only a portion of what it took to correct that. In addition to better coolers, we had to rethink the reservoir design, hose sizes, and overall system arrangement which resulted in reduced race temps by more than 100F.

 

[DMANbluesfreak]

You obviously know your stuff. I wish I had more know-how to do thermal CFD analyses to offer some help and run some simulations. I am pretty fluent in static FEA, but CFD is another monster altogether, despite using similar software packages. You're totally right that the entire system contributes to the temperature of the fluid... and really the only temperature we care about is the temp of the fluid coming out of the pump, since it'll be lower everywhere else. Spin on filters are probably a catch22 since they release heat with the additional high conductivity surface area, but also can generate heat with the flow restriction at high flow rates.

I'm not yet ready to redo my cooling system, as I want to do both my transmission and PS coolers at the same time to make sure they play well together (they currently don't). My current PS cooler has been 'fine' 95% of the time off-road, but I know that when things slow down that I can hear the pump start to whine if I'm really working the steering in the rocks (my truck weighs over 8k and has 40s and a locker). It was really bad in Moab when it was spooled and it was 107° on that super high traction surface. I digress.

The trick is getting the system to work at low temperatures since my truck also goes on the street in Chicago winters. Many people suggest not to use ATF for PS fluid, but I haven't found concrete evidence as to why. The reason I mention it is that ATF and the GM fluid are the only ones me and another wheeling/enginerd buddy have found that don't cause cavitation at pump startup when temps are around or below zero Fahrenheit. The Swepco 715 was the worst offender. I say this only to discuss the point of: what temperature is too low for a PS system during normal operation and is a more complicated cooling system required? Examples being a thermostat and large cooler or a smaller cooler with a temp-controlled cooling fan to bump the cooling only on hot days under heavy load. Certainly the downsides of a more complicated system are more failure points, which is never a good thing on a street/trail rig.

 

[TrailTamer]

DMANbluesfreak I discussed briefly earlier in this thread about heat exchanger. it may be an option to fit your needs, it will help bring up your PS & trans operating temperature in the winter time, and keep temperature in check when working hard.

 

[DMANbluesfreak]

The trans already has a heat exchanger shared with the radiator, which is why I'm not as concerned with the trans. Now that you mention it, the radiator also has provisions for an engine oil cooler that I could use for the PS heat exchanger... however, I worry that will bring PS fluid temps up too high in the summer. It seems most target max PS fluid temps in the 150-170 range.

 

[mdogg]

Yes, the Miller cars are running TT pumps (huge 1.22 in3 displacement, 20-30 HP consumed at high load) and "heatsink" style coolers. All of the Big B cars including Josh's that won last year are each running two of my finned tube coolers. Although these look similar externally to the Howe finned tube coolers, they hold about 6x the internal volume which means 6x longer residence time of fluid within the cooler (not to mention a very significantly thinner tube wall).

https://radial-dynamics.com/collect...cessories/products/finned-tube-cooler-3d-x-9l

I run a Howe TT setup with a single finned cooler very similar to yours, years ago before I got with them I used PSC stuff and a larger griffin rad style cooler w/ fan. howe was adamant their cooler was needed instead of the griffin one but the reasoning was that the flow through the griffin cooler was far to restrictive due to design and the fluid needed to get through quicker.

Im curious as you say yours has 6x longer residence time of fluid in the cooler, this mean the fluid is staying there longer. My understanding from howe was it needed to Flow in and out as quickly as possible for optimum cooling, which I didn't really believe at the time but its worked great for years no issues.

Maybe I didn't fully understand their theory and it wasn't just flow? Maybe you found a happier medium to keep fluid in the cooler for longer but still keeps flow up enough? Maybe I could use a cooler upgrade :D

 

[JBT]

Yes, the Miller cars are running TT pumps (huge 1.22 in3 displacement, 20-30 HP consumed at high load) and "heatsink" style coolers. All of the Big B cars including Josh's that won last year are each running two of my finned tube coolers. Although these look similar externally to the Howe finned tube coolers, they hold about 6x the internal volume which means 6x longer residence time of fluid within the cooler (not to mention a very significantly thinner tube wall).

https://radial-dynamics.com/collect...cessories/products/finned-tube-cooler-3d-x-9l

I won't argue that a radiator style cooler is a more efficient heat exchanger than a finned tube but at the same time, finned tubes have the benefit of being compact, easy to mount, and able to take a beating with reduced risk of leaks/bent fins. Given that two of these are able to keep steering fluid temps in check during the most demanding possible race conditions with the largest and highest HP pumps available, I generally have little concern with being able to dissipate the energy from smaller TC and CB pumps, especially in non-race applications.

Do you supply the TT style pumps for the Miller cars?

 

[Provience]

I run a Howe TT setup with a single finned cooler very similar to yours, years ago before I got with them I used PSC stuff and a larger griffin rad style cooler w/ fan. howe was adamant their cooler was needed instead of the griffin one but the reasoning was that the flow through the griffin cooler was far to restrictive due to design and the fluid needed to get through quicker.

Im curious as you say yours has 6x longer residence time of fluid in the cooler, this mean the fluid is staying there longer. My understanding from howe was it needed to Flow in and out as quickly as possible for optimum cooling, which I didn't really believe at the time but its worked great for years no issues.

Maybe I didn't fully understand their theory and it wasn't just flow? Maybe you found a happier medium to keep fluid in the cooler for longer but still keeps flow up enough? Maybe I could use a cooler upgrade :D

key difference is he said "6x the internal volume" and not simply 6x the residence time in the cooler, which could be accomplished by simply reducing flow. larger volume doesn't equal reduced flow, high flow = high BTU rejection.

 

[Provience]

The trans already has a heat exchanger shared with the radiator, which is why I'm not as concerned with the trans. Now that you mention it, the radiator also has provisions for an engine oil cooler that I could use for the PS heat exchanger... however, I worry that will bring PS fluid temps up too high in the summer. It seems most target max PS fluid temps in the 150-170 range.

i wonder if the cold side of the radiator isn't already hanging out at 150-170 * with a ~185* engine thermostat.

it's winter, so my engine never actually warms up, but it would be interesting to check with a temp gun.

GM radiators are nice for having the extra oil coolers, but dang are they wide


edit: kind of painful to find numbers and such eastwood advertising their radiator, starting with 200* inlet temp on some small block V8, 2 minutes through their rad nets 166* outlet temp vs 188* and 181* for "oe style" rads. Same conditions, same 200* starting, ending at 190* on the hot side for 2 of the 3 tested.

No More Overheating! Tri-Flow Aluminum Radiator Drops Your Cars Temperature 24°F - Eastwood - YouTube

 

[RadialDynamics]

I run a Howe TT setup with a single finned cooler very similar to yours, years ago before I got with them I used PSC stuff and a larger griffin rad style cooler w/ fan. howe was adamant their cooler was needed instead of the griffin one but the reasoning was that the flow through the griffin cooler was far to restrictive due to design and the fluid needed to get through quicker.

Im curious as you say yours has 6x longer residence time of fluid in the cooler, this mean the fluid is staying there longer. My understanding from howe was it needed to Flow in and out as quickly as possible for optimum cooling, which I didn't really believe at the time but its worked great for years no issues.

Maybe I didn't fully understand their theory and it wasn't just flow? Maybe you found a happier medium to keep fluid in the cooler for longer but still keeps flow up enough? Maybe I could use a cooler upgrade :D

On a small radiator style cooler, yes the flow could perhaps be too restrictive for what some of these high flow steering pumps put out. But to say that all radiator style coolers in general are too restrictive is completely unsubstantiated because whether a heat exchanger is too restrictive or not depends entirely on how large the internal flow passages are. I pointed out the key word "properly" sized in my earlier post because any heat exchanger with suitable flow capacity, radiator or finned tube, could be an acceptable option.

There are so many variables that influence heat transfer but among the most important are temperature differential (hot oil cools quicker in cold air than hot air), surface area (more contact between oil/aluminum/air means more heat exchange), and time (the longer fluid resides in the cooler, the more heat will dissipate before it leaves). I won't try to put words into anyone's mouth but I can only guess that the notion of passing fluid through a cooler as quick as possible has to do with maintaining the maximum temperature differential however, this is only one piece of the equation.

I have done nothing to change the flow rate of oil moving in the system, only how much time it spends in the cooler because there is more internal volume (and flow diffusers to make sure it does not simply pass straight through the center). I am curious if you monitor your steering temps with your current setup and if so, what you typically see? If you struggle with heat issues, my coolers will help over what you have now and there could also be some relatively simple changes that I can help you with to get additional gains.

To answer JBT's question, the Miller cars have all been running Howe TT pumps. I just recently stocked up on TT pumps from Lee Power Steering which are based on the same Saginaw base model. The only significant differences between the two are the cam ring material and the rear cover with high pressure o-ring seal which on the Lee pumps is threaded into the body rather than held in with a spring clip.

 

[Weasel]

I hadn't seen your cooler before, very nice I like it! Addresses alot of the things I had questions about on the other designs.

 

[JBT]

On a small radiator style cooler, yes the flow could perhaps be too restrictive for what some of these high flow steering pumps put out. But to say that all radiator style coolers in general are too restrictive is completely unsubstantiated because whether a heat exchanger is too restrictive or not depends entirely on how large the internal flow passages are. I pointed out the key word "properly" sized in my earlier post because any heat exchanger with suitable flow capacity, radiator or finned tube, could be an acceptable option.

There are so many variables that influence heat transfer but among the most important are temperature differential (hot oil cools quicker in cold air than hot air), surface area (more contact between oil/aluminum/air means more heat exchange), and time (the longer fluid resides in the cooler, the more heat will dissipate before it leaves). I won't try to put words into anyone's mouth but I can only guess that the notion of passing fluid through a cooler as quick as possible has to do with maintaining the maximum temperature differential however, this is only one piece of the equation.

I have done nothing to change the flow rate of oil moving in the system, only how much time it spends in the cooler because there is more internal volume (and flow diffusers to make sure it does not simply pass straight through the center). I am curious if you monitor your steering temps with your current setup and if so, what you typically see? If you struggle with heat issues, my coolers will help over what you have now and there could also be some relatively simple changes that I can help you with to get additional gains.

To answer JBT's question, the Miller cars have all been running Howe TT pumps. I just recently stocked up on TT pumps from Lee Power Steering which are based on the same Saginaw base model. The only significant differences between the two are the cam ring material and the rear cover with high pressure o-ring seal which on the Lee pumps is threaded into the body rather than held in with a spring clip.

What is the difference regarding internals if you compare a Howe or Lee TT pump to a Standard 143 series pump?

 

[HYDRODYNAMIC]

The surface area contact outside with the air and the surface area inside with the oil is what transfers the heat. The more surface area the better it is going to transfer the heat.
The bar and plate style has far more surface area than the machined or big round extruded tubes.
Volume alone does not mean that all the oil is in contact with the surface area effectively cooling. In a bar and plate, the oil has to flow across all the surfaces because the pass of least resistance is the same throughout the core. A core with large tubes allows the oil to flow faster through the middle of the tube or tubes and be slower along the surface due to friction. You might be thinking that all that surface area contact = restriction. Not so. A bar and plate cooler capable of removing 5-7 HP only has a 5 PSI drop at 15GPM. If you are running a regulated pump at or below 8GPM then it is somewhere around 2-3 PSI or restriction.
If the cooler inlet, outlets, manifolds, and core are sized correctly then it will flow without significant restriction to worry about. The cooler I mentioned has -16 ports on it so it will flow a full 1" ID as long as the rest of the plumbing is large enough. Some of the smaller coolers have -8 or -6 and the hoses and fittings alone will start to restrict flow.
Another important point mentioned is heat up and cool down in regards to ambient air. A passive cooler is going to be controlled by the ambient air only, so it can over or under cool. An active cooler with a fan will be off and allow the oil to heat up to ideal operating temps and then the fan will come on and cool until oil is back down to ideal temps. An electric fan with a temp switch acts a lot like a thermostat. Fluid thermostats are already being used for engines, transmissions and industrial oil coolers with mechanical fans. If you run an active cooler with a fan you can have the same benefits of a thermostat.

 

[RadialDynamics]

What is the difference regarding internals if you compare a Howe or Lee TT pump to a Standard 143 series pump?

Internally, there are modifications to the flow and pressure valving, a replacement chromoly shaft, and a few other bits and pieces replaced. However, the bulk of the effort in turning a Saginaw 143 into a TT pump (and the reason they are so expensive) is the extensive required machining and porting of the casting which was originally intended to fit within a sheet metal can like a P pump in stock form.

 

[DMANbluesfreak]

i wonder if the cold side of the radiator isn't already hanging out at 150-170 * with a ~185* engine thermostat.

it's winter, so my engine never actually warms up, but it would be interesting to check with a temp gun.

GM radiators are nice for having the extra oil coolers, but dang are they wide


edit: kind of painful to find numbers and such eastwood advertising their radiator, starting with 200* inlet temp on some small block V8, 2 minutes through their rad nets 166* outlet temp vs 188* and 181* for "oe style" rads. Same conditions, same 200* starting, ending at 190* on the hot side for 2 of the 3 tested.

No More Overheating! Tri-Flow Aluminum Radiator Drops Your Cars Temperature 24°F - Eastwood - YouTube

It very well could be below 170° on the cold side. Let's also consider that no factory OEM power steering system has a heat exchanger and they do fine in cold weather. I'm probably overthinking cold fluid being an issue on a PS system. If it's so cold that it starts to cavitate or cause flow issues in the hoses/hydro ram, it will heat up pretty quickly .

It's different in a transmission where the temperature of the fluid is critical for friction and fast actuation of operations, I would expect.

And yeah, my GM 34" radiator is MASSIVE. Fortunately, it's in a truck with a core support capable of fitting it without any modification.

 

[Provience]

It very well could be below 170° on the cold side. Let's also consider that no factory OEM power steering system has a heat exchanger and they do fine in cold weather. I'm probably overthinking cold fluid being an issue on a PS system. If it's so cold that it starts to cavitate or cause flow issues in the hoses/hydro ram, it will heat up pretty quickly .

It's different in a transmission where the temperature of the fluid is critical for friction and fast actuation of operations, I would expect.

And yeah, my GM 34" radiator is MASSIVE. Fortunately, it's in a truck with a core support capable of fitting it without any modification.

I had a ~2000 blazer for about a week and was it had the aux oil cooler and trans cooler in the rad as well, i don't remember if it was the same width and just thinner than the truck one or not, but it was pretty neat.

my donor van was a dodge 2500 that was previously a transit pig that came with a small power steering cooler. I saved that and will honestly probably run that on my setup until i can prove that i've got problems from heat

 

[HYDRODYNAMIC]

It very well could be below 170° on the cold side. Let's also consider that no factory OEM power steering system has a heat exchanger and they do fine in cold weather. I'm probably overthinking cold fluid being an issue on a PS system. If it's so cold that it starts to cavitate or cause flow issues in the hoses/hydro ram, it will heat up pretty quickly .

It's different in a transmission where the temperature of the fluid is critical for friction and fast actuation of operations, I would expect.

Most OEM steering pumps are not running on the edge of flow an gpm so they can tolerate cold oil being sluggish. Industrial hydraulic systems can have heaters to warm up the oil and thin it out to operating viscosity. Sucking oil as thick as grease or honey into a pump is going to cavitate, cause wear, and over pressurize things as it will not flow as easy as it should. Some really old worn out tractors with hydraulics will run great when its cold since it slows down all the leaks, but when its warmed up to a normal temp, everything leaks too much and its time to park it. On piston motors and pumps with rotating assemblies the case is full of oil and relies on the correct viscosity to keep leakage lubrication and case drain pressures at optimum levels as well as reduce drag on the rotating assemblies.
Yes some power steering pumps might be simple but the higher performance you go the more every aspect of proper design matters.