CBR Steering Pumps - OEM Applications?

[Provience]

RED

I fully agree that running the higher displacement is what gives acceptable low RPM flow. I wasn't trying to say that running something that will make 18 GPM is bad, but running 18 GPM through a steering valve intended for ~6 GPM isn't likely good. Finding a flow chart for the valve would be handy and easier than installing a pressure gauge and monitoring all the forces through various flow rates yourself.

as for the priority valve adding more or less pressure than running 3x flow through a steering valve, this is from the parker catalogue for their FP series Pressure Compensated Priority Flow Control Valve. Note that the bypass pressure is near to slightly below the priority flow pressure, but generally over 1500 psi which is above "typical" steering pressure. the big question would be: does the extra pressure on the bypass circuit (load) exceed the excess pressure generated by flowing 10-18 gpm through the steering valve?

 

[HYDRODYNAMIC]

I fully agree that running the higher displacement is what gives acceptable low RPM flow. I wasn't trying to say that running something that will make 18 GPM is bad, but running 18 GPM through a steering valve intended for ~6 GPM isn't likely good. Finding a flow chart for the valve would be handy and easier than installing a pressure gauge and monitoring all the forces through various flow rates yourself.

as for the priority valve adding more or less pressure than running 3x flow through a steering valve, this is from the parker catalogue for their FP series Pressure Compensated Priority Flow Control Valve. Note that the bypass pressure is near to slightly below the priority flow pressure, but generally over 1500 psi which is above "typical" steering pressure. the big question would be: does the extra pressure on the bypass circuit (load) exceed the excess pressure generated by flowing 10-18 gpm through the steering valve?

I go back to the point that plenty of racers and non racers are running the high flow CBR race pumps through the PSC//Eaton orbital without issues. Others are running Sweet servo valves with manual gear boxes and racks with high flow. Before spending money on a flow control and hoses and fittings to reduce heat get a good cooler and get ride of it.

 

[AgitatedPancake]

So on the WJ fan, you guys are correct it is electronically regulated via a solenoid that installs from the right hand side, and slides a valve left and right just above the hydraulic ports. The finer details of operation are beyond me, so it looks like you guys are further along in comprehension than I have got so far.

Hydro that's great info all around. On the topic of flow control, at least for hydro assist with a servo valve my experience has made me believe that you do want to limit the volume available to the box at higher RPMs and flow volume instead of giving it the uncapped potential of the pump (but my feelings on the matter are still somewhat fluid). When I started this thread I had two glaring issues that I remedied last night, that seem to have improved everything so far. First, I had the flow control fitting drilled out huge similar to the diameter used with the hydro fan in factory form. This was so big, there had to be almost zero pressure drop across the valve, so I don't know at what point it was ever opening to bypass flow. Wherever that point was, it was far more flow than people commonly run on these things. The second issue was using the small return line on the reservoir instead of the lower larger one facing the inlet. You mention the idea of supercharging the suction side of the pump, that's essentially what the lower fitting does from the factory, so minimal restriction. But as far as the flow control valve goes, I think that was the cause of the screaming pump at higher RPMs. I'm almost wondering if the only internal bypassing in the pump was the tiny pressure relief valve itself instead of the flow control, because the flow control valve was allowing far more volume than the box could handle, and the box restriction was actually creating enough restriction to build enough backpressure in the pressure line to open the relief. Either way though, the main point I wanted to bring up, was how incredibly sensitive the steering was at high RPM on the freeway, even with 7* caster. I'm talking one pinky on the steering wheel, lane change in an instant. The amount of flow I was getting was desensitizing the steering (even through the torsion bar in the steering box) to a very extreme level that made high speed highway driving uncomfortable. So last night I put a flow control valve in with a smaller more standard orofice along with swapping the return line to the lower "supercharged" return port, and the initial testing seems to be showing a quiet pump, and much more comfortably controlled steering at higher RPM.

So what I'm now curious about is stepping to a smaller pulley to gain volume and steering speed at idle, but play with the flow control orofice diameter further to keep the steering feel and sensitivity manageable at higher speeds.

 

[Provience]

I go back to the point that plenty of racers and non racers are running the high flow CBR race pumps through the PSC//Eaton orbital without issues. Others are running Sweet servo valves with manual gear boxes and racks with high flow. Before spending money on a flow control and hoses and fittings to reduce heat get a good cooler and get ride of it.

absolutely there are plenty of folks doing it and it works just fine.

pll_1585.pdf (eaton.com)

here is the eaton catalogue, this is the neutral pressure drop for their series 5 steering valve, which is probably a fairly common unit and we can go ahead and call the 5 gpm "typical". it ramps up pretty decently and the high side of the scale is even just 6 gpm, if we assume a linear (obviously it isn't) increase, then going from 6 gpm to 12gpm would take us from 125 to 250, going to 18 gpm would give us 375 psi, basically at a minimum. Even with a pressure compensated flow control adding some pressure to the system, there is no way it is taking on that much extra if sized for full flow. Limiting the steering valve to the 6 gpm that you are most happy with, or even 5 if that works for you, would also limit that neutral pressure to under 100 psi.....Granted! 300 psi at 18 gpm gives you a "max" savings of about 3 horsepower so it isn't like it is some hard to ignore loss or anything like that.

 

[Provience]

So on the WJ fan, you guys are correct it is electronically regulated via a solenoid that installs from the right hand side, and slides a valve left and right just above the hydraulic ports. The finer details of operation are beyond me, so it looks like you guys are further along in comprehension than I have got so far.

Hydro that's great info all around. On the topic of flow control, at least for hydro assist with a servo valve my experience has made me believe that you do want to limit the volume available to the box at higher RPMs and flow volume instead of giving it the uncapped potential of the pump (but my feelings on the matter are still somewhat fluid). When I started this thread I had two glaring issues that I remedied last night, that seem to have improved everything so far. First, I had the flow control fitting drilled out huge similar to the diameter used with the hydro fan in factory form. This was so big, there had to be almost zero pressure drop across the valve, so I don't know at what point it was ever opening to bypass flow. Wherever that point was, it was far more flow than people commonly run on these things. The second issue was using the small return line on the reservoir instead of the lower larger one facing the inlet. You mention the idea of supercharging the suction side of the pump, that's essentially what the lower fitting does from the factory, so minimal restriction. But as far as the flow control valve goes, I think that was the cause of the screaming pump at higher RPMs. I'm almost wondering if the only internal bypassing in the pump was the tiny pressure relief valve itself instead of the flow control, because the flow control valve was allowing far more volume than the box could handle, and the box restriction was actually creating enough restriction to build enough backpressure in the pressure line to open the relief. Either way though, the main point I wanted to bring up, was how incredibly sensitive the steering was at high RPM on the freeway, even with 7* caster. I'm talking one pinky on the steering wheel, lane change in an instant. The amount of flow I was getting was desensitizing the steering (even through the torsion bar in the steering box) to a very extreme level that made high speed highway driving uncomfortable. So last night I put a flow control valve in with a smaller more standard orofice along with swapping the return line to the lower "supercharged" return port, and the initial testing seems to be showing a quiet pump, and much more comfortably controlled steering at higher RPM.

So what I'm now curious about is stepping to a smaller pulley to gain volume and steering speed at idle, but play with the flow control orofice diameter further to keep the steering feel and sensitivity manageable at higher speeds.

all of that makes me think that the hydraulic fan valve was doing more of the work of regulating flow to the steering, even if the steering is priority and the fan is secondary. Note the Massive return line from the hydraulic fan clutch versus the standard return line from the steering box in factory form. If you were using just the small return line in the reservoir, that is likely 100% where your noise was coming from. More volume and use the big return line and you should be just dandy with that pump.

any chance you know or can measure with a shotglass what the Cubic Inch Displacement is on that pump? i can't find fawkall for it "online"

 

[AgitatedPancake]

all of that makes me think that the hydraulic fan valve was doing more of the work of regulating flow to the steering, even if the steering is priority and the fan is secondary. Note the Massive return line from the hydraulic fan clutch versus the standard return line from the steering box in factory form. If you were using just the small return line in the reservoir, that is likely 100% where your noise was coming from. More volume and use the big return line and you should be just dandy with that pump.

any chance you know or can measure with a shotglass what the Cubic Inch Displacement is on that pump? i can't find fawkall for it "online"

I've still got one torn apart on the bench, but don't have a great way to accurately measure fluid volumes very finely. I can give ya some dimensions though. I swear i stumbled upon someone describing the different displacement rings and such, but can't find it for the life of me now. I recall that discussion identifying them by the stampings on the outer rings, which is where I got the "double diamond" I referenced a ways back in this conversation. Let me try to hunt that reference down again as well

 

[AgitatedPancake]

The cam ring has a ~2.10" OD, .70 thickness, and the center hub that holds the vanes is appx 1.422", all are within a couple thou of true. Which looks to be the same dimensions as the cam pack Patooyee measured inside of his stock non-hydro fan TC pump 9 years ago over in the other place. Granted this is a reman so it can't be fully trusted, but this is starting to seem like a standard 1 size fits all for all TC pumps

 

[HYDRODYNAMIC]

absolutely there are plenty of folks doing it and it works just fine.

here is the eaton catalogue, this is the neutral pressure drop for their series 5 steering valve, which is probably a fairly common unit and we can go ahead and call the 5 gpm "typical".

The PSC valves are the Series10, which range from 3-20 GPM. The range that most everyone is using is rated nominal at 8 GPM. They do not have a chart to show pressure drop on open center, alot of other useless charts but not the one that would be helpful. Since the same housing is going up to 16-20 gpm I would assume that the lower range can flow at higher levels, it probably comes down to feel of the valve and sensitivity.

 

[Provience]

The PSC valves are the Series10, which range from 3-20 GPM. The range that most everyone is using is rated nominal at 8 GPM. They do not have a chart to show pressure drop on open center, alot of other useless charts but not the one that would be helpful. Since the same housing is going up to 16-20 gpm I would assume that the lower range can flow at higher levels, it probably comes down to feel of the valve and sensitivity.

i guess if PSC is using such an oversized valve, that is probably why. kind of curious because, outside of their full race pump, everything else is realistically internally limited from 3-6 gpm. guess that is their answer to dealing with stacking due to excess flow.

any chance you or somebody you know runs a gauge on their hydraulic system?

I have measured neutral load pressure at idle on an Ultra4 car with the un-regulated trophy truck pump at around 300 PSI.

took me a while to find, but here is a quote from a while back talking with RadialDynamics . apparently we didn't get into what neutral pressure they were running off-idle as that would be the area that flow regulation would make a difference

 

[HYDRODYNAMIC]

i guess if PSC is using such an oversized valve, that is probably why. kind of curious because, outside of their full race pump, everything else is realistically internally limited from 3-6 gpm. guess that is their answer to dealing with stacking due to excess flow.

any chance you or somebody you know runs a gauge on their hydraulic system?




took me a while to find, but here is a quote from a while back talking with RadialDynamics . apparently we didn't get into what neutral pressure they were running off-idle as that would be the area that flow regulation would make a difference

I had a pressure gauge on my old buggy. When it was testing the 1.2CI/Rev pump at 4000 rpm at 20GPM through the D03 valve and then through the orbital it was at 500psi of restriction. I then dropped down to the 1.0CI/Rev pump and the D05 valve and upsized the lines to 1/2". That dropped it down under 250 psi from best I can remember.
300psi at idle sounds really bad?
EDIT: I am having doubts on what the pressures were, this was my best guess from the notes I had.

 

[Fwjeep]

Tc pumps are offers in a few different displacements, .22 .44 .66cu in per rev come to mind. The wj’s had the largest.
Typically stock pumps are advertised at 1500 PUMP rpm, max tc I find to be 3.5gpm, cb pump 4.23 if I remember right. That compares with a old P-pump at 4.5 max?
After 1500, stock pumps are already bypassing back to the intake

 

[Provience]

alright, this is going to be horribly off topic and i apologize for that i just ended up reading a bunch of stuff and don't want to forget it all and haven't brought over my other hydraulic repository yet



Power Steering Secrets - GM (hotrod.com)

I like this article, it is about track cars and they generally want to go the other way i.e. low flow. Select quotes in case the internet wonks out in the future

All power steering pumps generate volume and pressure, but according to Roethlisberger, the older Saginaw pumps push especially large volumes—20 gallons per minute (gpm) at 5,000-rpm shaft speed. Unfortunately, much of this volume is internally bypassed inside the power steering pump, requiring more horsepower and in turn converting that excess work into heat absorbed by the fluid. The late-model Type II power steering pump generally moves around 15 gpm, which translates to less heat.

This would put the "early" saginaw pumps about 0.92 Cu In Disp and the "later" type II pumps around 0.69 Cu In Disp.

Combining a high-flow Saginaw pump with a typical production-car rack, such as from a Mustang II, creates this hyper-sensitive situation. Turn One offers a quick cure: a fitting that replaces the stock piece in a Saginaw pump that reduces the flow by more than 50 percent from 3.4 gpm to 1.5. Turn One also offers similar valves for Type II pumps to optimize flow volume in various production or aftermarket racks.

they are talking about the same twitchy/high flow stuff. if the saginaw pump referenced is a 3.4 gpm unit and 0.92 CID, then it is rated at 850 shaft RPM, if it is the 0.69 CID, then it is rated at 1,100 shaft RPM

Their solution? toss in a different regulating valve to decrease the flow. easy peasy.



Modifying your Power Steering Pump - GM Truck Central

this is a pretty good write-up on modifying the regulating valves for saginaw pumps. It has a section about "modify low RPM flow" which is a misnomer. it is modifying at what point the valve will limit flow and bypass (internally) the excess.

The fitting orifice controls the volume/speed that the pump can use to restore operating pressure (flow piston controlled). The larger the hole the more fluid the pump is able to use to respond the power steering pumps use of pressure.
...

I have had the best results when drilling the fitting to 5/32. This seems to be a good spot for responsiveness without over-doing it. I may go larger at a later date but right now I’m content with 5/32 opening.
The 3500 hydro-boost power steering pumps have a 5/32.
The 1500 Pumps I have worked on have 1/8 had a much smaller orifice.

drilling down the center of the valve. where are those 5/32 and 1/8 orifice sizes coming from? magic, mostly

Flow Through Orifices - Womack Machine Supply Company

flow through an orifice

we already "know" that GM saginaw pumps are rated to flow basically a max of 3.5 gpm, so if we assume that the 5/32" orifice on the 0.92 CID is giving us that, then that valve is using around 50 psi as the pressure differential to regulate.

if we wanted more flow from that same valve, drilling to 1/4" would get us closer to a "cutoff neutral flow" of a little under 10 G.P.M.

If we wanted 10 GPM, we would need 2,500 shaft RPM with 0.92 or 3,300 rpm from the 0.69. How much do you want to "overdrive" your pump to get that at idle? probably not that much

If we said we wanted 5 GPM to be the cutoff, then going to a ~3/16" orifice would probably work out. then we would only need shaft RPM of 1,250 (0.92) or 1,660 (0.69) and those would be a bit more manageable. getting a pulley diameter that is ~1/3 smaller for the pump vs the crank would net 7500 rpm shaft speed at 5000 rpm engine speed, and i'm not sure how well the pump would like that.

if we say we want to keep our pump at 6000 rpm if the engine is at 5000 rpm (ignoring the short bursts that would be above that) we get a 0.83 pulley ratio. ~750 rpm engine idle nets 900 rpm shaft speed, nets 3.6 gpm (0.92) and 2.7 gpm (0.69) so then steering would feel a bit slower until we hit ~1050 engine RPM for the 0.92 or ~1375 engine RPM for the 0.69


all of that to get back around to this:

AgitatedPancake

First, I had the flow control fitting drilled out huge similar to the diameter used with the hydro fan in factory form. This was so big, there had to be almost zero pressure drop across the valve, so I don't know at what point it was ever opening to bypass flow. Wherever that point was, it was far more flow than people commonly run on these things

any idea what those diameters where that you drilled it out to and what you replaced it with?

But as far as the flow control valve goes, I think that was the cause of the screaming pump at higher RPMs. I'm almost wondering if the only internal bypassing in the pump was the tiny pressure relief valve itself instead of the flow control, because the flow control valve was allowing far more volume than the box could handle, and the box restriction was actually creating enough restriction to build enough backpressure in the pressure line to open the relief. Either way though, the main point I wanted to bring up, was how incredibly sensitive the steering was at high RPM on the freeway,

i think you've got that a touch backwards, the scream being caused by the small return line and the flow control being the cause for the sensitive steering.

The internal relief pressure is whatever it happens to be and is (likely) your only system relief pressure. you are unlikely to have been causing ~1200psi (or whatever it is set at) just from excess flow in neutral through the steering servo.


edit: regarding the stock pressure limit, according to the chevy power link above

Spacing	PSI	Notes
Tall housing w/shim	900~1000 PSI	stock
2 shims	1050~1100 PSI	stock
1 shim or Loc-tite	1100~1200 PSI	stock
Flushed end cap	1350~1400 PSI	stock
+ 1 #4 machine washer	~1400+	Requires limiting stud modification
+ 2 #4 machine washers	undocumented	Requires limiting stud modification

the shorter the valve, the higher the relief pressure. The lower the relief pressure, that "safer" your system is, but also the less work it will do. Does this matter? depends, if you want to be able to push the car sideways up against a rock wall, you need higher working (system) pressure. If you don't care about that and you don't want to worry about destroying a pump or fitting, run a lower pressure

 

[Provience]

I had a pressure gauge on my old buggy. When it was testing the 1.4CI/Rev pump at 4000 rpm at 25GPM through the D03 valve and then through the orbital it was at 500psi of restriction. I then dropped down to the 1.0CI/Rev pump and the D05 valve and upsized the lines to 1/2". That dropped it down under 150 psi from best I can remember.
300psi at idle sounds really bad?

thanks for the info! I know we've talked about it before but, well, i'm old and my mind is slow

300 sounds bad to me as well, but again, this is KOH racer stuff, so in general, those guys don't care about too much border line efficiency when they can patch stuff with more radiators and half of them are already making way more horsepower than they need.

i'll have to go back and looksee what my well overly complex setup "maths out" to

 

[Provience]

Tc pumps are offers in a few different displacements, .22 .44 .66cu in per rev come to mind. The wj’s had the largest.
Typically stock pumps are advertised at 1500 PUMP rpm, max tc I find to be 3.5gpm, cb pump 4.23 if I remember right. That compares with a old P-pump at 4.5 max?
After 1500, stock pumps are already bypassing back to the intake

dope

yeah they should be "rated" at whatever their limit is set to, so if they are bypassing at rated RPM, then that makes sense. 1500 rpm @ 3.5 gpm would be a 0.53 CID. i'd be more comfortable running a smaller pump at a higher RPM for no real reason, guess the hard part is figuring what the displacement is of any given junkyard pump, then finding a pulley to run it fast enough to matter, then drilling it out enough to get what you want from it.

^which is why i'm comfortable spending a couple hundred bucks to buy one from a known MFG, like radial-dynamics

 

[HYDRODYNAMIC]

thanks for the info! I know we've talked about it before but, well, i'm old and my mind is slow

300 sounds bad to me as well, but again, this is KOH racer stuff, so in general, those guys don't care about too much border line efficiency when they can patch stuff with more radiators and half of them are already making way more horsepower than they need.

i'll have to go back and looksee what my well overly complex setup "maths out" to

I edited my original post => I had a pressure gauge on my old buggy. When it was testing the 1.2CI/Rev pump at 4000 rpm at 20GPM through the D03 valve and then through the orbital it was at 500psi of restriction. I then dropped down to the 1.0CI/Rev pump and the D05 valve and upsized the lines to 1/2". That dropped it down under 250 psi from best I can remember.
300psi at idle sounds really bad?
EDIT: I am having doubts on what the pressures were, this was my best guess from the notes I had.

 

[Provience]

I had a pressure gauge on my old buggy. When it was testing the 1.2CI/Rev pump at 4000 rpm at 20GPM through the D03 valve and then through the orbital it was at 500psi of restriction. I then dropped down to the 1.0CI/Rev pump and the D05 valve and upsized the lines to 1/2". That dropped it down under 250 psi from best I can remember.
300psi at idle sounds really bad?
EDIT: I am having doubts on what the pressures were, this was my best guess from the notes I had.

just ran some super rough math numbers. Based on using 7 bar resting load sense valve for steering, 4 bar resting load sense valve for brake boost, standard dual control valve for winch, filter, cooler and magic zero loss lines, i'll be at min. 255 neutral pressure at 6 gpm (i've given up on 1 pump to rule them all, and a full time 6gpm regulated pump will get me everything i want in life with a PTO pump for fun on the side)

so maybe 300 resting isn't so bad, but it does sound bad for "just" running steering

 

[Fwjeep]

dope

yeah they should be "rated" at whatever their limit is set to, so if they are bypassing at rated RPM, then that makes sense. 1500 rpm @ 3.5 gpm would be a 0.23 CID. i'd be more comfortable running a smaller pump at a higher RPM for no real reason, guess the hard part is figuring what the displacement is of any given junkyard pump, then finding a pulley to run it fast enough to matter, then drilling it out enough to get what you want from it.

^which is why i'm comfortable spending a couple hundred bucks to buy one from a known MFG, like radial-dynamics

(3.5x231)/1500 is .53 cu in, or did I do that wrong

 

[Provience]

(3.5x231)/1500 is .53 cu in, or did I do that wrong

you are correct, i am wrong

i was doing all the rest of the math with .0023 gallons and converted that part wrong

edited my above post

 

[AgitatedPancake]

I just measured the drilled out fitting because I couldn't remember, 5/16" bahaha. Which puts the 50psi pressure differential around 18gpm. Yeah... That would be around what, the 6,000ish pump rpm at .69 cu/in just glancing at your numbers? Hahaha. So yeah my 2,500 rpm whine was coming in around 8-9GPM. Where you note my thought process was backwards, I was just thinking about how much the stock steering box can flow, and how high the backpressure could potentially get when it's getting double (or more) the flow it's rated for. Then the thought was could it be enough restriction through the pressure line to open the pressure relief valve when the flow valve wasn't bypassing. But realistically as I learn more and more, as you said it's probably due to the way in which the reservoir was being replenished versus the new "supercharged" return location

 

[Provience]

so it was basically unregulated then (still with making a bunch of assumptions about sizes and such...flow meters and pressure gauges are neat, but rare), going to the 5/32 means that whatever level it hits now, it will at least bypass internally and keep from trying to starve itself and running such a high return flow rate.

so if you decide to drill it out any further, add more fluid and use bigger return lines give that poor pump a chance at life

 

[RadialDynamics]

Lots of good tech today (yesterday now for me), I'm finally getting a few minutes to catch up and jot down some thoughts. First of all, Provience, going way back to one of my earliest conversations! I do recall measuring 300 PSI neutral load pressure on that system although thinking back, it is more likely that this was high RPM neutral load rather than at idle. Unfortunately I can't say with certainty at the moment (although I do have the equipment to recreate this). This measurement came from Josh Blyler's Ultra4 car on the weekend that I first fell into all of this by accident in 2017. That system had some major flaws to begin with and my understanding of these systems (and subsequently, his steering system arrangement) has improved by leaps and bounds since that first encounter.

The "trophy truck" pumps are 1.23 in3/rev displacement so the non-flow regulated version being used at the time would theoretically have followed a very similar flow curve to the 1.2 in3 gear pump Hydro used. I have found, though, that when it comes to non-flow regulated pumps, whether the CBR XR race pump, the billet Howe race pump, or most any industrial pump (gear or vane type, doesn't matter), you will eventually reach a flow limit and that limit will be dependent on the rest of the system outside of the pump. At 4000 RPM, I can all but guarantee that 20 GPM was not the actual flow rate.

Hydro, kudos to you for the amount of engineering that you have put into this. I have come across very, very few people who have run the numbers as in depth as you and I fully agree with almost all of your points. Seeing some of the flow numbers that get thrown around without merit, yes, is terribly frustrating. For this reason I always try to be explicit when referring to the specs on my pumps as "max regulated (discharge) flow rate" and "pressure relief", not "pressure regulation". Of course, as you note, this does not tell the whole story (displacement). Displacement is a critical aspect in pump selection and there are some applications that will straight up need larger displacement just because of the steering demand that needs to be met at idle or low RPM.

Your points about heat, filtration, hose sizing, and most importantly, reservoir design all affect pump performance and longevity, typically more so than the selection of the pump itself. I could sell the greatest pump the world has ever seen but without the system to support it, it will be garbage.

In my opinion, the reservoir is THE MOST important component in the system and the most overlooked. In fact, if it weren't for the reservoir development that I obsessed over when first getting involved with Big B Motorsports, Radial Dynamics would not exist today. I felt so strongly about the influence that this has over steering performance that I decided to start a steering company to expand on it and although I am still in my relative infancy, the results so far have spoken for themselves.

Most people don't realize that oil consumes 1 HP to move 1 GPM at 1500 PSI. Convert that energy to heat through a pressure relief valve and you can quickly end up with a good sized shop heater IN your steering system. I will go internal or external pressure relief depending on the application. For the most demanding applications, I will recommend an external relief valve for the reason you stated, to get heat away from the pump. However, not everybody has room for additional valves and in probably the majority of cases, good system design can allow for use of an internal relief valve just fine.

The point that I will respectfully disagree with you on, however, is flow regulation. Your argument against internal flow regulation is to get solids contamination, air, and heat out of the pump rather than recirculating through the vane pack. The downside to using a non-regulated pump is that now your flow rate is variable with engine speed (to the extent of finding the system limit as mentioned earlier). For some, that's manageable, especially if somebody's engine speeds (or driving habits) only cover a limited operating range. But when racers need to be able to cut the wheel as hard at idle (coming hot into a corner and letting off throttle) as they do at redline of 6500 or even 8000 RPM, the displacement needed to cover the steering demands at low RPM would require designing an absurdly large system to support the flow at high RPM, not to mention the change in steering feel due to such an increase.

To me, the benefit of maintaining constant steering feel and being able to use a larger displacement pump without having to drastically oversize the system is a tremendous value. I am less concerned about contamination and heat recirculating within the pump just due to flow control valving considering that when bypass is occurring, in most cases at least 50% or more of the pump volume is getting refreshed with every revolution and the moment that you let off the throttle, you are back to 100% of the pump volume (theoretically) being refreshed each revolution. If there is a good filter installed, it will catch any solids before they exponentially increase wear in the pump. If the reservoir separates and removes air, that too will get pulled out of the system.

With proper system design, the benefits of a larger displacement flow-regulated pump far outweigh the challenges of using a non-regulated pump and as an example I will go back to Josh Blyler, 2020 KOH king. When I started getting involved with Big B, they were going through a pump per race (for a multitude of reasons). Since implementing my suggested changes and switching to my reservoir, filter, and coolers, they now only swap out their flow-regulated TT pumps once per year out of precaution.

I will always say that steering is not one size fits all. The best choices for pump selection, valving types (or lack thereof), overall system layout, it all varies by vehicle build, intended use, physical constraints, and of course, budget. The other great thing about hydraulics is that there are always multiple ways to achieve a performance goal. Very rarely will I say that something is flat out right or wrong. Rather, successful steering design is a balancing act of a series of tradeoffs to end up with something that reliably delivers steering performance you are satisfied with.

 

[AgitatedPancake]

so it was basically unregulated then (still with making a bunch of assumptions about sizes and such...flow meters and pressure gauges are neat, but rare), going to the 5/32 means that whatever level it hits now, it will at least bypass internally and keep from trying to starve itself and running such a high return flow rate.

so if you decide to drill it out any further, add more fluid and use bigger return lines give that poor pump a chance at life

Haha definitely looking into a larger cooler with less restriction all throughout the return system, along with a larger res as future improvements, especially once a smaller pulley goes on and it starts generating some extra heat.

I was thinking about that orofice size-restriction chart some more, and is there a standard assumption for the depth of the orofice in examples like that? Like is that pressure for an orofice that's only 1/8" in length? As that restriction gets longer and longer (such as a long hose), the backpressure (and in turn, pressure differential) increases right? The bottlenecked portion of the pressure relief fittings is somewhere around 3/4" long (super coarse estimate, tape measured), which probably means notably different actual numbers than we were throwing around depending on how those numbers are standardized.


Radial, yet another awesome response. Thanks again to everyone bringing the knowledge into this thread for guys like me to sponge up, this has been fantastic. A topic that has been brought up by you guys a few times which I'm very curious about yet 100% inexperienced - filtration. It absolutely makes sense and I've seen the particulate in toasted pumps before. As that builds up, the fluid becomes more abrasive and your components eat themselves up from the inside out, makes sense. So what do you look for when it comes to hydraulic filtration? I feel like I've seen some spin on filter setups, like what's offered by, PSC iirc? what do you look for when choosing a filter? I assume it's max flow volume, micron size, and maybe pressure drop?

Just in some quick searching for references I found this PSC:

And this Trail Gear:

 

[AgitatedPancake]

Looking around, I do find some generic low pressure spin on hydraulic filters such as this parker that's rated for 20gpm with a 10 micron filter and 15psi bypass, that seems like it's in the ballpark to my completely inexperienced eye?

https://www.grainger.com/product/PAR...n-Filter-4Z618

 

[HYDRODYNAMIC]

The point that I will respectfully disagree with you on, however, is flow regulation. Your argument against internal flow regulation is to get solids contamination, air, and heat out of the pump rather than recirculating through the vane pack. The downside to using a non-regulated pump is that now your flow rate is variable with engine speed (to the extent of finding the system limit as mentioned earlier). For some, that's manageable, especially if somebody's engine speeds (or driving habits) only cover a limited operating range. But when racers need to be able to cut the wheel as hard at idle (coming hot into a corner and letting off throttle) as they do at redline of 6500 or even 8000 RPM, the displacement needed to cover the steering demands at low RPM would require designing an absurdly large system to support the flow at high RPM, not to mention the change in steering feel due to such an increase.

To me, the benefit of maintaining constant steering feel and being able to use a larger displacement pump without having to drastically oversize the system is a tremendous value. I am less concerned about contamination and heat recirculating within the pump just due to flow control valving considering that when bypass is occurring, in most cases at least 50% or more of the pump volume is getting refreshed with every revolution and the moment that you let off the throttle, you are back to 100% of the pump volume (theoretically) being refreshed each revolution. If there is a good filter installed, it will catch any solids before they exponentially increase wear in the pump. If the reservoir separates and removes air, that too will get pulled out of the system.
.

I had an professor tell me that one can not agree or disagree over something until the topic is defined. So to further define:

Flow regulation creates a more linear output which can help the feel of the wheel.
Flow regulation does not free up horsepower and heat unless there is a highly restrictive valve that is being bypassed and it only saves when the restrictive valve is not being used.
Flow regulation outside of the pump body with bypass flow going through a filter, cooler, and de-aerating does not create the wear and shorter service life compared to an inside the body bypass.

That being said I have no intentions of running an internal bypass or relief valve. I am going to run both externally.

 

[HYDRODYNAMIC]

So what do you look for when it comes to hydraulic filtration? I feel like I've seen some spin on filter setups, like what's offered by, PSC iirc? what do you look for when choosing a filter? I assume it's max flow volume, micron size, and maybe pressure drop?

Just in some quick searching for references I found this PSC:

The XR race reservoir is really well engineered when it comes to fluid dynamics.
The suction is -12 and the dual returns are -8. The suction can pull from the filter or oil supply equally. The filter is being feed from the return flow so the filter is flowing right back into the suction, this term can be called supercharging where the oil does not need to go back to a reservoir to stir up air and get pulled into the suction during agitated reservoir conditions like sideways or zero gravity whoops. The oil in the reservoir does not see use once the system is full and all the air is purged to the high point, if you have a single ended rod then you will need some reservoir oil for volume changes and the oil will cycle in and out.
The return ports enter into a tangential area so any entrapped air is forced out under centrifugal force into larger bubbles and can work its way up into the top of the reservoir where it can say out of the working oil.
The filter is a common Napa spin on filter with high capacity and precise filtration media. I believe it is 8-10 micron. With the bottom down design during filter changes the contaminated oil can can only drip down and not into the reservoir.
Having the reservoir and filter in one housing saves weight and space. The PSC one is about as light as it gets, even the big chunk of billet is hollowed out for fittings and return paths.
The reservoir top has a recessed o-ring for a liquid tight seal and a anodized cap with top port to run excess air out of a breather during thermal expansion. To get the full benefit from the reservoir in its ability to keep air separated from the oil. An additional external catch can or overfill tank can be used so that the main reservoir is 100% full and expanding oil out into the catch can or overfill tank similar to a radiator. If you want to get fancy look into spherical aviation hydraulic tanks which pull from the center of the sphere so the air is always away from the pickup tube. Keep in mind the PSC reservoir is already not mixing air and oil and if the reservoir is on its side the pick up tube is at the center bottom which is below the oil so no air can be picked up. So the only direction you can not run it is upside down unless you keep it 100% full with an overfill tank, then you can run it upside down until your motor blows up.

 

[Provience]

Haha definitely looking into a larger cooler with less restriction all throughout the return system, along with a larger res as future improvements, especially once a smaller pulley goes on and it starts generating some extra heat.

I was thinking about that orofice size-restriction chart some more, and is there a standard assumption for the depth of the orofice in examples like that? Like is that pressure for an orofice that's only 1/8" in length? As that restriction gets longer and longer (such as a long hose), the backpressure (and in turn, pressure differential) increases right? The bottlenecked portion of the pressure relief fittings is somewhere around 3/4" long (super coarse estimate, tape measured), which probably means notably different actual numbers than we were throwing around depending on how those numbers are standardized.


...

- filtration. It absolutely makes sense and I've seen the particulate in toasted pumps before. As that builds up, the fluid becomes more abrasive and your components eat themselves up from the inside out, makes sense. So what do you look for when it comes to hydraulic filtration? I feel like I've seen some spin on filter setups, like what's offered by, PSC iirc? what do you look for when choosing a filter? I assume it's max flow volume, micron size, and maybe pressure drop?

Just in some quick searching for references I found this PSC:

that orifice chart is based on a thickness of zero. like everything i've been able to find on hydraulics, there is a ton of really technical and specific math and then basically everything should get a +/-20% next to the answer, because it is all assumptions and realty will be a bit different and without gauges on the actual system in use, it's just a best guess

hoses have issues with friction and velocity, and turns and fittings and such. There's a handy pocket chart for guestimating that stuff as well

basically, estimate your flow rate, draw a line from the GPM to the "velocity" and pick the high and the low for use, i.e. pressure/return/suction and that will get you a range for your dash size. then you will see what actually fits, probably not going to put a -16 hose into a pump body with a -8 fitting for example. and heck, odds are good you won't fit a -16 anywhere under the hood. For the lengths that automotive sees, the pressure drop through the hose is negligible and if you are getting too much neutral pressure for what "feels" correct, the first thing to look into would be the fittings that you use. straight and smooth is ideal.

general takeaway: Pressure lines are less sensitive to diameter, return lines should be larger up to about double the pressure lines, suction lines as big as you can fit

i just web shopped the trail-gear filter setup, it is basically the same price High Flow Remote Oil Filter – Radial Dynamics (radial-dynamics.com) except the RD filter has added cooling fins on it while the TG has a reservoir integrated. I'd wager your money on you not needing a larger cooler than what you've got (without knowing what you've got) if you add a filter housing and significantly increase the size of your fluid reserve.

it's one thing to be starting from scratch vs building with what you've already got. going the cheapo cast filter housing is probably just fine, but toss in the cost of a larger cooler as well and the desire for it to not crack and fail in service and it isn't as cheap as it seems up front.

 

[Sterlingfire]

i like this little tidbit right here. Calls out the actual standard. Pretty cool

.
Beware of manufacturers claiming a "nominal micron rating" when in fact, there is no industry accepted definition for "nominal". Filter effectiveness can be described by efficiency at capturing particles of a certain size, or Beta Ratio, which is determined in accordance with ISO 16889 international standard.

 

[HYDRODYNAMIC]

Here is my plan to externally regulate and pressure relieve the CBR XR race pump.
The Hydraforce FR12-33 has an inlet up to 30GPM and can flow up to 18 out the primary port and the rest bypasses to tank. The primary 18GPM can be turned down to 8 which I am guessing is a comfortable flow rate based on Eatons rating of 8GPM. The remainder of the flow will bypass to tank, which will vary based on pump rpm.
The RV10-26 is a pilot operated relief valve rated up to 30GPM
I am putting the RV10-26 in a cross port housing for plumbing purposes. The other housing port will have a FC10-20 which is being used as a plug. I already had it so that's why it is getting used. A check valve could also be used or a different housing.
The regulated bypass, relief, and return from the orbital will all go to the cooler and filter before returning.

 

[RadialDynamics]

i like this little tidbit right here. Calls out the actual standard. Pretty cool

That's just the standard for defining a filter's beta ratio using a multi-pass test with a special dust slurry. The recommended filtration requirements for hydraulic equipment are defined in ISO 4406 and if you look up fixed gear or vane pumps (pretty much anything we would use), the recommended filter media should be Beta1000 efficiency of 22 microns. Beta1000 means that if there are 1000 particles of a certain size upstream of the filter, only one makes it through downstream (99.9% filtration efficiency). Nominal filter ratings don't hold any value, similar to the issue "this is a 20 gallon per minute pump" and the question is at what RPM, the claim "this is a 10 micron filter" begs the question, at what beta ratio?

I stock two particular Donaldson spin on filters for different sized steering systems. My smaller one is rated for 7-9 GPM so I use it on flow regulated systems up to 6 GPM. The other size I keep is rated to 25 GPM and I use this one on any "TT" pump systems as well as any non-flow regulated systems which will (assuming the system is designed properly) experience higher flow rates up into the teens.

Even though filter manufacturers offer cross-part lookup lists, not all filters are the same. I will take the smaller one as an example, Donaldson P551324: 50% efficiency (Beta2) is 1 micron, meaning if there are 1000 particles of 1 micron size upstream of the filter, 500 will pass through. This filter has a 99.9% efficiency (Beta1000) of 23 microns. If there are 1000 particles of 23 microns upstream of the filter, only 1 will pass through. This is pretty darn close to ISO recommendations for fluid cleanliness.

Now take that part number to WIX and use their cross-reference list. The equivalent WIX filter, 57282, is advertised as having a "nominal 10 micron" rating but if you look closer at the specs, the Beta2 rating is 10 microns. They don't list Beta1000 but they do list Beta75 (98.7% efficiency) as 27 microns. These filters are not quite equivalent are they?

 

[RadialDynamics]

I had an professor tell me that one can not agree or disagree over something until the topic is defined. So to further define:

Flow regulation creates a more linear output which can help the feel of the wheel.
Flow regulation does not free up horsepower and heat unless there is a highly restrictive valve that is being bypassed and it only saves when the restrictive valve is not being used.
Flow regulation outside of the pump body with bypass flow going through a filter, cooler, and de-aerating does not create the wear and shorter service life compared to an inside the body bypass.

That being said I have no intentions of running an internal bypass or relief valve. I am going to run both externally.

Sounds like a good professor. I hear what you are saying and it's not without some truth but based on flow measurements that I have performed on both gear and vane style non-regulated pumps, I typically see volumetric efficiency (actual vs. theoretical flow) drop significantly above 3000 RPM. Good hose sizing and reservoir design help maintain better efficiency into higher RPM's but regardless, the drop is inevitable due to internal leakage in the pump and cavitation. With internally flow regulated pumps, the benefit I have found is that the forced recirculation helps get fluid back into those vane cavities at high RPM which is more helpful than harmful overall. This doesn't mean that you can't use or be happy with a non-flow regulated or externally flow regulated pump, this is just my take on the subject.

I also have my opinions on the combo filter/reservoirs and will just say that they are the reason I focused on developing a better reservoir. As noted above, fluid passes through the filter element on bottom then takes a sharp 90 degree turn and straight back out to the pump. There are two problems with this. First is that you might have a quart of fluid sitting in the upper reservoir canister that isn't doing a thing to help absorb and dissipate energy from the pump. Fluid capacity in the system is critical but it only helps if it's circulating. If your system has a total of 4 quarts and 1 quart of it is sitting stagnant in the upper canister, then you can theoretically pick up a 33% increase in effective capacity just by bringing the fluid that you already have into circulation.

The second issue is that if you do have air in the system, the fluid velocity through that outlet port is so high that air will not naturally evacuate up into the top of the reservoir, it will keep passing right out to the pump. It takes about 2 minutes for air to naturally work its way out of fluid. With a high flow pump, the recirculation time through the system might be less than 10 seconds which is why forced de-aeration is so important. Even once the system is bled, hydraulic fluids can contain up to 10% by volume dissolved air and just a minor pressure drop (like inside of a pump body at high RPM) will cause air to be drawn out of solution and entrained.

What I have found to be the most successful arrangement is my patent pending Vortex Reservoir, which separates and removes air, paired with a remote filter. Especially when it comes to systems with external pressure relief valves, I found that almost every other externally relieved system plumbed the relief valve exhaust port straight back to the reservoir, bypassing any cooler. This is why I initially started using remote filters because the two inlets were a way to bring the relief oil and main system return oil back together that could then be plumbing through a cooler.

In fact, my filter/relief valve combo originally came about to address this specifically for a fleet of monster trucks that were experiencing steering issues in part (again, one of many reasons) because their relief valve was mounted directly on one of two return ports to their reservoir design and was causing aeration issues when it opened. With this unit, high pressure is plumbed through the relief valve tee and when the system experiences relief pressure, that relieved oil is dumped straight into the filter. Main system flow returns to a separate low pressure inlet then the combined flow stream can be passed through a cooler before returning to the reservoir.