Pwr Strg pump output...which pump has the MOST gpm/psi?

nvrstuk · Apr 5, 2019

So has anybody researched WHICH p/s pump that we can adapt for our SBF's AND have the output and pressure to run:

- 40" tires
- Hydroboost
- Ram Assist
- little to no strg effort at idle
- quick, I mean quick steering wheel lock to lock at near idle rpm so IF you need to turn as fast as you can crank the strg wheel, the wheels WILL turn-not resist turning...I do not want to get used to slow strg!!

I've read about Saginaw's, Exploder's with mod's, other brands....BUT which one works the best?

Has anybody done or have access to actual, reliable gpm and psi numbers AT IDLE ?

I'm looking right now...if you read my other thread going right now you'll see that some things can reduce flow but I also need to fix this can't asap...

nvrstuk · Apr 5, 2019

I've read about and see that PSC modifies a GM pump that puts out ridiculous numbers stock-...like check out the pump curve from this GM pump that the company in the pic modifies to put out LESS flow and psi in an attempt to garner a few extra HP.

2.8 GPM at idle...

Look at the chart at the bottom. PSC is using these pumps ...

sykanr0ng · Apr 5, 2019

IIRC Viperwolf1 had found a pump that would bolt to the Explorer front dress and put out some really high numbers, but it was pricey, may have been made by Getrag.

Broncobowsher · Apr 5, 2019

And that can be cheated with pulley ratios as well. But you might have to worry about over-spinning the pump on the top end.

And at some point there will be a restriction that the pump can't push through. Just learned about the ported hydroboost to flow enough to keep up with high output pumps. But at what point will the spool valve in the steering box be the flow limiter?

And some comic relief regarding insane flow rates: https://what-if.xkcd.com/147/

nvrstuk · Apr 6, 2019

That's a concern that I'm very aware of as I spin at close to 6K for up to 2 minutes at a time in the winter... cavitation kills pumps...

Yeller · Apr 6, 2019

CBR pumps are what most of the u4 guys swear by. And they live at rpm and have to work at idle

Not promoting this company, but like this
https://www.pscmotorsports.com/cbr-power-steering-pump-8-out-12-in-15-0.html

Broncobowsher · Apr 6, 2019

Anyone ever do like they do with diesel C3 pumps? Run a second pump in parallel to get the flow.

nvrstuk · Apr 6, 2019

PSC is using the '99-02 GM pump from a SSR/Camaro/Trailblazer... here is some data from a GM site and these guys are trying to regulate flow for their R&P strg as too much flow is an issue for R&P... opposite of our problem

I will delete extra verbage on this quote...

Corvette-2.4/2.8 GPM 1250/1350 psi

Pontiac G8
2.0 GPM 1200-1300 psi

2009+ CTS-V from LSA motor:
2.7 GPM, 1625/1850

Next grouping is GTO/F-body depth accessories

Last is the Trucks:

All varied a little. For pretty much every 2000-2009 1500 or 2500 type truck/SUV,(Caddy, Chevy, GMC, etc), they followed this general guidelines:

4.7/s 5.3's, 6.0's:
~ 3.0-3.5+ GPM(some 2500's and later high end models like the Escalade were 3.5-3.9)
All were mostly 1425-1525 psi. The older,(2000 era) 2500 series were 1350-1450psi and the 1500's were 1450-1550.

Bottom line, most all truck PS pumps had 3,0+ GPM and ~1500 psi output.

The exception to spec range was the Trailblazer SS with of course the LS2 6.0 motor, and it was spec'd at 2.7-3.1, 1400-1500 psi. Not that far to be honest.

So in summary - car Pumps vary PSI output pretty significantly, now you can match the pump to your accessory depth and PS rack requirements. If the PSI is too high - cut coils off the relief spring.

Me again---
Kelvin at PSC told me yesterday that the SSR/Trailblazer pump is what I have...he says I got this from them a dozen years ago but the pulley was way too large a diameter... They do a couple small mod's now and it supposedly puts out - 3.1/3.5 and 1500-1600psi." No issues with it turning at 7K...

Steve- I've heard good things about the CBR pumps too...what is a stock application? Anybody know?

68ford · Apr 6, 2019

https://www.kartek.com/parts/howe-trophy-truck-power-steering-pump-1650-psi.html
My race truck has that pump. It is rated at 1650 PSI and 8 GPM. I do not think you can find higher gpm without it being really big. It's mounted to the pass side head above where an alternator would by on my 438W. My steering lock to lock is 90 degree wheel movement. Basically 9 to 3 o clock. At idle I can turn lock to lock really fast. The steering rack cylinder has a 3 or 3.5 pistion. So it is moving a lot of fluid.
https://www.kartek.com/parts/power-...ck-power-steering-pump-8-gpm-1750-psi.htmlrl]
https://www.instagram.com/p/BT0RhyelffK/?utm_source=ig_share_sheet&igshid=12darwof84aw9

nvrstuk · Apr 6, 2019

Guys on Pirate are running dual Saginaw 235 pumps to generate more gpm.

If the CBR pump can do it for U4 rigs, then it should satisfy our needs...

nvrstuk · Apr 6, 2019

3" + piston...that pump is moving some fluid... If I had a sponser maybe I could buy that pump! Ouch$$... that's out of my budget...

The important thing is bigger is t neccessarily better for this application either...

8gpm would be another huge heat generating source as the internal bypass would be wide open just recirculating fluid and developing heat...plus a limitation at some point in this system is the hydroboost I'm sure.

They seem to be a big mystery and Van at Vanco doesnt say much but charges a lot to "port" them...although I've heard several instances where porting didnt help at all but who knows what the underlying problems were/are...

Apogee · Apr 6, 2019

I haven't flow tested the various hydroboost units, however in talking with Paul at Hydratech, anything over 3.5 gpm and I think the HB will be the choke point.

I've seen some rigs with dual saggy pumps, some with front and rear steer, but it's a lot of belts and pulleys and I've seen several of those move towards standalone electric hydraulic pumps on dedicated buggy/truggy builds. Granted most of those are running full hydro-steering and BIG tires that make your 40's look like street tires. Since it seems like you do just about everything with your rig, I think I'd tweak the pump you have and see where you end up. It may not be as fast as you like, but it may be fast enough, and that would be a relatively cheap and easy first step to try.

Have you considered dropping the steering ram-assist cylinder size by 1/4" or 1/2"? You could calculate what that does with respect to steering force versus volumetric requirements...I know that most of the ram-assist rigs I've had the pleasure to drive didn't "need" as much power as they had, not that I was complaining.

SteveL · Apr 6, 2019

I just stepped down to a smaller pulley. What a difference.ps works much better at low rpm so far.ive test driven it but it's not ready to daily drive or road trip yet.

nvrstuk · Apr 6, 2019

Apogee - dropping the ram dia by a bit is a good idea...I agree that the HB will choke things off but like you said- at what gpm? Wonder if any truck HB units flow a bit more than the AstroVan or any of the others that we are trying/using??? I like the idea of reducing the ram volume also...a 1/4" might not seem like much but it could be a the difference... I'll do some volume checks after I go thru the pump and get the pulley dia that PSC recommends... thanks

SteveL- thanks for the info on the smaller dia pulley. You can feel a noticeable difference with it then? I think I'll try it since PSC literally guaranteed me it won't cavitate with the engine spinning at 6K. I will ask them to try to step the pump inlet up to a -12...pumps suck at sucking fluids!!

SteveL · Apr 6, 2019

Like I said I haven't really tested it hard yet. I have the under drive pulleys on the broncos. It was the quick solution to a 4bolt balancer on a 351 swap back when I did em. When I went hydro on the 66 I couldn't find a smaller press on pulley for the saginaw so I went with the stock Lincoln ps pulley. It drags a bit on the ps at idle. Since then I found a smaller steel pulley and had it machined for a Lincoln ps shaft and used it on the 72 swap. So far around the neighborhood the steering is noticeably better. I gotta finish up a few things before I do more driving in it and know all is good. The other option I was given was swap to a keyed shaft so I could run one of the smaller aluminum pulleys that are available

nvrstuk · Apr 6, 2019

I did some number crunching on keeping my 5 3/4" Exploder pulley and what the difference would be if I dropped down to the 4 1/2" pulley PSC now wants me to use...

If I'm idling at my same 800 rpm with a smaller 4 1/2" pulley on my pump it would be the equivalent of idling at 1022rpm now with the size of the current pulley...

SO I went out to the Bronco and cranked the strg wheel as fast as I could at 800...definitely pushing against the ram

--- but I'm surprised how much resistance it takes to turn the wheel...no pinky spinning the wheel on this...

Increased rpm to 1050 or so and I was still against the ram - but it didn't seem to be as much...

Raised the front end off the floor and did both 800 and 1050 rpm "crank the strg wheel" test...felt exactly the same. so it's not the resistance of the tires causing me to use a fair bit of effort to turn the strg wheel on a power strg system AND ram assist...

Went out to my wife's Honda CRV and cranked the wheel as fast as I could at idle...WOW, this is what I want...easy and as fast as I could turn it. Damn Japanese... lol

Went out to the barn and fired up my Duramax...almost the same as the Bronco...same stiffness to turn the wheel but I didn't feel like I was "up against" the ram at all. 800 and 1050 (appr) both felt the same.

Does the CBR pump use the same 3 bolt mounting holes as the SSR/Trailblazer/LS2 pump???

Viperwolf1 · Apr 6, 2019

You are also fighting the torsion bar in the steering box. A lighter torsion bar would open the spool with less effort. You can also get a spool with bigger holes to flow more. Typically quicker turn boxes have bigger holes in the spool. But that adds some vagueness in the feel at high speed. Kind of like driving a '60s Cadillac.

nvrstuk · Apr 6, 2019

No vaugness happening here at low speed for sure! If after I do some fitting replacement and possibly the pump...if I'm still having the same problems I'll see if there are any options of torsion bars for this box I have.

thanks Viperwolf

I think that the pump I have for the SSR/Trailblazer/Camaro is a CBR pump Steve...I will find out Monday for sure...

If it isn't, I wonder if the mounting holes are the same for the CBR? They look identical but I have appr. 1/4" above my high pressure line on my current pump...so not a lot of room if it isn't a direct bolt in...

68ford · Apr 7, 2019

I put on a PSC ported box and ram about a yr ago and mine does the. Same as what your describing. It's just plain stiffer to turn. Sometimes when trying to turn fast it feels like it can only be turned so fast. I have a steering quickener making the 3.5 or whatever box a 2 turn box so I thought I was just turning to fast. PSC told me I should use their pump. Right now I have a pump from a 2008 Duramax obviously with hydroboost. RPM makes no difference. I've been sliding around corner counter-steering back and forth at 6500 RPM and it feels the same. I'm convinced it's the box. My old stock 76-77 4 turn box was fine.

ntsqd · Apr 7, 2019

No one's talked about it, but as I mentioned in the other thread my friend Ruben has run into the ports in the box being the flow limiter for the Ram. Apparently WHERE those ports are located on the box is very important to flow to the ram.

Pwr Strg pump output...which pump has the MOST gpm/psi?

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