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Underdrive Power Steering Pulley

abrogate

abrogate

Red Skull Member
Joined
Nov 13, 2020
Member Number
3050
Messages
81
Loc
St Louis MO metro
I am looking for affordable solutions for low RPM, sluggish full hydro on my LS powered buggy. PSC offers a 2 piece P-pump pulley I am considering. I am curious if anyone else could share their experience with installing an underdrive pulley for full hydro.

My primary complaint with my current setup is when you try to turn under load while stopped or idling, the steering seems sluggish and bogs the motor down some. The pump can still move the tires, but the issue is noticeable.

Have you experience any side effects after swapping in an underdrive pulley? Excessive heat? High RPM consequences? Are there alternatives to the PSC pulley (I have't found one)

Any thoughts are appreciated.

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www.pscmotorsports.com

PP2444A - 6.0" TWO PIECE Power Steering Pump Pulley (Serpentine)

The Problem: You have a project with a GM LS based truck engine (5.3L, 5.7L, 6.0L, or 6.2L) and the low engine RPM power steering performance is suffering. Also, it is a time-consuming pain to install a pulley on the pump after the pump has been installed in the vehicle...there is no room to get...
www.pscmotorsports.com www.pscmotorsports.com
 
I don’t think increasing PS pump speed at idle will help you. Increasing PS pump rpm at idle will make it even easier to bog, or even stalling.

Sluggish = hard/slow steering?

The engine is cammed?
 
TrailTamer said:
I don’t think increasing PS pump speed at idle will help you. Increasing PS pump rpm at idle will make it even easier to bog, or even stalling.

Sluggish = hard/slow steering?

The engine is cammed?
Click to expand...
The engine is a 5.3 LM7 with stock internals. I would describe the symptom as hard/slow steering at idle. Really anything above idle (I don't have the exact RPM values at the moment) the steering feels fine.

The symptom going away above idle has me thinking that the underdrive pulley would help. Why do you think that a higher RPM at the pump would make it even easier to bog down? I'm not saying you are wrong, I just don't follow what you are saying.

I have also considered replacing the P-pump. I have run TC pumps previously and didn't have issues, but I went P-pump on this build because they are cheap and abundant. I may be asking too much from the P-pump.
 
I have the same slow response at idle with my TC pump just doesn't really bog it at all unless I put it full lock. I've considered a smaller pulley a few times.
 
Bebop said:
smaller pulley = overdrive, not underdrive.

abrogate : what P-Pump do you have currently on your system and what pulley diameter?
Click to expand...
This talk has me so confused.

Slowing pump RPM = less speed/pressure?

Is the engine tune the problem? Maybe wire a pressure switch in the steering line to trigger the AIC to increase engine RPM during steering (that's a wild plan)
 
He needs the power steering pump to spin faster.
This is achieved with the use of a smaller power steering pump pulley.

Making the accessory spin faster than the crank by the use of a positive pulley ratio is called overdriving.
 
Bebop said:
He needs the power steering pump to spin faster.
This is achieved with the use of a smaller power steering pump pulley.
Click to expand...
This is where you run into that problem of over speeding it on the other end of the trail though right?
Kind of have to balance this out.
 
abrogate said:
Why do you think that a higher RPM at the pump would make it even easier to bog down? I'm not saying you are wrong, I just don't follow what you are saying.
Click to expand...
The pump will take more power when running faster at idle for better power steering.

HP = PSI × GPM ÷ 1714

Flow = speed
Pressure = force

Based on the formula; the pump will demand more HP if either pressure or flow increased. Overdriving the pump certainly will increase the flow at idle.

Good pressure and too little flow = power assist steering is there but slow.

Good flow and too low pressure = good steering speed but power assist is lacking when you need it.

We with our off road rigs usually need power assist steering the most is at idle/not moving…

So, overdriving the pump may be too much for your V8 if it’s struggling at idle the way things are right now, assuming everything else is in good working order.

I hope that clear up!



I asked about whether it’s cammed as some camshafts kills engine’s idle/low end power. I think we can rule that out, assuming the tune it’s running on is good.

What about to change it’s idle from ~500 to ~800 rpm? Maybe that’ll be all it takes to get the steering you want and not to bog.
 
5.25" to 4.25" pully seems to be the size that stick in my mind as being common. Bumping up the idle a bit if possible isn't a bad idea either.
 
Is manually flipping the IAC input on a bad idea?
Electronic Fuel injected motor, use the electronic fuel injection for this purpose?
 
CarterKraft said:
Is manually flipping the IAC input on a bad idea?
Electronic Fuel injected motor, use the electronic fuel injection for this purpose?
Click to expand...
ECU gonna have a field day with you

Weasel said:
5.25" to 4.25" pully seems to be the size that stick in my mind as being common. Bumping up the idle a bit if possible isn't a bad idea either.
Click to expand...
On a 7” LS crank pulley, anything under 5.5” is asking for trouble.

@ OP I was asking what pump you have because factory units are known to be very limited and can be modified easily for more flow. OEM case is also a known flow limiter and should be replaced by a remote resi with big line (AN10 minimum).
 
CarterKraft said:
Is manually flipping the IAC input on a bad idea?
Electronic Fuel injected motor, use the electronic fuel injection for this purpose?
Click to expand...

Even if it's a stock computer I'd think you would be able to somehow trick the IAC into thinking the AC compressor is on using some kind of pressure sensor in the steering system and really doesn't seem all that hard. If OPs problem goes away a few hundred RPM over idle I'd be tempted to try that route vs swapping pumps, pulleys ect.
 
CarterKraft said:
Is manually flipping the IAC input on a bad idea?
Electronic Fuel injected motor, use the electronic fuel injection for this purpose?
Click to expand...
What about upping the idle rpm through a tuner? I never wore a tuner wizard hat & tuned an ECU before, so what’d I know.
 
TrailTamer said:
What about upping the idle rpm through a tuner? I never wore a tuner wizard hat & tuned an ECU before, so what’d I know.
Click to expand...
Something else to consider, though. Upping the idle can cause a side-step if the rig is auto trans. Good steering at idle but trading off with pushing through brake in low-low.
 
SLOWPOKE693 said:
Even if it's a stock computer I'd think you would be able to somehow trick the IAC into thinking the AC compressor is on using some kind of pressure sensor in the steering system and really doesn't seem all that hard. If OPs problem goes away a few hundred RPM over idle I'd be tempted to try that route vs swapping pumps, pulleys ect.
Click to expand...
Or you can just put a $60 pulley on and call it a day...
 
I used this smaller pulley on a LS swapped JK to clear the steering box, it also helped a bit for at idle steering

Dorman 300-202 Power Steering Pump Pulley​


 
Bebop said:
Or you can just put a $60 pulley on and call it a day...
Click to expand...
I'm just spit balling here but you are usually far more PRO electronics/tuning on these issues.

I understand if the RPM is not matched correctly a simple solution is pulley diameter but I also know first hand my dad's 5.3 swapped c10 has a pretty serious bog when the AC compressor kicks on because I have not wired in the HVAC IAC trigger.
 
CarterKraft said:
I'm just spit balling here but you are usually far more PRO electronics/tuning on these issues.

I understand if the RPM is not matched correctly a simple solution is pulley diameter but I also know first hand my dad's 5.3 swapped c10 has a pretty serious bog when the AC compressor kicks on because I have not wired in the HVAC IAC trigger.
Click to expand...
PS and AC don't really work the same way. PS is pulling load pretty much 100% of the time.
 
Lots to catch up on here! Thanks for all the insight.

My pump is a stock 2004 LM7 P-pump, the original reservoir removed and replaced with a PSC remote res can with a -10AN feed from one of the original PSC remote reservoir's with an internal filter. The flow control valve is an AFCO 37130. The current pulley is the stock LM7 P/S pulley. The buggy is at our farm and I haven't had a chance to measure it. I don't really have anything to add at the moment, but I am going to get to the shop and measure the diameter tonight.
 
Start fucking around with the valve.
PSC had different hole sizes for different flow ratings.
No idea what's in the AFCO.
IIRC the PSC high flow one was .180 but don't quote me for certain.
 
Bebop said:
Start fucking around with the valve.
PSC had different hole sizes for different flow ratings.
No idea what's in the AFCO.
IIRC the PSC high flow one was .180 but don't quote me for certain.
Click to expand...
I was browsing their site earlier and saw they offer one with a male -6 AN/JIC. I started wondering the same thing, if the AFCO is the same as the PSC option. I have been using the AFCO fitting for almost 15 years now, never occurred to me that it could be part of the problem. Maybe this weekend I could pull the fitting and measure things.
 
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