Question on rack and pinion with LS1, hydroboost.

Anyone using an LS1 with the F body pump with power steering and hydroboost?

I'm setting up with a GM hydroboost, with a LS1 motor. I've seen mention of some of the problems using the F body pump with the power rack. As the pressure is lower with the F body pump (1100-1200 PSI) vs (16000- 1800 PSI), I wouldn't see that as a problem with the rack, except requiring more manual input. It the problem with the higher flow (3 GPM)? What can be done to correct this, rather than purchasing another pump from Turn 1?

Really don't want to change the pressure of the pump, as I understand it works well with the hydroboost.

Failing that, how well does the manual rack work with an LS1 installed? Killer when parallel parking?

Manual rack is a work out.......
Get the hydro boost off of the 2004 Mustang, Master cylinder has metric fittings and works well with the Porsche brakes. Just use the factory Gm pump, the turn one pumps are noisy and I haven't seen any real improvement over the Gm stock pump.

If i remember correctly, you can modify the stock PS pump to output the higher PSI, I think it has to do with shimming the high side of the pump.

I have the LS1, Turn 1 and Hydroboost. I wanted to go with a PS that was set up for the PSI I needed. Everything works great together.

I am not sure what the effect of running the PS at lower pressure would be? I'll let the experts chime in.

I have the Turn 1 pump and I'm happy with it. It's not noisy, but it took a long time for the rack to bleed. I had to continually add fluid for a bit and while I was doing that it was noisy. Now that the level has stabilized it's quiet.

The Mustang hydroboost works really well on the street, but you need to use an adjustable brake proportioning valve with it if you track the car. Otherwise it sends too much brake pressure to the rear brakes and things get interesting very quickly!

Admin wrote: Just use the factory Gm pump, the turn one pumps are noisy and I haven't seen any real improvement over the Gm stock pump.

How long have you run the GM PS pump, so I have an idea of longevity? No modification for the higher flow rate?

I'll probably stick with the GM hydroboost, I already have it mounted (inverted) and the pushrod matched for length.

Vorsche944 wrote: If i remember correctly, you can modify the stock PS pump to output the higher PSI, I think it has to do with shimming the high side of the pump.

I am familiar with the modification for pressure, the inverse was done to run the lower pressure Mustang II power racks. Will probably just run the GM pressure so as not to upset the hydroboost.

docwyte wrote:I have the Turn 1 pump and I'm happy with it.

Do you know what they actually did to the Turn 1 pump?

Also your tip on rear proportioning is a good one.

Nope, just that he does something with the pressure to match what the 944 rack wants. I know it's not a "regular" Turn 1 pump.

Admin wrote:Manual rack is a work out.......
Get the hydro boost off of the 2004 Mustang, Master cylinder has metric fittings and works well with the Porsche brakes. Just use the factory Gm pump, the turn one pumps are noisy and I haven't seen any real improvement over the Gm stock pump.

I hate to disagree with you because i know you've done a lot of these cars, but my experience with the factory GM pump is that you'll boil your steering fluid in no time on any kind of road/autocross course. I even put a big cooler on it. The pressure/flow just doesn't work well with the Porsche rack for anything more than putting around town.

+1 vote for TurnOne.

Tony G had the same issue with boiling the power steering fluid on track with the stock pump.

The later Firebirds utilized a water cooler for the power steering lines just for the overheating problem that has been described here. Apparently with the wider tires when autocrossed they would overheat the fluid.

My thinking is that the problem is when autocrossed, the forces are greater on the rack, forcing the fluid on occasion to blow over the relief valve. This could generate quite a bit of heat. In normal circumstances the pump only produces enough pressure to make the rack move, where the rack itself is the relief.

Has anyone used the water cooled power steering cooler? Of all things, it is plumbed to the outlet port of the LS1 cooling fluid, which is essentially the hotest water. Could it not be plumbed to the inlet port instead for greater cooling?

Still curious what Turn 1 does to the pump, just bump up the relief pressure to make it less likely to blow over?

Here is a picture of the Firebird cooler on the LS1 outlet hose.

Turn One simply revalves the pump to correct the pressure. There was a "do it yourself" post somewhere on the old board. I spoke with someone at Turn One about this about a year ago. When asked how they determined what the correct configuration was, they said that they did not calculate it but that it was supplied by someone doing a conversion. So i dont know if that was RH or an individual.

I believe they change the pressure and the flow. I couldn't tell you what they set it at.

I was messing with it for a while (and i wrote a DIY on it), but i gave up. I got the pressure wrong and sheared the input shaft off in the power steering pump. At that point it was either $90 for a crappy rebuild or $300 for a brand new GM pump with the right pressure/flow and a nice billet pulley. I haven't looked back since!

It isn't a question of cooling the fluid with the stock pump, it's that the fluid circulates so much that it quickly overheats (and possibly at the wrong pressure). I have a decent-size trans cooler on there and it hardly slowed it down--i was boiling over after one short autocross run. (Edit: using Mobil1 Synthetic ATF, too)

I ran for 1 continuous hour on a high speed 15 turn track last week with the factory F-body power steering pump and stock 944 turbo rack. No issues with boil-over. Steering felt great. It was 85-90F at the track

And he has hydro boost too!

Admin wrote:And he has hydro boost too!

Which of the above are you speaking of that also has hydroboost?