About a year ago, my mechanical power steering pump failed. I never really liked the power steering feel in these cars, as I consider it to be too much servo assist. So, I tried for a while to make it work without power steering. To do this, I just cross connected the hydraulic lines after removing the mechanical pump. I then reduced the wheel caster angle as much as possible to reduce the self centering force on the steering wheel (Porsche specifies ridiculous amounts of caster anyway), and put in a slight amount of toe-out, which is typically done to reduce corner entry understeer.

That worked fine for street service above about 30 mph, but in parking situations it was a work-out. Unfortunately, it was also just too much effort for autocross or even a tight road race course, so I gave up and installed this TRW Astra electric hydraulic pump. As I understand, this is the same unit that is installed on the 997 GT3. It's still too much assist for my taste, so my plan is to add on a recirculation loop to by-pass the steering rack with a manual control valve that I can tune to my taste. Anyone else tried this?

 

I set this up on a 996 GT3, Boxster should be similar/identical. The pump is used on certain Vauxhall cars in the UK (and same one used on the 997+ Cup). Cheapest way is to find one on EbayUK, they are identical to the 997 Cup car pump. I had to build my own wiring harness and have the fluid lines custom made by an industrial hose shop. It did work well though. I would recommend installing an overflow reservoir. The stock reservoir tends to overflow in hot weather as the fluid expands, there is not enough expansion space for track temperatures.

 

I'd love to see your overflow reservoir set up on this.

I have all the parts to do this job on my 986 at some point. (Thanks Duke Engineering!)

 

Pic of the overflow setup here https://www.6speedonline.com/forums/...ring-pump.html

 

In the ad: Typical gains are around 10-15hp.

Seems like a great return on investment (dollars per horse).

Can you explain from where the additional 10-15 HP is coming? Sources? Make it scientific, while keepng it layman.

Thanks.

 

I thought one of the key advantages of an electric power steering setup was to be able to alter the assistance available, or to even make it speed dependent. The idea of an EPS that allows you to have good assist below 10 mph and then phase down to no assist above that speed does sound pretty awesome.

 

I think you can adjust the assist via a change in current to the pump - which will generate heat. It's unlikely you can have a dynamic change in assist with a DIY project unless you're just using an on/off switch.

 

Perfect - thanks.

 

Main advantage is that the PS pumps in these cars tend to overheat and fail in track use. Running an underdrive pulley makes it a bit better, but does not completely fix the issue. Going to the electric pump takes the belt driven pump out of the equation.
I suppose you could see a small amount of HP gain without the pulley drag, but I honestly doubt that is very significant.

 

Didn't think so. Snake oil.