Cast Iron KRC PS Pump

[fretless]

I am looking to possibly upgrade to power steering. I noticed that the KRC cast iron pumps are much cheaper than the aluminum ones and only about 2-3 lbs more weight.

Any reason not to use one?

With the "replacement" valve concept, it looks like you would not need a Heidts type valve for adjustment.

Thanks.

[Don Payne]

If you plan to autocross, you should get the large pulley. Otherwise the cast iron pump with the 4.2" pulley is fine. That is what it came down to when I spoke with them on the phone a year ago when I had trouble getting the aluminum pump. Basically the cast iron pump cannot handle the high speed. KRC did say that it should be fine for short periods of time at high speed but could eventually fail if spun too fast for a long period of time.


Pump Speed Calculation:
To calculate pump RPM use the following formula.
Divide the crank pulley diameter (cp) by the power steering pump pulley diameter (psp), then multiply that answer by maximum engine RPM.
Ex. 4.5"cp ÷ 6.0"psp = 0.75 x 7,200 = 5,400 RPM Pump Speed

I ended up picking up the cast iron version with a reducer valve and could not be happier.
KRC 50020100

[fretless]

Don,

Thanks for the info!

Which valve did you go with? Also, what rack do you have?

Thanks again.

[Don Payne]

I believe it was the ID:4, it was the least flowing valve. For the aluminum pump it gave 1.05 GPM, but the cast iron pump only makes like 1.5 GPM with it. KRC changed their site around and it seems harder to find info now.

ALUMINUM FLOW VALVE -6 MALE ID:4

[Cobra 302]

I am also looking at this pump.

But I have a 6" CP and with a 4.2" pump pully I am at 8857RPMs with the motor turning 6200RPM's. Way above5500 RPM's limits for the steel pump.


Alum is 9000 rpm's limit.

So with the motor spinning at 6200RPM the pump would be at 8857RPMS.
This combiniation would work for my application. Be carefull if autocross you can reach high rpms.....

[Bob Cowan]

Ill probably be purchasing a KRC pump in the next week or two. I'v looked at both of them pretty closely. The Alum is said have better flow, and you can get different pressure ratings.

The big thing is RPM's. The alum pump can handle 9,000 rpm's, and the cast iron around 5,800. Depending on the pulleys you're using, you can easily exceed 5,800.

For a street car, I think the cast iron pump will work well and last about forever - as long as you don't spin it to fast.

[edhunter]

I've run the cast pump on my AI racecar the last two years... I use the largest pulley (v-belt) available and a small cooler on the return line. So far so good. I would have bought the aluminum one if I'd have known the difference at the time, but they're not interchangable.. The ports are in different locations, so if you have custom lines for the cast pump they wont fit the aluminum pump - at least not in my case.

[fretless]

Thanks everyone for the replies.

I have a 4.5" crank pulley. I am looking at the cast iron pump with the 6" serpentine pulley. This will give me 4650 rpms on the pump (4.5/6*6200) with a 6200 rpm engine speed (my max).

The only thing bothering me at this point is the location of the outlet - bottom of the pump for the cast iron vs top of pump for the aluminum one. With a $375 diff in price, I hope it won't cause a hose to be in the way of other stuff.

[Don Payne]

Just use a 90deg fitting and port it out toward the steering shaft. This way you won't get in the way of the pulley. I routed mine under the steering shaft then up and over to come together with the return line. Then routed them both over to the rack. You can imagine it with this image. I don't have photo of my setup handy right now.

[emac]

FWIW, I did a lot of reading on adding PS over the last several weeks. I spoke with AGR, KRC, Jones racing and pm'd several people on the board. Lots of folks on the board have been very happy with the AGR rack that is "tuned" for our cars. So, once I decided to go with the AGR rack, I built the system around the rack. A few people had leaking AGR racks after installing. AGR admitted to me that they had a learning curve on developing the rack, and have made changes. He was very concerned about running over 1000 psi pressure pumps in his racks. I think he was suggesting leaking racks were possibly due to over pressured pumps. AGR also sells pumps to work with their racks. My thought was, if I have a leaky rack and he has told me about the pump issue, will he stand behind his rack? That wasnt worth the risk.

So, I ended up going with AGR rack and pump. I think the pumps look suspisciously very similar. Chris Jones of Jones racing coordinated my pulley, mounting bracket and belt setup. He is sending it all to Larry at AGR to be put together and I am paying AGR for the whole thing. They seem to work well together. Jones racing makes a nice aluminum resovoir for those that need the bling. I passed due to cost and the possibility of the AL heating up being adjacent to the headers. Chris was able to design a pulley system that allowed me to keep my water pump and not have to go with a reverse rotation pump. That is worth a couple of hours of work and a gallon or so of over priced antifreeze. He had me email pictures, take measurements and we discussed my engine specs. All I am going to need is hydraulic lines.

It has all been ordered and should be here in a week or so. I will post some follow up thoughts after it all arrives and is up and running.

I just cant say enough about this site and the people on it.

ernest