Okay, I've read all the hype about the Johnson CM30 pump, I have read the output rate is 6.9 GPM and it is more dependable. Does anyone know what the GPM output of the OEM pump is? The main reason I'm wanting to know is I have the front bumper off my car at the moment so I can get to the pump real easy. I have had no problems with the OEM pump and the car has less than 3K mile's on it so I kind of hate to blow the $$ on one of the Johnson pumps if it doesn't improve the performance and just be more reliable. I tried to get on the LEADING EDGE page because I had see a thread saying they were selling them, but their site no workie.

 

Its letmotorsports.com , and it works. And honestly I wouldn't buy it unless mine failed, or I was planning to install the larger heat exchanger also (which I plan to do eventually).

 

I was on a thread last night and that's what I was clicking on, "letmotorsports.com", the page would open and let me choose a vehicle for a search, but that's all it would do. I'm relocating my OEM heat exchanger 1&1/4 inches forward to add two 330 cfm cooling fans on the back side and while I'm in there I'm going to add a temperature gauge to the system. While I got the whole front end off the car I was considering replacing the pump if the OEM one had inadequate for a car running a Renntech kit. I'm going to make a thread with pic's of what I was doing as soon as I can get my wife to load the pic's off the camara, (she don't like me messing with her camara or I'd do it myself).

 

Some people are running the Renntech and equivalent (ASP pulley/tune) without doing this mod and they seem to be running fine without it. I plan on upgrading the pump and HE once I do step up to a bigger pulley tho. I'll probably be going with the ASP pulley and Inmotion tune (basically the same performance for half the $ of Renntech).

 

Steve, the OEM pump is the Johnson CMP7-1 and was licensed / sold to MB for use in this and some other SC applications... Here are the specs... Compare them... The differences are inlet / outlet sizes, CFM and voltage...

 

Oh, and the price if you purchased a replacement from MB or Johnson...

 

Thanks HDDP, if I ever replace the OEM pump, it will be with the Johnson pump. I was just wondering if the OEM pump was inadequate for the job and was considering replacing it while I've got my cars front bumper cover off. It's real easy to get to right now, but it don't look like it would be that hard to get to later since I've had no problems with the OEM pump.

 

So, the way I'm reading the chart you posted, the OEM pump is 4 GPM and the Johnson CM30 is a 6.9 GPM. Now the big question is, will pumping an extra 2.9 GPM thru the S/C system help in performance. I would hope that the MB engineer's knew what they were doing when they went with the 4 GPM pump on the car. But the car is no longer stock with the bigger pulley. I know there is a point to where you can pump the coolant to fast and not have time for the radiator/heat exchanger to cool it. I found this out first hand with my old Mustang when I put 3:55 gears in the rearend and had to change them back out for some 3:25's to get the RPM's back down at highway speeds (wasn't able to slow down the water pump with pulley's). I know there are a lot of people running the CM30 with no problems, but did they check the difference's in temps before and after changing pumps? You probably have some first hand knowledge of this, so what's your opinion here on this HDDP?
Thanks, Steve

 

According to everything I have read the OEM pump is a Bosch unit not a Johnson marine pump. Also the OEM pump is the same one used in the Ford Lightning.

 

Since I still have the front bumper cover off my car I just went out to see what it said on it. I seen Bosch stamped into the impeller housing, other than that the bracket just has some numbers. I think I'm just leave the stock pump on for now, I believe the slower pump may work better with the fans that I'm installing on the heat exchanger. I'm still waiting on the fans and tempeture gauge to be delievered that ordered 1/14/08, I've got the remote relay & wiring for the fans installed yesterday.

 

Look at the MFG code on the pump. It is made by Johnson... EDIT... Licensed by Bosch, Sold to MB