Bringing this thread back up just to add a little fun-fact about Flowkooler.
Way back when, when the company was still better known as Brassworks (they still are, but the Flowkooler pump name is more recognizable to most of us nowadays) they got their start into the high-performance water pump market (late-'70's or early-'80's maybe?) by selling either the impeller modification kit to enhance the customer's existing pump, or an off-the-shelf pump with a modified impeller thingy already installed to save you the trouble.
And all that high performance part was, was a small disc of galvanized sheet metal and some rivets!
What the installer would do would be to drill some holes through the existing impeller blades (hoping to get them centered correctly!) and rivet the disc to the backside of their existing impeller. Basically to close off the open face and close what was essentially a too-big gap between the back open face of the impeller and the engine block or timing cover.
Changed the flow pretty radically for such a simple thing. But it was a common fan blade "ducting" design brought to the automotive world.
Seems cheesy now in our high-tech world, but at the time a very simple and elegant solution to a problem.
They used that design to good effect on many pumps for awhile, but eventually went the direction we know today, which is some VERY high-tech custom proprietary impeller designs. As was mentioned earlier in the thread, those impellers look pretty impressive and give some pretty impressive results.
It's not just flow volume and pressure that are improved with the designs, but of course anti-cavitation properties at higher rpm levels, AND lowers parasitic drag and the ensuing horsepower gains. All big deals in the real world.
Even though Stewart is at the high end of water pumps and probably found more often on race cars than the street, I consider Flowkooler to simply be a less expensive alternative. But very close to, if not equal in performance to a Stewart pump.
That might vary by pump of course, as each company has different impellers for each application. But both are top notch.
The fact that some applications are not covered by Stewart then should not be a stumbling block or a source of concern if Flowkooler offers the alternative.
I've worked with both companies over the years and while you might find more Stewarts on a race car, I wouldn't even hesitate to run a Flowkooler on any of my engines.
I've been using them since the early eighties and have never been disappointed.
Anyway, just a bunch of fun FYI stuff. This thread was referenced in another thread about cooling and I wanted to relate my Flowkooler memories and experiences.
Not ashamed to say we sell them either. Those and the Edelbrock pumps have been excellent products. But the whole "home installed disc" thing makes me smile remembering those days.
Paul