johnsson f6B-9 pump question?
 

Have read many here uses this crank mount pump, and would like to here some feedback how much hp this supports, and what rpm you twist your engines whit this pump? i know johnsson rates this for max 5000rpm.


https://cimg0.ibsrv.net/gimg/www.off...20d4348bd9.jpg

I ran them for quite a few years on 600 HP N/A engines w/closed cooling, so they were for raw water exhaust and heat exchanger only. I would run up to about 5300 rpm for no more than 2 or 3 minutes at a time, but no real issues other than they built a TON of pressure at those RPMs which could also be related to speed and force feeding the system through the pickup at the same time.

They are completely rebuildable, much easier to service than the MERC/merc style pumps. If you have the room in front of the engines, I personally would use them any day over Merc style suff.

I have them and have put over a hundred hours on them without an issue. I accidentally ran them dry a couple times, too, and they still worked perfectly (I changed one out just to be safe… nothing wrong with it though so kept as a spare).

600 HP/NA. I’ve run 5100 or so for a few miles at a time and they stayed cool - 150/160 degrees. This is with closed cooling using a stock Merc big block heat exchanger, engines only, on my 311.

I dislike the Merc pumps so much that I might do the same conversion on the supercharged engines in my Cig Bullet (better room in the Cig’s bilge though so maybe not).

I have them now and no issues just 1 less belt to worry about.

Thanks alot! Now i have no doubts 👍