06-12-2013, 07:41 AM #1
Purpose and necessity of fins in the jet pump support?
I just bought a 2006 Challenger 180 CS, but I believe that it shares a lot (if not all) of the pump parts with RXP... so hopefully someone can help here.
We took off the pump because I was only getting 35mph and the boat is supposed to do 48 or so. I thought the impeller was going to be chewed up because the boat was cavitating out of the hole, but surprisingly the impeller and wear ring looked pretty good. We put in a Solas Concord 14/19 and new wear ring (and neoprene seal).... but noticed that the "pump support" had black stubby plastic nobs around the outer rim.
I looked it up on a parts website and it appears that the pump support had plastic fins pointing out toward the middle. I'm guessing that the previous owner sucked up something into the impeller, which then spun around and knocked off all of those plastic fins.
I am now getting 42 mph with 1 rider and a full tank, but I feel that the boat should still be doing more.
Is that part worth replacing for over $300 just to get those fins back? Would it be difficult to remove the old one, since it is stuck on with "Loctite instant gasket"?
I can't see the fins making such a huge impact on the pump efficiency that the lack of them would rob the boat of 6-7 mph... but maybe it is possible? I don't know what else could be hurting the performance that badly.
I attached a drawing to try and explain what I am talking about, and a printscreen of the part from the website.
We also changed the oil, put in new plugs, and removed the stock airbox.
I would appreciate any help!
06-12-2013, 08:09 AM #2
Those "Shark Teeth" as we call them need to either all be there,or all be gone....Shave them down flush with the pump shoe and you will be fine...the only way these shark teeth hurt performance is when they are broken into different sizes,then they cause the ski/boat to cavitate....There is no need to spend 300.00 for a new one...like i said shave them down flush and you will have no issues...NOW as far as the speed of your boat being down???well you might need to look in other areas...What RPMS are the motor pulling??How is the props condition???wear ring???plugs???Scer slip and condition??? all these can be a facter when a ski/boat has a speed issue....but as far as your sharks teeth killing your speed???not likely..
06-12-2013, 08:13 AM #3
The wear ring is brand new, and so is the Concord 14/19 impeller. The bearings looked good.
The motor is pulling about 7800 RPMs, and I believe it should be a little higher? It was the same before and after I switched impellers... the new pitch impeller didn't seem to affect RPMs much, if at all.
I am new to supercharged engines so I'm not sure about the slip of the supercharger. I will do some searching on how to check this out. But the boat has under 50 hours on it, and the supercharger washers were upgraded to the steel ones in 2011 (the previous owner gave me his shop receipt for the work).
06-12-2013, 08:15 AM #4
To add one thing about the RPMs.... it seems that the boat will do 8000 RPM upon acceleration out of the hole, but then when it reached max speed, the RPMs hold steady around 7800
06-12-2013, 08:16 AM #5
if shes only pulling 7800 you may need to have the prop pitched/tweeked for 8100...this will also help in hole shot and top end...
06-12-2013, 08:59 AM #6
Sounds like the SC will need the slip tightened up some, and then maybe a prop tweek, if still low. Make sure the oil level is between the 2 bends on the stick also, as that would drop a few rpms too.
06-12-2013, 11:17 AM #7
I don't know if it makes a difference or not, but I thought I should add.... the previous owner had bottom paint put on the boat (which rubs off a little when you touch it). I don't know if that could be causing more friction as well to hurt the speed
I will look into the SC slip too
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