if the a2 is only a 200 rpm drop over an a impeller that sounds fine. my main goal is to speed up a bit at idle speed and cruise at 40 mph efficiently.
Id check the clearances out on the pump like Chris mentioned above. I've got a tight A in my 21 and idle speed is fine. If after checking it is found to be fine then make the switch. A new wear ring is a pretty simple install and is a lot cheaper than a new impeller.
I have had 4 jet boats over the years. I have always ran an a impeller with all my boats. perfofmance was very good on an 18 footer, I now have a carrera 202xr 390 hp 454 and american turbin pump and {a} impeller. my top speed is 57 mph at 4800 rpm. I am ok with my top speed ( its a big boat) but I feel im at too high of an rpm crusing . 3500 rpm is 30 mph 4000 rpm is 37 mph. also when i go through a no wake zone im at 1700 rpm just to move up a slight current. my friends io can go through a no wake at 1000 rpm. would an a2 impeller be good for my application?
I'm seeing 55 with the 330 horse 454 and a B impeller in my 20.5 elite... when's the last time that pump was rebuilt? if it's been awhile you'll lose a few hundred RPM if it was loose before the rebuild. I've always cuised just before the secondaries kick in at around 4000 RPM
I can't imagine an AA in my boat... i think i'd be a huge mistake. my $.02
Id check the clearances out on the pump like Chris mentioned above. I've got a tight A in my 21 and idle speed is fine. If after checking it is found to be fine then make the switch. A new wear ring is a pretty simple install and is a lot cheaper than a new impeller.
totally agree. Sounds like you have something more going on in that pump, there is no way to say that an a2 impeller will drop every motor by 200 rpm, not every motor is the same just like not every boat is the same. What rpm will that motor make power up to? How much torque does the motor make?Start cheap and make sure the pump is in good order, then move on to an impeller change. At least pull off the bowl and look at the impeller that is on there if you haven't already, maybe its chewed up? You need to see what you are working with.
I have an 18.5 foot Nordic Bubble running a Berk with a Dominator Impeller (B-cut) and UWR. Running a 454, roller cam, Brodix BB-2's, 7AL, Pro-form 850..etc. It will pull skiiers arms right off if I wanted to even pull skiers. I am turning 5950 RPM's with GPS 73MPH right now(fully loaded fuel and people). I know the A's have more bite, but for a (B) not to pull a skiier out of the water confuses me unless the 20.5 ft boats are really heavy. I feel my holeshot is pretty good. Again I am talking a Dominator Impeller here and I think they are a little different than a berk B-cut impeller. Sorry I do not mean to highjack. Is the Dominator (B) close to the Berkeley's (A) impeller ?
T.J.
TJ-Im not certain about the dominators B versus the Berk A, although it sounds familiar. The 21's are considerably heavier though, lots more freeboard than an 18 too which translates to more draft and thus more boat to get out of the water.
its dead in here :skull:
I'm pretty familiar with the 202 xr, 20.5 elite, same hull. Normally 330 hp, 454 at 4400 rpm will give you 52 to 54 mph. With a 390 hp you are in the nominal range. Going to an AA is not a normal change for this hull. 1700 rpm is not out of range for no wake zone, (under 10 mph). Bring the boat up to plane. drop your RPM slowly until it drops off plane. Should be between 1800 to 1900 RPM. If so, do yourself a favor and save money. You are not out of range in RPM or speed. The boat weighs 2400 lb. Don't compare other's 18 ft. with your Carrera. You've got a great riding boat in most types of water adjust to it.
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