a2 impeller in 20.5 carrera ????

[sac carrera]

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?

[Squirtin Thunder]

I have always like the big impellers. You may want to get a loader as well. I have seen loaders drop 100rpm and more while picking up your speed.

[flat broke]

Have you checked the clearances on your current impeller? If the tolerances are sloppy, you'll defintely notice a hit to your cruise economy. If your side and front clearances check out, then you may want to consider the impeller swap. But be forewarned that you might drop some top speed along with the reduction in RPM depending on the engine's powerband.
Chris

[Outlaw]

My last boat a 21' open bow Outlaw (same bottom as a carrera)
when I bought it had a B and ran well, wouldnt hardly pull a skier.
then changed to an A lost like 2 mph but was alot better cruise and
pulling skiers.
Then changed to an AA stainless lost another 2 mph but made the boat
so much better, lowered the cruise RPM's , pulled like a mule from the start.
it was worth losing a few MPH IMO.

[Cruiser 509]

This is my first post so be gentle. I also have a 202XR. I am running about 500 hp (509 CI Clay Smith cam, heads 850 double pumper). With an A the combo turned 5200 at 62MPH (speedo). With a AA it turned 5000 at about the same speed. I added a loader grate and picked up 2-3 MPH.
Depending on how the boat is loaded the top speed can vary as much 2-6MPH. Cruising speed is much better. In the 3700 to 4000 range I will cruise at at a little better than 1 MPH per 100 RPM loaded with family.
I recently took the boat out alone, both tanks full and at 3800-4000 RPM was cruising 48-50MPH. But even bettter than that, it used a little less than 10 gallons per hour. That was the best ever as far as fuel consumption stock or modified motor.
The hole shot is so much better that, it will take a little time to get used to pulling skiers. Another thing you will notice is that putting it on the trailer requires a little more concentration as the boat speed at idle is much faster.
I bought my AA from Tom at Jet Boat Performance. A great guy to work with he even gave me his cell # to call him at the lake if I had any questions on a Saturday.
I would say that my experience with the AA, it probably makes sense to do it with the 202XR, as it is a heavy boat. These were casual observations with seat of the pants as the only data acquisition system.

[sac carrera]

thanks for the advise guys. I think an a2 impeller is the right choice for me.

[Outlaw]

Welcome Cruiser 509,
great first post.

[SmokinLowriderSS]

Yes, an AA impeller is probably a good size for your boat, just watch out for the RPM loss, which can be substantial depending on the motor's powerband.
Of course, RPM regained is just HP away. :idea:
$$$$$ :jawdrop: :jawdrop:

[CPBRIAN10THMTN]

Definetly watch the rpm loss, could be enough to bog you down, really depends on torque, how much you got. Use as much of your "powerband" as possible. Make sure you get the most out of your motor.

[Legal Chemistry]

I've been told that an AA will drop me down about 200 rpm (guessing same as your setup), that might put you below your peak hp? I'm surprised that the last 800rpm nets you 20mph -but I don't claim to know the dynamics of how the jet loads/etc. Can anyone chime in on this? Are you looking to gain a few mph at say 4k with the larger impeller to cruise faster at a lower rpm? Maybe the AA will do that, but there may be another option: Do you and a place diverter? Maybe you're still plowing at that speed and can pick it up with some trim adjustment to air it out better? There are some very knowledgeable people on this board that can probably put you in the right direction.
Just for reference... I have a stock MP 454 (390 hp) that spins an "A" 4800-4900rpm at WOT (low 50's). The pump was thoroughly gone through so it should be as tight as the girl on your senior prom . At 4200rpm I am at 42mph GPS which is a comfortable, yet slow, cruising speed (only the primaries are open.) BTW, my boat is a very heavy 24' and will easily pull a 200 pound skier with the "A". I'll agree about 5mph zones, they kill me!
Anyone have experience placing a loader on a large heavy jet such as mine? If it could show gains across the board that may be a wise investment this winter.....
Thanks