impellers

**boatermike** · 04-08-2009, 11:21 PM

are stainless impellers just stronger or do they also have a different profile/pitch?

**BIGA** · 04-09-2009, 09:10 AM

the stainless or bronze are simply stronger for high horsepower or extreme use. howeer aggressor jet drives makes a bronze that has a different pitch to its blades and american turbine makes a stainless, dubed a hi-helix ,that has a different pitch also.

**boatermike** · 04-09-2009, 11:25 AM

im getting some hi revs and would like to pitch up or sopmething to slow them down

**BIGA** · 04-09-2009, 03:10 PM

definitely the impellor size will limit your horsepower, there are charts that will closely predict what your rpms will/should be. are you certain of the condition of your jet as this is also a very common symptom of a worn or excessive clearance on the wear ring to impellor surface. the pump will have to be disassembled to inspect and get an accurate measurement.

**boatermike** · 04-09-2009, 03:13 PM

i have excellent hole shot and can remain on plane at very slow speeds with very low rpms a functional tach would help im guessing at rpms it sounds 4500 -5000 at wot and speed is 51

**BIGA** · 04-09-2009, 03:18 PM

what type of boat, how big how heavy. based on your estimate, something askew on the speed, in a normal jet 18-19 low profile we would see something ideally in the upper 60 mph for 5k rpm.

**boatermike** · 04-09-2009, 03:23 PM

heres a pic

**boatermike** · 04-09-2009, 03:26 PM

i put a pic of my pump in the other post compairing ir to one i found. its the "pump i found" one. i think i have a jb pump. no diverter

**boatermike** · 04-09-2009, 03:28 PM

is there such a thing? on the berkley site there is zero on a b pump

**BIGA** · 04-09-2009, 03:52 PM

most all of the full size berkeley pumps were a 12-j something and then a dash and the impellor size. i recall a jb, jc, jg the most desirable and a je and jf were insert type pumps. the letter after the j denotes mostly the type of bowl and steering. the pump internals are highly interchangeable as most all the parts are the same.

**boatermike** · 04-09-2009, 04:02 PM

decided i might look at the tag again and was suprised what it says

a2 impeller is what that means?

does seriel number help id these things its all still readable

**BIGA** · 04-10-2009, 09:32 AM

the a2 denotes a larger impellor usually great for take off and economical crusing usually not the best for top end with a stock engine. easy to cut down in size, you can always make them smaller i kid that its a lot harder to make them bigger.

**boatermike** · 04-10-2009, 10:07 AM

so i have a larger impellor designed for hole shot not top end and im going 50 mph, does this indicate its good or bad in your opinion?

**BIGA** · 04-10-2009, 10:14 AM

depends what you want to do with the boat. i like the larger for more economial crusing but they are generally a killer on top end. old jet boat "blueprint" trick cut the impeller down a size boat will run 5 to 10 mph faster. rebuilder a hero. customer can do the same for a very few bucks. remember that you are direct dr. and there is no magic bullet, what you pick up in upper rpm you will have across the band. ie if you can turn your engine 500 rpm more after the cut you will turn it 500 more to attain 30-40 mph crusing.