Reply With Quotecry Anyone?
I just spent $1000 to have my pump freshend up and polished to get more top speed my question is, is a B impeller for higher speeds and what HP do you need to run a B? I currently get 74mph up river with a 19ft miller and a built chevy 454. I want to be in the 80's, How do I get there?
cry Anyone?
What RPMs are you turning? Engine specs?
B impeller isn't really for higher speeds. That may be achieved as the motor will turn higher RPMs which could result in higher speeds.
RPM is 5100-5200, 454 30 over with ported polished Merlin heads Elderbroch intake 750 carb. Never put on dyno but the builder estimated 500+hp with 8.5:1 compression. Also have a nitros cheater system plummed inside the intake but have never installed a bottle.
Not being a Chevy guy, I am not sure how much you can spin that motor up to.
It looks like the builder went with a B to get your RPMs up into that 5100-5200 range. With an A you be turning more like 4800-5000.
With a C, up around 5300-5500.
You basically size an impeller by the RPM range where you are making the HP.
Hope this help a little bit. I am sure more experienced folk will add/subtract to this.
The 70's is a pretty good speed for an aspired non-tunnel boat.One week end last year we took a GPS to the river and out of 14 boats only 2 ran 80 or faster !!!
Cool. another Miller, what year is it? I too have a 19ft Miller and I can almost get to 70 (68.7 mph on GPS) what pump are you running?
Hear is some thoughts.Set the pump back get a shoe and ride plate.Loose all the weight you can out of the boat.Run headers OT or TT.If all of this is allready done work on the set up.Just some thoughts.Most all V bottoms that run 80 + have built engines and setback pumps.O yea and blueprint the last 3 or 4 feet of the bottom if there is any hook in it.Jake
[ April 26, 2003, 04:13 PM: Message edited by: Jake W ]
A 1000 dollars just for a "pump Freshen up"...wow. I hope that shop bought ya lunch...J/K
For your current motor and to get to top speed (max rpm's) what ever the known HP is, then it's a matter of using the proper sized Impeller. Several Manufactures as you may know show a chart that gives such info.
I would hope that your boat has the required hardware "if needed" (Droop, Diverter, Shoe, RidePlate)...then it's a matter of setting everything up.
To shoot for just top end would hurt your hole shot and or midrange cruising speed...something to consider.
I prefer to go with the largest cut (Aggressor full A)Impeller that will alow my 21 Daytona to rev at a lowered rpm, hurt top end some, and improve my cruise speed. It's some what of a give or take situation.
Chances are that "B" cut is taking your rpm's to the max= max mph...going to a larger A/B might help MPH??? Going to a full A will cut your top end speed slightly and lower your rpm's.
The boat is a 78 miller with a berkeley pump and jetavator, yes I thought that $978.00 was alot for a freshening up and porting work but the before and after speeds confirmed that I got what I paid for and Tom Papp is the man! The best the boat even had seen on GPS with my wife and I a LARGE cooler of Sodas and 3/4 tank gas 4900rpm was 64.2 up river, two weekends ago I had 4 people in the boat same LARGE cooler and 3/4 tank and got 74.6 on the GPS at 5100-5200rpm. I dont really care about whole shots or pulling a skier I wanted to be able to cruz at 60-65mph and have a top speed of 80mph but it just doesnt look like it will happen without throwing a boat load of cash at the back of the boat.
Thanks for the info guys.
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