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View Full Version : pre loader on a 21 ft tunnel?


wenkel
05-12-2005, 05:31 PM
I have a 21 ft tunnel, I was thinking of putting a pre loader on it.
572 big block currently spinning a "aa" impeller 5500 rpm's, will I lose any rpm's with a pre loader? I know it will improve holeshot but will it hurt top end?
Duane HTP
05-12-2005, 05:43 PM
will I lose any rpm's with a pre loader?
Not if your pump is loading properly now. If you do, you were not loading the pump.
will it hurt top end?
Almost the same answer. If it pulls the rpm down a little and slows the boat any. You were not properly loading the pump to start with. Trimming the impeller to regain your rpm and sometimes putting a little larger nozzle works to correct the top end deal.
MAXIMUS
05-13-2005, 06:00 AM
I don't think a preimpellor is worth the money or effort if you are running a AA . Those tend to benefit a little more on the smaller impellor set ups... I have run my A impellor both ways & don't really see any changes... at least none that would justify the extra dollars...
Duane HTP
05-13-2005, 07:42 PM
Maximius, If you have the HP to really spin an AA impeller in a larger boat,such as the 21, the AA will use up the water in the throat of the pump very quickly and then spin it because the heaver boat is not yet moving fast enough to replenish the supply. The inducer made a big difference in my twenty three ft tunnel boat with the blown 588 cid Chevy in it now. When it had a motor of about only 600 HP, it didn't make that much difference. I think they are well worth the money, if you are having any cavitation problem at all. Just MY opinion.
MAXIMUS
05-16-2005, 06:56 AM
Maximius, If you have the HP to really spin an AA impeller in a larger boat,such as the 21, the AA will use up the water in the throat of the pump very quickly and then spin it because the heaver boat is not yet moving fast enough to replenish the supply. The inducer made a big difference in my twenty three ft tunnel boat with the blown 588 cid Chevy in it now. When it had a motor of about only 600 HP, it didn't make that much difference. I think they are well worth the money, if you are having any cavitation problem at all. Just MY opinion.
Yes I would agree with what you said. If you have the hp to process the water faster than it is coming in then they do help. I think the majority of large impellor ski boats however don't really benefit from the extra money spent.