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Scott 852...impeller combos...

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Scott 852...impeller combos...

Postby phatboy07 » Sat Sep 02, 2017 4:08 pm

Hi
Just curious on everyone's thoughts on my observations on almost 2 identical boats as I am trying to get a better idea on how these 852 pumps work regarding there great ability to be set up for so many different applications...
-I am currently running an 852 with a standard and pro impeller. (front stand rear pro I believe?)
-My friends boat is running an 852 with two pro impellers...
-My boat is a 21 ft, 7 ft bottom, 109 beam...built heavy to take abuse. 12 deg delta pad.
-My friends boat is exactly the same only 20 ft long (1 ft shorter)
-Both boats have GM 6.2 LSA engines
-Both 111 mm nozzle
So far we have noticed his cruising speed per RPM is much higher than mine. As an example if I am running 3500 rpm at approx. 29 mph..my friend will barely need to run 3100-3200 to stop from overtaking me (slowly as if he was trying to follow me up river for example). My friends gas usage also seems to be much higher at equivalent RPM to mine. We ordered the boats together and decided to get the impellers set up different so we could gauge what would suit our running styles better and then possibly change impellers out in the future. Currently both boats seem to get on step the same time with roughly the same load, however we both have to feather the throttle ever so slightly. I switched to a 108mm nozzle size and my hole shot improved a little bit as I could almost go full throttle from a stop but I noticed no gain in cruise speed per rpm and seen more fuel burn. Top speed my boat is slower, I attribute that to my boat being 1 ft longer (heavier, more drag, etc)
What are the main characteristics, positives, negatives, etc of the different impeller set ups we have and changes in nozzle sizes? We generally will be using the boats for long loaded up trips.
phatboy07
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Re: Scott 852...impeller combos...

Postby riverboater » Sat Sep 02, 2017 10:36 pm

You didn't mention pitch of blades, I run pro 19's with a 108 nozzle, wot is 4850rpm, cruise 3150 at 33mph. 17ft boat not too heavy except for the three tanks to feed the bbc hiding under the box. burns about 35 to 40 ltr per hour at a quick cruise.
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Re: Scott 852...impeller combos...

Postby phatboy07 » Sun Sep 03, 2017 10:33 am

riverboater wrote:You didn't mention pitch of blades, I run pro 19's with a 108 nozzle, wot is 4850rpm, cruise 3150 at 33mph. 17ft boat not too heavy except for the three tanks to feed the bbc hiding under the box. burns about 35 to 40 ltr per hour at a quick cruise.


The impellers are all 19's
-Both motors still breaking in but they are rated for roughly 540 hp. 540 tq
-My top rpm with 19 standard and 19 pro with 111 nozzle is 4900 ish.
-Friends with 2 19 pros 111 insert is about 4700 give er take a little.
-Cruise for me against our current is at 27-28 mph @ 3450-3500, with current will yield me 32-34 mph same rpm. 50-55 L an hour at this cruise
-My friend will be @ 3100-3200 and faster same conditions. (not 100% on mph numbers yet) and will burn more fuel. He just got his boat while I have had mine for almost a month now so we are still trying to get his numbers down. Hes a little new to the boat as well also I don't want to not drive my boat and he doesn't want to not drive his so it makes it hard getting a ride in his boat to get the numbers right haha
phatboy07
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Re: Scott 852...impeller combos...

Postby riverboater » Sun Sep 03, 2017 12:12 pm

There must be a big difference in boat weights as speed / RPM / fuel numbers are a spread. you mentioned you tried a 108 nozzle, what wot rpm did you get when you tried this?
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Re: Scott 852...impeller combos...

Postby phatboy07 » Sun Sep 03, 2017 1:23 pm

around 4800 giver er take a bit with the 108.
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