SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: KonaCole on June 30, 2008, 08:41:38 AM
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I got the Kona together and have ran it a couple of times for tunning (still playing with jetting), but was wondering about top speed. I have an A2 that is turning 4850 (with logs, so not bad ???) and GPS'd the top speed at 61.3 mph with me (205 lbs) and dad (265 lbs). I was wondering if the A2 was slowing me down on top speed and if so, possibly by how much?
I do have to add that I am not dissapointed with the A2 as it comes out of the hole hard and will push the boat 30 mph at ~ 2850.
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Is it a heavier boat? What else is done to the pump? Is it tight?
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Engine hp?, torque?
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The boat is a 1971 Kona 18ft. I am not sure of the weight of the hull, but the boat loaded on the trailer, full of fuel, etc. weighs 2700 lbs. My dad and I pulled the hull off of the trailer, so it can't be too heavy.
The engine is a 468 Olds, (just built) and should make 1 hp per ci (or close to it), but i am using logs, so I am sure they are robbing some power. As far as torque goes, I would be guessing, but i would say 550lbs.
The pump is fresh (about 1hr on pump)
Berkley JC, A2 impeller.
I was thinking that i would have seen 65 mph, but I might get closer to that as I am still tuning the engine.
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So if you have a light boat you will go faster and take less hp doing so right? Im curiouse how mine willl run....
Ok back to you ;)
2sav
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Do you have a diverter? Rideplate? 4800 with an A2 impeller is pushing alot of water, I wouldn't think that the Rpm's are your problem. Maybe there is hook in the hull?
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So if you have a light boat you will go faster and take less hp doing so right? Im curiouse how mine willl run....
Ok back to you ;)
2sav
Steve there's a difference between light boat, and "don't walk on that part you'll fall through" like yours ;D
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Do you have a diverter? Rideplate? 4800 with an A2 impeller is pushing alot of water, I wouldn't think that the Rpm's are your problem. Maybe there is hook in the hull?
Berkley jet a vator and no rideplate. I will have to check for hook. I think that I will also be going to a place diverter next winter.
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Berkley jet a vator and no rideplate. I will have to check for hook. I think that I will also be going to a place diverter next winter.
Jetavator are basically the same as a PD, but I have heard they can bind when in a turn while they are up. Seems like you're turning a good rpm for that Impeller, I would say it's somewhere in the boat that's holding you back. But maybe one of the experts will come in and give their two cents
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whatever happened to that Berk HP/Impeller chart?
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I got the Kona together and have ran it a couple of times for tunning (still playing with jetting), but was wondering about top speed. I have an A2 that is turning 4850 (with logs, so not bad ???) and GPS'd the top speed at 61.3 mph with me (205 lbs) and dad (265 lbs). I was wondering if the A2 was slowing me down on top speed and if so, possibly by how much?
I do have to add that I am not dissapointed with the A2 as it comes out of the hole hard and will push the boat 30 mph at ~ 2850.
Hey 60 mph ain't all that bad. Go have fun and stop looking to spend money except for gas and restaurants along the waterway!! ;)
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I got the Kona together and have ran it a couple of times for tunning (still playing with jetting), but was wondering about top speed. I have an A2 that is turning 4850 (with logs, so not bad ???) and GPS'd the top speed at 61.3 mph with me (205 lbs) and dad (265 lbs). I was wondering if the A2 was slowing me down on top speed and if so, possibly by how much?
I do have to add that I am not dissapointed with the A2 as it comes out of the hole hard and will push the boat 30 mph at ~ 2850.
I'm at 50.8 MPH at 4900 with an A in a 21 footer.
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whatever happened to that Berk HP/Impeller chart?
Only chart I got :-\
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi227.photobucket.com%2Falbums%2Fdd6%2Fpw383426%2Fscan0001-1.jpg&hash=3023325f65482d491f1e3783cf660c44ba43bd14)
I've heard the original Berk chart isn't all that accurate because of how loose the original berk pumps are... just heard though
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Hey 60 mph ain't all that bad. Go have fun and stop looking to spend money except for gas and restaurants along the waterway!! ;)
Thats what I am screamin. I am just shootin the sh*t a little bit ^-^
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Only chart I got :-\
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi227.photobucket.com%2Falbums%2Fdd6%2Fpw383426%2Fscan0001-1.jpg&hash=3023325f65482d491f1e3783cf660c44ba43bd14)
I've heard the original Berk chart isn't all that accurate because of how loose the original berk pumps are... just heard though
I remember reading somewhere, maybe Berk's webpage, that the chart can have a %10 to %15 margin of error. That is a sh*t load when you are talking 450 hp.
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Kona, I see you're in Bakerspit too, maybe we should meet up one day at the lake? I'm off all week, BV is nice during the week, no wakebarges.........................
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Kona, I see you're in Bakerspit too, maybe we should meet up one day at the lake? I'm off all week, BV is nice during the week, no wakebarges.........................
I would like to, but I am assholes and elbows trying to get ready to leave on vacation Thursday, night.
I'll be back in a week and we will have to meet up.
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Steve there's a difference between light boat, and "don't walk on that part you'll fall through" like yours ;D
Damn, you make it sound like its cheap ???
2sav
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Damn, you make it sound like its cheap ???
2sav
Cheap? If you say so ;) I like them cheap and fast then >:D
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There are a couple of chart's in this thread:
http://www.performanceboats.com/html/forums/showthread.php?t=10176
Your rpm is a bit low for these charts though. I looked for the standard chart and didn't see it. Someone posted one not to long ago than included the AA at lower rpms.
edit: I found it. http://www.berkeleyjet.com/impeller_info.aspx
The question you need to ask yourself is: "how high do you want to rev your Olds ? " More than likley in a typical boat if you trimmed an AA down to an A+ or A and picked up 400 rpms te boat would be faster. How fast depends on the boat.
Hope that help's.
Sleeper CP
Big Inch Ford Lover :)
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There are a couple of chart's in this thread:
http://www.performanceboats.com/html/forums/showthread.php?t=10176
Your rpm is a bit low for these charts though. I looked for the standard chart and didn't see it. Someone posted one not to long ago than included the AA at lower rpms.
edit: I found it. http://www.berkeleyjet.com/impeller_info.aspx
The question you need to ask yourself is: "how high do you want to rev your Olds ? " More than likley in a typical boat if you trimmed an AA down to an A+ or A and picked up 400 rpms te boat would be faster. How fast depends on the boat.
Hope that help's.
Sleeper CP
Big Inch Ford Lover :)
By reading these posts and reviewing the different charts, if I had an A cut, I would probably be looking at about 5100 rpm and possibly only 2mph top end speed. I think I made a good choice for reliabliity, skiing and performance in consideration.