Impeller vs speed

« **on:** June 30, 2008, 08:41:38 AM »

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.

« **Reply #1 on:** June 30, 2008, 01:47:28 PM »

Is it a heavier boat? What else is done to the pump? Is it tight?

« **Reply #2 on:** June 30, 2008, 01:59:40 PM »

Engine hp?, torque?

« **Reply #3 on:** June 30, 2008, 02:27:19 PM »

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.

« **Reply #4 on:** June 30, 2008, 02:31:29 PM »

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

« **Reply #5 on:** June 30, 2008, 02:38:39 PM »

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?

« **Reply #6 on:** June 30, 2008, 02:39:17 PM »

Quote from: 2savage4you on June 30, 2008, 02:31:29 PM

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

« **Reply #7 on:** June 30, 2008, 02:52:20 PM »

Quote from: pw_Tony on June 30, 2008, 02:38:39 PM

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.

« **Reply #8 on:** June 30, 2008, 02:55:58 PM »

Quote from: KonaCole on June 30, 2008, 02:52:20 PM

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

« **Reply #9 on:** June 30, 2008, 03:14:53 PM »

whatever happened to that Berk HP/Impeller chart?

« **Reply #10 on:** June 30, 2008, 03:18:32 PM »

Quote from: KonaCole on June 30, 2008, 08:41:38 AM

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!!

« **Reply #11 on:** June 30, 2008, 03:19:17 PM »

Quote from: KonaCole on June 30, 2008, 08:41:38 AM

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.

« **Reply #12 on:** June 30, 2008, 03:26:39 PM »

Quote from: Luckie Stiff on June 30, 2008, 03:14:53 PM

whatever happened to that Berk HP/Impeller chart?

Only chart I got $:-\$

I've heard the original Berk chart isn't all that accurate because of how loose the original berk pumps are... just heard though

« **Reply #13 on:** June 30, 2008, 03:42:08 PM »

Quote from: GAWnCA on June 30, 2008, 03:18:32 PM

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

« **Reply #14 on:** June 30, 2008, 03:44:33 PM »

Quote from: pw_Tony on June 30, 2008, 03:26:39 PM

Only chart I got $:-\$

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.

« **Reply #15 on:** June 30, 2008, 03:44:54 PM »

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.........................

« **Reply #16 on:** June 30, 2008, 03:59:35 PM »

Quote from: Luckie Stiff on June 30, 2008, 03:44:54 PM

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.

« **Reply #17 on:** June 30, 2008, 04:12:17 PM »

Quote from: pw_Tony on June 30, 2008, 02:39:17 PM

Steve there's a difference between light boat, and "don't walk on that part you'll fall through" like yours

Damn, you make it sound like its cheap

2sav

« **Reply #18 on:** June 30, 2008, 04:14:14 PM »

Quote from: 2savage4you on June 30, 2008, 04:12:17 PM

Damn, you make it sound like its cheap

2sav

Cheap? If you say so

I like them cheap and fast then

« **Reply #19 on:** June 30, 2008, 06:19:09 PM »

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

« **Reply #20 on:** July 01, 2008, 07:56:28 AM »

Quote from: Sleeper CP 19 on June 30, 2008, 06:19:09 PM

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.

KonaCole

pw_Tony

shawnthedrifter

KonaCole

2savage4you

pw_Tony

pw_Tony

KonaCole

pw_Tony

Luckie Stiff

GAWnCA

speedymopars

pw_Tony

KonaCole

KonaCole

Luckie Stiff

KonaCole

2savage4you

pw_Tony

Sleeper CP 19

KonaCole