Boat size - vs- impeller cut??
+ Reply to Thread
Page 1 of 3 1 2 3 LastLast
Results 1 to 14 of 32

Thread:
Boat size - vs- impeller cut??

  1. #1
    Senior Member H20MOFO's Avatar
    Join Date
    Dec 2007
    Posts
    4,288

    Default Boat size - vs- impeller cut??

    Say ,same motor, going from an 18' to 21' ? Same ? I know everyone is going to say more info for your combo...but I'm wondering in general.
    Another Hot Boat refugee

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
    Join Date
    Dec 2007
    Location
    Newton Ks.
    Posts
    6,834

    Default

    Quote Originally Posted by H20MOFO View Post
    Say ,same motor, going from an 18' to 21' ? Same ? I know everyone is going to say more info for your combo...but I'm wondering in general.
    IMO, in general, larger heavier boats need a larger impeller for the greater push at the same engine speeds.

    You also need the motor to drive the impeller.
    "As democracy is perfected, the office of president represents, more and more closely, the inner soul of the people. On some great and glorious day the plain folks of the land will reach their heart's desire at last and the White House will be adorned by a downright moron."
    H.L. Mencken

    OBAMA: Some people deserve this.
    The rest of us are being dragged along kicking and screaming.

  4. #3
    About 500' AGL MudPumper's Avatar
    Join Date
    Jan 2008
    Location
    Santa Clarita
    Posts
    2,470

    Default

    It doesn't matter what size the boat is....you just want the motor to be able to spin the impeller where the motor makes the most power.

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    Super Moderator HammerDown's Avatar
    Join Date
    Dec 2007
    Location
    The Right Coast/SE-PA
    Posts
    5,488

    Default

    Quote Originally Posted by MudPumper View Post
    It doesn't matter what size the boat is....you just want the motor to be able to spin the impeller where the motor makes the most power.
    Is that the most HP or torque...?
    And how does one know if they didn't pre dyno the engine
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

  7. #5
    Member bennyb's Avatar
    Join Date
    Dec 2007
    Location
    Mission viejo,ca
    Posts
    688

    Default

    Ask BrendellaJet. he just went through this.
    20'5 Advantage classic cruiser
    Go on get your ass outa here

  8. #6
    Member TrynPas's Avatar
    Join Date
    Apr 2008
    Location
    Litchfield Park, AZ
    Posts
    310

    Default

    Quote Originally Posted by SmokinLowriderSS View Post
    IMO, in general, larger heavier boats need a larger impeller for the greater push at the same engine speeds.

    You also need the motor to drive the impeller.
    What is considered a 'larger impeller'? an A or B? How far do they go both directions? (AA-C?)

  9. #7
    Member TrynPas's Avatar
    Join Date
    Apr 2008
    Location
    Litchfield Park, AZ
    Posts
    310

    Default

    Quote Originally Posted by MudPumper View Post
    It doesn't matter what size the boat is....you just want the motor to be able to spin the impeller where the motor makes the most power.
    What exactly does this mean?

  10. #8
    Senior Member H20MOFO's Avatar
    Join Date
    Dec 2007
    Posts
    4,288

    Default

    I've been told my engine makes peak hp at 6500 rpms'.s I did'nt think my cam was that large. If it helps my motor would spin the panther to almost 6k,same motor- everything, spun a (energized) "b" cut to 5300 ish. Now I have a little larger boat and a berkly ab, and I was thinking with a heavier boat, maybe I'd need to spin her a little higher. Sounds like smokin is thinking the opposite(sp?), and mud pumper is thinking what ever cut would run best in an 18 is the one you'd want in a 21.
    Another Hot Boat refugee

  11. #9
    Glendale Arizona Squirtcha?'s Avatar
    Join Date
    Jan 2008
    Location
    Glendale Arizona
    Posts
    2,368

    Default

    Quote Originally Posted by H20MOFO View Post
    I've been told my engine makes peak hp at 6500 rpms'.s I didn't think my cam was that large. If it helps my motor would spin the panther to almost 6k,same motor- everything, spun a (energized) "b" cut to 5300 ish. Now I have a little larger boat and a Berkeley ab, and I was thinking with a heavier boat, maybe I'd need to spin her a little higher. Sounds like smokin is thinking the opposite(sp?), and mud pumper is thinking what ever cut would run best in an 18 is the one you'd want in a 21.
    Although it might be true that max hp is at 6500 rpm it seems the question would be how much more at 6500 vs. 6000 or even 5800. If it's only 10-20 hp more it wouldn't really be worth it to spin it that high. The hp numbers (10-20) are arbitrary, but you get the gist.
    Last edited by Squirtcha?; 06-15-2008 at 08:58 AM.

  12. #10
    Senior Member Brendellajet's Avatar
    Join Date
    Dec 2007
    Location
    Ladera Ranch
    Posts
    2,135

    Default

    Quote Originally Posted by Squirtcha? View Post
    Although it might be true that max hp is at 6500 rpm it seems the question would be how much more at 6500 vs. 6000 or even 5800. If it's only 10-20 hp more it wouldn't really be worth it to spin it that high. The hp numbers (10-20) are arbitrary, but you get the gist.
    Excellent point. My motor made 25 more hp at 6800 than at 6200, Im spinning a Heritage A to 5800(bigger than a berk A). At 5800im making 775 hp(YES, Sleeper CP, that is corrected HP!)... so Im leaving 25 hp on the table as I see it. I like the accelleration Im getting with my impeller so Ill probably just leave it the way it is.

    Running this power in an 18 foot boat with a Jacuzzi B was pretty sickening...Id love to see what it would have been like with an A.

    For a 21 I'd keep the bigger impeller. A heavier boat will need the increased efficiency unless you have lots of power to spare.

  13. #11
    Senior Member Brendellajet's Avatar
    Join Date
    Dec 2007
    Location
    Ladera Ranch
    Posts
    2,135

    Default

    Quote Originally Posted by H20MOFO View Post
    I've been told my engine makes peak hp at 6500 rpms'.s I did'nt think my cam was that large. If it helps my motor would spin the panther to almost 6k,
    The panther RPM does not transfer over...For whatever reason you can spin those things to the moon and from what I have seen it doesn't increase speed.

  14. #12
    Resident Ford Nut Sleeper CP's Avatar
    Join Date
    Dec 2007
    Location
    San Diego County
    Posts
    10,072

    Default

    Quote Originally Posted by H20MOFO View Post
    I've been told my engine makes peak hp at 6500 rpms'.s I did'nt think my cam was that large. If it helps my motor would spin the panther to almost 6k,same motor- everything, spun a (energized) "b" cut to 5300 ish. Now I have a little larger boat and a berkly ab, and I was thinking with a heavier boat, maybe I'd need to spin her a little higher. Sounds like smokin is thinking the opposite(sp?), and mud pumper is thinking what ever cut would run best in an 18 is the one you'd want in a 21.
    Is this a rec boat or a race boat ? If you do a lot of cruising with it I'd go with a larger impeller. Kind of like having 3.73 (a/b) gear's vs 4.54's (C) This all goes out the window if you have a MPD of simular full race prep'd pump.

    As far as your engine HP, post some spec's on it. There are a few guy's here that have desk-top dyno's and can give you a close number. Max Power at 6,500 ... how much does it make ?

    Edit: There is a strange balance between impeller load vs rpm and fuel usage. A more powerful engine spinning a smaller impeller at a higher rpm more than likely will have less load on it than a less hp engine spinning a larger impeller at a lower rpm ( at cruise rpm's) and the larger engine will use less fuel cruising. It can also be said that the same engine spinning a smaller impeller may do the same thing , use less fuel. You just have to find the balance.

    Sleeper CP
    Last edited by Sleeper CP; 06-15-2008 at 10:54 AM.

    "Dark Sarcasm"
    Going fast is only half the fun ... what you make go
    fast is the other half.
    " A Government big enough to give you everything you want is big enough to take away everything you have"

  15. #13
    Resident Ford Nut Sleeper CP's Avatar
    Join Date
    Dec 2007
    Location
    San Diego County
    Posts
    10,072

    Default

    [QUOTE=Brendellajet;217556]Excellent point. My motor made 25 more hp at 6800 than at 6200, Im spinning a Heritage A to 5800(bigger than a berk A). At 5800im making 775 hp(YES, Sleeper CP, that is corrected HP!)..QUOTE]

    Just wondering, how much more power did it make at 6,800 vs 5,800 ? And do you run nitrous on it ? At 5,800 are you spinning at your max trq #.?

    I ran a larger impeller for yrs and lugged the engine, but more like at 5,300 vs your 5,800. Once I brought it up to 5,800 I said " damn should have done this yrs ago." The throttle response was just awsome. Now it's reving 6,200 off the bottle and is even better. Two weeks ago with two of us in the boat with cooler's and skiies and full tanks 4,000 rpm's 52 mph cruise speed.

    Sleeper CP

    "Dark Sarcasm"
    Going fast is only half the fun ... what you make go
    fast is the other half.
    " A Government big enough to give you everything you want is big enough to take away everything you have"

  16. #14
    Senior Member H20MOFO's Avatar
    Join Date
    Dec 2007
    Posts
    4,288

    Default

    Thanks guys. My tach was junk the only times I've been in the water, I was hoping to hit the water today(with my new tach) ,but I don't think it's going to happen, I'd be suprised if I'm getting past 5k. As far as boat just pleasure-go fast (or at least trying to) not race or anything. Motor specs are 427 bbc,crower 1206 hyd. flat bumpity stick, brodix bb2plus heads cc'd at 116, 800 dp on a vic jr.compression just over 11.5 to 1. steel crank and dimple rods if they matter. oh and exaust is tt bassets.
    Another Hot Boat refugee

+ Reply to Thread
Page 1 of 3 1 2 3 LastLast

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in


Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95