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Thread: speed

  1. #1
    OK ,Question,I've got 468 fresh,turning 4600-4700,60mph,sometimes if im lucky 61.7,best run yet,all GPS verified ,berkley 12JB,with good condition berkley A impeller,both impeller and wear ring changed sametime,got a hyd place diverter as well and loader grate.anyway I need more speed, I dont want to mess with my engine as I just did it last year and I'd like to get some running out of it before I spend anymore so I'm thinking impeller I was hoping to get some opinions on what type and size, I was thinking about a B to try and bring my rpm up to 5000 or maybe a little more,my motor should be able to withstand that no problem .I sure would like to see 65mph,got a couple expensive prop boats on the lakes I would like to pass by,65 would do just fine.

  2. #2
    I would look at having the impeller that you have worked on before you look at buying a new impeller it can be worked and cut to reach your motors power band and I think you will be much more happer with it than with a new one . Also I would look into getting you bowl Blueprinted. I think if your motor is putting out 400-450hp this is an easy goal to reach with a little pump work. MPD in Costa Masa would be my first choise for this work.
    P.S. Pass the Donuts.
    [This message has been edited by Blown509Liberator (edited January 31, 2002).]

  3. #3
    Jet, I agree that the impeller would be the best next step. I my 468 BBC with a B impeller in a 12JG will turn 5500 RPM's. Thats enough to push a 19 Hallett to right around 70. Good luck.

  4. #4
    flat broke
    I'm gonna second what Mike said. Call Jack at MPD (949)631-2040 and run your setup by him. Getting the impeller turned down should give you the additional RPM your looking for. The more you know about the components that are in your engine (cam specs, heads etc.) the better the likelyhood any good pump guy can determine if more R's will get you to where you need to go.
    In looking at your rpm and speed the berkley hp chart pegs you right around 330-340HP with your current impeller setup. Using LVJetboy's JPC and the impeller charts says that using 338hp and 5000rpm with a b' cut impeller should get you to 65 on the button. But these tools are only used to estimate curves and should not be used to determine exact expected results. My advice would be to call Jack or any reputable pump guy and talk over your goals with them. 65 should be a fairly easily attainable goal for most 18'-20' boats with a shallow v and relatively light weight.
    If you have pictures of your boat and would like them on the web feel free to email me at for more details.
    Good luck,
    Chris (

  5. #5
    I was going to not post, but what the hell, I'll cross my fingers.
    "b" cut impeller is a must for the power your pushing. I would also look into your shoe setup as well as your intake grate. Good Luck, and if you live in Southern California, MPD is a good choice for quality pump work.

  6. #6
    I had a bbf turning 4700 at 68mph decided to go to mpd in costamesa and have him cut it down to an a-b cut with my combo i picked up 500 rpm(it allowed my motor to get in the power band)and got it to 70.and a pumpload of rocks(my mistake)I just got my pump back last night and had the new impeller cut to a b so i hope to improve more.I would give jack a call and have him explain the process to you.I used him for the first time a couple of months ago and was very pleased with the work.Thanks to people on this board who recomended him.

  7. #7
    greg shoemaker
    Before you start cutting an impeller make sure other areas in the boat are correct.What size is your boat? Take into consideration the strightness of the bottom because this will certianlly cut down the speed. Also when you cut the impeller down in a big boat you are going to loose your pull ability when you have full tanks of fuel, an ice chest full refreshments , 3 or 4 people in the boat, and then you decide to pull a skier you'll find the small impeller will m make it alot harder. Greg

  8. #8
    Oh what the hell, I might as well get my 2 cents in. Jet, you should call dave at aggggressor cuz he'll sell you an impeller that will make you go 92 mph @ 2300 rpm! Hero, you should have told him he needs a 'januwine' place deverter( cuz you own stock in it) and to call jack at mpd! Then you can call me cuz I got a slightly used 3/4 race cam (its got a few lumps left on it) that I'll throw in with a highly modified loader grate that I left lying around Gregs shop( you just have to weld it back togather).
    DON'T mind me race fans///I been drinking!!!
    However, in the haze that envelopes my foggy mind at the moment, NOWHERE did I pick-up on what type, size, weight(including how many FAT chicks, how large was his bullet box, and how much gas this tug carried). Remember kids, if it weighs 7000 lbs and ain't got no power it still ain't going nowhere even if you take it to good ol'
    Harold Bruce and have him put in a 'twinjet pump"!
    Forgive me people, i forgot to take my funny little pink pills this morning, maybe it was the exhaust fumes i wuz sniffen.

  9. #9
    mach1 454
    i have a 20 foot mach1 with a jet drive. my jet is different from all the other jets iv seen. its a berkely that mounts on to the transom unlike the others that iv seen that mount on to the buttom of the boat, and go thrue the transome. mine bolts straight on to the transom. what is the differnce in this set up. people who see my jet drive always tell me that they have never seen this kind of jet. also i bought the boat without a grate on it and till this day i still dont have one. the jet sticks out pretty far from the transom. any info on my jet set up would be apreciated. thanx
    mach1 454

  10. #10
    mach 1 it sounds like you have the insert type pump i believe it is the E MODEL maybe greg can clarify that.

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