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  1. #21
    Frequent Poster Shawtown_USA's Avatar
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    Re: 650 X2 Light Mod Impeller of Choice

    Thanks everyone for all your help, I really do appreciate the time you have taken.

    I'll try to answer some questions that you posed and ask for a few areas of clarification as well.

    John, I measured the compression at 4000 ft of elevation where I live and with a cheap compression tester that I've had for 2-3 years. Compression was even in both cylinders and the engine ran strong and well so I didn't think much beyond that. It was measured with the stock exhaust and 28mm carb on it.

    2strokesmoke, I plan to ride both fresh and salt water... some mild chop is likely in both situations. No racing, mostly just rec riding. Not looking for crazy top end but would like to be in the upper 30s.

    You guys mention loading the pump and then also loading the engine. If I understand right, John, you say that the larger hub (C-75 and Hooker) impellers load the pump more but won't overload my engine, is that right?

    It looks like a large hub "swirl" C-75 8/16 is comparable to the Hooker 9/15, any reason to consider one over the other?

    I've been shopping around for a standard 8/16 and have not seen anything... given the new technology, wouldn't I be better served to consider the swirl/large hubs instead? Impeller is the only thing on the ski where budget isn't as big a deal because I know how important this choice is.

  2. #22
    PWCToday.com Is My Home Away From Home john zigler's Avatar
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    Re: 650 X2 Light Mod Impeller of Choice

    Quote Originally Posted by Shawtown_USA View Post
    You guys mention loading the pump and then also loading the engine. If I understand right, John, you say that the larger hub (C-75 and Hooker) impellers load the pump more but won't overload my engine, is that right?

    It looks like a large hub "swirl" C-75 8/16 is comparable to the Hooker 9/15, any reason to consider one over the other?
    At 4000 feet, your compression is probably spot on. Still not a bad idea to have your head cut, or switch to an aftermarket head, and raise compression up some. At / near sea level your ski would be 150lbs stock, and typically 170-175 is safe on pump gas.

    Loading the pump is GOOD and translates to loading the engine. True, you do not want to overload, as you can cause issues. (IE too steep a pitched impeller, no matter what type). The Hookers, and large hub impellers are more efficient, and will work with lower numbers. Efficiency in a jet pump is important, and the difference between good, better, and holy cow this thing RIPS!!

    As I stated above, the Skat large Hub C-75 impeller, cut back 4mm is an excellent impeller in a Kawi, and typically my go to..... The Hooker is excellent right out of the box. (Already cut back). I would say either one would be good.

    Here is a thought.... Glen Perry who now OWNS impro's, and MAKES the Hooker impellers, came from Skat Trak. He worked there as their impeller/pump guy for ever. Thing is I don't know who they (Skat) have now making custom / mod impellers, and unsure of timeframe, quality, etc. I have been going directly to Glen now at Impro's, because I know, and like him. (I delt with Dave at impro's as well in the past, with excellent service)

    If you want/need I can supply you with whatever.

    Hope this helps some more.....
    RCJS also doing business as WATCON
    608-743-1305 9am to 5pm CST m-f
    email watcon@watcon.com

    Please visit our web site

    new parts / products / services www.watcon.com
    thank you

    Please check out and like WATCON on Facebook

  3. #23
    PWCToday.com Is My Home Away From Home john zigler's Avatar
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    Re: 650 X2 Light Mod Impeller of Choice

    Quote Originally Posted by runrider View Post
    Hookers load the nozzle harder, and that generates thrust. It also makes it harder for the motor to rev up as high, and many motors... Especially small pins... Can't reach their peak power RPM.
    Sorry, but this is just NOT true.... If you have an engine that is not reaching peak RPM's you are not dialed in.... IE, either your impeller is wrong, you have too small of a pump exit nozzle ID, or something else wrong. It is not just because of the design of an impeller... We have plenty of Skat, large hub, cut back and Hooker Impellers in race skis regularly winning, and RPM's right were they should be.

    If you think you need an old style impeller to reach a certain RPM, you are leaving HP on the table...

    I will explain like this....

    Back in the 90's I drag raced out board boats. I was CONSTANTLY testing Props, lower unit heights, etc to get my "slip" down as low as possible.

    "Slip" is a term used to describe efficiency of a certain set up.....

    I would figure my speed mathematically with a formula. (Which I do not remember off the top of my head now....)

    Basically you took your Prop Pitch ( I ran a 29 SXR or 30 Mazco), and your RPMS, and the gear ratio in the lower unit to figure a Mathematical top speed. IE with a 29p prop, my Lower unit at 7000 RPM's I should be going 97 MPH. We then used to shoot a radar gun, and get "real" speeds. IE maybe 92mph. The difference between the 2 is your "Slip".

    A boat prop Pitch is a number the prop would move through a solid "in Theory" . So, a 21 pitch boat prop should move forward 21 inches with one revolution. Make sense?

    Now your typical family open bow IO cruiser type boat will run in the 15-20% slip range.. We were regularly running 7-8% slip.

    A Jet pump is the same thing. It just works on pressure, instead of revolutions on a prop. Again a more efficient pump is a GOOD thing... You just need to know how to set them up properly...

    Not here to argue, or get into a pissing match, just want to educate...
    RCJS also doing business as WATCON
    608-743-1305 9am to 5pm CST m-f
    email watcon@watcon.com

    Please visit our web site

    new parts / products / services www.watcon.com
    thank you

    Please check out and like WATCON on Facebook

  4. #24

    Re: 650 X2 Light Mod Impeller of Choice

    Shawtown, I would recommend purchasing which ever impeller you choose from Impros or Watcon. Both offer excellent customer service. After Glen left skat to purchase Impros, Skats impeller customer service has been iffy. Please report back with you results. Too many times these posts die with no end result.

    John, 92mph sounds damn good. What hull, motor and lower unit?

  5. #25
    PWCToday.com Is My Home Away From Home john zigler's Avatar
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    Re: 650 X2 Light Mod Impeller of Choice

    Quote Originally Posted by 2strokesmoke View Post

    John, 92mph sounds damn good. What hull, motor and lower unit?
    1988 Hydrostream Vegas XT, Yamaha Excel with Hydrotech Power head, G-force tuner, Bob's Machine Shop Lower Unit.

    Consistently ran low 90's . Decent in it's day. (I have the trophy's to prove.) Ran right with similar hulls with Merc Mod vp 2.4 and the back then (1993) new 245 2.5 carb. Was LOTS of fun.....
    RCJS also doing business as WATCON
    608-743-1305 9am to 5pm CST m-f
    email watcon@watcon.com

    Please visit our web site

    new parts / products / services www.watcon.com
    thank you

    Please check out and like WATCON on Facebook

  6. #26

    Re: 650 X2 Light Mod Impeller of Choice

    Nice! Had a 19' Action Marine, similar to the Ventura, fun boat.

    Shawtown, what impeller are you leaning towards? Please report back with your results

  7. #27
    Frequent Poster Shawtown_USA's Avatar
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    Re: 650 X2 Light Mod Impeller of Choice

    Quote Originally Posted by 2strokesmoke View Post
    Shawtown, what impeller are you leaning towards? Please report back with your results
    I decided to go with the Hooker 9/15. Talked to a few guys on here with virtually he same engine setup who were in love with theirs. Impros is running a sale right now as well. Ordered it yesterday and its out for delivery today. You can't beat that service!

    Prior to starting this thread I was in contact with Glen at Impros and was impressed with his customer service and prompt replies to my questions. I'd like to also go on record and say that I appreciate John Zigler's input on this as well. I've ordered a number of things from John at Watcon over the past couple of years and his customer service is incredible! As soon as I get the cash on hand I'm ordering his RCJS intake grate for this build!

    Thanks again guys, once I get this project together and ready for sea trials I'll report back with how well the impeller is working!

  8. #28
    PWCToday.com Is My Home Away From Home john zigler's Avatar
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    Re: 650 X2 Light Mod Impeller of Choice

    Thanks for the kind words Shawtown, happy to help out as best I can anytime....
    RCJS also doing business as WATCON
    608-743-1305 9am to 5pm CST m-f
    email watcon@watcon.com

    Please visit our web site

    new parts / products / services www.watcon.com
    thank you

    Please check out and like WATCON on Facebook

  9. #29
    Resident Guru runrider's Avatar
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    Re: 650 X2 Light Mod Impeller of Choice

    Yeah, John, we are on the same page. I misspoke - I intended to say that big pins, not small pins, can struggle to reach their powerbands with impellers that are too tall. Hookers add more load than a comparable pitch number small hub impeller, and with a big pin, the powerband is high, meaning the engine responds poorly to being overpropped. I have personally ridden multiple big pin skis that were overpropped for the amount of mid-range power they were making, and they really struggled.

    Questiono hookers provide somewhat comparable pump load as other big hub Impellers? For example, a stock SXR is 13/18. Lots of guys seem to choose between that and a 10/16 hooker. Do those two impellers provide comparable load?
    Quote Originally Posted by john zigler View Post
    Sorry, but this is just NOT true.... If you have an engine that is not reaching peak RPM's you are not dialed in.... IE, either your impeller is wrong, you have too small of a pump exit nozzle ID, or something else wrong. It is not just because of the design of an impeller... We have plenty of Skat, large hub, cut back and Hooker Impellers in race skis regularly winning, and RPM's right were they should be.

    If you think you need an old style impeller to reach a certain RPM, you are leaving HP on the table...

    I will explain like this....

    Back in the 90's I drag raced out board boats. I was CONSTANTLY testing Props, lower unit heights, etc to get my "slip" down as low as possible.

    "Slip" is a term used to describe efficiency of a certain set up.....

    I would figure my speed mathematically with a formula. (Which I do not remember off the top of my head now....)

    Basically you took your Prop Pitch ( I ran a 29 SXR or 30 Mazco), and your RPMS, and the gear ratio in the lower unit to figure a Mathematical top speed. IE with a 29p prop, my Lower unit at 7000 RPM's I should be going 97 MPH. We then used to shoot a radar gun, and get "real" speeds. IE maybe 92mph. The difference between the 2 is your "Slip".

    A boat prop Pitch is a number the prop would move through a solid "in Theory" . So, a 21 pitch boat prop should move forward 21 inches with one revolution. Make sense?

    Now your typical family open bow IO cruiser type boat will run in the 15-20% slip range.. We were regularly running 7-8% slip.

    A Jet pump is the same thing. It just works on pressure, instead of revolutions on a prop. Again a more efficient pump is a GOOD thing... You just need to know how to set them up properly...

    Not here to argue, or get into a pissing match, just want to educate...
    Last edited by runrider; 02-21-2020 at 07:37 PM.

  10. #30
    PWCToday.com Is My Home Away From Home john zigler's Avatar
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    Re: 650 X2 Light Mod Impeller of Choice

    Quote Originally Posted by runrider View Post
    Yeah, John, we are on the same page. I misspoke - I intended to say that big pins, not small pins, can struggle to reach their powerbands with impellers that are too tall. Hookers add more load than a comparable pitch number small hub impeller, and with a big pin, the powerband is high, meaning the engine responds poorly to being overpropped. I have personally ridden multiple big pin skis that were overpropped for the amount of mid-range power they were making, and they really struggled.

    Questiono hookers provide somewhat comparable pump load as other big hub Impellers? For example, a stock SXR is 13/18. Lots of guys seem to choose between that and a 10/16 hooker. Do those two impellers provide comparable load?
    Again, it is important to MATCH your impeller to your engine, elevation, pump nozzle, ID etc. ANY set up with a too tall/overloaded impeller is asking for trouble. (Engine damage from detonation) this can occur with any type of impeller.

    The stock SXR impeller is a large hub, swirl type design. They are good for a "stock" impeller design, but do not compare to any aftermarket impeller. (IE Hooker, Skat c-75, etc)

    In stock form they are very thick. Now, if you send it off to Glen to be thinned, cut back, etc then yes, they perform even better, and are similar to an aftermarket impeller.
    RCJS also doing business as WATCON
    608-743-1305 9am to 5pm CST m-f
    email watcon@watcon.com

    Please visit our web site

    new parts / products / services www.watcon.com
    thank you

    Please check out and like WATCON on Facebook

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