Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 26

Thread: Advise on getting more low end power...

  1. #11
    rivercrazy
    I've heard that some company's manufacture a small super charger for that motor. If cost is that much of a problem.

  2. #12
    jetdrive
    Kiwi Legend Jetter,
    Actually, I am not sure what cut impeller I've got in my Legend. The boat came like that, however it is a set back pump and I put in a hydraulic place diverter and a ride plate on it. I probably need to change the impeller at some point, since I noticed that the guy that owned it must have chewed up rocks or something, 'cause just looking through the grate from the bottom of the boat, I can see the damaged vanes in the impeller (chewed up pieces on the ends of the vanes).
    By the way, at wide open throttle, I run about 4600 RPM (don't know how fast, since I don't have a speedo). Is there a way to tell what cut imeller without opening it up?

  3. #13
    jetdrive
    Rivercrazy,
    I've heard the same about the supercharger, but I've looked every where and have not been able to find a supercharger made for a carbureted 4.3 motor.
    Do you happen to know what the name of the company is?

  4. #14
    matt1
    The name of the company is whipple chargers
    or something like that.

  5. #15
    flat broke
    Jetdrive,
    Hearing that you have some damage to the pump, you can also pick up some efficiency there. While the gains are hard to ballpark any motor work you do will be noticed more with a tight pump than a sloppy one with busted vanes.
    In regard to the supercharger, it is a whipplecharger and will work for carbed motors as it sits between the motor and the carb like a typical roots blower you would see on a Big Block. If you are thinking about looking into the blower, do your research before you buy your carb and manifold as they will more than likely not be very usefull once you install the blower. If you're in southern California and are thinking about getting any pump work done, my recomendation and that of many others would be Jack at MPD in Costa Mesa. http://home.pacbell.net/jmcclure/ 949-631-2040.
    Good luck,
    Chris www.liquidaddiction.net (http://www.liquidaddiction.net)

  6. #16
    Kiwi Legend Jetter
    Taking apart you pump is easy, especially the setback instal. If you can change your spark plugs, you can take the bowl of to look at the impeller.

  7. #17
    Scarabjet
    Jetdrive,
    On my Scarab Jet, I had a Place Diverter installed, removed the muffler & ran straight exhaust through the transom with 4" Rex Marine SS tips. Also, replaced the stock mercruiser flame arrestor with a better breathing K&N. With the stock configuration I was running between 4800 & 4900 RPM's. With all the previous mentioned mods & changing the impeller from a D to a C-cut, I'm turning between 4700 & 4800 RPM's.
    My original theory was to stick to the D-cut for top end and add the Cavitation Reducer to improve bottom end. However, the results weren't that noticable. I CAN tell the difference with the C-cut. I too looked into a Supercharger and it is quite spendy. Even though my Scarab is not the Hot Boat caliber that most have in this forum, it's still a fun boat. With all the mods, I've been able to hit 55MPH (dreamometer, not GPS) running on fumes and just myself in the boat.Not bad for a normally aspirated 4.3.

  8. #18
    SB
    Fix the pump first, you'll notice that a lot more on the low end. Regarding the engine, note that the standard 4.3 puts out about 190 hp, the earlier ones, 170 hp. The Scarab 4.3 puts out 225 hp, so you might want to question Scarabjet closely about his setup. They knew what they were doing.

  9. #19
    jetdrive
    Thanx everyone for your inputs...
    Hey Scarabjet, guess what? my boat is a Scarab too. I am not sure if you are out in the west cost or not but if you are, you and I are probably the only two guys with Scarabs that have jetdrives in them.
    Sounds like that your is a later model than mine. Miine is actually a 92 which was really made with outdrives but a few of them were converted to jets and mine is one of them.
    Yours is probably a 19 footer (made between 96 and I think 99), mine actually looks identical to yours except it's a foot shorter.
    By the way, mine already came with thru-transom exhaust, so that's not a problem. As you know, the PJX pump is basically a Legend made for Volvo to put in that boat. You said that yours has a 4BBL Holley, did it come with that? I thought that they came with Rochester.
    Also, you said that you changed the flame arrestor with a bigger K&N. Was it really worth the cost? or did you do it mostly for the looks? (I called and found out that a K&N marine approved flame arrestor costs around $120.00).
    Any rate, I am down in Southern Cal and go to the River quite a bid, if you are also in this nick of the woods, maybe I'll C U out on the "RIVER"...
    Take care...

  10. #20
    Scarabjet
    Jetdrive,
    I have a 1998 ScarabJet. You're right, it's 19ft. They made them between '95 & '98. Dave (Legend) built the first 75 PJX's for Volvo. Everything behind the bowl is Volvo.Everything else, Legend. I did extensive research and talked to everyone, from Dave (Legend) to the person that actually built the hulls (down there in Southern California)& even Greg Shoemaker. I live in Northern California (Bay Area).
    The boat did come with a Holley & through hull exhaust that exited below the waterline. I dumped the big fiberglass muffler & exited the exhaust straight back, above the waterline (straight shot). The thing does sound nasty (big scarab sound) and now I'm going to buy Shotgun Silencers (no loss of RPM @ top end).As far as the K&N,I did all my mods @ the same time (dumb but eager) and don't know what did what. However, in talking to Greg, he did mention, less restriction on the intake is a good thing. & you're right again, it does look kinda cool. Also, try this. Torque peak for the 4.3 is around 2800 RPM's. Load her up first to the peak curve & then hit it. As you probably found out, it seems that if you hit it all the way, it just spins to red line & really doesn't go anywhere. Also, play with your Place diverter & make sure you're freeing up the bow & not "pushing" water in front of it. If you'd like to e-mail me I can send you pics and we can bounce ideas back and forth. As you can tell, I live this stuff! (precisionone@ca.astound.net)

Page 2 of 3 FirstFirst 123 LastLast

Similar Threads

  1. need some cam advise for my 505
    By IMPATIENT 1 in forum Gear Heads
    Replies: 23
    Last Post: 11-29-2007, 06:32 AM
  2. Power baby, power....
    By boatsnblondes in forum Sandbar
    Replies: 8
    Last Post: 10-04-2007, 06:29 AM
  3. How much power could a woofer amp power,
    By 1stepcloser in forum Audio
    Replies: 23
    Last Post: 01-04-2005, 11:09 AM
  4. need advise
    By a catered life in forum Sandbar
    Replies: 13
    Last Post: 11-14-2004, 08:23 AM
  5. You Want POWER? How About DIESEL POWER?!
    By MagicMtnDan in forum Sandbar
    Replies: 4
    Last Post: 03-31-2004, 09:49 PM

Posting Permissions

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