Newbie Jet Owner

[98 Ultra Jet Boat Newbie]

Awesome forum!! A real wealth of information here!!
So, against my outdrive buddies recommendation, I recently took delivery of a 21' 98 Ultra LX with Dominator 12TD pump and GM 454 Marine Power Sportpac engine. Believe last owner claimed she weighed in at 2900 lbs so she's a real pig when it come to weight. Friends think I am a real idiot for going jet, but I am actually pretty happy with the boat and it is a blast to drive.
My problem is these guys all have the same boats with small blocks/Alpha outdrives and here I am with a BBC (330HP) only pushing 48MPH top end. So they have been laughing at me for the most part. Recently had pump work done (blue printed and replacement of thrust bearing which was shot, cleaned up the "A" impeller). Pump already outfitted with Place Diverter and I have added droop and loader grate, which did all of about nothing. With all that said, I am pushing 52MPH top end now, the same as the SBC's with the outdrives?! Have heard a couple of wedges may have some gains? I really have to shut the prop guys up, anyone have any experience with this setup and/or suggestions on getting some more top end? Sounds like the pump is done and need to go into motor.
The motor is stock and I have a Jacobs OMNI PAK (left over from car application) that I was going to through on. Then maybe swap out the Q-Jet for a Demon? Add an intake manifold? I'm really lost here except for the fact that I have to shut the props up....pls, any suggestions are very welcome. THX
Scott - Newbury Park, CA

[Jake W]

Hear are some minor motor mods.Add some Lighting headers RPM air gap intake and a worked (holley)carb and more aggressive cam.Nothing to hard and I bet you would like the results.
Jake :D

[98 Ultra Jet Boat Newbie]

Thanks Jake, appreciate anything I can get at this point to shut the props up. Have a ride plate project going on now, but have heard that will really only get me out of the hole quicker, but hopefully won't hurt the top end. The stock ride plate ended at the back of the bowl (10" of plate) and am currently fabricating one to run to the back to the bottom of the droop (appox 22"). Hope I am on the right track with the ride plate but have notice most are of the shorter variety. THX again.
Scott
[ September 09, 2003, 09:05 PM: Message edited by: 98 Ultra Jet Boat Newbie ]

[LaveyJet]

98 Ultra Jet Boat Newbie:
With all that said, I am pushing 52MPH top end nowWhat rpm are you turning?

[BrendellaJet]

Not sure if you are on the right track with the ride plate. Just had mine done by thee pump guru, and mine also ends at the bowl. Hopefully someone more knowledgeable than me will chime in and set us both straight. I can however tell you that more power will give you more speed. It aint free though...If your friends boats can only go 52 mph, it wont be long before you are doing 60-65 with some wise upgrades.

[98 Ultra Jet Boat Newbie]

"secondchance"...turning about 4500 Rs at top end.
"Bredellajet"...yes, money is speed if you can do it right and not gernade the motor. I need reliability and have kinda always been from the school of "what you do top-end, you'd better do on the bottom-end also" (to say that if you get to wild on the top-end of the motor, the bottom end may not handle the higher RPMs, etc..). Have been suggested from the guys who did the pump work that a mild blower/super-charger setup and demon carb would make a real difference getting me close, if not at 60MPH. The ride plate thing is experimental but will let you know on my results in the next weeks....I hope. THX everyone!!
[ September 10, 2003, 07:29 AM: Message edited by: 98 Ultra Jet Boat Newbie ]

[Ultra21]

98, I'm in a similar situation with all my buddies driving SB props. I just went through my 454 and had the heads ported, new 750 vac secondariy carb, mild cam etc. Didn't add too much to the top end but pulls like there's no tomorrow. If you really want to shut them up here's a few suggestions:
~Pull them on a tube!
~Better yet, pull them on a tube and hit the jet-o!
~Invite them to the river (i.e. Parker or Needles)
~Let them drive your jet (nothing funner than a jet boat)
~And last but certainly not least... Roost, Roost, Roost!
Enjoy it!

[Wild Man]

Another NewBe
What is a ride plate and why would it help you come out of the hole faster?

[PLACECRAFT20]

If you have the money and the room under the engine cover go for the blower. I have installed two on outdrive boats and they both picked up about 15 gps mph. For the money i dont think there is a better upgrade. replace the Qjet with a Holley when the blower is installed. just my 2cents.

[THE BOSTON SIDEWINDER]

I HAVEN'T HEARD ANY TALK ABOUT BLUEPRINTING THE BOTTOM, HAVE YOU CHECKED FOR A HOOK OR A ROCKER ON THE LAST 4 FT OF THE BOAT?...BILL.

[ole war horse]

Just remember that on a jet boat set up,it is differant than a prop boat as far as cam,carb head work and so forth and jets love cfm's and not so much on the fuel curcrit and that's why you need somebody who knows jets. The guy that did my 455 gave me 510 hp with 525 ft.lb torque and single carb and now the boat runs fast and also good fuel mileage, so it is important to get the right person who does jet engines and the prop boat's won't be a problem.

[98 Ultra Jet Boat Newbie]

Well...thanks very much for the replys!! You folks have alot of knowledge and it soundS like itS motor MOD time.
:p Thanks Jake W - Headers, Carb and Cam will be a must.
:p Thanks secondchance and Bredellajet - money = speed if done right.
:D Ultra21 - were playing with the same setup so its time to take the props for a e-ticket shallow ride and throw the roost there way.
wink Wild man - ride plate typically mounts under the bowl. Some extend back further than others depending on your setup. See topic on ride plate I plan to post tonight. Hopefully we will be both enlightened!!!
:D Placecraft 20 - mild blower is most likely best bang for the buck with the right carburetion....but a real bleeder on the initial cost. It's just money right????
:confused: Boston Sidewinder, havent gone to the hull yet but visually, looks smooth as peach fuzz and straight as a good porno will get ya.
:D ole war horse - experience is everything and getting the right advise and seasoned knowledgable mechanic who knows the drill can save alot of frustration.
THX ALL FOR THE AWESOME ADVISE WIZARDS.....KEEP ON JETT'IN

[RandyH]

Better Check with Mud Duck on that mild blower addition. He has a similiar boat as yours and did the same thing. Had some bad luck this weekend but not sure of the reasons why.
http://forums.***boat.net/ubb/ultimatebb.php?ubb=get_topic;f=11;t=003890
I am surprised the droop didnt free it up a bit. It takes a lots of cubic dollars to get the 21 into the 70's. :D Good Luck,
RandyH