Whats next? Carrera should be faster.

[jag2]

1991 Carrera Eclipse 20' all stock Hardin 454/715 holley/bassett twistys, Berkeley 12JG-a /a impeller/ standard nozzel
I picked the boat up a few months ago, ran 53 MPH@ 3900RPM with lots of cavitation on take off. Secondary shaft was corroded shut. Rebuilt the carb and ran 57.9@4100RPM but still had the cavitation with 3 people and a good size full ice chest. Sharpened up the impeller and installed an older manual diverter and ran fastest at 1 notch above center on the diverter @ 57.8@4150RPM, no cavitation but it started to porpoise a little with 2 people in the boat and no other extra weight.
Whats next as far far a speeding this thing up a little? From what I can gather there is something wrong. Would setting the floats to low cause a lean enough condition to keep this setup from running 65? Everyone says this is a fairly quick hull and should run 65+ out of the box.
Any worthwhile ideas are appreciated.

[jag2]

Sell it and buy an aluminum hull :cool:
Thats sounds like a good plan with the exception of my alchoholic ass would get drunk, paint it up to look like a coors can, fill it with beer and promptly launch it and sink :crossx:
Edit: Actually might look into one of those if I end up heading back east, after watching the videos in this thread http://www.***boat.com/forums/showthread.php?t=131938 aluminum looks like fun :skull: Wonder what 360 horse in my 13 footer aluminum fisher would be like?

[Aluminum Squirt]

Besides sell it and buy aluminum I would look at a couple of things that need to be looked at together but probably need to be addressed separately, usually for finacial reasons: Setup, Hull, HP, Pump
Setup-Is your boat balanced front to back, side to side. Is the ride plate set at the proper angle, is your diverter working properly. Is your shoe adjusted properly. Do you have 400 lbs of crap in there that you don't need
Hull-Does your hull have a lot of hook or rocker. Is everything sharp, trued, blueprinted etc
HP-Is your motor highly tuned and fresh or wore out. Your RPM's sound a little low, maybe some carb or ignition issues, flat cam. Within reason, you can make your boat as fast as you want if you throw enough HP at it.
Pump-Is your pump tight and fresh. A tight pump can make all the difference in the world, but more than likely you will lose some more RPM's with a tight pump.
I'd look at motor issues first, start with simple stuff like a compression check, timing check etc. I have no idea what kind of HP you are making but 4150 RPM's sound a little low. Get that thing highly tuned and then you know where you stand. If you are still turning a low RPM you can look at cutting the impeller down to A/B or B to gain some RPM's back and hopefully put you running right at your HP peak. After that I would go after your pump and make sure it's tight, maybe have one of the guru's go through it, blueprint it, add an inducer, shoe, rideplate, all the gadgets.
Then when you decide you want a really fun project, pull the motor, flip the hull and blueprint it. Get after it, it should be done by summer.....of 2008. The sky and the wallet are usually the limit. I'd say at 60 you aren't doing too bad. Many stock jetboats are in the 50's, especially on GPS. Dash speedo probably says 65 but a stock motor in a non-race boat should get you around 60 and you should be happy with that. If you want to see 70 or 80, you are going to have to look at most of the things above....or buy aluminum :boxed: . There are tons of good guys on here that can guide you through the things I've mentioned with much more experience and knowledge than I have. I just know enough of the words to be dangerous. When some people tell you there boat goes 70, it may not be. Put it on the GPS and verify it. These guys running 80+ have put a lot of time, money, and effort into making their sleds fast, especially when running a bigger boat in lake trim-Aluminum Squirt

[LGCDEVIL]

58 is about right on for that hull (not blueprinted) on a 330 horse motor & a wore out pump. Sounds like you're a couple hundred rpm low, though.

[BLEWBAYOU1]

I think you should be about 4800 RPMs with an "A" impeller and about 62-65 mph.
Brian

[fatboy95]

Thats sounds like a good plan with the exception of my alchoholic ass would get drunk, paint it up to look like a coors can, fill it with beer and promptly launch it and sink :crossx:
Edit: Actually might look into one of those if I end up heading back east, after watching the videos in this thread http://www.***boat.com/forums/showthread.php?t=131938 aluminum looks like fun :skull: Wonder what 360 horse in my 13 footer aluminum fisher would be like?
How true. Let's buy 2 of them.

[Heatseeker]

Sounds to me like a power problem. If the pump was loose and/or worn out, you would most likely see a higher rpm with less speed.
I'd go through the tuning steps outlined above. Chances are you'll find a problem somewhere.

[jag2]

Paperwork says 360 hp. 131 hours on the boat when I bought it, about 160 now. But ive ridden in this particular boat alot over the years before I bought it and it did seem like it used to be faster. Over the years it has been very well taken care and stored inside but unfortunately it sat outside in Utah all last winter, it had a cover but rust got it a little.
Ive got lots of big hp BBC hotrod goodies laying around my shop but im not looking to get mass amounts of speed. I just want it to run to the full potential it had stock and have fun. It just seems it used to be faster.

[79Challenger]

Father in laws 91 eclipse runs mid 90's with 850hp, a/b impeller, blueprinted bottom.
Oh yea...its also an open bow

[jag2]

Father in laws 91 eclipse runs mid 90's with 850hp, a/b impeller, blueprinted bottom.
Oh yea...its also an open bow
Id like to see a picture of that, sounds interesting. Something he cut open himself?

[FILUCKY]

My family boat is a 20.5' Carrara open bow, and it runs 55mph@4200RPM on a "A" impeller with 4 people, a german shepard, cooler, and all the other family crap. :)

[BLEWBAYOU1]

Regardless of hull you should be getting higher RPMs.

[jag2]

Regardless of hull you should be getting higher RPMs.
Thats kind of the answer I had hoped for to verify what I was thinking but in a marine app I had a few people telling me not to go any higher on this stock motor. Thanks, ill do some carb tweaking and little tune up this week and see what she does.

[Aduner2]

My Eclipse ran 55-58 gps'ed @ 4700 rpm with A/T pump with an A impellar. Engine was a 330 Mercrusier with an Edelbrock Air Gap and a Holley 750 DP carb, Bassetts with mufflers.
The numbers, speed and/or rpms doesn't sound right to me. Are you running a AA impellar? You'll be lucky to break into the 60's with 360 hp.

[jag2]

My Eclipse ran 55-58 gps'ed @ 4700 rpm with A/T pump with an A impellar. Engine was a 330 Mercrusier with an Edelbrock Air Gap and a Holley 750 DP carb, Bassetts with mufflers.
The numbers, speed and/or rpms doesn't sound right to me. Are you running a AA impellar? You'll be lucky to break into the 60's with 360 hp.
I dont know a whole lot about pumps but I was wondering that myself, the tag say 12jg-A , then in the next box it says impeller-A.
Whats the A next to the 12jg?
Im using a Garmen to get my speeds, boat doesnt have a speedo.

[Aduner2]

I dont know a whole lot about pumps but I was wondering that myself, the tag say 12jg-A , then in the next box it says impeller-A.
Whats the A next to the 12jg?
Im using a Garmen to get my speeds, boat doesnt have a speedo.
The 12jg is the pump model and the -A is the impellar that the pump was set-up with when it was new. Impellars are sometimes replaced for varoius reasons, and the tags will not reflect that. There are different size impellars available depending horsepower and desired rpm. Your rpm sounds low to me for an A impellar and the speed your running. If your tach is correct, my guess you turning a AA impellar.
I concure that your speed is accurrately measured!

[jag2]

The 12jg is the pump model and the -A is the impellar that the pump was set-up with when it was new. Impellars are sometimes replaced for varoius reasons, and the tags will not reflect that. There are different size impellars available depending horsepower and desired rpm. Your rpm sounds low to me for an A impellar and the speed your running. If your tach is correct, my guess you turning a AA impellar.
I concure that your speed is accurrately measured!
There is 2 A's, one in the pump box 12jg-A and one in the box marked Impeller -A.
I just had the impeller out and it was stamped with a single capital A. It had a few blunt edges from rocks and such so I smoothed them out and made them clean and sharp but I made sure not to cut the blades down any. I have to guess that is what solved my cavitation problem and gave me the extra couple rpm. RPM is almost instantanious and is consistant with the diverter up, down or in the middle.
Does the AA make more thrust then the A as long as I have the right power to turn it? I really want to just keep it stock but if I cant end up getting it to 65 or so I have a set of 468 pistons and 871 that goes with them laying around here somewhere.

[Ken F]

First of all, put in your head that you have a heavy boat.
A lot of the advice you are getting is what has worked on lighter boats.
When you get into a heavier boat, the set-up/mindset changes somewhat.
You need to think of the amount of water volume you are putting out the rear, and not so much of the thrust. A larger impeller is going to put more water out the back which is what you need. Most large boats will go fastest with a larger (A or AA even AAA) impeller than one cut down to an AB or a B.
Read larger nozzle if yours are changable.
More water out the back, more weight/push going forward.
Cavitation issue could be several things. When you had your impeller out did you check clearances between the wear ring and the impeller? Your cavitation out of the hole (assuming your pump is tight) is caused by "starving" the pump for water until forward motion loads the pump.
When you are sitting still and hammer it, your pump must "suck" water into the intake. Once underway, it is loaded by the Intake loader, and the shoe at the back of the intake. I'd look at the type of loader you have in the boat.
When you take off, you need the pump to be able to suck a lot of water. Once underway, the intake size may be restricted considerably, which will give you more top end. This is a balancing act. It could be that someone has installed a "closed center loader" for top end, thus your pump is starving on take off. The "ultimate wear ring" from Hi-Tech performance really gives a good hole-shot. That would be my suggestion first. Check your clearance, and if it is off, try one of Duanes wear-rings.
An inducer impeller will greatly improve your pump loading on take-off, however they are a little pricy to install as your pump shaft has to be turned down to accomodate the inducer, and have a keyway added. Good investment though, especially for a heavy boat which you use for skiing, wakeboarding, ect.
AS stated above, tune up comes first. Make sure all is well. Run your boat WOT and shut it off. Coast to a stop & pull the plugs, read them. Are you running lean on the top end?
http://www.dragstuff.com/techarticles/how-to-read-plugs.html
ReCamming your engine would help. You want to select a cam for max torque in the range you will be running it. Recall "heavy boat". HP will follow along with the torque, but go for max torque, especially in your situation.
Hope some of this helps
Ken F