SoCal Jet Boats

Tech Talk => Jet Pumps => Topic started by: iloveitloud on June 28, 2010, 06:28:37 PM

Title: What impeller is in my boat?
Post by: iloveitloud on June 28, 2010, 06:28:37 PM

I have a 20' BAJA with a 454, and a 12JE pump. It runs 40 mph@ 4000 rpm. It runs 50 mph@ 4600 rpm, and thats all it has.  I'm not sure why it won't rev up more, but the boat is a project, so I'm working on it. Can anybody take a guess at what impeller I have in the boat now? I would like to know, because when I rebuild the pump, I may change it to something that lets it the motor rev up a bit more. Last owner said the boat ran 60 mph @5200 rpm, so thats what I am shooting for.

Title: Re: What impeller is in my boat?
Post by: 88CARRERA on June 28, 2010, 06:31:25 PM

a

Title: Re: What impeller is in my boat?
Post by: beerjet on June 29, 2010, 12:18:36 AM

AA

-beerjet-

Title: Re: What impeller is in my boat?
Post by: GT Jets on June 29, 2010, 12:29:51 AM

Quote from: iloveitloud on June 28, 2010, 06:28:37 PM

I have a 20' BAJA with a 454, and a 12JE pump. It runs 40 mph@ 4000 rpm. It runs 50 mph@ 4600 rpm, and thats all it has.  I'm not sure why it won't rev up more, but the boat is a project, so I'm working on it. Can anybody take a guess at what impeller I have in the boat now? I would like to know, because when I rebuild the pump, I may change it to something that lets it the motor rev up a bit more. Last owner said the boat ran 60 mph @5200 rpm, so thats what I am shooting for.

If the motor is running right, 4600 may be all she needs to make peak power, IMHO unless you build a motor that needs the Rev's to make the numbers, I would leave it totally alone...You would need to add more than 100 HP to make a really noticeable difference....

You have an A+ if that is all the motor has and is tuned correctly. If the motor is down on power for one reason or another, it may be an A...I guess what I am trying to say is...Not enough information.

GT

Title: Re: What impeller is in my boat?
Post by: iloveitloud on June 29, 2010, 08:28:52 PM

Ran boat again tonight,- about the same performance. Motor seems to run fine. Plugs look good, everything "sounds" good. It has about 3 hours of run time on the last oil change, and it is still full, and looks like new. The last owner claimed the motor made 450+horsepower, but he lied about everything else, so it most likely is significantly less HP, and maybe only enough to turn the impeller 4600 rpm. Either way, the boat actually seems to run flawless, so I plan on just leaving it alone for the rest of this season, and working on tearing down the pump this fall. Other than fine tuneing a few things, the boat is pretty solid, and I got it for a good price, so I'm pretty happy with it.

Title: Re: What impeller is in my boat?
Post by: OC2Vegas on June 29, 2010, 08:57:02 PM

I would bet you are 100hp less then what you were told...

Title: Re: What impeller is in my boat?
Post by: iloveitloud on June 30, 2010, 07:52:26 PM

Yea, motor sounds very cammy, and has pretty high compression, but so does anything else running through headers out of the water.  I'm sure the "re-built" long block is just a warmed over truck 454, with an aluminum manifold. It also only has a 6 quart automotive oil pan, so that leads me to think the whole thing came out of a truck at one time. I can't find much info on my boat. It is an 84 Baja sport 200. I am trying to find out what this boat had originally for running gear, and some hp and performance specs. Any help with that would be great. Thanks. Rick

Title: Re: What impeller is in my boat?
Post by: IRRebel on July 01, 2010, 02:01:15 AM

The oil pan would be a giveaway for me as well. Noone builds a solid bottom end, or tries to, without supporting it.  put myself in the "try to" group given what happened to my first run at it, but hey, it ran, and did for a long time!!  :thumbup: But a high volume oil pump on a std pan is a BAD idea.

Second thing is, it could well have good compression and a hot cam, but it also very well could be the valvesprings or lifters that are stopping the RPMS.... More to it than the cam itself. Spring pressure on the valvesprings have to be "on spec" to the cam, and good Lifters designed for aftermarket cams. In a way, that might be a good thing in this case because if a High Volume oil pump was installed, and you could rev to 5500 or 6k consistently, I think you'd have much bigger problems on your hands..........

Just my .02

Ray

Title: Re: What impeller is in my boat?
Post by: electrowoman on July 01, 2010, 11:13:30 AM

Gotta disagree with the stock pan with a high vol oil pump.   My 1977 cv23 jet came standard with
a 6 quart front sump pan.   I put in the hi vol melling pump in about 1980.

Never had an oil pressure issue till I put on the milodon 10 quart marine pan.   Go figure  :screwy:

This is a 460 but apples to oranges they are pretty much equal.

Stock your engine probably made between 320 to 350 HP.

Title: Re: What impeller is in my boat?
Post by: beerjet on July 02, 2010, 10:32:37 AM

With the power and RPM your makin, that pan should be just fine.
My Merc Cruiser 502 had an 8-9 quart factory pan and the previous owner ran the dog piss out of it with a whipple charger on it and never had a problem.

-beerjet-