SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: blowntaylor on July 25, 2009, 04:05:25 PM
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Im new to the board and spent considerable time reading to see if I could find an answer to this problem.
I have a 20 foot Taylor LP. The boat is beefed up with full length stringers and full floor, foam cored underneath, everything glassed in together so it is heavier than most Taylors. Ride Plate and shoe. Hyd Place diverter etc. Everything blended. I believe the flat in front of the intake in the hull is what is known as a delta plate.? The boat ran about 70 last year with 454 with cam intake and headers, alum heads. Long story short it dropped a valve and since I am an engine builder I thought it would be good to put together a solid roller cam 540 with a new 8-71, 2 850 annular discharge demons so on and so forth. It dynoed at 1000 hp. I have an aquamet shaft in it and everything was fresh and all clearences were where they are supposed to be. Of course I could only get to half throttle on the primaries with an A impeller and the moter was at 6000 rpms. Hole shot like crazy! I knew this when I put it in. I upgraded to an aggressor A3 and that loaded it better. Here is where the problem starts, at about 74 MPH (GPS) the boat would shudder like a high speed cavitation. just slow down a couple and it would go away. It is speed sensitive not impeller related, 5500rpms with A and 4000 rpms with A3, same speed. No loader installed. From what I am told I need a loader. I put in a loader that I had that is the basic entry level berk with the 2 angle iron peices on the sides. Big difference, The shudder is gone and the boat is able to go faster, havn't GPS the speed yet but def faster prob around 80. However still not quite enough load as I can only get part way into the secondaries and just a couple pounds boost and at 5500 rpm. Just working into it slowly too! Still hole shots like crazy! No low speed/high rpm cavitation.
So the big question is: Has anyone else had this shuddering/cavitation problem? What loader should I buy? Will the loader really make that much difference to lower rpms, load engine harder?
Already broke!!! so any advice so I don't buy 5 different loader$ would be a big help!! Any used ones anyone wants to part with? Sorry its long! Thanks
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loaders are trial and error, but, it sounds like you are on the rite path. get a hold of duane at hi-tech performance he is in your neck of the woods and can give you some sound advice.
ralph
ps welcome to the boards
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B/T Welcome ! I'm guessin your Taylor likely has a 12 JE ?? Tom
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It has a 12 JG.
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It sounds to me like you may need either a blocking loader or a plate loader, adjusment of the depth of your existing loader may solve the issue, but if it is a straight angle iron loader, you may not be able to achieve both worlds. I have had little/no success with a straight cut loader at anything above 70MPH, I think they are too harsh. :thumbdown:
A plate loader is what you are looking for IMHO. I have seen them work in excess of 100MPH in less than ideal water conditions. :thumbup:
BTW, where are the pictures? ;D
GT
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What is a plate loader? I will get some pics on soon.
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Get you some pictures and possible outlets for a loader this evening, I don't have the pictures on this machine :thumbdown:
GT
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You need to try this ;) Call me if you want to try one Tom
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