extension boxes
 

Anyone out there running extension boxes on their Cafe? I'm considering it for my 1992 Cafe Racer, who can tell me what realized gains they have experienced?

Re: extension boxes
 

Been there done that on a few. work good if its done right.

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I've often thought of this on my 89 cafe. What kind of gains did you see as a result?

Re: extension boxes
 

Hi Guys,
I was intendending to use the Miami Boat Show as a "shopping research trip"
for the very purpose of researching whether to add boxes on my '95 Cafe.

Tres,
What kind of dollar versus mph result is reasonable provided it's "done right"?

Do I have to "start over" with the external steering on the boat now?

Do you prefer a particular manufacturer of extension box?

Chasin Cash

P.S.
The fuel pickups work great... Thanks!

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Easy 5 MPH. new wing pates, long rams fill the transom. etc etc. Some of my boats had 7-8 MPH gains.

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Hey Tres,
I'm curious about which boxes you used too? I've been looking at the Imco boxes and I see they offer a neutral and a 3 inch rise. I'm running stock Bravos on my boat and I do not wish to raise my engine height, my flame arrestors are literally a half inch from the engine hatch.

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Stellings. is what I use.

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I would ride in a boat that has had it done before spending the money.
I would call Phil at Lip-ship before doing anything.

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I had extension boxes put on a Top Gun by a very reputable performance marine company with no gains.

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I would think that the power and/or the existing top speed of the boat in question would have alot to do with how much / how little speed is picked up. Meaning, I would think that extension boxes are more effective on boats that are ALREADY running over, say, 80 mph BEFORE the install compared to ones running, say, 60 mph.

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Is this a true statement, or just something you think? shouldn't you see the same percentage of gains no matter what your top end is before install? Just tring to learn as much as I can. Thanks for the help.

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The boxes "should" improve your angle of "attack" ... the "attitude" of the boat .

However .... I would not think you would see much speed increase starting at 60 ???

there's your mystery ... :D

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Just something that I think in theory would be correct, I never had extension boxes on my Cafe.

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projects;
1999 38 TG 635 HP, oringinal speed 78 MPH after the box and some bottom work and one size bigger prop 82 MPH. X was raised 3 inches
2000 TG 500 Carb speed 67 MPH @ 5000 RPM , Modify bottom raise X 3 inch with box, one prop size up, 73.5 MPH
same customer ordered a new 38 TG we rigged it here with boxes and 575s ,94 .6 MPH @ Lake X
Plastered. came here @ 86 with 575s after boxes and some bottom work, 93+........
these are a few.

Boxes when correctly installed will help leverage the boat in rough conditions and allow you to run the extended tab. It will also have the drive back in cleaner water to make
the prop more efficient . Some bottom modifications may be need to change additude. You do need to keep after the driveshaft and bearing with grease every 50 Hours. To install correctly you will need to fill 4 inch part of the transom to raise the X and raise the motor 2 inches up and back to follow the degree of the transom. This will require new motors mounts relocated. The steering cylinders need to be relocated so fill those hole when filling in the X holes. You will need either a extended wing plate or extra long cylinders to make the steering connection also.

Thanks for sharing that info Tres.

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Jamie B.
Whom ever you get to install the extension boxes get them to give you a written guarantee that if it does not give you the increase they have stated that they will take them off with no charge to you.This will take all the quess work and B.S. promises out of it.

Advice from someone who has been down that road.

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VERY GOOD IDEA !!!

I would also have a proposal in writing with a hard not to exceed cost number.
You should know in advance you will almost for sure reach that number.

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Thanks Tiger, though its SKRAMER that is looking into adding these to his Cafe, not me. As an additional thought on that though, you would then still have to relower the X :eek:

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There is only one boat that I know of that didnt take well to boxes, a 357 formula, but it did handle much better. every boat will except it differently. Weighing the boat for center of moment will help you decide the X,The speed you will get out of the boat will be determinded buy not only the box but the bottom changes, and a good prop designed to work for that application.As you know we try to get the most out of all the boat for handling and speed , you look numbers the drangon has produced.

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thanks for the great info, Tres. we are fortunate to have you around this board!

chad

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Cant forget that raising the engine, you will have to cut angle and reweld pipes to go out of the same holes.

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I love that grey paint...Reminds me of the playboy Cigs. :drink:

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Tres,
Thanks for all the great info! However, still not sure boxes are worth the money. You also did bottom work to the boats you added boxes to. How much speed was attributed to the addition of the boxes vs. the bluprinting of the haul? I've heard a good bottom blueprint job will add 5 MPH.