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Why don't you ever see extension boxes on the fast (120+), stepped vees??? >

Why don't you ever see extension boxes on the fast (120+), stepped vees???

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Why don't you ever see extension boxes on the fast (120+), stepped vees???

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Old 01-18-2015, 11:42 AM
  #31
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Notches were/are a manufactures way of using stock mild power to bridge a gap between performance and effecency. Think of the boat on a fulcrum and the further back you move it, it will increase one aspect but lower another. If running 700 hp and you set the drives back a foot, you will either havevto raise or lower your X to maximize perf.
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Old 01-18-2015, 01:54 PM
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I have installed extension boxes on two boats and had good results both times. They were both Fountains, the first a 96 38 Fever side by side 500hp with small steps and the second an 03 38 lightning semi-stagger with 525's and large steps. The 96 ran 79.6mph stock and after the boxes were installed it ran 87.5. We did change the props to four blade Hydromotive Intimidators that were not labbed and ran the highest setting in the boxes. They were Stellings boxes.
The 03 ran 90.7 stock and after the boxes were installed, also Stellings, it ran 98.4. The 03 took a lot of work with spacers and props to get it to run that fast. We started out with the drives a little to high and had to space them down to get the bigger props to work. I do not think that this boat gained as much from the boxes as the 96 did because we had a lot more props to work with. 6 blade Herrings were the best for top speed but Bravo one 4 blades were not far behind and they were a better all around prop. I am sure that if I had raised the rev limiter that the boat would have hit 100 with Herrings that were the best for top speed.
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Old 01-18-2015, 04:44 PM
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Originally Posted by ARB38 View Post
I have installed extension boxes on two boats and had good results both times. They were both Fountains, the first a 96 38 Fever side by side 500hp with small steps and the second an 03 38 lightning semi-stagger with 525's and large steps. The 96 ran 79.6mph stock and after the boxes were installed it ran 87.5. We did change the props to four blade Hydromotive Intimidators that were not labbed and ran the highest setting in the boxes. They were Stellings boxes.
The 03 ran 90.7 stock and after the boxes were installed, also Stellings, it ran 98.4. The 03 took a lot of work with spacers and props to get it to run that fast. We started out with the drives a little to high and had to space them down to get the bigger props to work. I do not think that this boat gained as much from the boxes as the 96 did because we had a lot more props to work with. 6 blade Herrings were the best for top speed but Bravo one 4 blades were not far behind and they were a better all around prop. I am sure that if I had raised the rev limiter that the boat would have hit 100 with Herrings that were the best for top speed.
Wow! Almost 8mph.....not bad
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Old 01-18-2015, 06:02 PM
  #34
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Would one think that the added leverage would tend to push the back end around even more so if you were trying to corner? Interesting points.
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Old 01-18-2015, 11:07 PM
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I don`t see the boxes doing anything for me considering the speeds are inline with other flatdecks.
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Old 01-27-2015, 06:21 AM
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Originally Posted by Bigyellowcat View Post
Funny you should ask.... I was machining on these till about 3 am this morning. They are for skater. 8" set back and wedge out of billet aluminum. Two different styles.

[ATTACH=CONFIG]535770[/ATTACH][ATTACH=CONFIG]535771[/ATTACH][ATTACH=CONFIG]535772[/ATTACH][ATTACH=CONFIG]535773[/ATTACH][ATTACH=CONFIG]535774[/ATTACH][ATTACH=CONFIG]535775[/ATTACH]
Nice work Tyson
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