Extensionbox questions !
 

I am planning to try a -3" imco-box on my scarab 29 (i allready have a -3" shorty ) the propshaft will end up 1" below bottomline with the box ! good or an..????

thats a lot of lift for a v-hull, will the prop get any water that high, do you have room under the hatch to raise the engine 3 inch's

Most likely going to be too high.

I had a stellings box on mine for a while. It was set nuetral with a stock bravo drive, so the prop was actually 1" below stock due to the set back. Stellings removes the rubber coupler on the motor so I had multible drive failures. Got tired of fixing drives so I removed the whole thing and never got to experiment with drive height. I know imco uses a long torsional shaft and keeps the coupler so reliability should be much better. As far as height I'm not sure where 3" would put you and moving the motor up and down will be a pain in the butt. maybe set the box @ -1" and try shorter drives. There is no notch in the hull so -3" may be too much try moving it up 1" at a time. Just my .2 cents. Good luck and I would actually like to know how it turnd out, maybe there will be a shorty in my future:evilb:
Scott

There's no adjustment in a IMCO box you have to raise your engine 3"

Didn't know that, I had a stellings so the box was adjustable. Maybe try moving it up 3" and use spacers in the drive to find the right height?
Scott

I went that high on a 24 single. 5 Blade P5X solved the height issue.

I think you should be close. If you error, you want to be too high on the X as you can always space down.

No i am not going to raise the engine ! i am thinking of the imco-box with 3 inch lift .

Think so ? now when i am going whith the propshaft 4" below bottom line ! Without box. I am running 66,5mph gps with a stock -09 496 magho XR imco 3 " shortie, bravo 1 26pitch. Thats ok for the small hp-numbers i think ! I am planning to go whipple/Raylar/CMI this winter, I would love to se 80 mph and a cruisingspeed in the high 50s or low 60s.
I dont have any problem now with the grip . (just need to be gentle on throttle when taking off ! 5-blade would take care of that i think ) Then with the box ! Ok i am raising the x with 3" but it also go back 12 " therefore the actual raise would not be so high !????

The box have a built in 3" raise !

How high was your propshaft with the box ? Improvements ? (scarab 29 whipple ! tell me more ! )

With the Imco 3" box you have to raise the engine. The drive shaft they provide is longer and solid. It will not allow for the extreme angle. That is why you MUST raise the engine to align your driveshaft.

Going back 12" and up 3" will most likely net you a 2 1/8" rise. You lose aprox. 7/8" for every 12" depending on transom angle.

You might want to do the motor mods first then the box to see the best results. Doing everything at once will be hard to tell what worked and how much. Or what didn't work and what to change.

I never really had time to play with prop height. I was having drive failure about every two trips or so. Boat is very heavy for a single and 750flbs of toruqe from a blower motor and no rubber coupler didn't work well. I can tell you that the box had no rise, it was set nuetral and had a stock length bravo. I actually gained speed when the box was taken off. I have heard that the 29's like a shorty, you are the first I've spoken to that actually tried it. If you are getting those numbers with a stock 496 then you should be fairly close with your x-dim. These boats need good power to get them going fast. Another thing you may want to look into is hook in the hull, I know mine has a good bit You can see it just by looking, you don't need a straight edge. There is speed to be gained there without engine mods. Alfons are planning the -3" box and the imco shorty?

You are so right !! Of course i have to raise the engine. But thats a small jobb compare to "rebuild" the transom ! I will try the box before the engine modifications !

I have heard that the 29's like a shorty, you are the first I've spoken to that actually tried it. I gained 6 mph with the -3 " shorty .

How did this work out?

I don't think he grasped the fact that he HAD to raise the engine in order to install the box. I think he thought he could do it later after he installed the box and tried it first.

I have now raised the engine and mounted the box/drive !! Looks good :-) Now i just have to wait for the summer :-( F..k winter its about -10 celsius and a lot of snow !