KAP,

Have you ever checked the prop slip numbers with your benchmark prop with both the SCX upper, and the SC upper?

I think you are going to see that your slip numbers are lower with the SCX upper, which is costing you some rpm and speed. This is due to the fact that the SCX moves the outdrive back nearly 3/4 of an inch due to the larger diameter upper gear set, and the fact that the SCX is about 41 lbs heavier than the SC upper. Both of these add up to your prop being lower in relationship to the water coming off the back of the boat... thus reducing slip numbers and speed.

I have now done back to back testing with a SC upper, and my SCX upper... they are nearly identical in speed (1 mph)... when I raise the lower... up 1/2 inch while using the SCX upper.... ie... go buy yourself a 1" shortie & a 1/2 inch spacer , and go do some more testing.

I think you will be pleased with the results.

Chris

P.S. I still dont think the gear ratio is exactly the same in the SC upper and the SCX upper. ( I think the SCX gear ratio is slightly lower)

I saw in the classifieds that Tres Martin has a Spectre cat for sale with "x power internals" in a bravo drive. Does anyone know about xpower offering a bravo upgrade??? It may be better for me because I'm thinking of swapping my SC uppers for either the SCX or Bmax uppers. Or if anyone knows of someone that wants some SC uppers let me know please.

yes they do build gears for stock b1's

Do they live any longer than Merc gears?

Hey Chris:

Always good to hear from you!

You know we were watching a video of the SCX upper combo on the boat and it seemed our boat was riding a lot flatter as well i.e... less bow lift. I could be wrong as I rarely if ever get to see the boat running unless I am in an event.

I will get a shorty SC lower and see what happens I'm gonna go up about an inch and see what it does. Got any leads on anyone selling a used one if so call me.

We discussed the gear ratio and the IMCO people assured me the gear ratio is the same. I happen to agree with you on that one going up on the lower will help make up my mind.

Thus, far I am very happy I can get a shorty and keep my existing lower as a backup spare.

KAP

Comment:

X-Power people in the past were selling XR gear sets which have been treated either by heat, cryo or vibration but allegedly they are supposed to be stronger. I have no data on this pro or con.

KAP

My plan is to upgrade to scx upper and lower this spring. The sc did not handle the power for me. I look forward to more feedback and will share my results in the spring.

SCX Update
 

We have a 96 Cigarette Cafe Racer, a heavy flat bottom boat! Running appr. 800 HP each motor with blowers. Blew 5 Imco SC's in 1 season! This year put on 2 complete Imco SCX's with 1.34 gears 2" extensions. We have put on 90hrs this year, NO problems or issues! Strong drives, very smooth shifting. Lost about 8 MPH but all worth it! Tried numerous props, can't gain it back! Well worth the investment!

Sounds like similar results I had with my Apache a bunch of years ago. Blew 2 Extreme SC's in 20 hrs and threw in the towel.

Installed BMax HT's and lost 3 mph (mainly due to the gear ratio change) then went 250 hrs on 800+ engines, in the ocean without any failure. I had one upper fail at 250 hrs but I later learned the upper bearings need to be replaced every 150 - 200 hrs.. I know this now! :drink:

I would take the 2" spacers out, and put in 1"-1.5" spacers... betcha see some of that speed come back. The SCX drives are alot heavier than the SC drives and therefore sit deeper in the water.

Chris

You do know there is a 1.5 Ratio now for the Bmax .

Just curious what weight of oil you were running when you lost the upper bearings. My rig had 300 hrs when I changed the gear set and my bearings looked good and the gears were starting to pit.