I posted this over in the main section, and the prop section without much feedback.

I am now worried about the durability of my IMCO SC drive.

I have an 09 Nordic Heat with a 600sci that I have been doing prop and spacer testing for the last 6 months. Below is the table of my results. These are real slip numbers. Tach has been verified with a digital tach, and speeds with my analog GPS, my digital GPS and a radar gun.

The current best prop is a Hering 26 pitch, 5 blade bravo style prop. Slip is coming in at 5.2%

I am not the first Nordic Heat to post such low slip numbers. The Illmore 700 Heat regularly posts numbers between 6%-8% with the same drive and hull.

For you doubters:
Prop= 26 pitch Hering 5 blade bravo style prop
Speed= 83.8 mph
RPM= 5400rpm -- On the rev limiter

I am about to upgrade my 600hp motor to aproximately 750+hp using some upgrades offered by Whipple for my motor.

What I am worried about is that 750+hp and 5.2% slip on a 28 foot boat, sounds like a recipe for a broken drive.

What do you think??
Should I switch back to a 4 blade prop for reliability sake?
How much horsepower is safe in front of the IMCO SC drive?

I would like to hear some opinions.

Chris

CB,
what kills these drives is torque. The more load and more torque the quicker they die. In your case, the five blade is asking for trouble. That SC motor will make a ton of power down low and if used will break any drive. If you let the boat air out before you start giving it to it.. well then chances are better it will live longer. I would use the 4 blade prop and use the 750hp's torque sparingly, till it airs out some. Of course once you break one, then you will know if you are too hard on it or not. Sorry couldnt resist it..
How much does that Heat weigh? If the drive is setup right and you keep it cool, it could live.. I would keep a close eye on the magnets while they are getting used to the new power..

Hope this helps..
Dick

Kinda goes like this...Drive how you like, BOOM, Drive it a bit easier, BOOM, Now you know were the sweet spot is.
Just kidding...Gadgets advise is less aggravating.
Good Luck, Have a great 09Summer!

Boat weighs about 4800-5200 lbs.

Chris

Chris, if the drive is setup properly and you take it easy with the torque.. it should live. But you never know. The XR upper gears are breaking teeth off the driven gears, for no good reason. My 283 Checkmate weighs in at 5700 dry and I have been runing 700-750hp for over 300hrs on my B1 with XR gears.. But the gears are ten years old.. not the new generation, self destructing kind..

Run it.. and enjoy it!! Dont loose sleep over it.. but you may consider a spare, just incase. The more you spend on a spare the less likely you have to use it.. Murphy's Law??

Does anybody make a stronger/better set of gears for the XR?

Chris

I don't think so. Someone should talk with a company like Weddel. I would think there is a serious market for a better than stock, replacement gears.



Darrell.

what about max machine do they use xr gears, how are the new B1 x drive with tower and diesel printed on it. is it any good. mr gagets

Teague platinum shaft XR is warranted for 1 year rated up to 900hp. Teague Custom Marine has the current drive supply contract to Ilmor and these units are super reliable.

Uncle Dave

The Lavey 28 Evo has that drive and its been a rock.
Its got an ilmor 710 as well and runs a true 100MPH + a couple.
Actually I think that drive is so beefy (harder to spin) its costing you a few MPH.


You're posting really low slip#'s (really low nice work on the chart) and yeah you risk a really hard bite. That said I think the Ilmor you have is a good match for it. Watch the magnets.


Your boat and mine are pretty close,(at least with the props Ive tried so far) but I like the greater slip of the 4 blade.

Uncle Dave
LaveyCraft2750 Ilmor 710
LaveyCraft 20.8 tunnel 406