I talked to the guys at max-machine today. They use the XR gear set. They say that part of the problem that people are having with the gears are because of the cases flexing. They use extra bearings and billet cases to make the outdrive live longer.

Having said that, they agree that XR/Bravo style drives are not going to live with much over 650 hp with 5 blade props. He calls the Maximus prop... a drive killer.

Sounds like I will be trying to get a 4 blade to work better on my boat.

Bummer... I really liked the way the 5 blade carried the boat. It required less trim, and was the fastest prop at this power level by over 2 mph.

Chris

Air Time,
the B1 X uses the helical cut gears, so power through that drive is limited. But, it does come with good parts for a base drive. It has the steel tower and if you put a good cap on it, can make a decent drive. My .02 is that if you have enough power to knock the teeth off the driven gears, then you have to go to XR. If not, then stick with the helical gears, they last almost forever, if not over powered..
I know several people that wont run the XR gears and have big power on medium sized boats, and have not had issues with them. But they are good with the sticks..

CB-BLR,
The Bravo cases have been flexing for years. Nothing new there. The issue with the XR gears is a quality problem. I had a customer that ran 950hp, then 1170, then 1400hp thru an XR. on the first two motors, he would wear out the upper gears in 60-70hrs. Drove it like he stole it all weekend long. At 1400hp I garanteed him it wouldnt last 5min.. He ran it for a short period, said he had 15 hard passes on it.. I tore it down and it looked good.
Now a days.. 650hp and the teeth break off at the root.... Techniques to stiffen the case do have positive effects, but the gear problem is one of quality in my opinion..

Dick

Mr. Gadgets

Seems to me that if someone would step up and produce a quality set of gears.... they could make alot of money.

Why is this not happening in the aftermarket?

Chris

It is happening.

Its hard- very hard to do which is why its expensive and there are few player.

Call Teague custom Marine-

They have the current drive contract with Ilmor Marine and their own line of engines.

My platinum shaft XR is warranted for 1 year with my 6300 RM 700HP Ilmor V-10 they also warranty this drive for 1 year with their super popular 800 engine.

A platinum shaft XR will hold up under a merc 600 with a ecu, and pulley mod just fine.

Uncle Dave

Uncle Dave,

I am still worried about using my 5 blade prop and 5% slip.

Even my 600sci in stock configuration produces a lot more mid range torque than an Illmore 700 does.

Tim at OCM has driven both the 700 Illmore boat and my 600 boat, and says that my 600 pulls much harder in the midrange. ie more torque

I can easily pull a Bravo 32 prop to 4800 rpm, and still out accelerate my friends 525 boat in the midrange.

My current configuration is limited to 4.5 lbs of boost. My upgraded configuration will be limited to 8 lbs of boost.

I am not worried about the horsepower as much as the torque.

The current 26 Hering prop I am spinning was tried by SouthOCG in his 700 Illmore boat. He spun it to 5100rpm at 81 mph. I am spinning the same exact (and I mean exact) prop to 5400 rpm at 84 mph.

My upgraded target rpm is between 5800-5900 with a 6k rev limiter.

Sorry for rambling... I am just trying to get this sorted out in my head while waiting for my Whipple stuff.

Basically... I have to start testing all over again... and that is alright.

Chris

CB your right, a blower botor combined with a 5blade and Bravo is recipe for disaster. Too much torque for that drive. My first call would be to BBlades and let them know what you have , and the direction you want to go. If you can keep the slip to 10% with a Bravo prop, it will help you out a bunch.



Darrell.

Yes torque is the primary killer- RPM the secondary one.

A 4 blade will be easier on it. but Ive seen that drive under a lot more beans than you are throwing at it.

I think its a strong drive - a few guys here on oso that switched to it complain that that drive "cost" them a few MPH because it takes more power to turn.

Ive been dialoging with southocg about our x-dims and for some reason his rig is a few MPH or so off what mine is, but it sounds like hes still getting it dialed in. Hes got an Imco as well.

Im spinning a labbed 4b 28 6100 running at 90MPH- a lot more slip than you guys, like 16%.

Curious- Can you run pump gas with that pulley mod?

Ill be watching your thread.

(Love a ride in your rig someday- trying to hook up with southocg - you can check out my 2750 in the laveycraft forum under out of the mold Im blown away)




Uncle Dave

Thanks guys.

I have been in contact with Brett at BBlades, and he recommended a modded bravo as well. He applauded my efforts and results in regards to the low slip numbers, but said I should shoot for 10% slip as well to keep my drive alive.

My boat is an open bow, so is a little more nose heavy than SouthOCG's. I am also guessing that it will be a couple of mph slower per given horsepower. He is running 4.5 inches of prop depth, and mine seems to work better at 5 inches of depth... once again probably because of the open bow.

My favorite 4 blade so far has been my brother-in-laws modded 28. That is the one I ran 81.6mph with. Slip on this prop is about 11.6% which should be right in the ball park. The guys that did this prop are local, and now out of buisness.

Spinning this prop to 5800-5900 rpm should put me in the 88-89 mph range. My goal is to break 90mph.

I am hoping that Brett can dial me in a blade that gives me as much bow lift as my 26 Herring does now. This prop is simply amazing at this power level!

I will keep you all posted.

Chris

P.S. Uncle Dave - at above 6# of boost, it is necessary to run 91 fuel in order to eliminate any posibility of detonation on a hot day, which would kick the motor into Guardian mode and slow the whole show down.

While your mid range cruise may be a bit lower with the Bravo, you "should" be a MPH or two faster with the 4 blade (less drag on the prop).
Keep us posted.


Darrell.