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Madcow
07-03-2011, 11:06 AM
Well, this boat has not killed me yet, it must be time to try something new. The best i've got out ot with a bravo is 79.6, and it is a handfull. We'll see what this does.

Carl C
07-03-2011, 11:48 AM
Nice. Should work well. Watch out for the steering popo....:nilly:

Madcow
07-03-2011, 12:09 PM
Nice. Should work well. Watch out for the steering popo....:nilly:
Yeah, that does scare me, I'll go easy at first see how the boat likes it. Trying to decide if I want to keep this one or buoild a 22.

silverghost
07-03-2011, 12:44 PM
Pretty slick !

Can't wait to hear how that blackhawk drive performs.:nilly:

craigdskilling
07-03-2011, 01:14 PM
I have an 18 with a bh running 75 with 27p.what kind of power do you have in that.Also what are you running in props.

MOP
07-03-2011, 01:25 PM
The handling will surprise you, -0- steering torque and less roll up in turns. You will not achieve the drives potential at the stock X, Think about this Steve's 18 at 17-1/2 X made 79 on a good day with a bone stock 300 Merc. A decent 383 should get into the high 90's possibly hit 6 digits with superb control. The gear case must be completely clear of the water flow, even the slightest bit into the flow produces quite a bit of stern lift which could make the azz end squirrely. Setup correctly it will ride on rails, will we only have one 18 that was setup right!

Madcow
07-03-2011, 01:32 PM
The top of the torpedo is 3+" above the bottom. The skeg on this thing is monstrous that must be why so much control. The steering is going to be the wild card. If I like the drive I may keep the boat ant put steering on it. There is no way this can last long with stock steering. The props are 31s and the motor is a 425 HP 383.

Madcow
07-03-2011, 01:33 PM
The top of the torpedo is 3+" above the bottom. The skeg on this thing is monstrous that must be why so much control. The steering is going to be the wild card. If I like the drive I may keep the boat ant put steering on it. There is no way this can last long with stock steering. The props are 31s and the motor is a 425 HP 383.

Carl C
07-03-2011, 02:06 PM
possibly hit 6 digits :eek:

MOP
07-03-2011, 02:18 PM
Steve's boat had internal hydraulic steering, with -0- drive torque external is over kill. You are running 125HP with a lot of torque over a stock 350/300HP and only doing .6 faster than Steve, that should give you a pretty good idea of what you are giving up speed wise. Also the stern lift you develop having part of the bullet in the flow makes for poorer handling at top end. I had just a hair over 1/4" of the very bottom below the bottom, over 4000 the lift was noticeable.

craigdskilling
07-03-2011, 08:14 PM
What is your ratio on the drive.mine is a 1:50 and also a 383with 400+.what kind of cost would you look at raising the x on the boat.

younger
07-03-2011, 09:38 PM
This could be interesting! For example my 16 with the bh has run 84.4 with a monster sbc. On yours sould be good for 5 or 6 mph. .

MOP
07-04-2011, 08:29 AM
What is your ratio on the drive.mine is a 1:50 and also a 383with 400+.what kind of cost would you look at raising the x on the boat.

You would have to pull the engine and drive, fill in the current cut out then re-cut it to 17-1/2". If you do it cost is minimal but a fair amount of work, having it done it would quite expensive, just a guess around $2,500. Look at it this way you could put the same $$ in your engine and not come near the same top end. Don Tamm built a radical big $$ engine pumping around 500hp and did not hit triple digits in his 18, he pretty much knew he was giving up on top end but did not want to make the boat a single purpose boat. I disagreed with single purpose, if the boat is modified for the BH you can still run a Bravo drive. It will still perform better than the same HP setup at the stock 15-1/2". It is similar to running a 2" shortie. Anytime you raise the X you gain top end, also raising the X helps to reduce porpoising.

Madcow
07-04-2011, 12:34 PM
One other problem with raising the X is then the engine would be sticking out of the hatch.

MOP
07-04-2011, 02:59 PM
One other problem with raising the X is then the engine would be sticking out of the hatch.

Quite true, Steve had a very nice raised section with a scoop in the front, leaving the X at 15-1/2 you might as well run an SS that will run faster than a low BH. Rootsy proved that with a pumped 350 that was not making near the hp you or Younger are!

craigdskilling
07-04-2011, 07:30 PM
when you say 17-1/2 x do you mean from the bottom of the boat to center of where the shaft would enter the engine.I think i will be doing that for shure this winter.I already have the hatch cut out to fit.

Madcow
07-04-2011, 08:28 PM
Well, that thouroly suked! Proposed wildly till 40 mph then just handled badly. Got it up to 70 but was not comfortable going any faster than that. Talked to the guy I got it fom, and he indicated it was too deep. If I had another drive with me today it would have wound up deeper.:bonk:

MOP
07-04-2011, 08:55 PM
when you say 17-1/2 x do you mean from the bottom of the boat to center of where the shaft would enter the engine.I think i will be doing that for shure this winter.I already have the hatch cut out to fit.

Yes and take some time to research it here there is a ton of info, there are some nice pictures. The BH drives have hashed and rehashed! Phil

younger
07-04-2011, 09:38 PM
On mine it does one thing and one thing only go fast, forget tubing, ski, or slow cruising. 3000rpm if I remember I am running in the upper 40's. 4000 well into the 60's. The bh is not just a bolt on. It will take some seat time to figure it out. The x is the key, top speed and handling improve. If I recall my x is 16.5 inches as high as I can go without major mods to the back seat and hatch. I have a 16 so realestate in the engine bay is at a premium.
Lots of info around, stick with it.

Madcow
07-04-2011, 10:51 PM
On mine it does one thing and one thing only go fast, forget tubing, ski, or slow cruising. 3000rpm if I remember I am running in the upper 40's. 4000 well into the 60's. The bh is not just a bolt on. It will take some seat time to figure it out. The x is the key, top speed and handling improve. If I recall my x is 16.5 inches as high as I can go without major mods to the back seat and hatch. I have a 16 so realestate in the engine bay is at a premium.
Lots of info around, stick with it.
I would have to agree with that, the faster I went the better it seemed to want to take a set, and all indications were that it could be very fast. With time I may have got more comfortable with it but i don't want a one dimentional boat.

thriller
07-05-2011, 09:57 AM
Wanna sell it?
PM me if interested..Always looking for spares:wink:
Mike

Madcow
07-05-2011, 11:09 AM
It's not mine I just borrowed it.

silverghost
07-05-2011, 12:34 PM
You sould try to find a Shorty lower unit .
It may give you far better results without a major X- dimension change that is really needed for that Blackhawk surface style twin prop drive to work correctly.

Mercruiser did not build this Blackhawk drive very long.
I was all excited when I first saw one at a boatshow.
In practice however it is a very trickey drive for many to drive properly and safely & it is NOT for all boat applications.
There IS a reason for it's being dropped by Mercruiser.

Many love it however when propely set-up on the right boat, at just the right X- dimension & with an experienced high speed boat driver.

VetteLT193
07-05-2011, 01:45 PM
The main reason the drive was dropped was the very limited market. It is only a drive for certain boats and a certain crowd. There are plenty of people that would like an 18 donzi to run fast and maybe tube behind occasionally, but that's out with a BH drive... fast only.

With that said... I'd love to try a set on my 28 ZXO :cool:

Madcow
07-05-2011, 01:52 PM
Yeah, thats the thing. It goes almost 80 now with a bravo shorty and a quad 4, and it is very well manered up to about 65. Only thing I wish I would have done when I blueprinted the bottom was sharpen the keel. I could not find anyone who thought it was a good idea, but now that I've ran her this way for a couple years I can see it would have been worthwhile.

yeller
07-05-2011, 04:00 PM
Well, that thouroly suked! Proposed wildly till 40 mph then just handled badly. Got it up to 70 but was not comfortable going any faster than that. Talked to the guy I got it fom, and he indicated it was too deep. If I had another drive with me today it would have wound up deeper.:bonk:I've tried all 3 drives. Stock Bravo, -2 shorty, BH.

I'm surprised your boat handled badly with the BH. Mine handled badly with the stock Bravo and the BH cleaned it up. (Mine's a 22 though).

Like yours, the BH porpoises wildly, except mine doesn't smooth out till about 50~55. After that it is absolutely awesome! With the stock Bravo, I could rarely control the boat above high 70's, and I could only break 80 for a few seconds at a time before having to back down. First time out with the BH I hit mid 80's and could have kept it there forever it felt like.

After testing all three setups, (for my boat) the best compromise would be a -2 shorty.

Bravo: Porpoised to 45~50, decent handling to low 70's, poop time at anything approaching 80.
Shorty: Porpoised a bit more (but not much) than the Bravo, good handling to mid/upper 70's, controllable (but cautious) handling into the 80's.
BH: Porpoise extreme to 50~55. Outstanding handling above that. Anything more than mild turns really suck though.

That said; Titan ran my BH on his 04 22 when I was trying his shorty and he didn't seem to notice an increase in porpoising. Seems to me that the BH (like props) is boat specific, and what works on one boat may or may not work on another.

craigdskilling
07-05-2011, 08:39 PM
The few times i have been out never felt any of that.porposing never happened felt solid all the way to 75 and climbing to the 80.but the rpm where still to high at5500.Younger on july22,23 I think Shea is going to the Muskokas for a get together.I'm not sure how your boat will be but you can have a seat in mine.Hope i can do some prop test.