720 hp gm big blocks
 

any info on 720 hp,modfided by high tec.The boat is a 34 foot scarb 3 with twin 720 hp .the drives are black hawks,with surface props.any info would be helpfull. the boat is a 19 87 .the drives are tr2 uppers with black hawk lowers.top speed should be 100+ mph

black hawk on a scarab III ??? taht is kind of a wierd setp. I had always heard blackhawks run like crap unless the hull was designed to run with them.

in any event 720hp through a blackhawk seem like a alot of power too. They use alot of bravo 3 parts and as we know non x series bravo drives weren't designed with more than 500hp in mind. Additioanly i'bve heard taht becasue of eth extra bite from the additional prop they break easier than a bravo.

as for the specific baot your intereste din i don;t know anythign abotu it. Where is it located? what year hull? where did you last see it?

No blackhawk lowers on TR2 uppers. If you have TR2 uppers, then you may have speedmaster lowers.

Blackhawks are not safe with anything stouter than what you'd bolt to a 1992 BravoI.

Puder is right - they share clutches and gears with B3's. If they really ARE blackhawks on 700hp on a big heavy vee hull, they are time bombs on a short fuse.

As far as BHawks not running well on a hull without proper setup, optimum performance always requires proper setup. When BHawks first appeared, I read a Hotboat test where they took 2 boats and tested them back to back with B1 and Bhawks. One was a 22' Nordic Vee Hull and one was a Eliminator airpacker. Both boats performed markedly better with the BHawk even though they were B1 boats from the factory.

HP limitations and price killed the BHawk. The warranty division was pulling their hair out. I don't reckon they ever made back their tooling and R&D costs back up on them...

Too bad. I thought they were WAY COOL.

I don't think that a 1987 SCARAB 3 with 1440 HP would go 100 + MPH.
Those boats are very heavy and not designed for speed.
I have a 92 34 SCARAB with 1200 HP and I am just under 80 MPH with a raised X.
The early 90's 34's were lighter and had some changes to the hull. My boat stock with 502's did 65 GPS -

tr2 upper and a wierd lookgin lower on an older boat??? soudns more liek a pair of speedmaster II. The SSMII bolts right up to a TRS transom assemblie. I think it might be the same upper with bullet shaped lower and some beefier guts.

i do definatly know that if its an 87 and has soem bravo derived drive the trasnoms been redone on eth baot and recut for a bravo. Doe sit have trannies??? if so you probably have ssmII drives as opposed to Blackhawks

thanks for the info guys they well mabe ssmII.i'm still looking more for moter spec.i'm brety sure they are 454 base. thats all i know about the moters.i would like to know comp. timming {max } bore and stroke. fuel requierments. max rpmthey where built by a compainy called pro tec ,in new york. witch might now be schafer racing.i'm going to run a compresion test that will give me some clue.if i can get my hands bettween the moters

Black Hawks are a one piece case,they cannot be used with anything else. There is no upper and lower case. Besides,pretty easy to tell,Got 2 props per drive? 700hp through a b hawk would last about 5 minutes if you were lucky. I can break mine with a 500efi. And yes,they do work rather well on a light cat. Gained 8 mph when I converted from a B1.

I would be interested to see what your boat and any one else that has a S3 runs. I have a 1987 Scarab 3 with TRS's. I dont want to burst your bubble but 100 mph is not possible with that set up. When my boat had 370s it ran 62.4 on gps that was the best i could get out of it. My boat is a Kevlar layup with a blueprinted bottom. I would like to here from anyone who has a scarab 3 so that i dont go in the wrong direction with my modifications. This winter I am fabricating extention boxes with the trannies in the boxs, raising the x dementions 3" from origanl location. If any one has done this I would like to know how far back to extend the boxes and how high to set the x demention. if nobody has attemted this I will let you know how it works. As for the changes in the hull in the post 90s boats there were none, just deck changes and a platform intergration. If anyone had different information i would like to know. I was told that the 34's had a hook in them, I have to disagree with that becuase when i went over my bottom i could not find any varyation that lead to a hook.

i've heard of et hook thing too. I wasn;t awrae that any scarbIIIs were made of kevlar though. Perhaps thats why your's has no hook. 62 with 370 hp seems pretty good out of a scarabIII.

If sonic can make there tanks do 100 i dont see any reason why my S3 cant do 100. Any one that boats the 1000 islands knows my boat. Its the only one up there like it.