PDA

View Full Version : How much HP to a blackhawk



craigdskilling
12-07-2012, 05:00 PM
How much hp can a blackhawk take.I am doing a 350 mag with a whipple charger.The motor will be mod and re worked with a bigger cam and pistons everthing bigger to handle 500+hp.I hope to have the revs no higher than 5200.the drive is a 1:5 ratio with 31p props.I was told that they can handle up to 600hp but they dont like high rpm.thanks craig.

MOP
12-07-2012, 05:34 PM
Curious did you raise the X, IMO you give up 8-10mph not doing so.

Phil

craigdskilling
12-07-2012, 09:02 PM
Phill when i get the motor out i am going to have the drive off to so i have a guy that is going to look at that.17.5" to center correct.what is the proper way to raise it.it might only be an 1" or so.you think that could make that much of a difference.what about the motor mounts do i have to get new ones.

MOP
12-08-2012, 11:20 AM
The higher X is important to get the gear case completely clear of the water flow, if any part of the case is in the flow it produces stern lift. Add that to the inherent stern lift of the dual props, what you end up with is the possibility of bow steer at speed. I think you may be shooting for more HP than you will be able to use, think about the fact that Steve's 18 which was setup with the correct X managed 79 MPH with a dead stock 300 Merc. The transom will need the plywood replaced and glass and gel work, the cost of that balanced against the speed gain makes for cheap money.

Phil

P.S. Do your best to get hold of a transom fixture, make the job a ton simpler!

craigdskilling
12-08-2012, 02:22 PM
What is transum fixture.I have to do some work on the hull.I was going to redo the hull is there anything i can do there with the strength.and how much can blackhawk take.

craigdskilling
12-08-2012, 02:33 PM
I was running a great 383 but i am pulling the motor tomorrow,it's sold and i have the motor being worked on.I have all winter now to work on the hull so i could use some help here.i now that asur88 is running 91 and i wonder did he do anything to the hull and what about the 18 mule running 115 i think.so with my set up if done right could see some crazy numbers .thanks craig I really want do this right the first time.

MDonziM
12-08-2012, 04:04 PM
Don't worry about your hp on a BH. 500hp is fine you just have to be carefull not to air it, remember, your propshaft is like 7" higher vs standard so you come out of the water quickly. I have a 540ci/600+ hp in front of mine with 75hrs and no issues. (and I bought it used from MOP so I have no idea what the total hrs are) I have seen 20cigs that have 750 to 850 hp and they grenade them (with 1.36 gears). Like Phil said, the x-dim is essential to getting the most out of it.

craigdskilling
12-08-2012, 04:24 PM
Did you raise your x and what about the hull im freaking out:eek!::eek!: i feel like the boat is going to grenade under me.

MDonziM
12-10-2012, 09:07 AM
I did not raise the X on my boat. There are a lot of variables to consider. I'm not sure what you are saying about your hull... Yes I had my eng compartment totally rebuilt. New stringers/gussetts, stregnthened bottom, new tabbed in "shelves" and reinforced bulkhead, custom eng mounts etc.

younger
01-13-2013, 01:23 AM
Craig hope you have it back together for the 1000 islands come summer. It is going to need to be fast if you want to run with the creamsicle. Mop is right that the x is criticle in this app. My 16 was at 17" ps to crank cl if I recall an it could have gone up more to take full advantage of my motor. I still feel to this day the boat would have run very close to 100. Before I sold it was running in the upper 80's. This is not to give any false impretions but I was forcing my speed with some major motor. As you know it worked well. For me I started with the goal of an 80 mph stock appearing 16. When I did my transom and stringers I raised it as far up as I could without cutting the hatch. The boat handled awsome to the mid 70's but was never family safe above that. I looked at padding the bottom to get my extra x dim. and some safety factor. That is when I decided It was time to move on. I have personally seen your rig run and run well it does. The awnser to your question is to go faster you HAVE to raise your x. If you are building a new motor go the old sayings way, carry the weight carry the cubes. A squeezed 350 motor spinning 5200rpm will not produce the power of say a 427 sbc. The hp numbers of the 350 may look good but torque is what moves ya. These stroked motors are awsome, look like a sbc but swing a hammer like a bb. Something to think about. pic of the creamsicle Norm

CHACHI
01-13-2013, 07:20 PM
Norm, Florida numbers?

Ken

craigdskilling
01-13-2013, 07:54 PM
Hello Chachi and Norm its been along time hope the holidays where good.So i think i will have the torque from the new set up, the whipple gives the torque of a 502 but more hp like 600.My boat is up at Port Rowan and ron banks were we are going to look at cleanning up the engine comp.we are going to get rid of the swim platform and raise the exhaust up.I'm not sure if we can raise the x because of the whipple but when the motor is done and up there we will see .I agree it would be great for the performance.But i'm sure it will faster than my old u look at asure18 and he is in the 90+not saying i'll be in your range but u never no:bonk:I think were all nuts going that fast but its the last plase to have fun with speed.I think it will be back together in time.

younger
01-13-2013, 09:29 PM
Ken the boat was made in the sunny state and was used in the Hot Boat cover boat in 07. As well as making its first appearence at the Miami boat show. Ken the 2 feet of snow has melted in my front yard and the river is a growing. Get ready for summer. Craig sounds like things are comming together. Hope you can run some numbers with the new combo. I sould be able to run along side! I'm looking at setting up a couple of gatherings come summer probably in june and then in aug. I will post in the gatherings section when I get things around. Craig have any specs on the motor, cam, heads, exhaust, carb, efi, do tell what the guts are. Was at the Toronto boat show today and was 8 degrees and sunny. Bring on the boats.