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View Full Version : Supercharging vs. Modifying



Jeff Griffith
02-27-2003, 05:59 PM
I bought a 22 ( '95)blackhawk last year--after having an 18 for some time.
I'm considering some modifications and interested in getting some experienced advice:

1. I have a 502MPI, with the standard manifolds and silent choice exhaust. I would like to upgrade the exhaust to a better manifold-- while maintaining the silent choice.
Have any of you undertaken this with a blackhawk? Which manifold OEM and what's involved?

2.I am considering the merits of supercharging versus engine modifications. The engine now is bone stock--probably 120 hours on it. An engine guy told me that I could probably pick up 100 or so horsepower, without radical modifications-- with some engine work--probably at less cost than a supercharger set up.
On the other hand, supercharging sounds interesting, also. After a little review, I would lean toward a Whipple system--even at the higher cost. But one concern I have is that
I am already turning 31" pitch props at about 4900RPM. Most of the supercharger
performance hype is based on being able to upsize the prop pitch several inches to pickup
speed. With a blackhawk-- the props aren't
available. What will happen to outdrive and engine life-- if instead I up the RPM 's? Any of you have experience here? Does the Blackhawk live in a supercharged setup?

I appreciate hearing about any related experiences
Thanks

Greg Maier
02-27-2003, 06:22 PM
Jeff,
I have a 95 Non LE Blackhawk. I just installed Stainless Marine Manifolds and long risers on mine. I don't have quick and quiet (why would you want such a thing :D ). The exhaust was easy to swap out.

With regards to upgradng the engine, keep in mind that you have a raised X-Dmension, and there is not much room between your engine and your hatch. On mine, there are actually a couple of places on the hatch that are notched out to to fit over the engne.

How fast have you had her up to? In my opinion, mine is fast enough. Mine did 80 GPS bone stock, and it was a wild ride. I don't have any plans on modifying my engine for more power.

Woodsy
02-27-2003, 08:05 PM
Jeff,

If you upgraded to a new exhaust system you could probably find an exhaust riser from whatever manufacturer you choose that would work with your silent choice. Thats pretty much a no brainer... Stainless Marine is an excellent choice. Don't forget to upgrade to a K&N Flame Arrestor to take advantage of your motor breathing better.

When it comes to enhancing your hp rating, either supercharging or naturally aspirated, you are 100% right that props are going to be an issue. Either way you go, you will have to rebuild the drive using the new XR gearset. Mercury has a bunch of other improvements for the drive available as well. You could gear down the drive to a 1.36:1 ratio, this will spin the props faster, but you will probably have to find a set of 29 pitch props. I don't think the motor will have the HP to pull 31P's at that high of a propeller RPM. But you won't know until you actually put it all together and test it. IF you don't upgrade the BlackHawk with the new gearsets, I don't think it will live very long in a high HP application. I would also suggest finding a spare drive... they are getting harder to find and more expensive... right now used ones are running about $3800 or so and you'll spend about $1K or so for the upgrades. New ones, when you can find them run $6K - $8K. Merc just released a dozen or so at a list of about $8800 no warranty. If you wreck your case your pretty much out of luck, although it is rumoured Merc is sitting on a few BlackHawk cases... but they are HUGE $$$.

I don't think you have the height in the engine compartment for any type of supercharger setup, with the exception of maybe a Procharger type. A whipple would require a new engine hatch, or extensive modifications to your existing hatch.

There are Pro's & Con's to either setup. There are quite a few on this board who have done it both ways, some like superchargers, others prefer big cubes. Its really individual preference.

One other option you might want to consider, get yourself a Bravo 1, and bolt it up in place of your BlackHawk. Keep the BlackHawk for those ever popular Donzi events, but use tyhe Bravo for your everyday running. Breaking a Bravo is relatively cheap compared to breaking or replacing a BlackHawk drive. Props aren't an issue either. Because of the raised X-dim from the factory, the Bravo will perform awesome, make sure you get one with the Low Water Pickup.

Woodsy Von BlackHawk :D

BigGrizzly
02-27-2003, 08:31 PM
Thr only superchargers that wi;; fit are the procharger or the Vortex ones. Your engine guy is stroking you. If you di the mods he wil be upping the antie as you go. than you have the issue of driving the Blackhawk, this isn't any little 18 with an alpha. th is a different bread of boat and requires your attention all the time while driving it. It will tak som getting use to stock. The drive isn't that strong to begin with. A super will net about 550 on that engine with 570 foot pounds of torque and no other mods. Now you have to keep it in the water. Drive it stock and lear how it works befor you mod the engine. the easyest way to go is a 540CID and headswith a Twister cam . I saw one dynoed friday at 624 with 630 poundas of torque and is not supercharged, and sounds almost stock- but it isn't cheap. I would do what Woodsy said and do a bravo, Merc is not going to do another run on the black hawk drive according th their powers to be. So save it.

Bad-Tat
02-27-2003, 08:40 PM
Jeff,
Listen to Greg and just drive it for a year. As Randy says it is a handful bone stock! and he has been driving Donzi's for years! (old guy!) Not a set it and cruise proposition at all! I have been accused of flying more than boating in mine. Seriously consider moving the trim tab switches to the throttle handle. when you need to dump them it's right now! Not when you can get your hand down to the dash at the stock location. Mine pulls 78 without even trying with serious tab dragging to keep the bow somewhere close to the horizon!

Greg Maier
02-27-2003, 08:59 PM
Bill,
How are you coming with the steering? You were going to put some Mayfair/Eickert Compact Rams on the Bad-Tat, weren't you? External Steering and the Gaffrig two handle throttle/shifter are my next upgrades. I already have the throttles, they have four buttons on them. One for each tab independantly, one for the tabs together, and one for drive trim.

DUCATIF1
02-27-2003, 09:46 PM
Whipple type superchargers are very durable and produce some good numbers. The Paxton style set ups are a lot cheaper and will probably adapt to your set up easier. Please also understand that a lot of supercharger set ups require additional ignition and fuel system upgrades. Is there chip in your stock system?, if not mods will be costly to remap computer without going to complete new FI set up. Why don't you try modern cam profile to match your RPM range you seem to be stuck in rather than trying to do the reverse. A modern cam (under $300) and about $500 worth of head work (pocket porting and competition style valave job) can easily add 50hp and in the range you needand increase fuel efficiecy. The biggest mistake people make is look at hp & tq numbers and not relate them to the rpm they are going to be used in. Read Lingenfelter's book he is the king of matching a set up. If you put a motor that makes 700 hp at 8000 rpm and 500ft lbs of TQ at 4000 and you spend most of your time at 3500 rpm it will be useless. Take that boat for a ride and log your cruise to top rpm and call cam company with info. You will be rewarded with faster boat not a dyno sheet that shows big numbers in a range you cannot obtain. Save the big dollars in re gearing set up and build up induction system to operate in that range. It is actually easier to sometimes start with one fixed varaiable. Low psi superchargers like bigger cams and lite port work so you have nothing to lose. Good luck Brian

Bad-Tat
02-27-2003, 10:04 PM
Greg,
Yes putting on Mayfair spacesaver steering on the Tat. Brett had to modify the wing plate as it seems there are 3 different rear covers for the B'hawk drive. He has it done and am picking it up next week as will be right by there for Bike Week. Have a big hole in the dash from removing the hyd steering pump so will plate that to mount the new steering. Let me know how your Gaffrig throttles work out. I have just put a small switch on the handle to do both tabs at once. Also going with the closed cooling as well as SM manifolds. Hopefully will do better without all that weight in the back.

Greg Maier
02-28-2003, 04:02 AM
Bill,
Is your steering going to fit inside oy your K-planes? You will have to send me pictures when you are done.

Greg Maier
02-28-2003, 04:03 AM
Bill,
Is your steering going to fit inside oy your K-planes? You will have to send me pictures when you are done.

Bad-Tat
02-28-2003, 06:31 AM
Greg,
Yes the steering will fit inside the K-planes. Everything in line with the gimbal. The Space Saver is the only one that does. He designed them for Cats with no transom space at all. Check out Eikerts web site to see the difference in the wing plate. About the only thing he doesn't include in the kit is the transom bolts due to the varying thicknesses of transoms. Will do the pix thing once they are on.