gcsprayjr

What would be the most bang for the buck upgrade for a 1990 7.4 Liter/Bravo 1.

The boat is a 1990 Mach 1 22 foot sport cuddy. The engine is the original. Currently it has the simple OEM Mercruiser through-hull exhaust, an MSD ignition, and is otherwise stock. It came from the factory with this exhaust, and has never had a trough-prop exhaust. According to the SN the engine is the 330 HP model.

With the 21 x 3 Stelleto the boat will run 54.9 GPS with a full tank of fuel, tank of fresh water, two people and gear.

With the 17 x 4 Revolution, the boat will run 44.9 GPS, loaded the same way.

With the Revolution 17 x 4 the boat will pull three 150 lb people on the salom from a deep water start, and holeshot is pretty impressive. The thing that keeps nagging me is that my 17 foot bass boat with a stock 115 2 stroke outboard is faster to plane, and although it will only pull two on the salom, it pops them up quicker then the big block will.

My mechanic says that it is running correctly for the beast that it is. Everything checks out, from vaccum to compression.

I am wondering if a marine crate 502 would bolt into the stock location, work well, and not over stress anything?

I would like to get more torque for a better hole-shot with the power prop, and possibly 65 MPH on the top end with a speed prop.

Thanks in advance.

pitts1313

I had a 22 scarab with your same engine, same style boat. Mine couldn't get a holeshot like a bass boat. The big block is a lot of weight in the rear and just heavier than a bass boat. I Had triton bass boat, that would run 67, wouldn't get one slalom skier up! But the boat would leap up on a holeshot. You probably got enough hp/torque. Trick is going to be overcoming hull/weight to pop up on top(tabs?) and propped for pulling, not speed. The engine will most likely swap out, but I hate to see you do the engine swap and still no holeshot.

4bus

iTrader: (4)

I disagree, I have seen HP make a smaller boat come on plane like the hull was re-designed. 25 Ft checkmate from 385HP to 600HP, a 271 Formula from 365 to 500HP, and a 24 Baja from 330 to 500HP. All of them "seat of the pants" tested and it was a different world. 2 of the boats required the back seat riders to move forward to plane if fully loaded before the increase. If you are going to go with a 502 go with a 500HP or 500HP clone.

apollard

You can get the holeshot and quicker pulling with tabs. I've done it on several boats. But, if you want the speed, you'll need more torque to move the prop faster (or move a higher pitch)- ie, more HP.

That said, you may still need the tabs to get the holeshot and pulling you want. Part of that depends on the hull.

If it was me, I'd try a set of tabs first. Second hand, you can get some good deals. I got a nice set for $250 bucks for a 21' hull. Made a huge difference, and I picked up a couple mph since I could trim for speed and still use the tabs to adjust the hull.

pitts1313

Tabs best bet.A marine crate 502 (guessing 50-75 more ft/lbs more than the 330) won't be that dramatic a difference as the high horsepower options mentioned above. From my past boats, I learned you cannot make bass boats or a performance hull into a ski boat. Can you improve the holeshot with horsepower? Yes, but the engines above are way more than a crate 502. Also V hull with a big block just isn't going to leap up like the shallow hull(shallow draft) of a bass boat. V hull w/ big block also has more weight to lift up and sits deeper(further to leap, and the deeper v will only rise to the top with speed). Horse power won't overcome a hull that is a hindrance to hole shots. Hulls are the most limiting factor in a boat's performance. You can throw as much HP as you can, only to find the gains diminish as you go higher. Most high hp setups with bravos avoid "hole shots" to preserve the drives.The tabs are best bet. Just hate to see a fellow spend a bunch of money on an engine for a little improvement or ripping a drive with a ultra high Hp on a bravo.
es.

Kidnova

I agree with 4bus. I had a 7.4/330 in my '95 23 Nova and it did 57ish. I put a ZZ502 GM crate in it (567 tq/502 hp) and would do 69-70 GPS any day. Best was 73. I only did a few hole shots... just to do/try them. No tabs and it was on plane in no time flat, pun intended. Now I have a 557 in the Humble Little Nova just shy of 700 hp. And no hole shots, won't even bother, want to save the OD.

You might want to try a Mirage 23, the old style, not the "plus". That's what I had on my Nova with the 7.4 and it was a pretty good all around prop. RPM was right at 4600.

Oh, if you change power, might wanna save your 7.4 for when you sell the Mach 1.

gcsprayjr

Thanks for all of the replies. It sounds, like the boat is not going to be the best boat for sking, regardless of what we do to her.

Just for the record, the boat has factory installed hydrolic trim tabs. They don't seem to make a lot of difference in hole shot. They do make a slight difference in top speed, however it is tricky to get the outdrive trim and the trim tabs set for perfect top end performance. My best speed run to date was with the trim tabs up and out of the water, with the ourdrive trimed up just slighly. The boat would run 56.7 GPS, but feels unstable running like that. My mechanic says that trim tabs are not very effective on boats less then 24 feet. That is why they seem to have minimal effect on the performance of this boat. I have found that the trim tabs work nicely for leveling an unevenly loaded boat, but that is another story.

The Mach 1 is a deep V style hull very similiar to a Well Craft sport hull. The boat is very heavy, 4000 lbs, however it rides very smooth and straight. It is also balanced so that it would be difficult to stuff the bow, which is a good thing for a boat that has multiple drivers with various levels of experience. So it is not all bad.

As for the bass boat, it makes a wonderful ski boat. My family has owned it since new. It is a 1980 model Astroglass 17.6 with a 1150 Mercury (115 HP 2 stoke six cylinder inline) outboard, The prop is a 19 x 3 Quicksilver. The boat has a top speed under ideal conditions of 41.3 GPS, however it will run a consistant 37 MPH all day every day with almost any sort of load. This sounds crazy, but the boat will pop two 200 lb skiers up on the salom without any difficulty at all.

My mechanic says that both boats are performing as they should and that what I have is all that I am going to get from these boats. It sounds like from what you all are saying and also what our mechanic has told us, that is just the way it is.

As for selling the Mach 1, probably not, or the other one for that matter. The Mach 1 is slowly but surely going to get some custom paint, interior, and guage work. She is in pristine like new condition with 350 hours on the clock. The boat has been a pampered garage baby all of her life and has only been used in fresh water. As she ages, I am planning on some custom refinishing to keep her looking her best.

At the age that I am these boats will probably last me as long as I am interested and able to boat.

Thanks to everyone for your honest feedback to my original question.

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Griff

Use a Merc High Five prop for pulling skiers. It will jump on plane.

gcsprayjr

What pitch would you suggest?

Budman II

iTrader: (1)

What about putting on a Bravo III lower? I know these are usually seen on cruisers, but a friend had one on his 25' Cobalt with a 454 Mag, and the boat would jump up on plane and run mid 60's.