rjcardinal

I'm in the market for a used 28ZX.

What is the true GPS top speed for the boat with twin 350 Mags and a normal load. How would the boat plane with a five people and a full tank?

What is the true GPS top speed for the boat with a single 502 Mag and a normal load? Would this boat have a hard time planing with five people and a full tank?

What about with a HP500EFI?

Does anyone out there have a single 502 Mag supercharged? If so how does it perform.


The problem is, the single engine boats in the condition I want fit my price range while the twin engine boats do not. Reading this Donzi Forum there are people with single engined 26ZX's that are only getting low 60's out of them. I am concerned that a single engine 28ZX will be underpowered for my tastes. My current boat is a 22 Scarab with a 502/502 that does upper 70's. I would like to do at least 70.

The twin Scorpion 28ZX is my dream boat, but out of my price range.

Any help and insight would be greatly appreiciated.

Ron

Kentz

Talked with a guy that had a leftover 2001 with 377 Scorpions. said it would run right @ 78GPS with Mirage 3-blades 25P. Hope this helps.

rjcardinal

Thanks Kentz,

However that sounds like salesman talk. 78mph with 25" props with a 1.5 Bravo calculates to over 5600rpm. I am looking for actual speeds with a normal load.

Ron

Out There

I have a 99 28ZX with 350 mags. 70mph on GPS. I have 25P mirage plus props that turn 4500 wot. Just sent them to York propellers in an effort to bring the rpms up 200 or so and maybe pick up 1 or 2 mph. I have read three magazine tests on the boat.
All three had 350 mags and speeds ranged from 70-72mph with 23P mirage plus and 5000 rpm wot.
I think it would take much more than a 500HP to hit 70 with a single engine application.

rjcardinal

Thanks for the reply bently.

I am still having trouble making your numbers work. 4500rpm with a 1.5 Bravos 10% slip and a 25" prop comes out to 64mph. To get 70mph with these numbers you would have to have a slip of 1.4% which is hardly possible. Are your drives 1.36 to 1?

5000rpm with a 1.5 Bravos 10% slip and a 23" prop comes out to 65mph.

Am I missing something here? Do all these boats come with 1.36 drives?

Anyway, how do you like the boat. The 28ZX with twin 350 Mags is what I am looking at. Does the boat labor when comming on to plane with a full load of fuel and people? How is its drivability in normal pleasure conditions?

I found a single 500EFI 28ZX with a Blackhawk drive for sale and the owner says it does 75mph but I am worried about the drive and finding props for it.

Thanks again for the response

Ron

Out There

I would not get to hung up on the prop slippage calculator. I have used it as well and calculated slippage on all three magazine test boats. They all came out very close and extemely low. Lower than would make sense. I found two of the articles and here are the stats:
http://archive.powerboatmagcom/2000/...ure/donzi.html
350mags 1.5:1 gears Mirage Plus 14 5/8 x 23 3 blade
71.6mph at 5250 rpm -" both standing start and mid range acceleration were strong "

http://free.hotboat.net/tests/docs/Donzi_28ZX_398.htm
Same engines/props- 70.9mph at 5000 rpm

The third review was in Hot Boat and was the bowrider model

Hopefully you can pull up these reviews. I looked at the reviews very closely before buying my boat. My boats performance has more than met my expectations. I have had it full of gas with 5 people and it planes very easily.

I would stay away from a 28 with the Blackhawk. My last boat was a 22 502/Blackhawk. Parts availabilty would be a concern at some point. Handling was a sacrifice with the 22.

rjcardinal

Thanks again for the reply bently. Its wonderful to get an owners first hand knowledge. Its great to know the boat will plane easily with a load. I have had boats that dont and with all the no wake zones around I feel its important that it does. I will not buy the Blackhawk boat. You and others have confirmed my suspicions about it.

I still cant get over the slip numbers on the boat. I have helped many people prop their boats and the formula has always been right on. The only time I saw slip numbers below 10% was on a perfectly dialed in cat with a conseritive x-dimension. I read the reviews you posted but 70GPS with 5000rpm and a 23" prop still seems impossible. I know twin engined boats are more efficient than single engined boats and that a step hull helps even more but 1.4% slip? I must be missing something. I'll figure it out sooner or later.

Hopefully I will get to test drive a 28ZX with twin 350 Mags soon. I will bring a hand held GPS to convince myself. If she can hit 70GPS then she is the boat for me.

ANYONE ELSE HAVE A 28ZX?????

Theres got to be another on the board.

Ron

pstorti

I had the pleasure of speaking with a number of Donzi factory guys at the boat show. I'm like you in the sense that I have a 22ZX and want a 28ZXO. I also thought I would rather have a single motor, the new 525EFI to be exact. I figured that motor with a whipple or a procharger would get me the same power as a pair as a pair of scorpions with less weight and less drag maybe good for 85mph on the right day. Nick Miller one of the VP's at Donzi was nice enough to give me a pass to go for a ride on the new 38ZR, the gentlemen who gave the test rides happen to be the same guys that do the actually testing of the boats with all the different motors and drives and props ect. They told me because of weight distribution the boat actually handles much better with twins and that Donzi was actually thinking about discontinuing 28's with single i/o's. So I've stopped dreaming about blown 525EFI's and now I'm dreaming about blown 6.2's. The stock 6.2's have 320 horse each so the boat should go low 70's no problem, they are capable of supporting the new smartcraft system which is awesome, and for an extra 10 grand a pair of whipple's will turn them into 500hp monsters which should get the boat into the high 80's if not low 90's with some tweaking. If you still want a boat with scopions Perico Harbor Marina has a brand new 2001 28ZX with scorpion's for $79,000 listed in the Dupont Registry, i'm pretty sure the graphics are standard scorpion yellow with blue checkers. Their number is 941-795-2628. I was going to buy it but i decided i really wanted the ZXO. I hope this helps.

32fever

Is that the one at the "used car lot" place down from Grand Prix? If so, I looked at that boat with a friend of mine. it's a nice boat for someone, and I bet RJ could get that on at a steal. It had some chips in the bottom, which is rare for a "brand new boat". It won't run 78, though, I'm sure of that. after talking with the guys (not the owner, we got there to look at he was an hour late to work, so we left), they also were saying how they ran a 38 Donzi and were smoking Fountian factory race boats or poker run boats or something somewhere. (I quit listening when they started speaking negatively about Fountains.) BUt, anyway, it might be a great deal..???? Kentz might have their info so you can check. I'm sure it would run well, 78 might be a stretch, but bet 73-75-ish would be possible. I'd at least make a phone call.

In my opp, better to exhaust your "dream" boat purchase options first, you never know. Nothing to lose, unless it's sold....

Mark

Kentz

Mark - that be the one!, Its been around a while, and sorry you ran into the Cincy boat dealer trash talk

Its been sitting a while and I think it would sell right. RJ, no expert on prop slippage, but I'm pretty sure those scorpions would run out to 5400. Bently is getting 4500, there is a LOT of room here (mph).

Seriously, if you need the e-mail address I can get it for you, now where's my commission check?