Donzi 22 Classic Performance
 

I have a 1996 22' Donzi Classic with a 502 Magnum MPI. It is absolutely stock and does 74.4 on GPS at just over 5000rpm, I am hitting the rev limiter at 5050 but just barely with a stock 25" Mirage Plus prop. Silent Choice open and trimmed well.

I am wondering if anyone has any suggestions regarding performance upgrades for this setup without getting into the heads/cam/block, etc.

I have read much about exhaust changes, intake changes with ignition/fuel pressure reg/reprogram ECU, labbed prop, etc.

Does anyone have experience with any of these. Would anyone recommend for or against any of these changes or anything else.

I look forward to hearing your input.


Thanks very much,

Pismo

I just put Stainless marine exhausts on my '99 502MPIs. They really woke the boat up on top.
It would be ideal to do a K&N and a remap at the same time. You'll pick up about 300 rpm with the same prop, but you'll probably be able to pull a taller prop... 26, maybe 27p.. That should get you damn near 3mph.

I read an article about a 22' Donzi Classic a while back in Power Boat Magazine. They tested a special edition with an HP500 in it. If I remember correctly it ran 78mph. The test driver said that it was overpowered and the hull was maxed out.

I also have a friend with a 1987 22' Classic. He has a 454 making about 450HP. His boat does an honest 75mph and is a real hand full.

You may want to start with blueprinting the bottom before adding more power.

Good luck with Her...
I have owned 2 Donzis and the 22' is my all time favorite!

A 4 blade prop might calm it down some. Don't forget what we're talking about here. A 22' hull with a 7' beam and 24 degree deadrise. There is a point where you reach "terminal hull velocity". You might be there by the sounds of it. Try the forum over at: www.donzi.net
I too am a fan of the 22' Classic. Great lines!

It really is not that crazy at 74.4. If you overtrim it, like Teague would do in the Powerboat test, it starts to sway big time, rolling on the rounded pad at the peak of the V. All you need to do is trim it down a hair and it smooths right out. It could certainly handle more speed.
Has anyone had any luck with Turbo 1 or Turbo lightning prop. I am getting recommendations for these on a Classic 22.

Thanks very much

If you feel that your boat can handle more, Tim G is right.
Start with a good exhaust system.

I have a friend that gained 1-2mph @ +150rpm with Stainless Marine Manifolds on his 502MPI in a 29' Fountain. If you can afford CMIs, you will gain more, but you will need your ECU reprogrammed.

I ran a 23p Turbo Vector on my 24' Pantera. It was about 1mph faster on the gps than a 23p Mirage plus, but it would break free easier than the Mirage plus.

more speed
 

The quickest upgrade you can do is :

SS exhaust Headers
Upgrade Ignition like MSD
If you wanted to you could have your ecm recailbrated

These are cheap and about the fastest ways to improve speed...wait...

Changed filter to K&N

Dave

If it chine walks like my old boat, then add hydraulic add-on steering to your list.

THE MENU
 

Appetizer
Full external single ram steering ( goes well with any entree)

Main course
Serloin Remap ecu, Flame arrestor, Exhaust

Lobster tails 1" shortie drive, bigger prop

Surf and turf Combo of the above (Very satisfying)

Fillet Mignon special All of the above plus a whipple and dual ram steering

light fare Flame arrestor and prop tune

Dessert
Dana or K planes mounted at 17 degrees ( for a nice smooth finish)

I can't wait to help you dial it in Cheers from The Ironman