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IpanemaSports
12-02-2010, 12:30 PM
Hi,
New to this great forum and looking for some opinions for a 1986 Donzi Z25 we just picked up. It is originally equipped with a single 454/TRS combo that needs total rebuilding to be ship shape again.

We have a few questions for you experienced Donzi owners.

How fast did this boat go back in the day?

Is it possible to use a small block Chevy instead of the big block or does it need the torque of a 454 engine?

Would it be possible to run top speeds of 60-65 mph with a 350/370hp or higher small block engine and a more modern outdrive unit?

Also, would the fuel consumption and range be greater with a small vs. big block engine?

Your experience and advice would be greatly appreciated.
Thank you all very much!

Tidbart
12-02-2010, 02:33 PM
PM Donzigo about the Z25s he knows them very well. He had a 25 for 8 years and now has a Z33.

Bob

IpanemaSports
12-02-2010, 07:55 PM
Thanks Bob!

Jeff

LKSD
12-03-2010, 08:23 AM
Not a bad boat. However not very fast by todays standards, but respectable none the less. They just were not speed demons, it also was probably only the 330 version big block that was in there. Especially if it is equipped with an Alpha as it is a 1986 model..

I will caution you if it is an alpha that boat and power is a lot to put an alpha thru. It is the wink leak and should be upgraded to a bravo for optimal longevity.. If it is a TRS, then not so much of a worry as it is a durable unit, however I would have it gone thru and make sure it has been serviced well. If it is a trs and in rough shape then still a bravo conversion may also make sense.. ;)

Anyway, on to your other questions....

Torque is going to be important, a small block would fit in there and work if it was high output, but it will have to work harder in that application because of the size and weight of that boat. IMO you would be best putting in a healthy big block as it would not have to work as hard and would be able to give you better speed and fuel economy in this scenario..

Actually I did a Z21 over for one of my clients recently & re-powered it. It originally had a 330 hp big block merc in it. I re-powered it with a new custom 450hp big block. He picked up some speed and his fuel economy is much better. The boat can cruise easier and use less fuel when doing it now..

Hope this helps.. :) Jamie / Lakeside Restorations

IpanemaSports
12-05-2010, 03:25 PM
Thanks for the tips.

Been looking into the 383 small blocks because of the weight reduction/RPM and HP figures, but maybe a new 454 might be an easier way to go.

Anybody out there run a boat of this size with a warmed over 383 stroker small block?

LKSD
12-05-2010, 04:54 PM
As I mentioned to you on Friday night when you called me, Nothing against the 383. It is a great engine and works very nicely in many smaller applications. However IMO the BBC will work better for this application for the reasons I already discussed with you the other night.

But as with anything I guess, usually one needs to do what makes them most happy and fits their budget the best..

:) Jamie / Lakeside

IpanemaSports
12-06-2010, 10:49 AM
Thanks Jamie, was just putting it out there just in case someone might have tried it. I was searching around and found some info on some new Vortec engines Mercury Marine was offering in Europe.
It looks like we might go with a 502 base engine, but this is an interesting read.
http://www.gm.com/vehicles/innovation/powertrain-technology/engines/specialized/marine/REV_3_2011_Marine_Engines.pdf (http://www.gm.com/vehicles/innovation/powertrain-technology/engines/specialized/marine/REV_3_2011_Marine_Engines.pdf)
Thanks again!

Tidbart
12-06-2010, 10:53 AM
It looks like we might go with a 502 base engine,......


There is one for sale on the board, right now. I believe it is fully dressed.

B

IpanemaSports
12-06-2010, 11:01 AM
Thanks, looks like a good deal.

We're looking to run a 502, Merlin heads & carb set-up. :wink:

joel3078
12-06-2010, 03:19 PM
Z25 is pretty close to a 24' black widow hull bottom and weight. I had a 24 widow and so did fishnsucks. Figure a 454 with 365hp is a 60mph boat. Need about 500hp to go 70mph. Assumes the correct diameter size/pitch prop of course. Chevy 454 marine engines seem to be very plentyful so I would go that route. I see a couple late 80's Z25 boats for sale in MN, WI, and OH area from time to time. All freshwater boat histories and an inexpensive way to get into a Donzi. They are well built nice boats. Most are kinda rough shape after all the years however. Nothing that 5-10 grand worth of TLC wont fix however.

KerrLake
12-06-2010, 09:41 PM
It took me over 500 hp to break 70 with a trs. It's a fun boat to drive now though.

IpanemaSports
12-07-2010, 06:13 AM
Thinking of switching from the TRS to Bravo drive. Was talking with an old friend and he said that it would be a good idea to keep the engine in the same location and that with a "drive shaft" it would be possible.

He said it wasn't a "plug & play" conversion, but would be worth it to maintain balance of the hull.

Have any of you guys done this or know what or who makes the parts needed for this conversion?

Thanks for the help guys!

IpanemaSports
12-07-2010, 06:29 AM
Here's a pic of her.

Donzigo
12-10-2010, 10:47 PM
Change it to the Bravo 1 drives.

Stay with whatever Lakeside advises and you can't go wrong. Jamie knows his stuff.

Richard

LKSD
12-11-2010, 11:07 AM
Thinking of switching from the TRS to Bravo drive. Was talking with an old friend and he said that it would be a good idea to keep the engine in the same location and that with a "drive shaft" it would be possible.

He said it wasn't a "plug & play" conversion, but would be worth it to maintain balance of the hull.

Have any of you guys done this or know what or who makes the parts needed for this conversion?

Thanks for the help guys!

Dont worry about the shifting back of the engine to mate to the B1. If you are going to do it, just plug the transom & run a conventional B1 style set up if you are not staying with the TRS. Going to a B1 with a jack shaft application or plug in model will only greatly add un needed expense and grief for this boat. Usage of a jack shaft is primarily done in boats with staggered twin or triple engines. No need to re-invent the wheel here.. :)

The TRS BTW is not a bad drive, and if in it and it's tranny are in good shape they can hold reasonable power, it is just getting tougher to get some of the parts for them, and some parts are just NLA..

FWIW, In regard to switching to a B1 set up from TRS. It is not that the B1 stuff is always more reliable or tougher. It is just usually easier to get parts and service for them since the TRS line up was dropped years ago.. Other than that the Bravo is just a little shorter than the TRS which usually also allows a little less drag & potential for speed increase on some hulls.. ;)

Jamie / Lakeside

LKSD
12-11-2010, 11:17 AM
Change it to the Bravo 1 drives.
Stay with whatever Lakeside advises and you can't go wrong. Jamie knows his stuff.
Richard

Thanks for your kindness & Confidence in me.. :)

But do feel free to also elaborate in your experiences as well. I know you have owned & been running your Z's for quite while and have info that may help from an owners perspective as well... :)

Jamie

LKSD
12-11-2010, 11:20 AM
Here's a pic of her.

I think I saw that boat on an ebay listing a while back.. It looks better now if it was the same boat.

I dont remember all of the details, but from the pics on the listing it did look like it would be a nice project for the right person.. They are worth doing and keeping IMO.. :) Please do keep us all posted as to what you do.. :)

Jamie

IpanemaSports
12-11-2010, 12:21 PM
Thanks guys.

Our Z25 restoration has begun with a serious clean up and removal of the gas tank.

After that is done we’ll be replacing transom, stringers, bulkheads and whatever else is needed to guarantee a solid foundation to build upon.

The great news is the factory gel coat and fiber glass are both in amazing pristine condition.

The upholstery is in good overall condition, but the plan is for a new interior to give the boat a more modern “late model” appearance.

We do have concerns with having to move the engine aft due to swapping out the original TRS/Transmission for the Bravo drive. Moving the engine will affect the hull’s “CG”, this is something we’d like some of your thoughts from experiences.

Searching the internet for information on “Jackshafts” and manufactures has yield very little results. I’ve personally seen several boats with “staggered” engines using them, but who exactly makes them and can they be ordered in specific lengths or if they're really needed?

Any thoughts, advice or directions are greatly appreciated!

Thanks again!

LKSD
12-11-2010, 12:55 PM
The Jackshaft or plug in stuff is offered by merc.. Also moving the engine back further is not an issue.. It would actually be better if you are converting to a B1. Dot forget the B1 is lighter than the TRS & the B1 does not use a tranny.. SO it would be better to move it back.. ;)

Beyond that please please do not make the boat into something it is not as far as appearance. The Z has such nice classic lines and a very retro cool classical style interior. Just my opinion, but trying to make it look more like a ZX, ZR or something else IMO just cheapens the boat's classic elegant look, and wont generally add to the value or desirability. I find on certain boats like this keeping an original style interior, or one that highly mimics it is usually more favored.. ;) Again JMO for what it is worth.. Hope it helps.. ;) Jamie

IpanemaSports
12-11-2010, 01:18 PM
Not to worry, the interior upholstery changes planned are in the vinyl and not so much in terms of major modifications to the original design.
We’re also considering a color change to something like this, done in publisher.
The new interior will follow the same theme too! :wink:

IpanemaSports
12-11-2010, 01:40 PM
Here is the interior cabin concept color, we wish to re-create something along these lines to give her a more modern feel and yet retain the magic of the era. :wink:

Donzigo
12-15-2010, 08:29 PM
The gel coat is so thick that to change it doesn't make much sense to change that, unless you just hate the color. That's a nice idea about the interior.

How far are you from Jamie? He has done a Z-21 that turned out nice. I sure would want the right person doing the work on this vessel. It insures that the value is credible after the work is over.

Richard

LKSD
12-16-2010, 10:08 AM
Rich, I think he is in FL.. I am in NE PA.. Although I have had people come in from further away than that many times over the years.

I also think he wants to do the majority of the stuff himself, I am not certain, but that was the vibe I got when he and I talked initially about a week or so ago..

Nothing wrong with one wanting to tackle a job from a DIY perspective. Some can handle it and others cant or shouldn't. Either way It is good to see these boats getting redone and held onto.

:) J

Donzigo
12-16-2010, 07:52 PM
Jamie,

Yeah, that seems to be the case.

Happy Holidays to you and your bride.

Richard

LKSD
12-16-2010, 09:32 PM
Jamie,
Yeah, that seems to be the case.
Happy Holidays to you and your bride.
Richard

Thanks.. Happy holidays to you guys too.. :) Jamie

IpanemaSports
12-17-2010, 12:05 AM
The Z25 bucket seats need to be replaced, anyone know where to buy stand up bolsters? :wink:

Thanks again guys and Happy holidays to all of you too.. !

DAULEY
12-18-2010, 12:54 PM
if redoing the transom would twin small blocks fit
that would be awsome

LKSD
12-18-2010, 01:05 PM
The Z25 bucket seats need to be replaced, anyone know where to buy stand up bolsters? :wink:

Thanks again guys and Happy holidays to all of you too.. !

They can usually be Rupholstered and repaired/resotred, which we do. Also we do offer new bolsters, however unless completely custom made the new replacements wont match the boat/interior. ;) Jamie / Lakeside

LKSD
12-18-2010, 01:07 PM
if redoing the transom would twin small blocks fit
that would be awsome

Width wise you can probably get it done, however frame wise and set up wise it would be a major reworking and undertaking. Also not likely cost effective compared to 1 big block with a healthy dose of power. ;) Jamie / Lakeside

DAULEY
12-18-2010, 06:04 PM
but would be a smokin boat with twins and no worry getting back if you blew a motor
just a thought

gellis11
02-06-2011, 10:41 PM
I have an 87 Z25 454 approx 365hp with an alpha ss 23p prop. She pushes 64 gps wot, lite, and with the wind. Police radar said 62.

Donzigo
02-08-2011, 11:45 PM
The engine room is not big enough for twins.

Stand up bolsters wold be far too tall for this boat.

The Hedgehog
02-09-2011, 09:35 PM
I like the ideas. That is a good color already. I do like the color you picked as well, but the easy way would be to paint it. I would avoid that unless the gell is not holding a buff or you can't get that logo off the side. I have painted two boats and would do it again, just as a last resort.

The fusion of old and new can be pulled off without taking away from the classic Z theme if you do it right. Be careful, I agree with Jamie about not taking away from the original character.

I would not even consider the two small blocks. That would be WAY too much project and would not yield much. You can make a big block scream.

You can do mini bolsters. Some of the 22ZX guys have done that. You can't stand up but they look and feel much better.

Redoing the cabin would be a great idea. Enjoy the project and keep us in the loop