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View Full Version : Any info on a 25zx..set up questions and general ?



Antonietti
07-11-2009, 08:18 PM
Ok.. Just bought a 1996 Donzi 25ZX .. several of you have talked about this exact boat on here and want to get some of your thoughts... it is a 1996 hull with a 2007 496 magum motor( not the HO )What prop works the best on these..it has a 22p 4 blade bravo now.. before i start playing was hoping to benifit from someone elses experience. what do you think about this having the 496 and not the 502? Did all of these have a pad on the hull? i read somewhere on here it was a option but not sure..Lets start with these questions for now .. i am sure i will have more...thanks

BigGrizzly
07-12-2009, 09:34 AM
Prop is depending on many options and opinions Tell us what is there first. As for the pad all that I have seen have them.

Antonietti
07-12-2009, 11:06 AM
Not sure what info you need.. it is a basicly stock 25zx hull.. thru hull exhaust, bravo drive... im down here in florida so no high elevations..It has a 2007 496 Magnum. 375 hp. stock X dimension. nothing done in the boat that would change the stock weight...

SilverBack
07-12-2009, 11:58 AM
Hello my 25 ZX brother!!! Some 1996 ZX had a pad some did not. For a while I thought that I had the only one but I have found 2 others that have a pad so I guess that it was not all that uncommon. It is on the other hand uncommon to find a 1996 25 ZX with a 496 engine. I don't think that anyone will know exactly what you will need for a prop with that engine setup. It would be good to know how deep your drive is mounted. Mine was mounted very deep from the factory and I think that raising it was one of the things that really helped my boat out. I have modified just about everything on the boat at this point but I will be glad to help where I can.

Antonietti
07-12-2009, 06:51 PM
ok first am i reading that right?? you got 103 out of your 25zx??? how...now were talking....

SilverBack
07-12-2009, 07:01 PM
ok first am i reading that right?? you got 103 out of your 25zx??? how...now were talking....


How.....do you have some free time on your hands????:wink: Yes you are reading that correctly. It is going to change in the next week or two though. I just got done with a few more mods and I am looking at 110 as my new goal. Who knows if I will get it but I think that it is very doable from my previous runs. This hull is really a great hull and pretty stable. My boat ran 65 with the stock Bravo one and the stock 502 MAG. (415 HP) Let me know if I can help!

Antonietti
07-12-2009, 07:14 PM
ok ... so i am sure you have done that in stages...what do i need to do to be looking at mid 70s or even to break the 80mph mark... 75 would be nice though, put me where i was in my last boat...

SilverBack
07-12-2009, 07:15 PM
http://www.donzi.net/forums/showthread.php?t=51761&page=78&highlight=25+zx+pad


This is very hard to dig through and it is very long winded but this is a lot of information on my buildup.

SilverBack
07-12-2009, 07:19 PM
ok ... so i am sure you have done that in stages...what do i need to do to be looking at mid 70s or even to break the 80mph mark... 75 would be nice though, put me where i was in my last boat...


Do you know if you have the older 496 with forged pistons? A supercharger (Procharger) would get you there.

My first choice on this boat if your drive is as deep as mine was is to get a 3 inch IMCO 3 inch shorty.


What is your current prop and what is your top speed?

Antonietti
07-12-2009, 07:21 PM
i did start reading that thread last night but i think there are some deleted entrys in it .. i skips around alot .. i will read it all now... also i have a blackhawk drive i was going to sell what do you think about trying that out??

Antonietti
07-14-2009, 09:48 PM
ok got out in the boat with a gps and had time to really get some seat time in... i know it is under pitched. It currently has a 22p bravo 1 4 blade prop. i only got 56.6 mph right at the rev limiter (5100-5200) it felt like it would get to about 5300 maybe as much as 5400, if i ran it out just right ... the weird thing is it didnt feel like the prop was holding the boat right .. it kept dropping the bow.. I was thinking maybe a 25p mirage plus?

mrfixxall
07-15-2009, 12:04 AM
ok got out in the boat with a gps and had time to really get some seat time in... i know it is under pitched. It currently has a 22p bravo 1 4 blade prop. i only got 56.6 mph right at the rev limiter (5100-5200) it felt like it would get to about 5300 maybe as much as 5400, if i ran it out just right ... the weird thing is it didnt feel like the prop was holding the boat right .. it kept dropping the bow.. I was thinking maybe a 25p mirage plus?

are you sure its not a ho? from what ive heard a mirage + would be the fastest prop on that boat..

SilverBack
07-15-2009, 04:11 AM
The Rev 4 was the fastest prop on my boat when it was stock. The mirage plus was the second best out of the props that were tried.

Antonietti
07-15-2009, 07:55 AM
No its just a 496 magnum... not sure why they didnt spend the extra $$ for the HO ..does it sound like im right about a 25 pitch?

SilverBack
07-15-2009, 08:16 AM
I think that the rule of thumb is 200 rpms for every inch of pitch. Do you have any pictures of your boat that you can post? Can you measure how far it is from the bottom of the pad to the prop shaft? If you don't have a prop yet you may want to borrow one from a friend or from BBlades and try a Rev 4.

BigGrizzly
07-15-2009, 01:07 PM
I would try a rev4. ot an os1.

SilverBack
07-15-2009, 04:12 PM
Grizz may be able to hook you up with a really good choice! Grizz...I think that the OS1 or that prop that you sold me for the Chris Craft would be good choices.

Antonietti
07-15-2009, 09:32 PM
i picked up a mirage plus 25p today..as soon as i get it on the boat i will let you know what it does...what is a os1?

mrfixxall
07-15-2009, 10:05 PM
i picked up a mirage plus 25p today..as soon as i get it on the boat i will let you know what it does...what is a os1?


Here ya go:)

http://www.turbo-props.com/4blades/offshore1/TOI/?prodID=14932

Antonietti
07-19-2009, 02:16 PM
Ok put the Mirage Plus 25p on the boat...Still not right ... need a 23p but this is what it did.. WOT 4400rps @ 60.2mph with 2 people 1/2 tank of fuel. 4000 rpms 55mph.. 3500rps 45mph... ok here is the problem, i know the rps not right yet but it still hops at any speed over 45mph and now at 58-60 it is starting to ride like a small pad boat. violently falling off pad until you drive the boat.. it didnt do that with the bravo prop but also it never got over 56mph with that prop.. I didnt expect it to do that at such slow speeds on a large boat.. I think my next step is a 23p mirage plus prop.. Soon i want to go to a shorty drive what are your ideas..

mrfixxall
07-19-2009, 03:40 PM
Ok put the Mirage Plus 25p on the boat...Still not right ... need a 23p but this is what it did.. WOT 4400rps @ 60.2mph with 2 people 1/2 tank of fuel. 4000 rpms 55mph.. 3500rps 45mph... ok here is the problem, i know the rps not right yet but it still hops at any speed over 45mph and now at 58-60 it is starting to ride like a small pad boat. violently falling off pad until you drive the boat.. it didnt do that with the bravo prop but also it never got over 56mph with that prop.. I didnt expect it to do that at such slow speeds on a large boat.. I think my next step is a 23p mirage plus prop.. Soon i want to go to a shorty drive what are your ideas..


as mentioned,try a 23p rev 4,you will get the speed of the mirage and the handling of a bravo 1...best of both worlds:)

Antonietti
07-19-2009, 04:01 PM
I have been looking for a rev 4 23p... they are much harder to find... i was reading and they say a 4 blade will keep it running on the pad easier.. in your experience is that true? Also any where i can read on what props are designed to do what ...i am sure the bravo 1 and rev 4 have lots of differences ( bow lift, stern lift, etc ) any idea where to find a used rev 4?

mrfixxall
07-19-2009, 04:19 PM
I have been looking for a rev 4 23p... they are much harder to find... i was reading and they say a 4 blade will keep it running on the pad easier.. in your experience is that true? Also any where i can read on what props are designed to do what ...i am sure the bravo 1 and rev 4 have lots of differences ( bow lift, stern lift, etc ) any idea where to find a used rev 4?

A 4 blade will keep the boat glued to the water,wait for silver back to chine in he has more expierance then me with your boat.you may want to drop to a 21 rev 4,seem that prp has more bite then the mirage and yo will loose 2-300 more rpm...

ck ebay for the prop or comtact bblades or throttle up, one of them have a try before you buy program for a certain $$

SilverBack
07-19-2009, 04:20 PM
I have been looking for a rev 4 23p... they are much harder to find... i was reading and they say a 4 blade will keep it running on the pad easier.. in your experience is that true? Also any where i can read on what props are designed to do what ...i am sure the bravo 1 and rev 4 have lots of differences ( bow lift, stern lift, etc ) any idea where to find a used rev 4?


BBlades has a loaner program. They charge you 25 bucks plus shipping. They will get a 23p rev 4 if there is not one in inventory right now. I think that it may do the trick. Also try to bump your tabs down just a hair when you get up to speed. It may help stabilize the boat for you. After you give it a little tab you can trim your outdrive out a little further. This will help it be stable and get up on pad a little better.

Antonietti
07-19-2009, 05:33 PM
BBlades has a loaner program. They charge you 25 bucks plus shipping. They will get a 23p rev 4 if there is not one in inventory right now. I think that it may do the trick. Also try to bump your tabs down just a hair when you get up to speed. It may help stabilize the boat for you. After you give it a little tab you can trim your outdrive out a little further. This will help it be stable and get up on pad a little better.


Thanks for the tips.. i will try messing with the trim and tabs tomorrow..I will let you know what it does when i get my hands on a rev 4

Antonietti
08-09-2009, 05:24 PM
Ok .. Now i bought a 23p rev4 getting better... its running at about 4600-4650rpms... at 61.4.. trimmed up ... it it super easy to drive now at that speed.. no more falling off pad.. boat feels alot lighter...

so i guess my question is what next.. 61mph is just not enought ( not that anything ever is ) i was hoping to gain more than 1 mph with the correct prop but oh well ..i guess better than the 56 i started with ... so i the boats on a lift so its difficult to measure the drive height but from the bottom of the pad to the bottom of the transom assembly ( the mounting plate not the mercathod ) it is 5 1/2 inches... not sure is someone could measure theirs and see if i need to bring my x up and how much ( 2 or 3 inches ) .

SilverBack
08-09-2009, 06:52 PM
Ok .. Now i bought a 23p rev4 getting better... its running at about 4600-4650rpms... at 61.4.. trimmed up ... it it super easy to drive now at that speed.. no more falling off pad.. boat feels alot lighter...

so i guess my question is what next.. 61mph is just not enought ( not that anything ever is ) i was hoping to gain more than 1 mph with the correct prop but oh well ..i guess better than the 56 i started with ... so i the boats on a lift so its difficult to measure the drive height but from the bottom of the pad to the bottom of the transom assembly ( the mounting plate not the mercathod ) it is 5 1/2 inches... not sure is someone could measure theirs and see if i need to bring my x up and how much ( 2 or 3 inches ) .

An IMCO -3 lower could not hurt. You should pick up some speed with that. An IMCO -2 is a little easier to find.

The Hedgehog
08-09-2009, 07:58 PM
You are lucky in the fact that Silverback hung it out there and has tried pretty much everything that has been considered with that hull all at the same time!

It seems to like the shorty. I would start with that. See if someone has one that you can borrow.

Also, Keith has an extension box so he does have more leverage. Extension boxes look important.

Antonietti
08-09-2009, 09:36 PM
Anyone know of a 2" or 3" imco for sale ..how do i figure if it needs a 2 or 3... . and i really dont want to go down the stand off box road .. trying to keep the boat trouble free as much as possable...

The Hedgehog
08-10-2009, 09:00 AM
Anyone know of a 2" or 3" imco for sale ..how do i figure if it needs a 2 or 3... . and i really dont want to go down the stand off box road .. trying to keep the boat trouble free as much as possable...

You can only get 3" if you use an IMCO upper.

There are plenty of 2" shortys to be had

Antonietti
08-10-2009, 04:59 PM
You can only get 3" if you use an IMCO upper.

There are plenty of 2" shortys to be had

ok good.. i was wondering if there were any differences.. so will all imco 2" shorty drives bolt on to a bravo upper or are there different lower units.

also any idea of how much of a gain i should look forward to with the shorty change...

where do i need to be looking for a good deal on a shorty

mrfixxall
08-10-2009, 05:12 PM
ok good.. i was wondering if there were any differences.. so will all imco 2" shorty drives bolt on to a bravo upper or are there different lower units.

also any idea of how much of a gain i should look forward to with the shorty change...

where do i need to be looking for a good deal on a shorty


Your still not going to be happy with the speed with the shorty. your best bet is to ditch the 496 and sell it and find a hp 500 or a 540 bulldog..that will put you in the low 70's..

The Hedgehog
08-10-2009, 05:16 PM
ok good.. i was wondering if there were any differences.. so will all imco 2" shorty drives bolt on to a bravo upper or are there different lower units.

also any idea of how much of a gain i should look forward to with the shorty change...

where do i need to be looking for a good deal on a shorty

A shorty will bolt on.

Then you will probably have to try a number of props. The pickup is usually somewhere between 1-5mph. Some boats go backwards. The concept is to reduce parasitic drag below the surface. Conversely, this reduces bow lift and increases slip. What you gain in reduced drag below the surface, you may lose by increasing the amount of boat in the water. You will need to go with a prop that has more surface area and bow lift.

Welcome to the world of trial and error.

The Hedgehog
08-10-2009, 05:17 PM
Your still not going to be happy with the speed with the shorty. your best bet is to ditch the 496 and sell it and find a hp 500 or a 540 bulldog..that will put you in the low 70's..

What he said.

Get power and then go for dialing it in.

SilverBack
08-10-2009, 06:08 PM
The Rev 4 should still be a pretty good prop for you even if you go up 2 inches with your outdrive. I think that you will gain a few MPH with a shorty. It is like these guys said though..if you really want to go much faster then you will be best served to ditch the 496 and go to a 502 or 540 platform.


OR .....you could just save yourself the trouble and trade me your boat and 25K for mine and be over running 100 MPH and have turnkey boating and the dialing in and headaches already taken care of for you. Just a thought....:wink:

mrfixxall
08-10-2009, 06:16 PM
The Rev 4 should still be a pretty good prop for you even if you go up 2 inches with your outdrive. I think that you will gain a few MPH with a shorty. It is like these guys said though..if you really want to go much faster then you will be best served to ditch the 496 and go to a 502 or 540 platform.


OR .....you could just save yourself the trouble and trade me your boat and 25K for mine and be over running 100 MPH and have turnkey boating and the dialing in and headaches already taken care of for you. Just a thought....:wink:


And then you will take his boat and the 25 grand and put a mountain motor 700cid alulimun block sonny lennard with a 1000 hp and a arneson serface drive with a standoff box and clean everybodys clocks and be the king of speed:biggrin:

SilverBack
08-10-2009, 06:19 PM
And then you will take his boat and the 25 grand and put a mountain motor 700cid alulimun block sonny lennard with a 1000 hp and a arneson serface drive with a standoff box and clean everybodys clocks and be the king of speed:biggrin:


698 CI Donovan with an X power drive sounds more like it but you are close....or keep it like it is and do all the stuff we just mentioned in a Critter!! :popcorn:

EDIT....I just saw the 1000HP reference :confused:....no....5 Liter Whipple, Dry sump...more like 1350 HP 1350 FT/# monster!!:kingme:


I think that a 130 MPH Critter would be "The $hit"!!!!:yes:

SilverBack
08-10-2009, 06:35 PM
I have got one that is really nice that I am dying to get my hands on and ship it over to Lip-Ship to have rigged out with the monster aluminum BBC!!:yes:

If he wants to do the deal ...I am game!!:popcorn:

mrfixxall
08-10-2009, 06:36 PM
698 CI Donovan with an X power drive sounds more like it but you are close....or keep it like it is and do all the stuff we just mentioned in a Critter!! :popcorn:

EDIT....I just saw the 1000HP reference :confused:....no....5 Liter Whipple, Dry sump...more like 1350 HP 1350 FT/# monster!!:kingme:


I think that a 130 MPH Critter would be "The $hit"!!!!:yes:


Donovsn is a engine block builder,sonny is a engine builder:)
if your going to spend all that coin then you may as well build a 805 cid,1100 hp on motor:wink:


or procharge this.http://www.steveschmidtracing.com/engines/801-hoosier-daddy-drag-racing-engine.html

BUIZILLA
08-10-2009, 06:50 PM
the Critter is waiting....

I found something this weekend that I just GOTTA have so hurry it up...

it'll give Grizz and Catch a fit... :yes:

and it has a bimini for the sandbar.. :pimp:

The Hedgehog
08-10-2009, 06:53 PM
Donovsn is a engine block builder,sonny is a engine builder:)
if your going to spend all that coin then you may as well build a 805 cid,1100 hp on motor:wink:
or procharge this.http://www.steveschmidtracing.com/engines/801-hoosier-daddy-drag-racing-engine.html

Now we are talking.

The aluminum Donovan would cause some interesting things to happen in a marine environment. I do think that it would be interesting to pull off 1,100hp with closed cooling. WAAYYY out of my league.

An no, you would NOT want to do fresh water cooling on the Donovan block.

Doable? Anything is but you would want to have someone that has been there.

I have been pondering the 805 for a while.

Antonietti
08-10-2009, 09:16 PM
ok ok lets get back to reality.... the 496 in my boat is only 1-2 years old and only has 80 hours on it ... i really like the fresh water cooling as i leave it on a lift ...so i would like to keep the current motor ... so as for your sugestions about more power first i was going to do the drive and steering first and then a procharger after i sell my Sundancer....but i can just wait and do it all at once.... procharger has a nice kit for the 496, great hp gains... i was thinking shorty-procharger and right prop i should be close to 80mph and under 10k right?

mrfixxall
08-10-2009, 09:41 PM
ok ok lets get back to reality.... the 496 in my boat is only 1-2 years old and only has 80 hours on it ... i really like the fresh water cooling as i leave it on a lift ...so i would like to keep the current motor ... so as for your sugestions about more power first i was going to do the drive and steering first and then a procharger after i sell my Sundancer....but i can just wait and do it all at once.... procharger has a nice kit for the 496, great hp gains... i was thinking shorty-procharger and right prop i should be close to 80mph and under 10k right?


Your going to smoke the 496 with a supercharger,the internals are not forged and wont withstand the abuse unless you convert to forged internals..call tyler crockett or young performance racing engines and they can give you the lowdown..

SilverBack
08-10-2009, 09:41 PM
ok ok lets get back to reality.... the 496 in my boat is only 1-2 years old and only has 80 hours on it ... i really like the fresh water cooling as i leave it on a lift ...so i would like to keep the current motor ... so as for your sugestions about more power first i was going to do the drive and steering first and then a procharger after i sell my Sundancer... procharger has a nice kit for the 496, great hp gains... i was thinking shorty-procharger and right prop i should be close to 80mph and under 10k right?


I am sorry for hyjacking your thread. The deal with the 496 is that usually they have a cast crank and I have heard horror stories about supercharging them. Don't be fooled. A procharger is a real supercharger and puts stress on your engine just like any other supercharger. 10K ...I used to think the same thing and when I started I was shooting for 80 so I went way too far but there is always something and things with boats never turn out just like you plan. Now...I have spent over 10K on tabs, prop, glass work alone. I have spent 6 times that on the boat. Your Bravo 1 will not hold up to the power that you are talking about. Carl C just found this out on a stock 525. Kaboom!!! The stock Procharger kits are crap and do not run too good. They have a really bad tune most of the time. I think that the 496 does not have a MEFI computer. More money to do it right. You can do whatever you want but just go into things with your eyes open.


As one of the wisest guys on this site once said about going 80 in one of these boats...it is going to take...


$$$$$$$$$$$$$$$$

If 80 is all that you ever want to do..I would double or triple the 10K and you may have a start.

SilverBack
08-10-2009, 09:43 PM
I would call the best in the business...Mark Boos...pmefi.com if I was going to go forward with this project.

Antonietti
08-10-2009, 09:54 PM
And this is why i ask questions before i pull out the check book..

im going to start by finding out exactly what my motor is ... it was bought from Mercury about a year ago as a reman motor... it has the ecm stamped i think 2002.. so i will call merc tech tomorrow and see if they can pull a build sheet on it and see what its deal is ..see if it was built to 2002 specs or 2007 ( i was told the early ones had forged pistons and crank... )

not sure what direction i want to go with this anymore...all i know is its a blast to drive...

The Hedgehog
08-10-2009, 10:56 PM
And this is why i ask questions before i pull out the check book..

im going to start by finding out exactly what my motor is ... it was bought from Mercury about a year ago as a reman motor... it has the ecm stamped i think 2002.. so i will call merc tech tomorrow and see if they can pull a build sheet on it and see what its deal is ..see if it was built to 2002 specs or 2007 ( i was told the early ones had forged pistons and crank... )

not sure what direction i want to go with this anymore...all i know is its a blast to drive...

Ask Jamie. He is an advertiser here (Lakeside Restorations). He knows the 496 well. He can tell you what you can do and not do with it.

He is also a Procharger and Whipple dealer

SilverBack
08-11-2009, 04:46 AM
Ask Jamie. He is an advertiser here (Lakeside Restorations). He knows the 496 well. He can tell you what you can do and not do with it.

He is also a Procharger and Whipple dealer

Yes..I think that if I had a 496 ..Jamie is where I would start too!!

Antonietti
08-11-2009, 12:34 PM
Talked with Jamie.. said would be no problem running a supercharger on the stock 496 but would suggest a whipple not the procharger..Said to run low boost around 3lbs and keep up on the maintence on the motor, should be trouble free...

plus so far all the answers i have from mercruiser is my reman motor was built to 2002 specs and will have the forged pistons and better rods and crank... but still trying to get a build sheet on this motor... they are saying the compression ratio will be different from 2002 to now but no one knows what those numbers are ...

still not sure what i want to do ...

The Hedgehog
08-11-2009, 04:12 PM
Talked with Jamie.. said would be no problem running a supercharger on the stock 496 but would suggest a whipple not the procharger..Said to run low boost around 3lbs and keep up on the maintence on the motor, should be trouble free...

plus so far all the answers i have from mercruiser is my reman motor was built to 2002 specs and will have the forged pistons and better rods and crank... but still trying to get a build sheet on this motor... they are saying the compression ratio will be different from 2002 to now but no one knows what those numbers are ...

still not sure what i want to do ...

If you go the Whipple route, make sure that you get a big enough blower that you can turn up the boost later.

It all depends on where you want to end up.

I wanted to make big power later so I went 502 and a Procharger M-3. I seem to be learning that a M-1 is a better blower for lower boost but in my application I would have run out of blower with a M-1.

You can make decent power with a 496 but even with refresh and more boost they seem to be peaking around 650 hp. I am sure that someone has generated more but that is mostly what I see. I see lots of 502 based setups running 750hp +.

Decisions decisions.

Antonietti
09-18-2009, 01:20 PM
ok boat is back out of the water and acouple of you asked my drive height and pics so we can see if i should go with a 2" shorty drive..i have 8-8.5 inches between the propshaft and the bottom of the pad. seems deep to me what do you guys think?

BigGrizzly
09-21-2009, 11:25 AM
Everyone has a different opinion, but If it were me I would do the engine and test first. Pads and shorties can have handling issues with power. If you do power and shorty at the same time it can be an issue with the driver. Tec has a shorty and Hedg does not so go from there

SilverBack
09-21-2009, 12:03 PM
I went up 5 inches from the stock location and my boat handles like a dream. It will do nothing but help to go to a shorty.

The Hedgehog
09-21-2009, 06:52 PM
Everyone has a different opinion, but If it were me I would do the engine and test first. Pads and shorties can have handling issues with power. If you do power and shorty at the same time it can be an issue with the driver. Tec has a shorty and Hedg does not so go from there

Good advice.

Your boat may very well like a shorty. Silverback's boat loved it. He is also pumping out some pretty big power and can swing a big wheel.

Tex runs a shorty. I don't. Our drive heights are about the same because my x-dimension is higher. I am swinging 2 more inches of prop. His comes out of the hole like a ski boat compared to mine but it is not due to power. I run mine to the edge of blowout and have to let it nose over. That is less than 1/2 throttle. His hooks up fine. Like Grizz said, go figure.

I would do the power first. Then you can borrow a shorty.

BigGrizzly
09-22-2009, 09:33 AM
I am with the Hedgehog on this one. Silverback has a stand off and different tabs etc. It is not like he just bolted on 5 inches short and went to town. Remember with a stand off the clean water back by the drive is now higher about 2 1/2 inch over that of the transom drive with 12 inch set back. The boat is now longer and handling characteristics are different. You now have apples and grapefruits. My Criterion with the Konrad now handles and props different then the TRS drive. This is a major difference in a good way and the TRS is a great handling drive too, just different.