Speed for a 88'Z21

[wolfgang1]

Just bought a 88' Z21 with a year old 350 magnum. What should I be getting for speed? Anybody with the same boat, what are you getting?

[EricG]

First off, welcome to the Registry! Tell us about your new boat...I sold mine about a year ago...and still miss the extra room!

The best I ever got with my old one was 53.5 MPH GPS. Mine had a pretty tired (550 hours) 350Mag with original exhaust manifolds, so a newer/healthier motor ought to get you better performance.

I do know that in a comparison article in Popular Mechanics between the 21 footers of the day (pachanga, checkmate, Donzi Z21, and a couple of others..I'll have to find the article again) they did a lot of prop experimentation and the Z21 with the 350Mag ran 56-57 on Radar. Its speed was about in the middle of the pack, but I seem to remember that none of the boats broke 60...how times have changed! :mad: :rolleyes:

Good luck with the new boat...post some pics when you have them.

-EG
...where did I put that cuddy cabin again?

[da donz]

What lake are you running this on? Did you keep it in Minnetonka?

[wolfgang1]

What lake are you running this on? Did you keep it in Minnetonka?


yes it's still on Minnetonka, I think you were the person looking at the same boat. Did you ever find one?

[wolfgang1]

Thanks for the reply, I just ran tonight with my gps and got about 53 also. I was paranoid and backed off because the lake has a 40mph speed limit and I saw the water patrol. I think that I could have tweaked it and go maybe 2 or 3 mph out of it.The water was also little too flat with no chop. The boat came with a 19 Cleaver. I just bought a 21 revolution 4 - 4 blade and am going to try it this weekend.

I love the boat,the look, the room, the ride and the handeling. It also barks nicely. The fastest boat that I had was a 20' HydroStream Vegas with a tricked out 200. It ran 81 on the gun. It was fun and fast, but I like the Donzi Better.

Did I see a posting that you bought a 18 classic. What speeds are you getting with that?


First off, welcome to the Registry! Tell us about your new boat...I sold mine about a year ago...and still miss the extra room!

The best I ever got with my old one was 53.5 MPH GPS. Mine had a pretty tired (550 hours) 350Mag with original exhaust manifolds, so a newer/healthier motor ought to get you better performance.

I do know that in a comparison article in Popular Mechanics between the 21 footers of the day (pachanga, checkmate, Donzi Z21, and a couple of others..I'll have to find the article again) they did a lot of prop experimentation and the Z21 with the 350Mag ran 56-57 on Radar. Its speed was about in the middle of the pack, but I seem to remember that none of the boats broke 60...how times have changed! :mad: :rolleyes:

Good luck with the new boat...post some pics when you have them.




-EG
...where did I put that cuddy cabin again?

[EricG]

Yup...'76 18 350/Volvo 280...I get about 56 on the GPS. But it feels WAY faster...due to the lack of freeboard :yes:

Have fun with the Z... like I said...I miss mine.

EG

[HamrenDan]

I have had my 90 Z-21 for about 2 months now, and didn't have it in the water untill 2 weeks ago, thats when I figured out what needed to be done. I got roughly 45 MPH with the dash guage, and a new rear plastic sender. This is on a 460 engine with a Holley 4 barrel carb that had in-op vacuum secondarys, loose wires on the cap, old corroded rotor, and wires that were tied together.

So needless to say the carb is being rebuilt, I have a new cap, rotor, and plug boots. I took off the manifolds and risers and they have been soaking in a heat tank. I am going to paint them and re install them. Ohh and the carb is getting a half inch spacer for better flow..

The one thing that I am thinking of getting is a new prop. I cant see any numbers on my current prop, but It feels like a torque prop the way it pops out of the water. If any of you guys have extra props that you want to sell let me know. Thanks in advance

Ill keep you guys updated as I go along...

Dan Hamren
Redwood City CA soon to be Cottonwood CA

[Fish boy]

with the mercruiser standard power, the best they ever got from the factory was high 50's with half a tank of fuel, one person and nothing else in the boat.

[da donz]

yes wolfgang i did find a z21 and it is on minnetonka as well, If you would like to get together and run these things side by side for comparison, i'm up for it amytime. i am running a 21 pitch on mine and it seems to go good, although i would like to get a few more rpm's out of it. its running at about 4100-4200 rpm's WOT.
Give me a call anytime to talk about it.
Shaun.... 612-599-1046

[TuxedoPk]

When did they institute a 40mph speed limit on Minnetonka? I used to live on the Lake in Wayzata back in 97-98.

[da donz]

its always been 40, because you have to be so far from shore and on minnetonka there is no place that is far enough out exect for one little place that you could get away with the 50 mph speed limit, it sucks! now they are talking about putting a size limit on the lake due to all these 40+ foot boats out there.

[Zudnic]

Yup...'76 18 350/Volvo 280...I get about 56 on the GPS. But it feels WAY faster...due to the lack of freeboard :yes:

Have fun with the Z... like I said...I miss mine.

EG

Eric,

First off sorry bout the Coug thing, elsewhere! My question, given the choice would you rather have the Z over the 18?

Reason found good deal on one in our back yard. No offense to anybody, but I like the lines of the Minx or the 18, the Z's are not really my taste, like em but not love! The deal is good enough that its worth getting, maybe even over the X-18 in Northern Cali. Hence my question, just thought it would be nice to know if someone in my backyard might be willing to trade in the future!!!!! :biggrin:

[EricG]

Eric,

First off sorry bout the Coug thing, elsewhere! My question, given the choice would you rather have the Z over the 18?

Reason found good deal on one in our back yard. No offense to anybody, but I like the lines of the Minx or the 18, the Z's are not really my taste, like em but not love! The deal is good enough that its worth getting, maybe even over the X-18 in Northern Cali. Hence my question, just thought it would be nice to know if someone in my backyard might be willing to trade in the future!!!!! :biggrin:

The coug thing cracked me up...I just couldn't think of a clever response :D

The Z and the 18 are absolutely different boats in every sense of the word. It's like traveling in an SUV vs a Motorcycle.

I sold my Z because my fiancee' is finishing up school and I needed to downsize a bit financially, and because my ultimate goal is to have a classic to drag to Donzi gatherings etc, and a bigger go-fast for poker runs and running in the sound. I was very close to buying a couple of bigger boats right before Kath went back to school full time...but in hindsight, I'm glad I ended up with the 18 for now. Mine also had a couple of issues that made me not want to keep it, mainly a tired small block and an alpha drive with a lot of hours. Had it had a stronger motor with a bravo...I'd probably still have it (see below about the idea of upgrades).

Anyway, for an owner with 1 boat, I actually like the idea of the Z better than the 18. The 18 has NO room. Last saturday just Kath and I took it out, and with a minimal amount of refreshments...the boat was full. For 2, the boat is fine...but we miss the swim platform, the lounge over the hatch area and the cuddy for changing, storage, and a porta-potti. The other thing I really miss is the freeboard. With the Z I could stand and run it, the 18...no way.

As far as performance, the 18 wins. The classics ride better than boats many feet longer in rough water. The Z's have a different hull design than both the classics and the ZX's. The entry at the bow isn't as "sharp", so if you try to cruise in the rough stuff moderately, the hit and/or slam a little harder than the others. However, get a Z running on top of the rough stuff (i.e. get it flying), and it's a whole new ball game. It was more intimidating to fly the Z just because it was so much bigger...but once you got it going, it really did ride nice. I just think the 18 rides better because you don't have to fly it to get a smoother ride..and when you do fly it...well...you've just go to try it to believe it :eek: .

The Z's are heavy. As with the topic of this thread, they take some pretty big power to get a lot of speed out of them. I think with stock power, the Alpha will be a fine drive, but you are very limited with upgrades. And the switch to a Bravo may not be that tough mechanically, but it costs somewhere over 5k, and that's if you do it yourself (and you'll NEVER get the money back). My 18 has a volvo, and although it suffers from the lack of trim, I have no fears about it's ability to handle upgrades. If I decide to supercharge, or build a stroker, I can just bolt it up without worrying about the integrity of the drive (fundamentally), with an Alpha, you just don't have those options.

Finally, the 18 gets more attention...I get stopped CONSTANTLY with comments, compliments, and questions about the boat. I got a lot of praise for the Z also...but the classic I think wins a bit more in that category. For whatever that is worth.

So, for me I like my 18 more than the Z I had. However, if I didn't plan on also getting a bigger boat in the future, I think I would regret the move, only from a practicality standpoint. I live 2 miles from Puget sound, and although I still take the 18 out there...it requires a bit more willingness to get wet and cold than the Z.

Now, the Minx is an interesting compromise...it has some of the good attributes of both, but I've never ridden in one, so I can't really comment. Don't forget about the Hornet III either, just check out MXRoadsters boat and you'll understand just how cool they are.

The mistake I have always made when buying a boat is not riding in enough of them before I make a purchase. They are all different, what works for some may not work for others. Buy what YOU want and be happy with it.

Which Z are you looking at, I may know the boat... Good luck.

EG