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22classic
03-06-2016, 09:12 PM
Hello all, this is my first post and introduction since I bought my boat about 2 years ago. It is great having this forum to reference from.

It is a 1990 with the 460 and KC since I bought it I have rebuilt the drive and purchased a spare in case the inevitable happens.

Now that I have that taken care of, I am building my engine up.

so far.
Closed cooling, 552 stroker, edelbrock heads(original exh port location) long tube double wall headers (304 stainless made at my house) and of course the usual cam and 850 CFL carb, etc...

my plan is to keep the revs around 5000 to keep parts together, is it really true that rpm kills out drives or is it just power in general? No, I don't water ski and gun it out of the hole.

As for planning my prop do you have any suggestions? I was thinking something around a 26-27 prop? I should be making somewhere around 600-650hp, but that is only a guess. Do one brands work better than others?

hopefully the attachments come through.

joseph m. hahnl
03-06-2016, 09:52 PM
Welcome aboard:kingme:. Torque and heat kill outdrives. I think the KC is a resilient drive. People blame Rpm on the destruction of a drive because at speed the drive is never adequately cooled with out a drive shower. The gear oil has a tendency to burn and loose it shear strength . Aside from blowing it up:biggrin.: 650HP through my Alpha would require at least a 30P to keep the RPM under 5000. What is the ratio of your KC?

22classic
03-07-2016, 12:47 AM
Thank you for your info, I understand that the KC has a large oil sump in comparison to the bravo so it cools better, but should I work out a drive shower? Does it matter that I am in cold water? Lake Tahoe and the pacific? 50-60ish degrees.

my ratio I believe to be 1.47

Is one brand or style of propeller better than another for this boat?

Thanks again! I'll have more pictures once I get back to work on Monday.

Greg Guimond
03-07-2016, 07:05 AM
Welcome! Folks have had great success with the older Mercury Rev4 props. They come in 27 pitch and tend to run just a touch stiff. If you like what you get with the Rev4 you can always add a little more cup to get more top end out of it but most folks run them bone stock. They have PVS holes also.

What model and pitch prop did it come with?

Pat McPherson
03-07-2016, 10:05 AM
The Merc Rev 4, four blade is my prop of choice but they only come 25p max stock. Even modified to 27p, I don't think it will be enough to stay close to 5000 rpm at WOT.
With 600+ HP and big torque from a stroker, my guess is that you'll want to start with a 30" pitch prop. There are guys running modified Bravo 1 props. Personally not my favorite out of the box/stock, but I've had good luck when modified for more bow lift.
Hydro, Power Tech, and Turbo do make other neutral lift 4 blade props.
I really like the Hydro P5X 5 blade but they are pricey.

Carl C
03-07-2016, 11:32 AM
Welcome. Revs and horsepower are bound to take a toll on drives but what really kills them are hard holeshots and air time (re-entry). Everyone speaks highly of the KC drive though so they must be pretty strong.

22classic
03-10-2016, 01:09 AM
Update pics. Final measuring of push rod length, and then it's time for final assembly.

Thinking about a Dyno tune, but don't know of anyone in the Bay Area with an engine dyno. (San Jose, CA)

The exhaust is not going to fit with these valve covers, so they have to go.... Sad because I liked the look and machined them flat....

Headers still need the water inlets installed, and need to be cleaned up. When I started, I cared about the appearance and having small welds, then I realized I still work for a living and need to hurry up... The rough parts are at least buried in the bilge!

How would I plumb a crank mounted water pump? Do I keep pulling through the factory outdrive pump and get rid of that impeller?


And thank you for any help and knowledge.839788397983980

more to come!

Best,
Matt

Pat McPherson
03-10-2016, 11:32 AM
How would I plumb a crank mounted water pump? Do I keep pulling through the factory outdrive pump and get rid of that impeller?




I believe you need to keep the impeller and housing in the drive; not sure an engine mounted sea pump would pull the water thru.
If you need higher flow for your new engine you can add external water pickup at the transom like a inboard or old TRS drive. This would feed your crank driven sea water pump. The guys with high HP Alphas use the raw water pump in the drive to feed a drive shower when they go to the external feed.

gcarter
03-10-2016, 09:41 PM
How would I plumb a crank mounted water pump? Do I keep pulling through the factory outdrive pump and get rid of that impeller?

Best,
Matt

I've done this to every Donzi I've worked on. Outside, remove the Alpha impellor, the pump design is too small, install a Stainless Marine transom pickup like in the picture. Remove the connecting hose between the bell housing and the external gimbal plate.
Inside, remove the hose aqdapter bolted to the gimbal housing and cap it (parts are available from Merc). Mount this crank driven Johnson raw water to the crank balancer:
http://www.marineexhaustmanifolds.com/raw-water-pumps.htm

In the pictures, see the transom pickup and strainer. Also notice the cap on the inside of the gimbal housing where the hose adapter was.

http://www.donzi.net/forums/attachment.php?attachmentid=82644&d=1277069183

http://www.donzi.net/forums/attachment.php?attachmentid=82645&d=1437353874

yeller
03-11-2016, 03:38 PM
As for planning my prop do you have any suggestions? I was thinking something around a 26-27 prop? I should be making somewhere around 600-650hp, but that is only a guess. Do one brands work better than others?

hopefully the attachments come through.26~27" will be too small. At about 550hp I was running a 27" 4 blade or 29" 3 blade. You'll probably run out of prop at 650hp. Every boat handles differently to different props. If you can, try and borrow from people to try out. It seems most prefer 4 blades. For my boat, I preferred a 3 blade. I tried a 28 Bravo, 27 Hydromotive QIV, 29 Mirage Plus and a 28 Tempest Plus (supposedly tweaked to a 29). Mirage was good but experienced blow out. Blow out never seemed to be a problem for others, but it was for me. Tempest ran very similar to the Mirage, but no blow out. 4 blades were never a fun ride, (I have lots of brown shorts now :biggrin.:) but the Hydro was much better than the Bravo. Lots of guys really like the Bravo though. Sorry, not much help.

Pat McPherson
03-14-2016, 12:39 PM
For an old school V bottom, you need a bow lifting prop. Most 3 blade round ear props are bow lifters. A 29/30" pitch Mirage/Mirage plus or Turbo 1 (if they make one that big) would be good options to try. A stock Bravo or Hydro QIV is going to lift the stern too much. A 30" pitch Bravo 1 that has been modified for bow lift would be another good prop to try if you can find one; BBlades made a 28p bow lifting B1 for me that worked great on my 24' Superboat.

yeller
03-14-2016, 02:40 PM
A 29/30" pitch Mirage/Mirage plus or Turbo 1 (if they make one that big) would be good options to try.Won't find a Turbo in that size. I tried. You can't go wrong with the M+. (I think I'm the only guy that ever had issues with one). FYI, I tried the Tempest on the recommendation of Mr. X.

Pat McPherson
03-14-2016, 04:10 PM
Won't find a Turbo in that size. I tried. You can't go wrong with the M+. (I think I'm the only guy that ever had issues with one). FYI, I tried the Tempest on the recommendation of Mr. X.

I have found my 22 Donzi runs too loose with the Mirage+; more stable with a regular Mirage or Turbo 1. The M+ may have too much bow lift for my liking. No prop as good as a Rev 4 but those stop at 25p.
I did run a "labbed" Mirage plus 27P on my 24' Superboat with great success; vary fast +2-3mph over my "labbed" 28p B1. I tried a Tempest on my Superboat but I blew out often; I think that's more of an outboard prop.
I think Power Tech may have some options but not sure if there is a company that has a test program.

yeller
03-14-2016, 06:41 PM
I have found my 22 Donzi runs too loose with the Mirage+; more stable with a regular Mirage or Turbo 1. The M+ may have too much bow lift for my liking. No prop as good as a Rev 4 but those stop at 25p.
I did run a "labbed" Mirage plus 27P on my 24' Superboat with great success; vary fast +2-3mph over my "labbed" 28p B1. I tried a Tempest on my Superboat but I blew out often; I think that's more of an outboard prop.
I think Power Tech may have some options but not sure if there is a company that has a test program.Looks like you had the complete opposite results with the Mirage and Tempest that I did.
I have heard of two companies that do a test/exchange program. Can't remember them both, but I know BBlades does...or at least they use to. If I remember correctly, you had to buy a prop and for $25 + shipping you could exchange it at least a couple of times

Carl C
03-14-2016, 07:51 PM
Will a Mirage+ hook up with a -2" shorty?

Pat McPherson
03-15-2016, 10:12 AM
Will a Mirage+ hook up with a -2" shorty?

The prop shaft on my 22 Donzi is really deep at like 7" below.
On my 24 Super it was about 5" below but that was a straight V not a round bottom.

I know guys with 24 X 7s that run the prop shaft at 3" below but need 4 or 5 blade props.

My guess is that a Mirage Plus would work on a round bottom Donzi with the prop shaft at 5" below and maybe as high as 4" below. Give one a try; what have you got to loose

gcarter
03-15-2016, 10:27 AM
For what it's worth, Catch22 (Jim Collins) ran a 31" Hydro Q4 and could hit 94 on most days.
(Supercharged 454)

Carl C
03-15-2016, 03:16 PM
The prop shaft on my 22 Donzi is really deep at like 7" below.
On my 24 Super it was about 5" below but that was a straight V not a round bottom.

I know guys with 24 X 7s that run the prop shaft at 3" below but need 4 or 5 blade props.

My guess is that a Mirage Plus would work on a round bottom Donzi with the prop shaft at 5" below and maybe as high as 4" below. Give one a try; what have you got to loose

I do have something to lose because I would have to pay a fee to try one. I've been running a BBlades labbed 30p Bravo One. It works great on my boat. No bad handling characteristics at all. I'm just wondering if a Mirage plus will get the boat on plane. If it will then all indications are that I will pick up 2-3 mph and still have a good handling boat. It seems that everyone I know with a shorty is running a four blade. The batteries are out of my boat now so I can't lower my drive to measure but I think I'm 4-5 inches below the bottom. :propeller:

Pat McPherson
03-16-2016, 10:14 AM
I do have something to lose because I would have to pay a fee to try one. I've been running a BBlades labbed 30p Bravo One. It works great on my boat. No bad handling characteristics at all. I'm just wondering if a Mirage plus will get the boat on plane. If it will then all indications are that I will pick up 2-3 mph and still have a good handling boat. It seems that everyone I know with a shorty is running a four blade. The batteries are out of my boat now so I can't lower my drive to measure but I think I'm 4-5 inches below the bottom. :propeller:

Come on Carl, surely you'd spend the $25 or even $50 fee plus shipping to BBlades to try a 29p Mirage plus. Like tires on a car, increased performance from a prop is the best bang for the $$...:yes:

My 24' Superboat handled better in the rough with the BBlades labbed B1 but I did run the labbed M+ on calm day when doing speed runs...

Nice to have options and since no one seems to want to buy my 25p Mirage, I'll likely be sending that out to be labbed for top speed run in my Donzi...:biggrin.:

Carl C
03-16-2016, 11:51 AM
Come on Carl, surely you'd spend the $25 or even $50 fee plus shipping to BBlades to try a 29p Mirage plus. Like tires on a car, increased performance from a prop is the best bang for the $$...:yes:

My 24' Superboat handled better in the rough with the BBlades labbed B1 but I did run the labbed M+ on calm day when doing speed runs...

Nice to have options and since no one seems to want to buy my 25p Mirage, I'll likely be sending that out to be labbed for top speed run in my Donzi...:biggrin.:

I'll discuss it with Brett and maybe start a new thread about it. If everyone says it won't get the boat on plane then I'd just be throwing away $$ trying one. And yes, I'd have to drop to a 29 or maybe even a 28 pitch.

b.guggenmos
03-19-2016, 08:07 PM
Glad you are sticking with Ford power and the King Cobra. While it has been many years since I had my 1988 Testarossa with a 460 and King Cobra it was the only reason I bought it in the first place. If my memory is correct the stock prop was a 3 blade 14 1/2x 24 Raker. Good luck and enjoy! Brian

22classic
05-10-2016, 11:42 PM
I'm starting with a 29p mirage plus.

The dash is finally done. I designed my own dash, wrote the code, and laser cut the piece out. (Let me know if someone wants one)

The engine is in and I have test run it. But have not taken the boat out on the water yet. I can't wait. Saturday should be the day!

93viperboy
05-11-2016, 07:02 AM
Looks great

JParanee
05-11-2016, 08:36 AM
Looking good

what CC system did you go with ?

RickSE
05-11-2016, 12:12 PM
Will a Mirage+ hook up with a -2" shorty?

I run a Mirage+ and my drive is up 1.5". It works fine on mine but you have to walk it up or it'll blow out.

22classic, The boat looks great. You must be up in N. California? Your original post, second picture, looks like the South West. Just wondering, I'm in N. AZ.

22classic
05-11-2016, 01:10 PM
Yes I'm in Nor Cal, the boat usually lives on the west shore of Tahoe, but does make a random delta and Santa Cruz trip. (I live in San Jose)

The CC system is a San Juan that I bought from a buddy. So far it works great. But getting all the hoses and lines hooked up can be a bit of a pain and ugly. Maybe in the future I will clean it up, but we'll see what kind of time I have.

Ill post a video of it running next, and some better shots of the dash.