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View Full Version : Will the 383 Scorpion fit in a 1993 Donzi?



Blind Horse
05-23-2013, 01:45 PM
Call me crazy, but I own a new Mercury 383 stroker scorpion, 400 HP, bravo configuration. I want to put it in a nice 18 Classic with a windshield. I am on the west coast and it is hard to even look at a Donzi way out here. I would prefer to find a newer 18 classic but there is a nice looking older one (1993) in Seattle (HINCCVBB122D393) that is available and I sea trialed it. Finding a real nice 18 out west is proving to be hard for me and I am getting antsy to get a boat for the summer. I am considering buying the old 1993 Classic 18 in Seattle if I could determine that the 383 might work in it. The Classic 18 in Seattle has a King Cobra outdrive and an OMC 351 HO. My approach would be to junk the tired 351 and try to use the King Cobra outdrive if reasonably possible.

Do you guys think my 383 will fit in the 1993 classic and bolt up to the King Cobra outdrive? The exhaust setup on the OMC 531 is kind of wierd with 90-degree bends they put in it after the elbows for some reason, but I suppose I could cut new holes in the transom and have someone patch the old ones for a fee. Here is a link with photos of the Classic 18 I am considering for my 383 scorpion:

http://www.parkplaceltd.com/all-cars/detail/1993-Donzi-18-CLASSIC/282/CCVBB122D393/~/Make_Donzi~ModelActual_~Year_/1

And by the way, if someone has a sweet 200? 18 Classic out there to sell, I am very interested. I missed the pretty 2006 in Thousand Islands that was posted a couple weeks ago unfortunately. I should have jumped all over it.....

Blind Horse (Jeff)
Bellingham, Washington
383 Stroker Scorpion MPI 400 Bravo (no boat)

JayZ
05-23-2013, 03:18 PM
Much much easier if you start with a bravo boat and probably cheaper too since you are talking about a ford to gm conversion. If you start with a small block gm / king cobra boat then it would be easy too.

mattyboy
05-23-2013, 03:19 PM
just a few thoughts that may help.

OMC used both Ford and Chevy power with the KC not sure if the adapter is the same but it can be sourced Volvo also makes an SX/cobra adapter for a Chevy that should work.

The 383 Scorpion Stroker 400hp usually comes with merc spec'd CMI headers, I have seen the 350HP version with standard Merc type risers.

The CMI headers made for Merc are not the best you will need to adapt from the back of the header to the current tips not sure if that is possible to re-use the existing holes.

They fit a 377 scorp into an 18 , it may pay to visit the X-dim. as well , so a late model bump out hatch might help. I would Imagine the 351 sits pretty high in there now.

Also make sure the Scorp is setup for an I/O not a v drive that will lead some head aches.

the cut out for a KC and a merc boat should be the same

http://www.donzi.net/forums/attachment.php?attachmentid=51777&d=1256423142

http://www.donzi.net/forums/attachment.php?attachmentid=54921&d=1270990887

http://www.donzi.net/forums/attachment.php?attachmentid=54969&d=1271071703

yeller
05-24-2013, 04:22 AM
Lots off good advice from Matty.
Definitely looks like a nice clean boat. May be the way to go for you especially seeing as you won't have any shipping costs, but check out the final costs of what you want to do first.

I know what you're going through. Pickings are pretty thin out west. I had to ship mine from Chicago. If you do decide on that boat I'd work them hard on the price. OMC boats don't sell as easily as Bravo boats.

Good luck....and keep us posted

Blind Horse
05-24-2013, 09:40 AM
I appreciate the good advice. I plan to hold out looking for a bravo configuration. If something doesn't come up in the next few weeks, I might end up in Seattle bringing the king cobra home. I am a motivated buyer, owned lots of boats, and have cash.

Thanks again, there is a ton of great stuff on this forum. Hopefully I can return the favors.

Blind Horse (Jeff)
Bellingham, Washington

MOP
05-24-2013, 09:52 AM
You need to find a GM/OMC bell housing that is an easy bolt together package, the King is actually a better drive than the Bravo it is also slightly faster due to its lower unit design. A 383 in a classic is a hoot, we have one around here very warmed over with dual quads it runs in the upper 80's.

Phil

MOP
05-24-2013, 09:57 AM
Here ya go a page full of GM/OMC bell housings, GM uses a standard bolt pattern. All will fit but the 5.0 and up "may" be a bot better not sure.

http://www.ebay.com/sch/i.html?_odkw=&_qfkw=1&_ssov=1&_osacat=50440&_fln=1&_trksid=p2045573.m570.l1313.TR0.TRC0&_nkw=omc+bell+housing&_sacat=50440&_from=R40

You want one that looks like this: http://www.ebay.com/itm/5-8-5-0-4-3-V6-V8-OMC-Chevy-Cobra-Flywheel-Bell-Housing-911659-913283-3857846-/400434545913?pt=Boat_Parts_Accessories_Gear&hash=item5d3bc244f9&vxp=mtr

Blind Horse
06-25-2013, 07:06 PM
Instead of the 1993 classic 18 I was considering, I found a 2001 Donzi 18 and bought it. It has a 350 mag mpi with alpha drive, 35 hours apparently. I want to put my stroker 383 400HP in the boat but I need to order a new bravo 1 for it. Does anyone have advice on what gear ratio to purchase and what prop to start with?

Additionally, I want to become a paid subscriber to this website and get listed on the registry but I don't know how. Do I simply use the donate button and give some money or am I supposed to register some other way with a set price?

Blind Horse
Bellingham, Washington
2001 Donzi 18 Classic

gcarter
06-25-2013, 07:21 PM
The Alpha drive is faster (it's smaller) than a Bravo, and 400 HP isn't too much for it.
Why not install your engine w/the Alpha, at least until (if ever) it fails.
Before I sold my Minx, I upgraded everything inside the boat for a Bravo (inner transom plate, Bravo (large) coupler, Bravo flywheel cover. The idea was, if I found a deal on a Bravo, all I had to do was change the gimbal housing and drive.
I think a 1.5:1 is the ideal ratio for good prop selection.

Ghost
06-25-2013, 07:31 PM
I think you can just hit the donate button and follow the prompts. Not sure if any magic happens such that if you do all this while logged in, the donation is tied to your user account. Regardless, I'd think the Harbormaster would figure it out by matching at least the email address on the donation form to the one on your user account.

As for drive ratio, I would think a typical 1.5 ratio would be what you wanted. That said, I know of at least one HIGH HP supercharged 18 that runs a 1.65 ratio. (There's a debate to be had there about turning a steeper prop more slowly, among other things.) I'm thinking there will be folks with very similar setups to yours who can point you to more certainty and some likely props. One of which will hopefully be the Mirage Plus 25 I need to sell. :)

Another question might be whether you should go Bravo1 or Bravo1x...

osur866
06-25-2013, 11:51 PM
Great find on the low hour 18, when you mention 383 400hp is it the blue scorpion racing engine or the black scorpion? Either way 400 HP in front of a Alpha'd 18 I'd think would be a tick faster than the bigger Bravo case and if driven with respect and throttled properly would last a longtime, remember you can buy what 2-3 Alpha's for the cost of 1 Bravo. When I added HP to my 18 many told be I'd have to step up to a Bravo X or XR, I never did, mine is a stock Bravo boat, the 18 is a light boat and I honestly believe there are a few factors that have kept the drive alive, I change fluid often (25 hrs) even if it doesn't look like it needs it, NO fast holeshots, I've never pulled a skiier nor plan to, and albeit I'm not perfect on the throttle I don't zing the prop much when it leaves the water, and I am running 3 bladed props which tend to slip a little more than say a 4 or 5, ill hold back on the prop debate but I've found a 3 blade to work nicely for my set up. Ratio well I'm in the camp of running a higher ratio gear and larger prop more slowly than a smaller prop faster, true it may take longer to find the correct wheel but I've found it to be worth it in lower slip numbers and an awesome acceleration, my .02 worth, I'd drop that 383 in save your money that your spend on the bravo and conversation and apply that towards a good hydraulic steering system and start prop testing.
Steve

Just Say N20
06-26-2013, 07:08 AM
I would listen very carefully to the advice given. It is a very knowledgeable and helpful group of people.

Osur866 KNOWS of what he speaks. And in true classy fashion, his answer isnít about him, or his remarkable boat.

A little searching will reveal that he has a supercharged, high hp 18 that runs exceptionally well at speeds most lust after.

Alpha with a drive shower, easy on the throttle during take offs and any air time, and hydraulic steering with the money not spent on the Bravo.

osur866
06-26-2013, 07:37 AM
I would listen very carefully to the advice given. It is a very knowledgeable and helpful group of people.

Osur866 KNOWS of what he speaks. And in true classy fashion, his answer isnít about him, or his remarkable boat.

A little searching will reveal that he has a supercharged, high hp 18 that runs exceptionally well at speeds most lust after.

Alpha with a drive shower, easy on the throttle during take offs and any air time, and hydraulic steering with the money not spent on the Bravo.

Thanks Bill, I forgot to mention the drive shower.

Blind Horse
06-26-2013, 11:29 AM
Most importantly, I made a donation to the website this morning and I hope to get my boat info on the registry tonight after work.

Secondly, thanks for the good advice.

My insurance company told me yesterday that they wouldn't insure my 2001 classic 18 with the 300 hp motor. The insurance company doesn't even know yet that I plan to increase it to 400 hp. I am a 39 year old civil engineer, married, own a house, own a company, with no driving record whatsoever. I wonder if this insurance issue is a problem for anyone else who runs Donzis?

Blind Horse
2001 Classic 18, 350 Mag MPI, Mirage Plus 25

Just Say N20
06-26-2013, 11:47 AM
Insurance is a whole other issue. I have a home, 3 cars, motorcycle, and a 38í CARVER all with State Farm, good driving record, etc. They would insure my Donzi Ski-Sporter, but at $890/year.

My agent told me SHE wouldn't use State Farm to insure my boat.

Some searching on here will bring up discussions regarding the peculiarities associated with insuring Donzi classics, and what others have done.

And I always put out this disclaimer. Be honest with the insurance company about what they are insuring. If you upgrade the engine/or replace it, tell them. If you ever have a reason to submit a claim, and they find out your engine is modified/replaced, they will not pay, saying what they were paid to insure, was NOT what you submitted the claim on.

If you do end up with the Alpha drive and 400 hp under the hatch, I predict you will be dancing around 75 mph.

Carl C
06-26-2013, 01:12 PM
Try AllState just for kicks. Age, credit score, driving record, years of boating experience, past claims history all factor in. The site owner, Scot, has a pretty full plate right now so while I'm sure he appreciates the donation it may take him awhile to get your membership squared away. Keep us informed on the progress of your boat. Sounds like you are putting together yet another sweet Donzi Classic!

MOP
06-26-2013, 01:26 PM
Stick with the Alpha you can replace it several times before equaling the cost of a Bravo drive and a Bravo transom assembly. Look around any marina you will find tons of much heavier boats with Alphas, many will be quite a few years old. I made the mistake of spending over 6k converting, that equals 4-5 replacement drives. SEI replacement drives go for $1300 with a 3 year warranty, quite a few guys are running them! Also you will be 2-3mph faster!!!!!

osur866
06-26-2013, 01:45 PM
I too had State Farm, when I added HP they woulda dropped me like a hot potato, try Markel they have it now twice the coverage on almost twice the HP and they are aware I run poker runs with it, price 775 a year couldn't be happier.

I concour 75-77 with 400 HP Alpha 18

Good luck

Blind Horse
06-26-2013, 04:55 PM
Steve,

I forgot to answer your previous question about what motor I bought. It is the black reman 383 400 HP with the flame colored flame arestor, 2008 model.

I like the idea of keeping the alpha and installing the bravo inner transom assembly as someone suggested in case I decide to upgrade later.

I might try my mirage plus 25 on the boat first after I get the 383 in there and see how it works.

The 383 and the alpha I own both have power steering. However, I assume that the recommendation to install power steering is the Latham steering that is often referred to on this website. I will google that and try to figure it out. Frankly, I have no idea what Latham steering is.

Thanks for all your help. When I figure out how to post pictures, I will get one or two up of my superclean 2001 18. It's really fun to run on our lake because nobody has seen anything like it around where I live, lots of compliments.

Jeff

joseph m. hahnl
06-26-2013, 07:53 PM
Steve,

I forgot to answer your previous question about what motor I bought. It is the black reman 383 400 HP with the flame colored flame arestor, 2008 model.

I like the idea of keeping the alpha and installing the bravo inner transom assembly as someone suggested in case I decide to upgrade later.

I might try my mirage plus 25 on the boat first after I get the 383 in there and see how it works.

The 383 and the alpha I own both have power steering. However, I assume that the recommendation to install power steering is the Latham steering that is often referred to on this website. I will google that and try to figure it out. Frankly, I have no idea what Latham steering is.

Thanks for all your help. When I figure out how to post pictures, I will get one or two up of my superclean 2001 18. It's really fun to run on our lake because nobody has seen anything like it around where I live, lots of compliments.

Jeff external hydraulic steering :drive: Just use the 350 Mag beauty cover on it . The only one who needs to know you have a 383, is you:wink: I'd also understate the HP on the Registration like 265HP :propeller:

osur866
06-26-2013, 09:23 PM
Hydraulic steering will not only vastly improve upon the handeling but also make the boat much more safe, Latham is one choice as there are others maybe more affordable, such as Imco, Mayfair and Zeilger I'd also look at.

smokediver
06-27-2013, 07:24 AM
I am gonna guess you will need to swap over the ignition for the alpha set up you have along with the shifter and throttle bracket. Your 383 is probably set up for a bravo and you running an alpha will have to change those items along with ditching the sea water pump. The coupler and bell housing are an exact fit so no worries there

smokediver
06-27-2013, 07:32 AM
One more thing , if it were me , i would get an extra upper gearcase and have the hd gear set installed in it. Should be under 600 bucks . I fried several and it was always cruising at 3500 rpm with my 383 powered 16. Never out of the hole or at top end but in the fat part of the torque curve. After i finally took the advise of some on the board i had the hd gearset installed and never had an outdrive problem again. It was never the lower it was always the upper. I went through 4 gearsets 😳

Blind Horse
06-27-2013, 10:35 AM
Smokediver,

Are you running a drive shower with your alpha?

I found insurance at under $500 a month through progressive, with the 383 in the equation.

Jeff

smokediver
06-27-2013, 11:20 AM
Smokediver,

Are you running a drive shower with your alpha?

I found insurance at under $500 a month through progressive, with the 383 in the equation.

Jeff

That was a few boats ago but yes i did have a drive shower

BUIZILLA
06-27-2013, 05:03 PM
I found insurance at under $500 a month through progressive, with the 383 in the equation.

Jeff $500 a MONTH ?

Blind Horse
06-27-2013, 05:52 PM
Ooops. Less than $500 a year. I was confusing it with my insurance policy on my 36 Skater (just kidding).

Blind Horse
07-25-2013, 10:52 PM
I got the 2008 383 scorpion in the donzi and kept the alpha drive. Everything is ready except for the shift interrupt switch. My bravo configured engine will not use the shift interrupt that my alpha drive needs. Do I have to buy a new ECM (ouch!) or is there a workaround for this? I have read about a bravo A-C jumper that I might be able to remove and wire to my shift interrupt switch. I have also seen references to wiring the interrupt switch to the coil ground but I am concerned it will mess with the ECM and make the engine think it's starting again each time I shift the boat. Has anyone dealt with this?

Jeff Vander Yacht

gcarter
07-26-2013, 06:57 AM
I don't think so, but I'm not positive.
Id suggest buying a new interrupt switch, which, if I remember correctly, requires buying a a whole new shift plate. Anyway, replace the shift plate, and wire in the switch mounted to it. I don't remember which side of the coil it's wired to.
It's a really good idea to spring for a $25.00 manual. In the manual would be a lot of wiring diagrams covering the various engine and drive combinations, you'd know the answer, and everyone would be impressed you did it all............all for only $25.00. At your local Merc dealer and some book stores.

joseph m. hahnl
07-28-2013, 09:19 AM
I got the 2008 383 scorpion in the donzi and kept the alpha drive. Everything is ready except for the shift interrupt switch. My bravo configured engine will not use the shift interrupt that my alpha drive needs. Do I have to buy a new ECM (ouch!) or is there a workaround for this? I have read about a bravo A-C jumper that I might be able to remove and wire to my shift interrupt switch. I have also seen references to wiring the interrupt switch to the coil ground but I am concerned it will mess with the ECM and make the engine think it's starting again each time I shift the boat. Has anyone dealt with this?

Jeff Vander Yacht The interrupter switch grounds the distributer:shocking:

miike
07-28-2013, 10:47 PM
The king cobra is decent but its tough to get parts for as in even the impeller isn't made by Omc any more. Tough drive though. I wouldn't buy a running king cobra boat and then pay to convert it. If you want to buy and keep a king cobra, make sure you can get your hands on the bell housing. Just because there's an Omc part number for something doesn't mean there are any for sale.

The alpha is probably enough for an 18 because its light enough but it won't hold if you want to run real hard like the boat is meant to be driven. Might be tough to find a bravo 18.

Blind Horse
08-11-2013, 10:30 AM
My dream of having a classic 18 repowered with a 383 is now fulfilled and I wanted to post this thread as a report in case it might help someone else in the future with a similar project. Here is exactly what I have; 2001 Classic 18, 2008 383 stroker black scorpion (reman 400 hp, factory merc manifolds, MPI), 2001 alpha 1.62:1 drive with shower.

The 383 mpi was originally built for a bravo application which posed a number of challenges for me as I wanted to use it with the alpha drive. The throttle cable connection on the motor was likely a MIE setup even though the engine was for a bravo. Not sure why merc set it up this way, but I had to make a stainless bracket to hold the outside of the cable while the inside of the cable attached to the 383 throttle lever on the motor. After plenty of hours considering the bracket, I came up with a clean and simple way to do built the bracket and I can share if someone needs it. The bravo configured engine needed the shift interrupter function activated in the ECM. Dustin Whipple (whipple superchargers) reprogrammed the ECM and did a perfect job. I have learned now that Dustin Whipple can reprogram nearly any function in the ECM. He was actually able to lower my idle RPM by 25 only when the temperature exceeds 140-degrees. I had to purchase a new shift interrupter switch for my alpha shift plate because the 2001 model from my previous engine was a 2 pin plug pigtail and didn't have the built-in 10K ohm resistor. The new model is a simple switch with a 3 pin pigtail plug resistor, and it communicates with the new motor after Dustin's reprogram. I also needed a 14-pin to 10-pin harness adapter. We left the impeller in the alpha drive but made a blockoff plate inside the transom assembly. I installed a stainless marine transom pickup with reinforced hose between the pickup seacock and the pump (the flexible hose was collapsing due to suction unless the boat was planing). I installed a pressure gauge on the water pickup, I get about 10-psi at 40 mph and I didn't grind or adjust the pickup. I may have installed my pickup a 16th of an inch too high. If I could do it again, I would have the leading edge of the pickup be a hair below the boat to achieve more pressure and the ability to fine tune the pickup with a grinder.

I did a lot of research on engines with large cams like the 383 as it relates to reversion. It sounds like water reversion is a huge risk if backpressure isn't considered. With the short exhaust length typical in a classic 18 through the transom, I would be very hesitant to install a large overlap cam without studying reversion first. Mercruiser told me that a minimum backpressure of 2 psi is necessary to prevent reversion, my 383 has a 270 degree overlap. I have corsa quick and quiet plus. Corsa claims that my backpressure is likely 5 or 6 psi with the silencer tips. I have my fingers crossed that water isn't reverting into the engine.

Once I overcame these minor challenges, the boat is exactly what I wanted. I am still in the engine break in period and being careful with the alpha drive but I do drive it reasonably hard. The boat is a completely different animal with that 383. I don't have a gps yet, but the speedo is reading around 58 at 4000 rpm with the Mirage Plus 25. If I end up getting WOT of 6500, the boat should fly. Nobody around here has seen a donzi, most don't even know how to pronounce it. I appreciate the advice I have received from this website and I hope I this report helps someone in the future.

Jeff Vander Yacht
Bellingham, Washington

gcarter
08-11-2013, 10:51 AM
If your drive ever breaks and you replace it w/an SEI unit, I think it will have a 1.48:1 ratio. That might make it even more interesting.
Good luck w/your new packaqe.

BUIZILLA
08-11-2013, 01:31 PM
my 383 has a 270 degree overlap.

If I end up getting WOT of 6500, the boat should fly. if I can offer a couple tidbits..... first, your cam does not have 270* of overlap, advertised duration maybe, but not overlap.. second, do not turn that 1.62 drive over 5200, or the explosion won't be pretty... by going from a 1.47 to a 1.62 grear ratio in the drive you have theoretically added an additional 10% torque multiplication into the equation, which is very beneficial, and i'm all for it, but requires more throttle tempermant...

joseph m. hahnl
08-12-2013, 05:51 PM
My dream of having a classic 18 repowered with a 383 is now fulfilled and I wanted to post this thread as a report in case it might help someone else in the future with a similar project. Here is exactly what I have; 2001 Classic 18, 2008 383 stroker black scorpion (reman 400 hp, factory merc manifolds, MPI), 2001 alpha 1.62:1 drive with shower.

The 383 mpi was originally built for a bravo application which posed a number of challenges for me as I wanted to use it with the alpha drive. The throttle cable connection on the motor was likely a MIE setup even though the engine was for a bravo. Not sure why merc set it up this way, but I had to make a stainless bracket to hold the outside of the cable while the inside of the cable attached to the 383 throttle lever on the motor. After plenty of hours considering the bracket, I came up with a clean and simple way to do built the bracket and I can share if someone needs it. The bravo configured engine needed the shift interrupter function activated in the ECM. Dustin Whipple (whipple superchargers) reprogrammed the ECM and did a perfect job. I have learned now that Dustin Whipple can reprogram nearly any function in the ECM. He was actually able to lower my idle RPM by 25 only when the temperature exceeds 140-degrees. I had to purchase a new shift interrupter switch for my alpha shift plate because the 2001 model from my previous engine was a 2 pin plug pigtail and didn't have the built-in 10K ohm resistor. The new model is a simple switch with a 3 pin pigtail plug resistor, and it communicates with the new motor after Dustin's reprogram. I also needed a 14-pin to 10-pin harness adapter. We left the impeller in the alpha drive but made a blockoff plate inside the transom assembly. I installed a stainless marine transom pickup with reinforced hose between the pickup seacock and the pump (the flexible hose was collapsing due to suction unless the boat was planing). I installed a pressure gauge on the water pickup, I get about 10-psi at 40 mph and I didn't grind or adjust the pickup. I may have installed my pickup a 16th of an inch too high. If I could do it again, I would have the leading edge of the pickup be a hair below the boat to achieve more pressure and the ability to fine tune the pickup with a grinder.

I did a lot of research on engines with large cams like the 383 as it relates to reversion. It sounds like water reversion is a huge risk if backpressure isn't considered. With the short exhaust length typical in a classic 18 through the transom, I would be very hesitant to install a large overlap cam without studying reversion first. Mercruiser told me that a minimum backpressure of 2 psi is necessary to prevent reversion, my 383 has a 270 degree overlap. I have corsa quick and quiet plus. Corsa claims that my backpressure is likely 5 or 6 psi with the silencer tips. I have my fingers crossed that water isn't reverting into the engine.

Once I overcame these minor challenges, the boat is exactly what I wanted. I am still in the engine break in period and being careful with the alpha drive but I do drive it reasonably hard. The boat is a completely different animal with that 383. I don't have a gps yet, but the speedo is reading around 58 at 4000 rpm with the Mirage Plus 25. If I end up getting WOT of 6500, the boat should fly. Nobody around here has seen a donzi, most don't even know how to pronounce it. I appreciate the advice I have received from this website and I hope I this report helps someone in the future.

Jeff Vander Yacht
Bellingham, Washington Minimum , so too little back pressure causes reversion, :confused:

mattyboy
08-12-2013, 09:17 PM
in the 383 400 yes