# 13 Donzi MINX Build!!! Please Help

[biggie]

Okay guys, I have hours and hours and hours of forum time and I seem to be going in circles now. I just bought my first boat (against my dads wishes..."son never buy a boat, make friends w people that own boats. Break out another thousand" ) It seems to be in pretty good shape but its an old boat so Im restoring everything. Right now Im stuck on the power plant. As you all know it has a stock 350 Mag in it w/ a base WOT speed of around 60ish. Well my desired results are 90z, Im building my own motor and have the time and money to do it. I don't wanna spend 20k on it but I want a "wow" motor that'll give me the results Im after. I was thinking a blown 383 stroker to save on weight and space but I dont really know which direction to go for the best "bang for my buck". Could I please get some specific build combos so I can weigh my options based on the best advise and start buying parts. Thanks in advance and Ill post timeline pics of my build as it progresses.

[katanna]

How reliable do you want it to be? A small block pushing that boat to 90 wont last too long. To get there you will be using up your 20k in engine alone. Now you have to address the steering, thats another 3500. The drive wont hold up so you will be switching to bravo set up I assume, at least another 4.

Good luck-post some pics, I have an 88 Minx

[dsparis]

Bravo won't hold up either.

[VetteLT193]

If you really want 90's start by pre-planning everything and add it all up.

My gut says the Minx will run best setup like the Cig 20's. They tend to run flatter Vs. the 22 which really likes to run bow high.

A Big block will fit in the minx, there are a couple of them out there.

The short list (most already mentioned)
-New Drive, probably Bravo XR or better
-New Transom assembly
-Hydraulic Steering
-X dimension change? Going for a higher X to get more speed? fill in the transom and re-cut
-Beef up stringers (the later Minxes had a different setup from the factory that was beefed up, so at least that ++)
-Props
-Exhaust
-Optional... Extension box?

An educated guess puts the Minx in the 80's with a Merc racing 525 + XR drive + hydraulic steering + raised x or shorty or extension box with raised X. Substitute a blackhawk (with XR gears) + box + raised x instead of the XR drive and you might get upper 80's on a good day.

Consistent 90's you'll probably need 650 HP. In order to get there with a small block reliably you probably need a new block like one of the bigger inch motown blocks.

[ralphvc]

I am 3 years into Donzi's and originally wanted to do same to an 18. The cost to get that fast is extreme plus the boats aren't built for it. How much time do you have in a 60 MPH boat???? That is fast. Suggest you pull the 350 go with a mild 383 stroker or if starting from scratch go with a 406. I think the Alpha will hold if you don't hammer on it plus not costly to replace.First crawl then walk then run if you must. Have fun and be SAFE. Again 60 with the wind in your face and a light chop is very fun. Good luck.

[VetteLT193]

I posted a detailed reply but it got lost I guess.

Based on an educated guess: Bottom line 90's in a Minx you'll need 650-ish HP.

The Alpha won't last.

You are looking into at least a Bravo XR, plus transom assembly and either a shorty or extension box + X dim. increase. Props, hydraulic steering, beef up the stringers, etc. $$$$$$.

My gut says the Minx will run like a 20 cig with power (i.e. run pretty flat at speed) so take a look at them to see what it takes to make them move. Most run raised X, blackhawk drives with XR gearsets, and have big power Big Blocks.

With a Bravo XR, shorty lower, hydraulic steering, Merc 525 or similar, and props you should be in the 80's. Emphasis on 'should' because no one has really gone this route before... at least no one has and documented it for others to learn from.

[olredalert]

----Saying you want to go 90 in a Minx is a bit like an obese old guy saying he wants to diet back down to high school weight. You would better serve yourself if you go in steps. If the boat goes a true 60 now think 70-75. Thats realistic, but still wont be cheap to do right. You can think about higher speeds after you have hit the first plateau. Remember that steering comment above. I have two 383s built for my Spitfire more for durability that dynoed at 416hp, but the really important figure is the torque and both these motors pulled 460 ft/lb! Torque is what really moves your boat, not HP.
----As well, you would be over-stressing the Minx hull even at 75 without some extra strengthening of the hull in the right places. Any Donzi you see mentioned on this sight that actually really goes 90 has a bunch of extra fiberglass work done, unless the owner has a death wish!!!.......Bill S

[VetteLT193]

----Saying you want to go 90 in a Minx is a bit like an obese old guy saying he wants to diet back down to high school weight. You would better serve yourself if you go in steps. If the boat goes a true 60 now think 70-75. Thats realistic, but still wont be cheap to do right. You can think about higher speeds after you have hit the first plateau. Remember that steering comment above. I have two 383s built for my Spitfire more for durability that dynoed at 416hp, but the really important figure is the torque and both these motors pulled 460 ft/lb! Torque is what really moves your boat, not HP.
----As well, you would be over-stressing the Minx hull even at 75 without some extra strengthening of the hull in the right places. Any Donzi you see mentioned on this sight that actually really goes 90 has a bunch of extra fiberglass work done, unless the owner has a death wish!!!.......Bill S

I agree and disagree at the same time. From a perspective of seat time, etc. your thoughts are well understood. However, from a value perspective it's a whole lot cheaper and easier to pick a goal and go after it one time Vs. going after it chunk by chunk. I'd wager that every guy running 90 that did it in steps could have saved 10 grand by doing it all at once in the beginning.

[BUIZILLA]

while I always love someone's admiration to undertake a project, and Lord knows i've done a few of those

nobody has ever gone 90 in a Minx...

or even 75 for that matter

much less 80ish

you'll spend 40k + attempting on doing it, and wish you bought the ebay 22 that does run a legit 90 on a good day...

it's free to dream it, but it's purty darn expensive to do it

[gcarter]

Yep!
I had $25K+ in my Minx that'd do 65 on a good day, not that going faster was a goal.

I can think of 15 or 20 reasons why a Minx would be the wrong boat to start with.
Not the least of which is that the hull layup is WAY too light.

[ralphcrocker]

Hello olredalert. Although ok at drag car motors I am embarking on building my first marine motor. I would like to build a 383 and your outcome sounds dead on. if you would be willing to share specifics on your 383 please call Ralph at 248-214-9285 or email ralph@nutechgraphics.com. Thanks in advance.

[HallJ]

Pull the deck and replace the stringers first. The layup and workmanship is poor at best.

Jeff

[biggie]

Thanks for the advise, Im aware that the Alpha wont hold up and the steering needs to be upgraded and I am addressing those issues as well Im just specifically stuck on my power plant issues. Okay maybe 90's is a dream but 80 for sure isnt. I don't want to build in stages bc then Ill have to spend more money after Im bored w that stage. I have a 2004 Kawasaki zx10r on nitrous dino'ing @ 220 mph but I don't ride that fast daily. I want to build a "good" RELIABLE engine that'll give me the results for when Im ready for them. So a 383 wont last, what does everyone suggest? I saw 22 Shelby w a v10 that ran around there. Im just wondering what motor I should build to achieve that and what the suggested way about doing it is. If a built bbc is gonna give me that then thats what Ill do but if I can do a reliable sbc....this is my issue lol someone save me!

[mattyboy]

it should be noted the only 2 similarities to the Minx and the 20 cig is the LOA and the beam . the cig is 800 + lbs heavier, the bilge is designed for a Big Block and the newer ones have a pad. even with that said the general rules of thumb that apply to making the 22c faster hold true for the minx. make it stronger both hull and motor, and raise the X

[joseph m. hahnl]

Thanks for the advise, Im aware that the Alpha wont hold up and the steering needs to be upgraded and I am addressing those issues as well Im just specifically stuck on my power plant issues. Okay maybe 90's is a dream but 80 for sure isnt. I don't want to build in stages bc then Ill have to spend more money after Im bored w that stage. I have a 2004 Kawasaki zx10r on nitrous dino'ing @ 220 mph but I don't ride that fast daily. I want to build a "good" RELIABLE engine that'll give me the results for when Im ready for them. So a 383 wont last, what does everyone suggest? I saw 22 Shelby w a v10 that ran around there. Im just wondering what motor I should build to achieve that and what the suggested way about doing it is. If a built bbc is gonna give me that then thats what Ill do but if I can do a reliable sbc....this is my issue lol someone save me!