View Full Version : 99 Donzi zx 350mag project!
ttshibby
06-26-2009, 10:46 PM
Hi everyone, i just bought a 99 donzi, It has the 350 mag efi and bravo drive.
Where should i start to add more power? Can eanyone help me out on what ecu i may have or how to determine that. Where can i look for good ideas, i find it very hard to find info on marine engines... can i upgrade heads etc on this engine? add boost? and i am wondering on what extent the ecu can be modified. Im looking to reach 450-500 hp......
I have built a mustang dragster with 1000 hp,complete aftermarket efi etc, so i know where and how to do it, i just need to know the base of motor, im assuming the merc is a chevy or something. right.... I just know 4.6l 's like the back of my hand.... nothing about boats.
Thanks everyone! i appreciate any help, advice!
zelatore
06-26-2009, 11:32 PM
Welcome aboard...
You didn't say which boat you had, but I'm guessing a 22ZX since it's a small block? I'm not that familiar with the ZX series myself, but there are plenty here who are. You'll no doubt hear from then shortly.
Yes, the Mercruiser 350 Mag began life as a 350 Chevy. And just like in the automotive world, it's probably the cheapest and easiest motor to modify.
That said, if you want to end up in the 450-500 hp range there's a quick and easy way to get there:
Step one - remove the 350 Mag complete.
Step two - purchase a 502 Mag complete as a take out. Try looking places like OSO.
Step three - install 502 with minor upgrades as desired; sell 350 to offset costs.
OK, I've over-simplified in the extreme, but you'll have a MUCH easier/cheaper go of it starting with a big block.
Otherwise, I'd think blower for easiest way to big power. And more cubic inches never hurt anybody either...
ttshibby
06-27-2009, 09:49 AM
Awesome, thanks for the reply, However i would like to keep the 350 for weight savings....I feel there is already an abundance of weight in the rear in already. especially with passangers. I was thinking of boosting it, with a water intercooler. Just needed the base to find some better heads,cam maybe stroker kit. etc.... Ill probally build my own supercharger kit.... I fabbed in twin turbos on my 2000 mustang and there is way more room to work under the hood of my boat... and yes it is a 22zx.
Does anyone know about the computer, and what programs are used to flash it?
Thanks.
Troy
zelatore
06-27-2009, 09:54 AM
99 .... probably MEFI III (?)
If you're familiar with the technology, you would of course have far more versatility and tunability doing a custom injection system. Of course, then you need a good wide-band O2 sensor which can be tricky unless you go to dry exhaust.
BigGrizzly
06-28-2009, 07:36 AM
TTS, If you want to keep the 350 and you know how to build, Go the 383 route. The 350 won't be a good option because it has to be done just right and the 383 is more forgiving. Just a caution warning, boating is not a drag application and people and high po guys are just guessing. I will admit I am with Zel on this one, but a good 383 will do fine. Do not get your sights on being a world beater with this, it just does not happen in real life.
ttshibby
06-28-2009, 11:01 AM
thanks... ill keep my options open... I was hoping to keep the weight as low as possible. but if a find a deal on a 502 i wont pass it up. What things need to be changed to fit that beasst in?
osur866
06-28-2009, 04:27 PM
Exhaust, and whipple = 470 HP ish, hope you have a Bravo on the back if your going with that kinda HP. My .02 Steve
fasttrucker
06-28-2009, 08:29 PM
Awesome, thanks for the reply, However i would like to keep the 350 for weight savings....I feel there is already an abundance of weight in the rear in already. especially with passangers. I was thinking of boosting it, with a water intercooler. Just needed the base to find some better heads,cam maybe stroker kit. etc.... Ill probally build my own supercharger kit.... I fabbed in twin turbos on my 2000 mustang and there is way more room to work under the hood of my boat... and yes it is a 22zx.
Does anyone know about the computer, and what programs are used to flash it?
Thanks.
Troy
The whipple supercharger company reflashes your ecu when you buy their kit.
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