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View Full Version : Beef up a 7.4MPI 310HP


FlyingDutchman76
08-13-2006, 12:26 AM
Any suggestions how I can beef up a Donzi 22 Classic with a Mercruiser 7.4MPI 310HP ? What suggestions do you have and who can perform the upgrades.

This engine needs some serious modification to boost power. The 310HP just doesn't seem enough. It's current top speed is 65mph, but would like to go around 80mph.

Any suggestions and guidance in the direction of more power is greatly appreciated.
Donzigo
08-13-2006, 06:18 AM
Ditto...............you can throw a blower on it, roller-rockers, if the 7.4 doesn't have it, some stainless exhausts and you've spent a lot of money and gained little. Sell what you have and repower with the right stuff..............it's cheaper that way.

Horsepower isn't cheap................then, you gotta consider the outdrive, too
FlyingDutchman76
08-13-2006, 06:44 AM
Ditto...............you can throw a blower on it, roller-rockers, if the 7.4 doesn't have it, some stainless exhausts and you've spent a lot of money and gained little. Sell what you have and repower with the right stuff..............it's cheaper that way.
Horsepower isn't cheap................then, you gotta consider the outdrive, too

It has a Bravo One outdrive. Will it keep up with more power ? What do you consider the "Right" stuff ? Who is Grizz ? I'm new to this and don't have much knowledge of how to repower my Donzi :idea:
blackhawk
08-13-2006, 12:56 PM
You can easily get more power out of the 310 hp motor as long as you are looking for moderate gains. There was a thread on another forum awhile back that had some good examples. But it was for the carb motor. Cam, intake and exhaust gave some impressive gains. But it always cost money! :D I agree swapping out the motor is easier and provides peace of mind but can cost some $$$.
Monster Truck
08-13-2006, 01:25 PM
take it out and put a 496 ho in it 425 hp stock, dont worry about your bravo one its bullet proof. the 454s are junk. btw i can go 65 with a stock mpi 350.
ITTLFLI
08-13-2006, 02:24 PM
Would this hp/tq do?
blackhawk
08-13-2006, 02:32 PM
dont worry about your bravo one its bullet proof. the 454s are junk.

Hmmm, a bravo one is bulletproof and 454s are junk? :rolleyes:
Cuda
08-13-2006, 02:48 PM
take it out and put a 496 ho in it 425 hp stock, dont worry about your bravo one its bullet proof. the 454s are junk. btw i can go 65 with a stock mpi 350.
The 496 HO won't get you to 80. The power needed as well as the money needed go up exponetially once you start thinking of 75+.