Freind just bought a 18' Donzi the boat came with a 454 gen 4 and a 350,it has a Bravo drive. What motor should he put in, and how fast will it run with each motor?

for an 18 footer, the 350 will be plenty power for general use... for a more ''racing or fast'' way to drive... 454 !!!

Can't tell the speeds ....

454

Stock for stock, a big block in a smaller boat is cool. If you are building on a budget, you will be amazed at the power you can squeeze out of a small block.


John jr

18 Classic's are made for SBC/ 375-450hp +... period.

The boat will handle way better with the SB!!! If both are equal in power the SB will not only handle better but be prolly faster due to less weight!
Something else to take into consideration is space while working in the bilge, a small block is pretty tight in there with the classic 18's low freeboard, yes the 454 will fit but will be even tighter. Spend a lil coin on the small block and you'll have a better handeling set up.

Go with a 383 still a small block with a little more kick

+1.

On the spot....

Or go with a 383 run it for a couple years, put shorty, steering on then add a Whipple and run into the low 90's, what I did with mine