I took a 88 311 on trade. Really like boat but feels slow. I would like it to 70mph it only has 330hp with bravos. Whats the most cost effective way. Besides on the trailer. What heads intake,carb,exhaust Im sure it will take about 500hp per side.

What does it run now? Sell the 330s and put hp500s or similar in it. Problem solved.

This sounds like Dave in West Michigan. If so give me a call, Rick

I had a 311 bravo 525ish hp 502's ran 75 gps best ran 72 73 any day. Most cost effective way is definetly just removing those motors and finding a pair of hp500s or 502s and dropping them in.

twins makes it much more difficult and expensive. In the end if you looking for 500~525 hp all thats going to be left is the blocks.

The 330 has a cast crank, little rods, cast piston, peanut port heads. So plan on a better complete forged rotating assembly, new heads, intake, cam, exhaust etc.

With a single you can look for take out parts, twins you need to match everything. A 454 mag or a 502 both have forged cranks and better rods. with some scrounging you can find a 502 takeout crank and rods from somebody turning their 502 into a 540. Some rectangle port heads off a 454/502 that somebody took off to put better heads on. Then you will need a decent cam and valve train.

Unless yourgood at scrounging or you have friends with tons of parts laying around, its cheaper to by better motors thasn to build them from 330's.

My boat runs 70-71 depending on conditions with TRS drives. They are bone stock 454/420 motors with the exception of Marine Kinetics roller cam conversions. Bob estimated about 500 horse per motor, but they have never been dynoed. With bravo drives your boat should be a little faster, so if you were to get 500 per motor you should easily eclipse your goal. Probably your easiest option is buy some take out 420's, refresh them and roller cam them. You can offset some of the cost by selling your 330's complete.

Prochargers, done.... lol

If these were mag motors that would probably be a quick and easy option, but I would be very learey throwing boost at a cast crank, cast piston, small rod motor.

Low boost lots of fuel, it'll be fine .... But I get it... I would but that's me or drop hp 500's and go 73-75 all day long

Leaning towards trying to find some 500hps or maybe stroking these with all new parts.