repower from 454/330hpcarb to 6.2l/320hp
 

can someone tell me if i replace my 454/330hp's to 6.2l/320hp's using bravo1 drives would i still have the same performance since the 6.2's are lighter and have better fuel consumption. i have a 34foot offshorer which is quite heavy. not like the american made ones. i used to get 48 mph full speed at 4400 rpm. do i need to make any changes to my drives or props using the 6.2l/320hp's

thanks
jack

Re: repower from 454/330hpcarb to 6.2l/320hp
 

Good question. Its one I would like to know also. I have been told the 454 make more torque. But as far as overall performance Im not sure someone has to know on this site.

Re: repower from 454/330hpcarb to 6.2l/320hp
 

Without having a technical answer for you...
Torque moves boats, not HP.

A stock 454 vs a stock 6.2 sbc won't be too far off in torque values.. THe gas comsumption would be better w the smaller motor, but I would rebuild the 454s to 496+ in a heartbeat.
(it won't help the GPH issue however you'd have alot more fun)

Re: repower from 454/330hpcarb to 6.2l/320hp
 

Jack,

You need to carefully compare the power and torque curves of the two motors. If your old 330's were peaking at 4600 rpm, but the 6.2's do the trick at 5000, you'll need to go to lower pitch props to maintain your performance. There are some thumbrules people throw out there, like 1" of pitch is worth 300 rpm, but those don't always work, and if you change the blade number, you need some more scientific prediction method. I encourage you to visit www.speedboatperformance.com, and put in your "before" and "after" conditions. For your power level, you can run the application for free.

Re: repower from 454/330hpcarb to 6.2l/320hp
 

There's alot of option out there, if your looking for more performance, 6.2 liter motors aren't the anwser. I'd find yourself a set of warmed over 502's for some reliable power you should be able to find a pair for a good price, or throw some money into your engines to create some power. If your looking for fuel economy and not to worried about performance gains or lose then yes 6.2 would be fine. Your drives should be fine unless you go with some serious power combos, props will most likely be trail by air to find your boats sweet spot..... Good luck, keep us posted with what happens.