am i crazy?

[mikeseng1990]

some basic info on my boat...

1977 Formula Thunderbird 23'3ft and a 8'ft beam
5.0L v8 305ci and an F233 outdrive, mercarb 2 barrel throttle body injection system

absolutely nothing wrong with this set up i love my boat the engine is strong reliable and dropped in '06 it's practically new
it'll pretty much open up at about 48-52mph wot and with the 2 barrel carb its great on gas...

i want to put in a GM 7.4L 454ci and a bravo III outdrive

i know if it ain't broke don't fix it... i'm just throwing the idea out there to get some opinions
does anyone think this is crazy?

 

[62 ROYAL SCOTT]

Re: am i crazy?

HEY How fast do you think it will go at WOT then ? I asume that's why you want to change out everything.

 

[HT32BSX115]

Re: am i crazy?

1977 Formula Thunderbird 23'3ft and a 8'ft beam

i want to put in a GM 7.4L 454ci and a bravo III outdrive

does anyone think this is crazy?

Howdy,


Well, not really. It will perform a little better.... Maybe 5 MPH faster but a WHOLE lot faster out of the hole.

I don't know if it will be worth it. I paid $5000 for the 454/Bravo III I put in my 87 211 Liberator in my sig, but I did the entire job myself and I got a total of $3500 parting out the previously installed OMG 460 King Kobra.


You'll have to decide if it's worth it to make the switch.


Regards,


Rick

 

[bnicov]

Re: am i crazy?

How fast do you want to go and how much fuel do you want to burn???? Those are the two questions that should be going through your mind. You will definitely burn more fuel with the 454 but you will also get much better performance out of the hole. As for top end, HT is probably right with his 5mph estimate.

 

[Volphin]

Re: am i crazy?

I'd stick with the 5. Gas keeps going up.

V

 

[HT32BSX115]

Re: am i crazy?

If you run your current boat at about 30 mph for example, and it takes about 10 gal/hr or so to 30,

THEN, put a 454 and Bravo III in it, prop it correctly it will probably STILL burn about 10 gallons per hour. (at 30 mph)

In any boat, it takes a certain amount of power to go a particular, efficient, planing speed regardless of the engine you install.

(Put both a 454 anda 350 on a dyno and they'll both burn close to the same fuel at the approx same power output.....It's just that the SBC will work a LOT harder to do the same thing)

So you won't ALWAYS burn a LOT more gas with the 454 if you cruise and operate at the same speeds as before. (you WILL however get FAR better hole shot (which will burn more because you'll use it) and better top speed (which will also burn more because you'll do it!!)

The Bravo III will perform better all the way around. You will especially like the low speed handling.

If you can do it yourself and you can get a swinging deal (like I did) on a complete engine and drive, I would do it!


Cheers,


Rick