383 Mag Mpi Vs 454 Questions
 

How much weight difference is there between the two?? How much do you guys think that weight difference makes on performance?? Anybody running the 383 that used to have the 454?? How much of a difference in mpg if any??

Anybody

I was wondering same thing... speed anyway.. found a 29ol with 383's and i need to have at least a 70 mph boat for my upgrade now that the 25ol is sold.

i heard the number of about 150 lb per engine. if you go alum intake-heads-exhaust about another hundred...

Based on this chart you can roughly figure 200 lbs per unit difference.

http://www.perfprotech.com/store/app...ower_Guide.pdf

Given very close power and torque numbers the 383 becomes the obvious choice. In the larger displacement big blocks 496/502 and beyond...there is very little if any weight gain but BIG power gains so in that arena for larger boats the Big Block wins hands down. I use 30' center line length and 8000 lb displacement as the breaking point where you favor the Big Block vs the Small Block.

If you consider what Ilmor has done with the 6.2 LS based platform...the line at 500~600 horsepower gets blurry. Beyond that the traditional Big Block Chevy architecture holds a decided advantage considering 'Bang for the Buck".

If I was considering say a 292 Formula step hull I would favor the SBC. In a 302 straight bottom i would have to go BBC.

Good question heard a huge difference in wieght ?The price of repower is much less also!Just wondering small block vrs big block which is faster and which will last longer???

Sprink58 you make a very good point on the weight of the boat I do think it has to be under 8000 lb what do you think the mpg on the two is??

On the last longer issue... you can make a 383 make 500 hp, but its kinda workin to do it, a big block making 500 hp hasn't even woken up fom its afternoon nap....

True

Now in my little 22' resin bucket, If I wasn't getting ready to hang an eggbeater on it for 7, it would be getting a nice little 383 with alum heads a small whipple and intercooler and I would be fast enough to get myself in trouble real quick like.... but it would definitly be a blast.