small block vs big block

[steelcomp]

Hey, if you're just doin it for the fun of it, I'd say do it. One thing for sure, it takes a little more knnow how to get a small block to run good in a boat. Problem with a boat is they're ALWAYS under a load. Take your foot off the gas in a car, what happens? You coast. Take your foot off the gas in a boat, what happens? YOU STOP! :coffeycup

[Squirtin Thunder]

ok, I already have a boat with a BBC. I'm contemplating this for the Tahiti/Panther that's become a sleeping place for our cat in the back yard.
No intention on racing it, not even half a thought of making it go faster than maybe 65.
Cas,
My cusin has a 19' with a panther it is a nice running boat but not a 70mph boat it runs right in the 50-60mph range. His is way over kill on the engine and can't use the power he has with his set-up. And listens to his cowpock friends on set-up. I am sure you would be happy with it as a project and as a general lake boat. The lighter wieght of the SB causes a bit of a problem getting the bow to lift a bit.
Jim

[77468sleekcraft]

No But Seriously Yea In A Car You Can Have A Small Block Compete With Big Block But In The Water Big Blocks Are In My Opinion The Way To Go..

[Aluminum Squirt]

SBC's can't be all bad, we all make ZZ4's go over 80MPH-Aluminum Squirt

[WUTWZAT]

I don't want to get too deep into this argument, but I do want to add one thing here. If you already have a boat equiped with a big block chevy, the major cost involved isn't going to be the motor here really but switching all your plumping and exhaust and things that won't work from one motor to the other.
And yes I do run a SBC in my 18' Jetboat.
Jason

[LVjetboy]

An opposing view from someone "not in the business"
Jet performance is all about power (not torque) to the impeller and hull drag, to a lessor extent the rpm at which that power's applied (pump efficiency). Other than that, your jet doesn't care if SBC or BBC. As for hull drag, that depends on weight and an SBC is typically 100 lbs less than a BBC. That means for a small jet you may need 20-40 hp more to the impeller with the BBC just to equal the performance of the SBC because of weight and drag.
So comparing apples to apples, a SBC can deliver up to a point. Problem is, most people compare apples to oranges. Like a stock SBC to a mild BBC. If you build both to the same power, the SBC will likely win on reduced drag. Until you reach the point where pump efficency drops way off and cancels out power gain, or you have a big heavy jet not sensitive to weight change, or the cost of building the SBC to your desired power level is more than the cost of building a BBC to a slightly higher level.
jer

[miketsouth]

I have the opportunity to trade a basically stock dissassembled BBC that's in need of a rebuild for a 350 hp small block that needs a head gasket.
I know there's a pretty big weight savings with the small block and they can be made to make some pretty big HP for less money.
thoughts?
I saw ~70mph in a sbc thru LOGS this summer. No big build, just a little cam. B impeller. Still less than 300hp. Less than 5000rpm. Better than 3mpg too. 55mph@4000rpm
Same boat with a mild cammed BBC and headers got 80+mph on an A impeller. 'Course they were lightweight tunnels. Blew my doors off.
The weight savings in a light boat may be ok up to 55 or so MPH. (my calculations say a little more than 100lbs for iron engines, like 250, or one mother-in-law) After that pump characteristics which suck HP gonna load that SBC up and drag it down.
Dont matter what you do the SBC got to turn RPM to get HP. This makes your impeller small and therefore your pump ineffecient. Hard to get HP without RPM or CID.
My rule of thumb is >1hp/cid @5000rpm in a N/A engine
With that said, the SBC stuff is very inexpensive and the SBC seems to be rather stout.
Oh, yeah, the SOUND. SBC just dont have the BB sound.
and WUTWZAT is right, SBC jet parts are not as available as BBC stuff.
After seeing what the SBC would do in my little tunnel i will NEVER put BBC in it....BUT i am HP challenged. No way around that with small displacement. Reason i did it is because i am cheep.
mikeT

[Cheap Thrills]

I've seen 60Mph in my heavy old 16' Jet with mildly modified SBC.
cost wise I cant see useing a BBC.
IMO You can get more HP Per Dollar Spent out of the small block than you can with the big block but when it comes down to maximum performance it's like the old saying goes.,
Theres no replacement
for displacement.
ya gotta pay to play.
C.T. :wink:

[Hallett19]

BBC-----THERE IS NO SUBSTITUTE..JUST ASK THE GUYS WHO RUN FORDS IN THERE TOYS....
Yeah, my big block Ford runs great, thanks for asking !!! :wink:
In boats (jet or I/O) 18ft or less, small blocks are fine. My neighbor has an 18ft boat with a sbc and a panther and he gets about 50 mph out of it. It has a 2 bbl carb and he says it gets descent fuel econmy. I think a sb with a jet is bad, sb with a I/O is ok on 21's and smaller. Jets arent very compatible with small blocks.

[JEThro]

Since you have a boat with a BBC in it already,put a SBC in the other. My Tahiti does 60mph at 4900rpms with a 350[.060 over] spinning a Panther and I'm totally happy with that from a 9.0 to1 motor. Especially since it cost me only 1600 bucks for a COMPLETE rebuild.
valve job with new valves,seats and springs-550.00
motor work and assembly-850.00
timing set and oil pump-200.00
Included in the motor work and assembly are-
bore job,replace crank,replace rods,new pistons,new cam,new lifters,new bearings,complete gasket set,freeze plugs,install rotating assembly.
I say go for it. I'll give you a set of logs if you pay for my camp site and slip at Tower Park V.