Small Blocks in Jets? Just Foolish?

[miketsouth]

Anyone have any experience?
DIfference in mounts between a 454 and 350?
Difference in PTO connection?
Looks like a 200lb weight savings between an iron454 and an aluminum headded 350(383?)
What cam profile with what exhausts? How much HP can i get and keep it there for many minutes and expect a whole engine when i get done.
Impeller matching for speed? (self answering, match impeller to HPmax)
Impeller matching for longevity? (Sustained RPM with what HP?)
4bolt crank necessary for 4600WOT rpm?
Reason i asked:
My wallet is extremely small and i am extremely tight.
350's with ADVERTISED big horsepower are CHEEP. Disposable cheep.
Many types of jets have little freeboard as it is. A light engine might help this too.
If i have to replace my 454 or if i buy a new hull (light white PickleFork :) and want to put a motor in it, is this even a consideration.
I like the water jacketed exhausts. Lots of choices for a 454/502 but not so much for a 350. Any thoughts?
Pullin a 454 in the street is a task. A 350 might be a LITTLE easier.
Any kind of information would be great. I have ridden in a jet with a 350 and was quite impressed. This jet had a well preped pump, though.
mikeT

[Blown 472]

Jungle Boy?

[Jetdriver]

I have an old buddy that has a 18 foot Hondo hull with a blown 327 chevy in it. Gets up and goes too!

[quiet riot]

Small blocks are packaged up in jets here in the nw. 350's are all over the place here, everything from mild fishing jets to wild racers. Any of you guys ever see the mighty mouse hydro run? Its a pro mod that ran in the low 6's for demo purposes when he was trying to sell it at CDBA races. Not too shabby for a small block.
I've got a sbf (351w) and it turned a legend a imp to 5k rpms for 8 years. Its a basic edelbrok performer rpm build just over 400 horses. Turned it to 5500 rpms with lots of n2o also. never had an issue. With the 350 chevy bottom end you prob want to go 4-bolt if you want to put much power to it. 302's, zz4's, and bone stock 350's are packaged with pumps by american turbine, kodiac, hamilton, etc.... by the thousands. 350's have a decent amount of stuff from center riser exh man. to headers from many places.
PTO's, bellhousings, mounts, all the stuff is out there. Check out rex marine or many of the other places that deal with the stuff. Like anything, if they're built for it they can last a long time. My buddies stock 350 efi runs at 4400 rpms all day long in his jet (he needs it to keep the big pig moving, 24 ft jetsled weighs over 4k lbs). zz4's are raced in stock river and sprint boat classes in many boats.
jd

[Jet Hydro]

I`m still looking for a set of Headres for a 350????????
Anyone know of where I can find a set????
T/T headers that is.

[quiet riot]

I`m still looking for a set of Headres for a 350????????
Sure, I just picked up the HB magazine and lightening had an ad for them in there.
Back to the small block thing though, gotta also remember that some of those rare manufacturers have put out a few small blocks in boats in there days, like mercruiser, omc, volvo, etc. Actually at a rate of about 50 to 1 when compared to big blocks. Just gotta remember there are more boats out there than just offshore or racers, like the recreational ski and runnabouts.
jd

[Jet City]

Quiet Riot gave some good info there, I don't see anything wrong with a SBC for a jet. If it were me, I would consider a 406 SBC instead of the 383, the build cost is very similar, but those 5.7" rodded 400's really rock (SRP makes some really nice pistons for these in various cc volumes). You might check with Jim Brock, Duane (HTP) and Rexone for parts and availability for your needs.

[miketsouth]

Very good. Thank you all.
What about camshafts with various types of exhaust
I dont want logs or open headers
Aluminum manifolds like CMI, or tubular lightnings seem like they would fit the bill, Pricey, yes and not everywhere used (actually used lightnings would be kind of risky, i suppose, for their tendancy to crack)
I know there are some reversion problems with extended range camshafts. Im supposing the same thing makes them reverse as the bigblock, to much overlap.
Again, thank every one of you.
Got any more?
mikeT

[dgie]

You should PM "Frostypop" I believe he has a SBC in his jet boat. I brought up this subject in the past, I want to eventually switch out my 455. A lot of people on the board said go 454 instead of 350 due to the Torque that a big blocks puts out.

[miketsouth]

Hammer said that someone would mention 'torque'.
Torque dont matter to me. Only thing that matters is HORSEPOWER@RPM(that i can run all day)
Dont take that as an insult. It is not. I know what you probably mean. Brother Hammer said the same thing, but maybe in more picturesque terms:
One things for sure...at 4300 rpm's in a jet boat, that small blocks working...where as the big block is burping. Bigger CI is just making power easer.
NO REPLACEMENT FOR DISPLACEMENT.
I know that. Even I know that.
I still think a light(white) P/F with a light engine can do the job i need. If it blows, get another one (stick on another sheep)
MORE, please MORE about this. I am new to this and cheep and poor.
like this...in considering total cost of rigging a new boat or even changing a motor there are nickle/dime things that will kill you:
Marine Alternater
Marine Starter
Motor Mounts
Exhaust
Drive Coupling
Other things that have not even occured to me yet
I am convinced that the weight savings will offset the HP on acceleration in a PF and that the PF design will lend itself to the lack of HP on top end. I like acceleration, dont need to much top end. So far the money saveings are up in the air.
Thank you all again for the valuable advice and insite
mikeT