sonic28

thank you chris you came out with the information and answers i was looking for. and thank you all others for your response.
paul

Kent Perroux

I have been playing with different options for over 10 years on my 350. It started as a 300hp/5200rpm. Many mods and lots of money to around 370hp. All of my speed gains were from hull, drive and prop and weight mods. I think I gained 4-5mph on all the engine mods If I did not change anything else.

Changed to a 406 shortblock and that alone was the biggest jump in accelleration and top speed.

If you are going to change the rods, pistons and crank, got for the 383 rotating assy and decent cam. You will then have a good base from which to grow.

You can upgrade everything else slowly and not have to pull the engine.

Torque is the key

Kent
18 Donzi Classic 438hp/497lbs torque
"Mala"

pullmytrigger

there is a twin sbc buildup in my future.Id like to make 360 to 400hp. I too am concerned about long term reliability, not just blasts across the lake and back. Im talking Poker runs where your at near top rpm for 20 to 30 solid minutes at a time and 2.5 to 3 hrs for the day. has anyone ran a 383 or 406 in this type of environment?? I know the 350 may be short on displacement but theres lots of meat in the block and they can handle this type of use, Ive done it........doug

Whitey

Travis I do believe that you are on the conservative side on your hp #s. Dwight

dirtyplumber

basic logic ,if GM parameters are9.4to1with89octane,30deg.adv.timing&4800rpm@WOT then the perfectly logical nut would go a little beyond knowing full well GM is not going to even come close to pushing the envelope as durabillty/warranty constraints dictate.
"torque is the key"(Kent)granted the relatively low(compared to a bush nascar,twin29)RPM a hotrod boat engine goes
you can find sonicsss'caveman engine in dennis moores'book(mercruiser280TRS)and see what he siad about it
high tech,high compression tolerent,efficient ,heart shape combustion chambers(like vortec)and roller cams are the way to go.GM made their 300HO into a 330HO
just by switching to vortec heads(same compression and valves with better combustion)the ram jet 350 is rated@350hp which is a(marine vortec)with a tunnel-ram-like EFI setup and headers
like you paul i'm from massachusetts and i only saw 89 octane fuel once or twice 92-93 is all i can get locally, why risk it any way.
i am looking for more torque between 4000and5200rpm wishfully hoping to turn the same prop faster, and you?

220BR

Don't want to hi-jack this thread, but I have a ? for Liberator21. You and I have the same 383, but I used the stock merc heads (but 2.02/1.6 valves, planed to 74cc, 9.7:1). My ? is about the melling 55A pump (Z-28 hi-volume). What are your pressures at idle , 2000, 3000?

At idle, I'm 50-60 at idle and can reach 80 at 2500. What about you. Seems high.

dirtyplumber

oh ,ya !my point is,i think your combo is good but a little old shool and if you are going to go through all the trouble?...and if any way possible GET SOME BIG BLOCKS
and stop kidding yourself

Ratchet

Here is a link to what my 355's are.............I spin them 6000 all day long...........I also do the poker run thing. I ran them for 400 hrs before a freshen up.

Also, don't let anyone scare you away from solid roller cams. Set up right they idle awesome & make some awesome power.

If you have any questions, feel free to PM me.

http://www.offshoreonly.com/forums/s...ghlight=Crower Canfield&pagenumber=2

RJ

dirtyplumber

ya seems high you'll wear out your distributor/oil too heavy?

Ratchet

Oh yeah, you'll have to go to the second page where I list the engine specs