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  1. #1
    Join Date
    Apr 2002

    How much reliable HP can I build out of a 350sbc?

    I want to upgrade my engines and was wondering how much hp I can get without crossing the realiable border? also roughly what would I be looking at in cost to build?

  2. #2
    Registered dreamer's Avatar
    My Boats:
    boatless... with money in the bank!!
    Join Date
    Mar 2002
    5,799 has 377 scorpions for 10k... ted

  3. #3
    Gone Fishin' Charter Member Waterfoul's Avatar
    My Boats:
    1988 Tracker Pro 17, 40 hp Mariner.....1972 Glastron GT 140, Merc 50 power!!!
    Join Date
    Nov 2000
    Grand Rapids/Holland/Grand Haven
    With GOOD parts (rods, pistons, bearings, lifters, crank, roller rockers, etc....) and some head work you should be able to get 400+ pretty easy without making anchors out of them. Bear in mind, compression builds HP, and needs higher octane fuel. If you fuel on the water often, this can be an issue in many places. Which is why I stayed below 9:1 on my BBC.

    If you can do the dissassembly and re-assembly yourself, you should be able to do it for $2000 each or so. If you have it done, You're looking at $5000 plus each. Crazyhorse and I did all the wrenching on mine. Parts and machine work set me back about $1200 or so. We did re-use some of my parts though. Rocker arms, push rods, heads. Then again, I may be all wet with my estimate as I have been doing it myself for years now. Last motor I had "tuned up" cost me about $3000 and lasted about 30 hours before it ate itself.
    [b]M Go Blue.......Gator boots, gator luggage, gator purses... all at cut rate deals!!!!

  4. #4
    My Boats:
    29 Fountain
    Join Date
    Jul 2001
    oshawa ontario
    I  Voted
    To see 400 in a sbc your pretty well into a cyl head change if you dont want to use too much compression to make power and you'll probably have to spin it to 5200 rpm or higher......thats for a 350, a 383 is a different story, but if your going for the extra $ to make a 383 you might as well go a few extra hundred bucks more and make a 406.......Ive been all over this lately , I have two 350s in the back of my 29, Make a stout 383 or 406 and you'll have to be careful with the alpha you probably have hooked to that 350..........Doug

  5. #5
    Registered Havasu Hangin's Avatar
    Join Date
    Sep 2001
    273.76 miles from Havasu

    Cool After I smoked my 350...

    ...I looked at all my options. 383 kits are so cheap now, that it was cheaper to buy a race-prepped 383 short block, than do the machine work to bring my old 350 back to life with a new set of pistons. If you go with the stroker, the extra cubes will help reliability (can run less compression and cam).

    I squeezed over 450 HP (at 5,200 RPMs) and over 460 ft-lbs (at 3,000 RPMs) out of my semi-mild 383 for under $7K. This included Edelbrock aluminum heads, Crane hydraulic roller cam, TRW forged slugs, and SCAT crank. Idles around 900-1,000RPMs, and has gobs of torque (did I just say "gobs"?) very early in the power band.

    Like twinn29 pointed out, you can go 406, but there are clearances to address.

    Phaff sells these 383 motors for around $10K, but he uses the Brodix heads, and makes a little more HP a little higher in the power band (around 5,800 RPMs).

    SBC parts are very cheap. Reliable? I would say 380-400 reliable HP is a piece of cake...

  6. #6
    Join Date
    Apr 2002
    OK thanks guys now my question is what kind of speed increase can I expect with another 200hp on a on a 5000lb. 28ft. vee hull?

  7. #7
    Banned cuda's Avatar
    Join Date
    Sep 2001
    Deland, Florida
    I've always used the 1 hp/1 cid as a rule of thumb for reliable. Anything above that is getting more in the radical side. As far as speed increase, I went from 200 to 330 hp in a 3100# 20 footer and only saw an 8 mph increase. That is a 65% increase of power for for a 21% increase of speed. I was hoping for more.

  8. #8
    Gold Member Gold Member Iggy's Avatar
    My Boats:
    '88 Formula F-206 LS
    Join Date
    Jan 2001
    Kissimmee, Florida
    I've been looking into 383" engines and ran across an article in Chevy High Performance magazine. They were working on a 383 GM crate motor. They swapped the factory cam for a GM Performance parts cam, swapped the rockers to roller type 1.6:1 and topped it with an Edelbrock RPM Air Gap and a Holley 750. This combo pumped out 446 [email protected] and 473 lbs. [email protected] on 9:1 cmpression.

    The cost of all this was:

    Engine 3699.00
    Rockers 301.00
    Intake 210.00
    Cam 193.00
    Carb 430.00

    Total cost 4833.00 +/-

    Sounds like a good deal to me.
    I see no reason this wouldn't work in a marine environment.

  9. #9
    Registered 26scarab's Avatar
    Join Date
    Mar 2001
    st. clair shores mi ,us
    A friend of mine has some 350's that are pretty indestructable.

    Stock (2 bolt)
    Stock crank
    Lunati rods
    JE pistons.
    Canfield aluminum heads (10:1)
    Solid roller cams
    I don't remember what intakes.

    Well he spins these motors 6000 , they pushed a 85 Wellcraft Nova to a best of 74 on GPS.
    He just went thru them (350hrs ) and everything looked good except some of the Crane roller rockers were worn.
    He now has those same motors in a 96 31 Scarab. They were out testing Sunday with it and with 5 people it went 71 on the Nordskog speedo.
    I would say those motors are making around 425 a piece and they are pretty reliable.

  10. #10
    Registered traviss's Avatar
    My Boats:
    1989 18.5 ft XLT powerplay
    Join Date
    Oct 2000
    On the river
    I built a 383 over the winter...

    4 bolt block ( w/ clearancing)
    eagle forged crank
    eagle forged H beam 6.00" rods
    SRP 9.8:1 forged pistons ( dished)
    vortec cast iron heads ( w/ screw in studs, guidplates, guidplates, and pushrods holes clearanced)
    edelbrock RPM air gap intake
    crane roller cam...
    1.6 roller rockers
    750 holley

    I am guessing around 400-410 hp...

    The stock 350 mag spun a 21" pitch at 4500 rpm now the new 383 spins a 25" around 5200

    Its about the same motor as Iggy is talking about in the chevy high performance magazine

    I have run the dog **** outta this thing for 35 hrs now.... found a broke piston at 20 hrs.. fixed that and have had no other problems..


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