Go Back  Offshoreonly.com > General Discussion > General Boating Discussion
Small block instead of big blocks? >

Small block instead of big blocks?

Notices
General Boating Discussion

Small block instead of big blocks?

Thread Tools
 
Old 05-26-2011 | 10:48 AM
  #1  
Thread Starter
Registered
 
Joined: Jun 2006
Posts: 377
Likes: 0
From: Sunland, CA
Default Small block instead of big blocks?

I am sick of paying hundreds of dollars for fuel for a weekend. Its fun, just not that fun.

So I've pulled both big blocks out of my boat, filled in the transom, tweaked the stringers, and I'm going to put in a single. Getting 1250 lbs or so out of the ass end (15% of the total weight of the boat) will certainly reduce fuel burn.

But all of us who ever owned hot rods know that big blocks consume an awful lot more fuel than small blocks.

So I'm considering putting a single, stroked, small block instead of using one of the 454s I pulled out.

Typically, I cruise the islands off Southern California. The Pacific Ocean sets the speed, not the throttle. Most of the time the ocean sets the speed at 20 to 25 knots, where I use 200 to 250 HP, with full tabs down, drives all the way in. When its smooth, the same fuel flow but tabs up and drives out a bit gives me 35 knots. Its really never smooth enough in the ocean to go faster than 35 (well, maybe once every other year). So 250 HP is all I need with two big blocks in the ass end. With 1250 lbs less aft, I'll certainly use much less power, probably 150 to 200 hp for these speeds.

A boat with similar weight, the Skipjack 262, works great with a single 200HP diesel, running these same speeds.

Any comments?
carcrash is offline  
Reply
Old 05-26-2011 | 11:00 AM
  #2  
Registered
20 Year Member
 
Joined: Jun 2004
Posts: 1,395
Likes: 16
From: Freehold, NJ
Default

I know money is always the main concern but you could put in two of these but they are worth more than the boat itself http://www.cmdmarine.com/Products/Re...82062_6_08.pdf

If you were going to the trouble of converting to a single why would you not look for a used 250hp - 330hp Cummins B series engine? You would get the cruise you wanted and burn little to no fuel.

I would bet if you looked around you could fine a pair of 220hp or 250hp B's, they are 4 cyl and would drop into where the big blocks were. You could bolt these to a Bravo with no problem don't even go down the diesel torque issue as you won't prop it big enough to get the cruise speeds you want plus.

I know it's costly but would probably make you happier in the look run.
HabanaJoe is offline  
Reply
Old 05-26-2011 | 12:59 PM
  #3  
Registered
20 Year Member
 
Joined: Feb 2006
Posts: 1,826
Likes: 85
From: Tallahassee, FL
Default

a SB putting out the same power as a big block will burn about the same amount of fuel.

Personally, I'd have opted for twin small blocks. I don't do all that bad with twin small blocks.
VetteLT193 is offline  
Reply
Old 05-26-2011 | 01:07 PM
  #4  
Registered
15 Year Member
 
Joined: Jan 2007
Posts: 6,473
Likes: 357
From: Mansfield, TX
Default

You'll hate it. It will be a dog out of the hole (if it even gets on plane) and you won't save much gas. It will also kill the resale.

Have you considered lobbying your socialist state legislatures. They seem to think $8 a gallon would be a good thing for their god.........I mean mother earth.
TexomaPowerboater is offline  
Reply
Old 05-26-2011 | 01:09 PM
  #5  
Registered
 
Joined: Jul 2010
Posts: 779
Likes: 2
From: Conway, AR
Default

I've heard it many times here before. "If you're worried about gas money, you may have the wrong hobby". I do however understand your frustration, I just bought a twin big block boat last year and am selling my single BB boat. How long will you have to run the single SB before your investment pays off?
CrownHawg is offline  
Reply
Old 05-26-2011 | 01:16 PM
  #6  
Registered
15 Year Member
 
Joined: Jan 2007
Posts: 6,473
Likes: 357
From: Mansfield, TX
Default

Have you considered a trawler?
TexomaPowerboater is offline  
Reply
Old 05-26-2011 | 01:27 PM
  #7  
Registered
 
Joined: Jul 2008
Posts: 2,801
Likes: 1
Default

Originally Posted by carcrash
I am sick of paying hundreds of dollars for fuel for a weekend. Its fun, just not that fun.

So I've pulled both big blocks out of my boat, filled in the transom, tweaked the stringers, and I'm going to put in a single. Getting 1250 lbs or so out of the ass end (15% of the total weight of the boat) will certainly reduce fuel burn.

But all of us who ever owned hot rods know that big blocks consume an awful lot more fuel than small blocks.

So I'm considering putting a single, stroked, small block instead of using one of the 454s I pulled out.

Typically, I cruise the islands off Southern California. The Pacific Ocean sets the speed, not the throttle. Most of the time the ocean sets the speed at 20 to 25 knots, where I use 200 to 250 HP, with full tabs down, drives all the way in. When its smooth, the same fuel flow but tabs up and drives out a bit gives me 35 knots. Its really never smooth enough in the ocean to go faster than 35 (well, maybe once every other year). So 250 HP is all I need with two big blocks in the ass end. With 1250 lbs less aft, I'll certainly use much less power, probably 150 to 200 hp for these speeds.

A boat with similar weight, the Skipjack 262, works great with a single 200HP diesel, running these same speeds.

Any comments?
Tex is correct.

Stick with the BBC.

Actually small block are more expensive per HP to build and marinize. Its also harder to make a small block idle well and be outdrive friendly.

Between a BBC and a SBC either one putting out say 250 HP at speed cruise- they will consume about the same amount of gas.


UD
Uncle Dave is offline  
Reply
Old 05-26-2011 | 01:52 PM
  #8  
Banned
 
Joined: Mar 2008
Posts: 981
Likes: 0
Default

Put a small block in it and tell us how it works out . Then when you go to sell it you can let us know how that works out for you as well .
Jeff P31 is offline  
Reply
Old 05-26-2011 | 02:02 PM
  #9  
CigDaze's Avatar
Platinum Member
20 Year Member
Platinum Member
 
Joined: Jun 2001
Posts: 21,346
Likes: 10
Default

So you want to replace two big blocks with a single small block in a 32 foot sport cruiser?...I don't think that'll work out.
CigDaze is offline  
Reply
Old 05-26-2011 | 02:12 PM
  #10  
Registered
 
Joined: Jan 2007
Posts: 505
Likes: 1
From: hingham,ma.
Default

Fill the transom, install O/B bracket, put 150 -200 H.P. on. Done !!! And still have twin motors for docking & dependability . "HIGH LIFE"
HIGH LIFE is offline  
Reply


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.