More SBC Upgrades
02-24-2006, 10:56 AM
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Re: More SBC Upgrades
Originally Posted by LiberatorII
Sorry if this subject has previously been beat to death but I've got some more questions. I've read much of the posts and responses here. I have a 1987 Liberator 211 that I intend to restore - re-paint, upgrade the engine and redo trailer. The boat currently has the Mag 350 w/Alpha. I'd like to get as close to 400hp as possible without going completely thru the engine. Don't want to go the 383 route just yet. I've talked to the factory and was told this hull was developed for the Liberator and should be good for 70mph. My goal would be as close as possible to this number (without going BB) I intend to check engine condition - if compression etc is ok I plan the following: Vortech heads, air gap intake, change to a Holley, not sure about the ignition yet, still puzzled on cam choice, install new exhaust - thinking about the Revolution manifolds, and compete re-plumbing of fuel system. Would like to keep the mechanical fuel pump. Some questions:
1. What cam
2. Is the stock ignition system sufficient
3. Any recommendations on a decent fuel/water separator
4. Exhaust manifolds - without breaking the bank.
I've also read some of Dennis Moores SBC book and he does write that most of the original equipment is just fine. I can't see a staggered bore carb being as efficient at fuel/air mixture flow as a square bore carb (at 1/2 and greater throttle) for example. I'm not doubting his marine knowlege,but maybe I'm looking for something a little more radical than he suggests.
Thanks
1. What cam
2. Is the stock ignition system sufficient
3. Any recommendations on a decent fuel/water separator
4. Exhaust manifolds - without breaking the bank.
I've also read some of Dennis Moores SBC book and he does write that most of the original equipment is just fine. I can't see a staggered bore carb being as efficient at fuel/air mixture flow as a square bore carb (at 1/2 and greater throttle) for example. I'm not doubting his marine knowlege,but maybe I'm looking for something a little more radical than he suggests.
Thanks
To get the 325 to 350HP and be "user friendly" you'll need the following:
A good set of iron or aluminum aftermarket heads in the 170 to 180cc range. World Product S/R torquers come to mind.
I would run a high rise dual plane intake like the edelbrock rpm or the edelbrock airgap rpm. Both good choices for your goals.
Camshaft based on the SR torquers would be something around 220 on the intake and 230 on the exhaust with lift being in the mid 500's. Hyd roller would be my choice of type of cam.
Carb I would go with a nice BG 750 Sea Demon.
Stock Merc ignition works great on a NA engine that is not going to see over 6000 rpm.
Stock log manifolds need to be upgraded. New or used get you something that is more anti reversion then the stock stuff.
Remember HP is torque x RPM. In a boat you are limited on rpm, so big torque numbers at low rpm are best suited for boats. The easiest way to accomplish this is with cubic inch.
Puting a huge camshaft in a boat is not the answer either. Even though a boat engine runs say between 3000 and 5500 rpm, boat engines don't have the advantage a car does with a transmission. We can't rev the engine to 3500 and dump the shifter. We have to start at idle of 800 and the engine has to climb to the powerband under load, so the cam has to make power below the 3000 to move the boat.
Hope this helps.
02-24-2006, 11:38 AM
#12
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Re: More SBC Upgrades
cstraub: Thanks for the input, exactly what I'm looking for. Why S/R Torquers over Vortech? Are these heads that much better etc? Any recommendations on fuel filter/seps? thanks.
02-24-2006, 11:49 AM
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Re: More SBC Upgrades
The SR's are great bang for the buck. The use the old style intakes so you have more choices and could get a deal on a used one. The Vortec's are great heads but are OEM production stuff. The SR's have thicker decks and more meat and already come with 2.02/1.6 valve sizing.
Fuel/Sep's I have just always run the Merc or Sierra.
Fuel/Sep's I have just always run the Merc or Sierra.
02-24-2006, 03:34 PM
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Re: More SBC Upgrades
Liberator II, Follow what CSTRAUB is telling you. He hit it right about heads, cams, etc. Been there done that myself. (1986 211 Liberator) The only thing that I would suggest is to use the Performer RPM manifold, not the air gap. A boat does not have the air flow through the manifold that a car has to benefit from this design, save the money.
Dave
Dave
02-24-2006, 04:55 PM
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Re: More SBC Upgrades
Originally Posted by LiberatorII
I'd like to talk to you about your parts, I'll have to upgrade site membership for pm's I guess. I thought about doing the Bravo swap as well and going BB and all problems would be solved. I've got a 461 laying around now that I could use, but the $ for Bravo swap on this boat doesn't make sense at this time. If I had a twin though....I'd do it. Will upgrade what's there, stay with the Alpha and look for something else with twins for now. Thanks
02-24-2006, 05:02 PM
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Re: More SBC Upgrades
Originally Posted by David Stotz
Liberator II, Follow what CSTRAUB is telling you. He hit it right about heads, cams, etc. Been there done that myself. (1986 211 Liberator) The only thing that I would suggest is to use the Performer RPM manifold, not the air gap. A boat does not have the air flow through the manifold that a car has to benefit from this design, save the money.
Dave
Dave
Thanks, what speeds were you getting with your 211?
02-25-2006, 07:09 PM
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Re: More SBC Upgrades
I will be doing an engine build up soon too,I am using vortec heads and plan a zz4 crate motor cam,or similar,I was told by a good engine builder that should put me somewhere around 37-390 hp and still be very friendly,I am going to go with 9.5:1 and will use a 650 dp that already exists,I think a 750 is a little big for a low compression 350 (9-9.5:1) I made 450 hp with my ford with a 650 no problem,you want to keep the engine with torque.
Hope I helped.
Hope I helped.
02-26-2006, 10:19 AM
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Re: More SBC Upgrades
Originally Posted by 245 limited
I will be doing an engine build up soon too,I am using vortec heads and plan a zz4 crate motor cam,or similar,I was told by a good engine builder that should put me somewhere around 37-390 hp and still be very friendly,I am going to go with 9.5:1 and will use a 650 dp that already exists,I think a 750 is a little big for a low compression 350 (9-9.5:1) I made 450 hp with my ford with a 650 no problem,you want to keep the engine with torque.
Hope I helped.
Hope I helped.
