Why not more SBCs in boats?
 

Seems like the new generation of stroked small blocks pack a pretty good punch and are lighter, cheaper, and smaller (easier to work on in tight engine rooms of smaller cruisers) than BBCs. I know we always say "nothing replaces cubic inches" but if your vessel only needs 400ft lbs of torque and 450HP isnt it possible a SBC will suffice?

Did some searches and really didnt find this discussion anywhere.

I always wondered that myself, especially supercharged. Getting too old to squeeze into the engine room

I love my small block chevys. I have two in my 35' cruiser. Two in my 270 Mirage. And three others in my trucks. Power to expense is great. Cruiser cruises at 20mph, Mirage at 40mph all stock reliable power. No problems and just as thrilling to me and my crew crossing Lake Erie.

They're very common in water sports boats. Not enough reliable power for a go fast. Mercury Racing has upped the cubes to at least 540 on their engines. Also the very popular 525 EFI burns 87 octane. That saves a lot of money in fuel cost.

The 377 super scorpion got the job done but the cost was too much for the people.

I'm very happy with mine. Twin 355 Vortecs with mild roller cams making 400+ HP and 400+ # Ft. TQ. Running thru twin Bravo I's. They're in a '79 Formula 255 Liberator.

Prior to the LS motors, the Vortec Heads and Roller Cams caught up with the BBC's quickly. If you only need to make HP and TQ in the 400~450 range you're going to be ahead of the game with the SBC's due to the weight savings.

Yup ^^
IMO the weight savings translates into a well balanced package in the 30ish foot range twin engine boat

I'm building 2 ls motors for my 32 sunsation

What are you building ? I'm a big fan of the LS motors. Had a 6.0 LQ-9 in a '05 Escalade and now a 5.3 Direct Injection motor in a '16 Yukon. When you look at the intake ports on an LS you UNDERSTAND !!

I will be joining the boats with small blocks gang very soon !!:)

Couple reasons -

1. low end torque.

2. Marine Parts availability is huge between small and big blocks.

3. At or above 500 HP - Hp per HP a big block is cheaper---I had 500HP/ 500Ft LB 406 for decades that finally blew up for what it cost to rebuild from scratch I built a big block.

Those are the reasons you dont see them as much , but I still love them and had a ball putting big block on the trailer with my small block.

UD

Simple! Lots of cubes, lots of torque, move heavy lard azz boats better than high strung small blocks.

Simple! Boats are not cars. Big grunt rules in this deal.

For me its weight, cost and dependability. Im building a 525sc clone currently.

1. THats a proven dependable motor. There is no guesswork, the recipe and improvements are well known and have withstood the test of time. Im not trying to figure out cooling, wondering about reversion, trying to make sense of the computers and sensors, trying to figure out the "right" cam etc..

2. Weight. Weight isn't always the enemy. In a 22 foot boat weight in the right place can help the ride.

3 Cost. BBC/merc stuff is everywhere. If your a poor bastard like me, decent used parts, mag cores etc... are readily and cheaply avail. here, on FB, from friends etc.

But I have a small single...its relative. If I had something like a 28 cigarette, replacing big blocks, trannies and trs drives with a couple 550 hp na ls motors hooked to bravos , that could get fun in a hurry.

I yanked the all iron 454 out of my Checkmate and replaced it with an all aluminum 408ci LS2. The motor made almost 600hp and 550lbft N/A and really isn't very radical at all. It also weighs 500lbs less than the big block I took out. They say there is no replacement for displacement, well I respectfully disagree. I believe technology is a very good replacement.

Simple,,,,,lack of low end torque.

Peak numbers dont tell the whole story.

Two scenario's

1. Hey man what you got in that boat " its a 350 " ......O ok
2. Hey man what you got in that boat " its a 632 " ......hell ya let me take a look :santa:

This is so true, got compliments all the time on my Pachanga 22 which ran a warmed over cammed SBC. People loved the sound, loved the look, but the minute I said 350 they looked completely disappointed almost acted embarrassed that they dare think an SBC sounded "killer" :lol:

My 408 started making 500ftlbs at 3100 rpm's and doesn't drop back below 500 till 5900. I think that's more than enough torque to get a 4000lb boat on plane and out of the water.

SBC seems like a good fit for small singles and even some smaller twin applications. Formula built a 353 a few years ago with the Ilmor 570s SBC. Haven't seen another one from them since. In person it sounded good but there was no performance advantage.

Overall just cheap and easy to get 500 horse out of a big block.

I think the SBC advantage is weight and accessibility with twins, especially 30 feet and below.

Add to the mix the LS platform and it gets even better.

But like I said my 2 cents about little light weight diesels, when it comes to moving a 15000 pound boat there is no reason not to go with simple displacement if the hull can handle the weight.

Ill be that guy and ask why they dont put more big blocks in new wave of surf boats. 1 motor hauling 9k endlessly across the lake at 50% throttle and 3-4000 rpm. Maybe a good profit margin on those supercharged ls motors and stroked vortecs

I think on smaller boats they're fine, even smaller twins. But on big, heavy boats as mentioned, it's just simpler to make torque with a traditional big block, and they will do it all day. I like the LS, but it's the same reasoning they aren't used in 18-wheelers. A "big" block is just a lot of metal (translate strength) to take a butt-whipping and keep on going. My plain jane 454s make 500ft/lbs. at 2500 (that's were the dyno readout started) and was about flat all the way across.
I was told by an offshore engine builder once that "boat motors are built to haul 10,000 pounds up a mountain all day at 5500 rpm". Not that small blocks can't, but BB are just a better, more reliable and cheap option I think.

Fuk'm. Most big block boats go under 70 anyway...and these are usually the one's that ask...so, if you either beat them or stay with them, when they ask, the answer is "It's a 307 olds rocket motor with a Harley carb." They either get embarrased believe you) or they look twice and walk away (they think you are fuk'd in the head) or they stare at you, pause, and then laugh knowing you are sandbagging.

Good stuff. My beast is 42ft and 15,000 so not a candidate for SBC - just curious what the board would say. Happy Holidays all.

Ilmor also claims that they had to do significant work to the oiling system to get the longevity they needed which runs counter to all the little guy builders that claim LS's are bulletproof.

Corey- can you share your dyno sheet and parts list?
You were running lighting headers right?
I remember something from earlier this year.

Thanks.

UD

This discussion sort of reminds me of my Sea Ray days when I had a 40' EC with twin 3208 CATs. The Gas version of this boat had twin 454's and wouldn't even stay close in open water....and used almost double the fuel. It's all about the torque.

Then one day a guy showed up in a 34 EC with twin LSA's and blew all my "Small Blocks can't build torque" theories to hell. !! LOL

My rule of thumb has become that around 30' and 8000 lbs is the tipping point for SBC's...beyond that you go to BBCs up until you get to 40' and 14,000 lbs of displacement...then you look seriously at diesels.

I have been on 27' and 30' Formulas with both: Twin BBCs and Twin SBCs. In that length and weight category I feel that the SBCs (Vortec Roller and beyond) yield a more balanced package overall. Beyond that size boat...it's a "Fool's Errand" to try to match the bang for the buck torque that a BBC brings to the table.

My mechanical Engineering background dictates a lot of my thinking on this. Big torque demands the durability provided by the mass of iron in the blocks and sectional modulus of the cranks available in the BBC architecture. I will say though...as available LS motors find there way into our marine applications, I think the Bang for the Buck advantage enjoyed for decades by the BBC is beginning to tip in favor of the LS technology.

It's a great debate...and having said that...it's time for another Single Malt !! LOL

Sprink what are the specs on your SBCs and what kind of coin did you have into them minus exhaust ?

What kind of speeds you getting out of your Formula and did you change your x -dimension?

yes, besides enjoying the go fast boats, I have also had several sea rays, and yes I had years ago the 39 ec sea ray with 454 was under powered. in fact the shop that did my 547;s , also put a pair of 547 in a 39 sea ray ec. but I think bottom line is weight, as stated by sprink58, I think he stated the ''line'' 30 ft..8000lbs. I could not imagine a pair of small blocks trying to push my 10,000 scarab. also someone mentioned a small block is 500 lbs lighter,,??? not sure on that one.

Parts List:

Stock LS2 Block, bored .030
Callies 4" 4340 Crank
Callies 6.125" 4340 Compstar Rods with ARP 2000 bolts
Wiseco forged pistons -8cc dish
Stock 317 truck heads with PRC (Texas Speed) stage 2.5 CNC Port, opened to 70cc's. Makes 10.5:1 Compression
Bob Madera cam, 243/250, .621/.613 112ls
Its a carb motor running Daytona Sensors Smart Spark LS ignition

To address the oiling issue, which is that the motors can actually pump too much oil over long hard runs, and can drain the pan before gravity can put the oil back down, I had a custom 12 quart oil pan made by Kevko Pans. I am also running a 29"x3" oil cooler with a built in thermostat and dual remote oil filters. All in all I have just over a 14 quart capacity.

I am running Lightning headers. I fought reversion a big part of last year, so I completely dried up the exhaust.

I tried to find my dyno sheets last night, but seem to have misplaced them. I'll have to get a new printout from my engine builder. I will however be dynoing it again here pretty soon. I am changing over to closed cooling and want to tweek the ignition a little. I feel like there is more power in the motor with a little more tuning.

Here is a pic of the motor right after I set it in the boat and before I dried up the exhaust.

https://s25.postimg.org/x7anfi4ov/image.jpg

Here is a quick video of it idling at the dock my buddy took the first time I had it out last summer. I am in love with the way a cammed up LS sounds!!!

https://www.youtube.com/watch?v=MtwwjdHgAr8

my stock motor was a 310hp carb'd 454. It had iron exhaust and an iron intake. Fully dressed with accessories, it weighed right around 1100lbs.

When I dropped the ALL ALUMINUM LS2 into my boat, we did it at my buddies farm on his truck scales. As you can see here, the LS2 only weighed 480lbs.

https://s25.postimg.org/5xp66rqyn/image.jpg


I then went home and weighed the headers, oil cooler and alternator. They weighed in at almost 70lbs. The Aeromotive Fuel System weighs almost 10 pounds. Making a dressed weight of 560lbs. 1100lbs minus 560lbs equals a weight savings of 540lbs.

So yeah, you can save over 500lbs. I will agree that I had about the heaviest BBC there is in the boat. But I will still think that you would save 300-400lbs over a hp500 or similar motor.

Tommy, here are the Dyno Runs and build specs on my 355s:

SuperFlow
Dynomometers and Flow Benches
SF-902S

355 MARINE CHEVROLET Result Summary Date 12-20-2012 1:46 PM Temp 80 Deg F. RH 74%

RPM TQ* HP*
2600 399 198
2800 408 218
3000 421 240
3200 430 262
3400 436 282
3600 440 302
3800 444 321
4000 448 341
4200 451 361
4400 450 377
4600 443 388
4800 438 401
5000 431 410
5200 421 416
5400 409 421
5600 396 422
5800 373 411
Max 452 422
Avg 426 339

* Test Exhaust 1.5" Diameter Dyno Tester Supplied Headers.

355-cid VORTEC SPECS

Bore / Stroke / CID: 4.030 / 3.48 / 355 cid
Compression: 9.4:1
Block: GM factory four-bolt 350 L-31 VORTEC
Crank: SCAT forged-steel PN 1101-11133
Pistons: Probe forged (PN 130212334-030)
Rods: Probe (PN 1201-10062) 5.7"
Rings: Total Seal Moly
Bearings: Clevite
Gaskets: Mr. Gasket and GMPP
Cam: COMP Cams (XM264HR) 212/218 at .050, .488/.495 lift, 110 LS
Lifters: COMP (PN 875-16)
Chain: COMP (PN 2100)
Pushrods: COMP (PN 7372-16)
Rockers: COMP 1.5:1 (PN 1417-16)
Heads: GMPP Vortec (Scoggin-Dickey PN SD8060A)
Manifold: Edelbrock Performer RPM Air Gap (PN 7516)
Carb: Demon (PN 1402010VE)
Distributor: Davis Unified Ignition DUI-7000
Spark Plugs: Autolite AR103
Oil System: Milodon HV (pan PN 31505)

I bought the motors complete less water pumps, ignition, carbs and fuel pumps for $4500 !! A Hi Po shop in Pompano had built them for the owner of a 27 Ft. Pachanga. His charge was $10K for the pair. He put $5K down and never came back. I had to basically finish all the externals including starters so I guess I spent another $3500 total including oil coolers and exhaust. From scratch it would cost between $10K~$12K to reproduce what I have motor wise.

I thought about raising the motors to get a shorter "X" Dimension but the boat runs so good I never did it. It will run 75 GPS at about 5200 RPM without a whole lot of fooling around with trim...I've scared myself a few times approaching 80 and backed out of it....this old hull was never intended for those speeds. It feels very much like my 272 did up until about 65. Beyond that it feels heavier...probably because there is a lot of hull in the water...very deep freeboard on these 255's. I'm running twin counter rotating 23" Mirage set up by Jimmy's in Ft. Lauderdale.

This old heavy boat with that power will cruise 35 at 2200 RPM !!...50 at 3000. So I can run around all day at 50~55 on the primaries....stab the throttles and it jumps to 65.

Honestly...it's a bit over powered. Lots of times I've been out and wished I had 6' more of boat under me !!! LOL

What kind of money you have into the long blocks ? You buy them pre assembled or have them built?

What kind of speed you end up with?

I edited the post with that info...

I agree. My old SBC setup's used to raise some hell!

https://youtu.be/fyKTqEhzfCc

How does the boat go with that power? Any issue with taking that much weight off the stern?, I found they can get unbalanced/bow heavy. What did it run before, a friend has that boat with a 502 and runs 63 or so.

With the 454 the boat ran upper 50's and saw low 60's on one or two occasions with just me in the boat, 40 degree air and running on fumes, lol. I haven't had the boat wide open with the new set up yet. I spent a lot of the summer fighting my reversion issue. Once I got that all worked out, I babied the boat for awhile just making sure everything was working right and the engine was properly broke in. I designed the cooling system myself, so I wanted to make sure everything was ok with it, which it was, and I also was trying something a little different for my power steering, so I wanted to make sure it was working properly. Once I was ready to really start hammering on it, I developed a water temp issue. The temp issue ended up being a blown starboard head gasket. I originally thought it might have had to do with the reversion, but we have since found out that it was most likely due to a faulty MAP sensor that didn't let the ignition retard the timing at low rpms. My guess is that it was detonating while I was getting on plane, but between the dry exhaust and the hatch, I couldn't hear it. This is why I will be re-dynoing it this spring. I'm going to try a different style MAP sensor. I have also picked up a set of Drew Marine Shotgun Mufflers that I am going to run. I have identical twin 3 year old girls, and while they love loud boats, with the dry exhaust, its a little too loud with them in the boat.

As far as handling goes, I haven't had it up to speed yet, so we will see. However, just cruising around, the boat feels great!! Brett from BBlades doesn't think the weight loss out of the stern will be an issue at all once we get the prop figured out. He's thinking a worked Bravo will make the boat handle just fine and should push it into the upper 70's, maybe knocking on 80 in perfect conditions. I will say that you can definitely tell I have cut a lot of weight out of the stern when the boat is setting idle. This past summer at the Annual Checkmate Owners Rally at Lake Cumberland I tied up with a buddy of mine who has the exact same boat, even the same year, that is running a hp500, and the back of my boat sat about 2-3 inches higher out of the water than his.

Cool, good luck with it and have fun

Just saw on finnegans garage his LT4 weighs 461lbs. With some decent exhaust and cooler air coming in that's easily a 700-750hp boat motor. The only reason we aren't seeing the LS in new boats is that the performance market is dead.

My 33 Apache has twin 350s in it top speed 65 in rough water. Have 2 M&W turbo kits all the parts except bonnets for the carbs. Thinking of selling the boat and parts though from time to time.
Economy beat out my 7.4 in my Sunsation Agressor while apache was travling at a higher average speed

The LS's being used in Seven Marine outboards and I think Volvo just bought that company,