DonMan only you can make that decision. Here is a shot of a friends boat. This thing is a tank. Has twin small blocks,and runs with the best of them !

 

Donman, what year is this Sonic you are looking at? Where is it?

 

I haven`t seen any of these in person, just pictures on the net. There is a `93 28SS offered on the Sonic website, I assume it is in Florida at Sonic`s HQ. It has twin 350`s.
Another 28SS (1994) with twin 350`s is in New Jersey.
The 26' is a 2000 and it`s in MD. It has a 502 EFI. It is my favorite so far, but the priciest, due to year model.

 

DonMan only you can make that decision. Here is a shot of a friends boat. This thing is a tank. Has twin small blocks,and runs with the best of them !

OK, so that answers the speed question.
Does he use twice as much fuel as a single big block to run with them?

BTW:
I like the Pink Floyd inspired name.

 

As far as fuel consumption with the twin 350's vs the single 502EFI, It would probably be only slightly more with the twins.
A good rule of thumb I heard to caculate fuel cosumption at WOT is HP divided by 12 for EFI and HP divided by 11 for carbed engines.

WOT for the 502 = 35 gal/hr
WOT for the 350's=47gal/hr

 

I don't know what you want for speed Donman, but my buddy's 01 28 with twin 350 mags, did about 63, down hill!

 

To be honest, I`m wanting a bigger boat that will go faster than my Hammer and it is just a hair shy of 70...
63 is going the WRONG direction..

 

Than I wouldn't be entertaining a 28' Sonic with twin 350's. Not to preach my boat but have you looked at Sunsation?

 

Got a nice 272 with a 502 that will put you right about 70 !!!!!!!LOL !!!!

 

Don`t laugh Obnoxus, if you still have your 272 after I sell my Hammer, I`ll probably be giving you a call.

 

I had the same thoughts last year. I wanted as big of a boat as would run decently with a single BB. I ended up getting one with twin sbc's. After a season of having it, I don't think I could go back to a single. I was worried about the same things, fuel, maintainence and speed. I don't think the fuel could be much better. Our usual trip to where we go it about a 50 mile round trip. I usually burn about 30 gallons. I don't imagine a single BBC being much better than that. If you maintain your engines BEFORE something goes wrong, the cost of it is neglibible, even doubled. In my boat (Formula 242 LS) the twin sbc is faster than the single bbc. That being said, I think a 28 footer is near the max that either one of those packages will push. One exception that I know of is the Donzi 28zx. The twin sbc's run it over 70.

 

I'd try for a 502 with room in the engine compartment to build it up. It'd be easier to build up one engine than 2, plus you'd have the space to do it with onle one engine in the back. A 502 would come with a bravo drive too which is usually preferred over the alpha drives, it'll handle more hp too, but I guess if money is an issue it may be hard to be picky. There will be a lot of boats for sale as spring and summer approach, and prices will drop as people want to sell their boats before the season starts.

 

That Sonic looks like a heck of a deal. Those 330's will run forever.

 

Well, with the twins you are correct in the assumption that you'll have twice the maintenance. Everything I once did to one engine is required on two. If something is replaced on one engine I check the other and usually end up changing on both. The fuel bill will be somewhat higher also. The benefit is having the additional HP and additional engine to limp home on if one fails. I pilot an 89 Pachanga 32 with twin 330's. Original to the boat with 700 hrs and still running strong. 160 gallon tank lasts a full weekend of boating. So not too bad on fuel. I've had single engine vessels and twins. I prefer the twins.

 

There are good points for going either with the single 502 or twin 350's but I would stay away from a Alpha drive in a performance boat especially one as big as a 28'.
A Alpha drive in a 16-20 bowrider is fine but not a performance boat.
Mike

 

Ole Sonic

I believe that older Sonic on Sonic's websit has been sold for awhile.
They had a pic of it at the Ft.L show that had SOLD across the pic. I think they only wanted around 40k for it.

I know this nut that has an '84 Formula 23' with twin small blocks and old Alphas. He rebuilt the motors to 300 hp each. Those old Alphas are still holding on.
He abuses the hel out of those drives...
The other "know it all" has a 26 Sonic with a single 502 and bravo.. He kills one or two drives each year..

 

twins are easier to handle around the dock and give you additional reliability so if you go off shore ... twins get you home more often. I spend most of my time 50 miles off shore and would not go without a secondary means of propulshion ... kicker if needed. Even new motors, new transmissions, new electrical systems screw up and out there ... you are on your own. My 2 cents

 

I have twins and love them for the reliability factor. My buddys got a single and I don't feel near as confident when I'm out with him . Particularly after he blew the upper on his Alpha and we had to get a tow.
Likewise I had a problem with one engine in the same area and made a 20 mile ride home on one engine.
Ok , so it took 2hrs and we didn't get back till 10pm , but so what , it was a gorgeous evening
In those immortal words of Captain Ron"If anything's gonna go wrong , Skip , it'll go wrong out there". :laugher: :laugher:

 

When your talking about Twins and a Single it's not just speed. Twins may run the same as the 502 top end but try to bring the single 502 down to 30 mph and see what it does. I had a 27 Fountain with single 502. It was a pain to plan out with if you had more then two people in it. And when you go out at night and the speed limit is 30 it just want's to come off plain it really had to run at about 40 mph. 502's like there gas as well don't let anyone tell you different.

 

I have never had twins myself but everybody I know that has gone to twins say they would not go back. I also like the limp home idea that has been presented here. I personally think that the small block is a better designed engine than the big block(boy, I'll bet get response out of that comment )