Ok here we go, need opinions, I am about 1/3 of the was redoing 1977 30 ft scarab, it came with Sbc merc grands and trs drives, the first motor is done(388imches) forged blower pistons aluminum heads and aluminum water manifolds. I switched it over to Volvo duo prop 290 drives with 1/95 ratio, I just came across a mint condition 1989 311 sr1 with no motors or drives, I know these boats came with bbc and I see they lists at 7400 lbs(the scarab lists 6800lbs) I don’t know if the formulas were bravos or trs boats, I was thinking if they came with trs and bbc ditching the all cast iron bbc and trans and trs drives the Sbc would be significantly lighter, I figure the better part of 500 pounds lighter(unless they came with bravos. I am not after 65 or 70 maybe high 50 low 60, the 388 will eventually have blowers(2 magnusons blowers in my closet are looking for a home) what do you guys think, yes I would love to have bbc but I started with what the scarab came with and budget does not allow for switching to them as I already have all the parts for the second motor. The scarab would require several hundred more hours labour and the formula is completely ready and really nice. I have switched most of my boats over to Volvo penta 290dp drives as I find them quite tuff and have gotten 60 plus speed out of them in my other boats.

So what do ya think, would I be wasting my time with healthy Sbc with the roller cams and aluminum heads I figure 325-350hp and maybe 400 torque, will break motors in with intake manifolds and go to the blowers next winter which should get me 425hp and 450torque, as I am after reliability versus a ton of power and rebuilding every couple years, will be doing carbs first then switching to Efi with blowers for fuel and timing control. I am going to try the aces tbi Efi system, the system is the killshot 2 pro tbi it has remote ecu as I don’t trust the Efi systems that have the computer in the throttle body, it hs remote mount ecu. I currently run an old Holley commander 950 tbi on my tall deck bbc in my old Bayliner, it works great and has been dead reliable, I think Holley built them better back then.

You would have to go and measure the transom openings to see if its a bravo or TRS. The Bravo came out in 1988 so you are right there as a possible Bravo contender. But I've also seen the TRS drives used on boats well into the mid 90's
The other thing is engine space. The TRS boats use a trans so it moves the motor forward more than a Bravo boat. Swapping over to TRS when it was built for a Bravo may not work if the back seat bulkhead is in the way too.... Just FYI

Actually I am switching it over to Volvo penta 290 dp drives, so it’s just cutting a larger hole in transome, I have switched Merc to Volvo before, I will be using the 388 Sbc that I am rebuilding from the old scarab I have, was just wondering how it would work with healthy sbc, with aluminum heads, water manifolds, intake and water pump it would be significantly lighter than an all cast iron bbc 330 especially if it was a trs boat and the heavy transmission too. Obviously not looking to break speed records but 55 or 60 would be nice.
would also raise x-dimensions a bit when going to Volvo dp drives, I have hit over 60 with dp drives before(stainless props)

I replied in your other thread…

The 311 is a very heavy boat for its size. The published numbers on NADA or in Formula’s brochure are way off. Towing weights with aluminum trailers are near 10k pounds so figure about 9k pounds fueled up with gear.

There is the balance issue that I mentioned in the other thread, too. The 311 was designed with the big block Chevy and TRS setup.

Formula never outfitted the 311 with small blocks because they do not build enough torque. Even a stroked small block is going to have issues because the torque isn’t there down low like with a big block.

Id reconsider this idea.

Unfortunately my salary does not give me the option to switch to bbc, I will consider selling formula and going back to the scarab as those are my only options. I have one completed 388 and all the parts for the second motor from oil pan to water manifolds.

Understood.

Sell the 388s and theVolvo stuff.

With the proceeds, pickup some base 454s (find some mid to late 90s Vortec-based engines probably cheap). Full take outs on eBay are around 5k. That’s with carb, exhaust, accessories, belts, pumps, etc.

Bravo transom assemblies can be had for 1500 to 1800 each if you look around. Bravo drives are easy to find and can pickup around 2k again if you look hard enough.

Or get the Scarab back but even tha boat will want some power.

Have been doing this a long time and the above is the way.

Or convert the boat to outboards.