1990 270 da

[JerryS]

40 is pretty impressive with 4 adults on board.

 

[streetdoc432]

My 270 has the twin 4.3's. I love it. I researched about this for months before my purchase. According to my marine shop guys, the twins are much more efficient than the single because they don't work as hard, not to mention the low speed balance. I am not sure about my prop pitch, but I cruise @ 28.5 mph on GPS @ 3500rpm full of fuel, 2 adults and 2 kids aboard. Just got the boat & haven't "opened her up" to WOT yet :-(

 

[CV-23]

A few things to remember....the second outdrive causes additional drag in the water so twins really are not more efficient. You do get 220hp x 2 (440hp) vs 330HP from the 454. The added weight of the second engine and outdrive are about 800-1000lbs. 100 extra HP is not free as far as fuel burn. 42mph (twin) vs 38mph (single) so the factory claims. An additional 100hp = 4mph. I'm thinking a Bravo III upgrade may be the ticket for me to boost cruise efficiency and better off-plane steering, Mike.

 

[CV-23]

Time to wake up this thread!!! What props (pitch) and drive ratio are you running with the BIII? That could be my next upgrade.

I've never had twins (engines that is) so I can't compare but I do like the room around the single big block when its time for maintenance. I switched to a Bravo III outdrive with the duel props and that was a major performance enhacement. I cruise at 26-27 mph @ 3,150-3,200 rpm and hit 39-40 @ WOT.

The Bravo III takes care of the handling issues around the docks at slow speed. With the counter rotating props I can back up straight and pull forward straight at even idle speed.

Because of the limited beam of the boat I'd opt for the single rather than the twins due to the ease and reduced cost of maintenance. Best wishes which ever way you go. These are great boats and fit a very nice balance between cruising size and trailerability.

 

[Beachside]

Doesn't appear this threat has been used in awhile. I am doing major overhaul of everything on this boat. Have replaced 4.6 engines that always seemed I was having to push rpm high to maintain plane. They were rebuilt numerous times and replaced several times. I now have twin 350's. With a 9 foot beam it's a bit tight. Any suggestions for placement of a generator. My thoughts were to ditch the water heater for a generator. I have a/c under the booth seating in cabin. I added electric head. Replaced all the deck area wood with starboard as well as the helm seat. The helm is now a bench seat with the flip back.
I have a long way to go before she is wet again but thoroughly enjoying this restoration project. Would enjoy hearing from others who have tackled such a project.

 

[Thornton69]

Doesn't appear this threat has been used in awhile. I am doing major overhaul of everything on this boat. Have replaced 4.6 engines that always seemed I was having to push rpm high to maintain plane. They were rebuilt numerous times and replaced several times. I now have twin 350's. With a 9 foot beam it's a bit tight. Any suggestions for placement of a generator. My thoughts were to ditch the water heater for a generator. I have a/c under the booth seating in cabin. I added electric head. Replaced all the deck area wood with starboard as well as the helm seat. The helm is now a bench seat with the flip back.
I have a long way to go before she is wet again but thoroughly enjoying this restoration project. Would enjoy hearing from others who have tackled such a project.

Did you mean 4.3's? Did you do anything with the drives (gears/props)?
Any pics of the upgrades? Lots of us here like the restorations as well.

 

[Beachside]

Thank you Thornton69 for your reply. I also striped out the dash panel and painted the fiberglas under the windshieldwith awlgrip paint. Very pleased with the outcome.
Because my dash now is nothing but a bird nest of wires have had no chance to determine how alpha ones will work with twin Mercury V8's. Definitely believe props will need to be changed.
The dash will be replaced with rocker style panel and updated with combination gages, USB, and updated fuse panel.
Have yet to find a good idea for replacing the headliner. I had a water leak where the horn is attached. Removing the headliner was no cake walk. It is sanded and ready for the right "fix" for that project. Suggestion are carpet, auto upholstery, or truck bed spray. Open to further suggestions...

 

[Thornton69]

That's a pretty good jump in hp. Propping up enough to hold the 350's back will likely destroy your current drives.
You should consider replacing the gears in the uppers or upgrading them all together before that happens.
They likely have some decent resale value to them now. Wasting money on the wrong props and losing them altogether could be a costly mistake.
Will be interesting to see how the hull responds when you get them all set up. My 245 starts to get a bit squirrely when it approaches 40.

 

[keokie]

I've done a lot of re-powers on 80's Se Rays. The Alpha's have no problem handling small block V-8's.

I bet the hull will perform fantastically with the new power. Let us know what you think when you run it.

 

[Thornton69]

I've done a lot of re-powers on 80's Se Rays. The Alpha's have no problem handling small block V-8's.

I bet the hull will perform fantastically with the new power. Let us know what you think when you run it.

Have you had success replacing 4.3's with 5.7"s? The drive reduction for the 4.3's are 1.81. 5.7's are 1.47.
I wouldn't think adding 3+" of pitch to a 32 year old drive would be wise.

 

[keokie]

Have you had success replacing 4.3's with 5.7"s? The drive reduction for the 4.3's are 1.81. 5.7's are 1.47.
I wouldn't think adding 3+" of pitch to a 32 year old drive would be wise.

Personally, no. But I have put a few big blocks against Alpha's in heavier boats. And for that, you do have to be careful, or you will definitely break things!

Seriously, though, I have worked closely with a very reputable and accomplished shop that specializes in re-powers. They know alphas inside and out, and they hold 350's just fine even with the 1.81's.

Now, a 32 year old drive, if it is all original, is a risk with any power. I'd run it though, and closely monitor it for any odd sounds, or metal in the oil.

The thing with outdrives is catastrophic failure generally only comes from 3 things: hitting something, running with bad/no lubrication, or ignoring a click, rattle, or other unusual sound. They can often be maintained for decades and thousands of hours of use as long as you replace bad bearings, clutches, gear sets, etc. before they fail completely and wipe out the rest of the drive. They almost always warn you before complete failure.

Yes, over-powering a drive can lead to catastrophic failure, but a 350 against an alpha is not it.

 

[Thornton69]

We ate up 2 of earlier pre alpha's in as many seasons after only installing a newer roller cam 5.7. We were pushing it hard a bit loaded up with the single I suppose though. At the time was warned by several and told the alphas were only reliable below 300 hp and to be gentle with it. The drives we lost were matched to their correct ratios (1.47), but we did end up throwing more good money at the bad with nothing but a couple props to sell in the end.
Anyway, we bumped up to a B2 in 2016 and it just isn't a thing to worry about anymore.
Hope all works out well for the twins in the 270. It will be a decent push if ever having to come back in on one.