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Supra6
05-29-2011, 05:12 AM
Well new here to the forum looking at 18 Classic and it looks as though the motor / drive have come to the end. So looking to repower, 302 putting out about 350hp. Currently VP 270 outdrive.
I'll assume full trim will be a must so I guess that means a 270T what's the diff in going to a newer 280? Next is it worth the work changing over to a Mercruiser OD? If so what's the real benifit of giong to a Bravo over and Alpha or Gen 2 Alpha? Merc vs VP, yes I know it's a large debate but what are your opinions? I am not looking for an 80mph rocket, I am thinking more in the 60-65 range, seems prop choice is better with the Merc but then again once I figure what works best anything is possible in that department?
Boat will be on an inland lake worst waves I have seen there in 10 years are max 3', probabaly should be looking at a 21'ish.
Thanks in advance for the opinions.

Sweet little 16
05-29-2011, 07:27 AM
a 350hp volvo 270 18 with the correct prop would be right at the door step of the speed range you want, the 280t would be the next step up for trim without too much effort. the question is will that really be enough 60-65?? or once you're there you want to be 65-70??
there are quite a few volvo boats that run high 60s to well into the 70s here
all of them have strong motors and trim.

MOP
05-29-2011, 08:51 AM
Stay with the Volvo, the switch to Merc is costly. The Alpha is weak compared to the Volvo, the Bravo is far more durable but will cost you 2-3mph at top end due gear case size. Since you have already considered redoing the transom for a Merc setup think about raising the X for your setup. You can get decent performance out of the Volvo with a nose cone and even more important raising the X, only a few of the knowledgeable have raised the X on Volvo setup.

joseph m. hahnl
05-29-2011, 09:16 AM
Well new here to the forum looking at 18 Classic and it looks as though the motor / drive have come to the end. So looking to repower, 302 putting out about 350hp. Currently VP 270 outdrive.
I'll assume full trim will be a must so I guess that means a 270T what's the diff in going to a newer 280? Next is it worth the work changing over to a Mercruiser OD? If so what's the real benifit of giong to a Bravo over and Alpha or Gen 2 Alpha? Merc vs VP, yes I know it's a large debate but what are your opinions? I am not looking for an 80mph rocket, I am thinking more in the 60-65 range, seems prop choice is better with the Merc but then again once I figure what works best anything is possible in that department?
Boat will be on an inland lake worst waves I have seen there in 10 years are max 3', probabaly should be looking at a 21'ish.
Thanks in advance for the opinions.

Personally, I don't think it is worth changing the out drive to Merc.
Volvo's are excellent out drives. If it was OMC it might well be worth changing, as parts are hard to find. But being a Volvo there are plenty of parts and used drives out there.

Alpha's are good for moderate horse power. Bravo's have high performance after market lowers available.
http://www.cobrapower.com/components/com_virtuemart/shop_image/product/DSC02525.jpg

The idea is to get the boat in the water. So if it were me I would stick with the Volvo and rebuild the 302 and pump it up . You'll need to run at least a 23P to run 65 MPH .

Supra6
05-30-2011, 05:42 AM
So lets see if I have this straight,
A 280 with the better trim system (then a 270T) will bolt right up to a 270 transom plate?
The 280 has a better underwater profile so it should yeild a bit more performance, and props are not a problem.
As for the 302, it may be a bit weak, stroke it or just go to a 351? I like the idea of lower weight and balance will be an issue so I'd like to keep the block size small though not that much difference.
As for getting the hull OUT of the water, yes it seems running on the last 2-4 ft' of the hull will really help, so if it turns out thhat transom work is needed just how much higher should the outdrive be mounted? Back from old outboard racing days for max top end we ran the gear case just about half way out of the water. How high before you loose trim authority, also there is a point if to high she will not plane of, it's a fine line as I remember.

Sweet little 16
05-30-2011, 07:17 AM
the 280t will need it's own transom plate it will fit the 270 cutout with the addition of drilling 2 holes for the trim connections. it might be easier and more cost effective to build up a chevy SB in front of the volvo.The ford performance stuff is hard to find and expensive to make like exhausts.


raising the X might take some planning. If you go to the 351 the motor is taller than the 302 so hatch clearance might be an issue and limit your raise in the x. If I were going to all the trouble to re glass the transom and cut a new hole I would not cut an old volvo back into it. If that was the case I would go to a bravo then that brings all sorts of performance stuff into play.
shorties, external steering but now we have gone past 60-65 :)

maddad
05-30-2011, 08:10 AM
Trim is a nice option, but you don't need it to make an old Volvo go fast.

Supra6
05-30-2011, 02:41 PM
Well the external steering was going to be the next question, internal mech steering can lead to slop (correcter with proper maintenance) which as I understand can cause handeling problems when you start pushing the designed hull speeds, in reality I think I am pretty honest of the desired speeds but I do appericiate handeling and overall performance vs flat out speed.
I have access to CC labled 327 ot of a 1965 CC 35' Sea Skiff (those here great boats, double lap/strake hulls) not orig in a Donzi but time correct.
I guess the question is how far should I press this and I guess the answer is how deep is the wallet.
Thanks for reading and any thoughts would be good.
As far as the Trim issue, I think it's required not just for the speed but also for the day to day shallow water close to beach to pick up the kids.