Volvo Penta vs Mercruiser

[Hofty]

I have a AQ115 Volvo B20 motor with an AQ100 stern drive, which i intend to rebuild from bottom up. Complete rebuild. I have all the parts in my cart and I'm looking at $1,400 USD.

There is also an option to purchase an old boat (boat pictures are my current project, not the salvage motor boat) which I can salvage a Mercruiser 3.7 with Mercruiser Alpha 1 drive. Looks to be in decent condition (see pictures). $370 USD. No rebuild or condition status on the motor.

The boat that I'm restoring is a 1976 Starcraft Chieftain 20ft. So on the one end I could go with a 4 cylinder 2.0L or a 3.7L 6 cylinder. I intend to have a relatively fuel economical boat but also go on trips up the coast and local lakes 90km long. Volvo vs Mercruiser, I'm struggling to figure out what to do

What would you forum readers do?

 

[Scott Danforth]

the 3.7 is a 4 cylinder that shakes vertically like a dog passing a peach pit. it is an aluminum block, iron head issue prone motor. its half a ford 460 and parts are getting hard to find

the B20 motor is easy to find as they powered milliions of volvo cars. the AQ100 drive is ancient.

what motor is in the boat now, because one has a little keyhole shaped hole in the transom, one has a hole you can crawl thru.

If it was me, I would find a post 1996 4.3 motor and drive, rebuild the transom and go that route.

 

[Hofty]

The boat came with a Volvo B20. AQ115. I have torn it down, checked it over and cleaned it up. I have a buddy who works in a machine shop who will clean it up and bore/hone cylinders. Easily can rebuild the motor and put it back in the boat. The concept is to have the boat as a cruiser. It will be my first rebuild so playing with ideas. If the keyhole on the transom fits a different motor I'm good to go that route.

Just wondering if the B20 will power the 20ft Starcraft Chieftain nicely or not.

 

[Lou C]

I’m thinking a 4.3 V6 is minimum power for a 20’. An alu boat may be different due to lighter weight but a ‘glass boat no. I have a 4.3 in my 88 F/W and at 4200 lbs it’s just adequate.

 

[Scott Danforth]

since the boat has a VP and AQ drive, unless you redo the transom, you are limited to the AQ style drive.

The 2 liter will push the boat, as it has for the past nearly 50 years. Top speed maybe a tick or two past 30mph

 

[captmello]

sure it's an aq100 outdrive? they were obsolete in 1976...doing all this work, I'd look for a newer drive train. cool old boat however, good luck!

 

[matt167]

My dad’s 73 Chief 21’ would run into the 40s on calm water with 140hp Mercruiser. They don’t weigh anything..

The B20 is adequate but antiquated.