B31 engine over haul

[Art Sutch]

I'm repowering a 63 31 moppy and one of the options on engines are twin GMC 471s. Was wondering if anyone knows how they would work?

[Harry Babb]

The 4-71's are good rock solid engines but not necessarily the best choice.

I think the 4-71 makes about 150 horsepower. My guess is a cruise of 15 knots.

For about the same weight, or less, you can get a lot more horsepower in the Yanmars or Cummins and the latter will burn less fuel and give you higher cruise speed........and a lot less noisey.

There are folks here on bertram31 that are much more qualified to talk engines and application than me.....these are just my thoughts.....and an effort to get the conversation going.

Welcome to our board....good place to hang out and a world of knowledge and experience with these 31's as well as other boats.

Your gonna enjoy your time spent here on our website...welcome aboard

Good luck with your repower.....keep us posted

Harry

[Tony Meola]

Art

As Harry said, the yanmars and cummins are the more popular choice's. Check out the Cummins remans. You can not beat the deal for the money.

[Bruce]

Start with a budget figure. Throw it out the window after doubling it.

Then add another 5k. Start from there and go up. I'm not trying to be funny or smart ass as most anyone who refit a 31 can attest to.

That should let you know where your at on engine costs and then choose your options from there.

If you've already done that and the 4 71s are it then your going to mirror Tropic Star lodge as far as performance.

The 4 71's are a work horse but are slow. If you can be happy with a mid teen cruise and thats all you need, that answers your question.

With the higher HP comes running gear upgrades which can add another 7k to the pot easy.

[Bill Mckinnon]

I agree the best way to go is the yanmar and cummins. I went the Yanmar route and no matter how you cut it gonna run about 70k with you doing alot of the work yourself

Capt: Bill McKinnon
Charleston SC

[In Memory Walter K]

The guy's in Juneau Alaska. I suspect he doesn't have too many options and reliability is more important to him than speed.

[spencer]

Was just at tropic star about a month ago
The engines are pretty noisy being on the boat for 6 days
However, they run great, and the dock master said few problems but like all said top end is not to great , but seemed fast enough to get us to the fish caught 14 marlin, its amazing to see how the 31 does when fighting marlin