Bertram31.com General Bulletin Board

Re: Cummins ...Sir UV

Posted By: vic Roy
Date: Sunday, 19 March 2006, at 10:00 a.m.

In Response To: Re: Cummins ...Sir UV (JP Miller)

The 4BTA 250 had some injector tip issues (tips breaking off) early in its history, but Cummins stood behind them and came up with a new Bosch injector that fixed the problem. So as far and I know there are no major durability issues between the two engines. The 4BTA is rated at 3000 rpm while the 6BTA 250/270 is rated at 2600 rpm. Cruising at a lower rpm for your high cruise makes the 6B appear on paper, at least, to be somewhat more durable.

The 6 is a lot smoother at low speeds and produces more torque in the low and mid ranges. Fuel consumption should be comparable at similar boat speeds.

The small size of the 4 gives more room to work, especially at the front of the engine. The good news is that because of the huge motor boxes on our B31s with unlimited headroom over the top, engine maintaince access on either is excellent.

My personal preference is the 6 because of the smoothness and torque, coupled with the low cruising rpm. I've had the 6BTA 250s now for about 12 years with no major problems at all. The Sherwood raw water pumps on all 4 and 6Bs are a weak link and must be considered a throw away item after about 1000 hours. Tony Athens' aftermarket impellers are a major improvement.

UV

Messages In This Thread

Cummins
Greg -- Saturday, 18 March 2006, at 9:03 p.m.

Re: Cummins
vic Roy -- Saturday, 18 March 2006, at 9:33 p.m.

Re: Cummins
Brianb -- Sunday, 19 March 2006, at 12:08 a.m.

Re: Cummins
Brianb -- Sunday, 19 March 2006, at 12:25 a.m.

Re: Cummins ...Sir UV
JP Miller -- Sunday, 19 March 2006, at 9:00 a.m.

Re: Cummins ...Sir UV
vic Roy -- Sunday, 19 March 2006, at 10:00 a.m.

Re: Cummins ...Sir UV
JP Miller -- Monday, 20 March 2006, at 7:59 a.m.

Re: Cummins
JP Miller -- Sunday, 19 March 2006, at 8:29 a.m.

Re: Cummins
Greg -- Sunday, 19 March 2006, at 9:27 p.m.