Page 1 of 1
1999 DAUNTLESS 14: Which Engine for Re-powering
Posted: Sun Oct 22, 2023 3:34 am
by Lazygator
I am looking for advice on [which of two engines mentioned below will be useful for] re-powering a Dauntless 14.
A Yamaha F70A is light enough [at what was later mentioned to be 248-lbs and is a three-cylinder engine], but it has only a single overhead cam.
The Suzuki DF70 has dual overhead cams, four-cylinders, and weighs 334-lbs.
The original engine, a 1999 Mercury 75-HP two-stroke-power-cycle engine, weighs 300-lbs
Re: 1999 DAUNTLESS 14: Which Engine for Re-powering
Posted: Sun Oct 22, 2023 8:27 pm
by Phil T
The Yamaha F70 has the best power-to-weight ratio in [the 70-HP] class. You will be saving 50-lbs right off the bat.
The key to good performance on the Dauntless is [the engine mounting height]. [Mount the engine at] two-holes-up or three-hole-up; use a quality stainless steel propeller.
I would start with either:
- PowerTech SCD3 13.25-inch x 17-pitch
- Turbo 1 13.25-inch x 17-pitch
- Yamaha painted stainless steel 13-inch x 15-pitch
Re: 1999 DAUNTLESS 14: Which Engine for Re-powering
Posted: Mon Oct 23, 2023 7:42 am
by jimh
Lazygator wrote:A Yamaha F70A engine is light enough...
To make a better comparison, tell us the weight of the Yamaha F70A.
To better understand engine mounting height terminology, read this article (which is pinned at the top of this forum):
Engine Mounting Height Nomenclaturehttps://continuouswave.com/forum/viewto ... ?f=7&t=739
Re: 1999 DAUNTLESS 14: Which Engine for Re-powering
Posted: Thu Oct 26, 2023 2:23 am
by Lazygator
Phil--thanks for the prop and mounting information. I appreciate it.
Jim--the dry weight of the Yamaha F70a is 248-lbs, and it is a three-cylinder single-cam engine.
I’m concerned the Suzuki may be too heavy, but [put it might produce] more power.
The dry weight of the Dauntless 14 is 1000-lbs, and it carries a 25-gallon internal fuel tank.
Further information on engine choice will be appreciated.
Re: 1999 DAUNTLESS 14: Which Engine for Re-powering
Posted: Thu Oct 26, 2023 1:29 pm
by jimh
Lazygator wrote:...the dry weight of the Yamaha F70 is 248-lbs...
Hmm, Yamaha thinks their F70a weighs 253-lbs, and Suzuki says the DF70 weights 341-lbs. That is a difference of 88-lbs, which is quite a bit of extra weight on the transom of a 14-foot boat.
Re: 1999 DAUNTLESS 14: Which Engine for Re-powering
Posted: Fri Oct 27, 2023 9:24 am
by Phil T
If you are concerned about stern weight, do a test.
Figure the added weight of a Suzuki DF70 from what you have now and add that weight to the splashwell. You can use bags of sand, water etc.
Run the boat, observe the changes in the hull behavior—planing, coming off plane, backing down into waves—and static trim.
I often recommend this exercise for owners concerned about stern weight.