Repower Avance 40 question

CaribouCapt · Member

Repower Avance 40 question

Stanley · Guru

Hello and welcome to the forum. From the drawing shown on sailboat data, it appears that the engine is installed in your boat at quite a steep angle.
It may pay to consider using a down angle transmission to level out the engine a bit. This will make for easier maintenance in the long run.

Depending on the size of your Max Prop, I would recommend either the Beta 35 or the 38. Both have replaced the MD17 series of engines before. They are built on the same engine block but the fueling is different. If you let me know what size your Max prop is (also 2 blade or 3), I can run some prop calculations to work out the best engine /transmission ratio combination for you.

Where will you be doing the work?

Stanley

CaribouCapt · Member

Hi Stanley,

The drawing on sailboat data.com doesn't represent my installation. My Volvo is essentially horizontal with a 7 degree angled transmission. So I'll be able to match that with the angled TMC 60A transmission.

My MaxProp is 3 blade. I'll need to measure it this weekend but I believe it's 12".

The boat is in Anacortes, Washington.

Thanks!
Doug

CaribouCapt · Member

Hi Stanley,

It took a little longer than I planned to get back to the boat and measure the prop. It's a 3 bladed MaxProp, 16" in diameter. Let my know if there is any other info you need. Thank you!

Doug

Stanley · Guru

To work with your propeller you will want either of these 2 options.
Beta 35 with 2:1 transmission or
Beta 38 with 2.45:1 transmission.
If you can have your propeller freshened up by PYI and the blades changed for 17" diameter (if this allows for enough tip clearance), you will have better motoring performance.

Stanley

CaribouCapt · Member

Thank you!

Doug

CaribouCapt · Member

Hi Stanley - One more question. Will the 43 give noticeably better performance in this application and what would the right gear ration be for this installation?

Thanks!

Doug

Farron · Senior Member

Hello Doug,

There is a limit to the maximum amount of horse power that can be efficiently transmitted to the water by a propellers blade area. Propeller diameter is a significant factor of blade area.

You are currently fit with a 16" diameter, three blade Max Prop. The Beta 38 with a 2.45:1 gear or the Beta 35 with a 2:1 gear, maximizes performance efficiency with this size propeller and vessel.

As Stan noted above, you would benefit from increased blade area with either of these engines. Increasing the propeller to 17" diameter would increase your blade area and give a little better efficiency.

The extra HP and torque of the Beta 43, even with a 2:1 gear, would over power a 16" diameter, 3 blade, Max Prop. You would be on the margin with a 17" diameter propeller .

The Beta 38 would be a great choice for this repower. The horse power is right for the size of the vessel and works well with your propeller.

CaribouCapt · Member

Farron,

Thank you for the info. Just wanted to validate before placing the order.

CaribouCapt · Member

We are well into the re-power and working through a couple of challenges as I'm sure everyone does. The biggest challenge right now is the exhaust. The exhaust port on my boat is 1-3/4" and the (44mm) and it will be very difficult to change. So I'll ask the question first - is reducing the exhaust down from 2" (50mm) to 1-3/4" (44mm) and measuring back-pressure after installation a viable option and would it affect engine performance?

Also, I had to go with the ABVW panel to replace the old panel but still plan to add a water temp gage. Is the to wire a gage in at the panel without affecting the alarm and light or is the a place to put a separate sensor on the engine?

Thanks so much!!
Doug

my1972ih · Member

2.4sq inches is a substqntial amount less than 3.14sq inches. You'll kick yourself if you don't upgrade to at least 2". How many thousands are you investing to install a brand new engine and then choke it down? Might as well go with a smaller engine.