Repowering Cummins engine with V-Drive

[Darren Kinvig]

I have a question about Re-powering my vessel with a V-drive using a Cummins engine. I am hoping someone can help with this. The manual for the cummins engine states the engine needs to be mounted in a nose up application. Between 3 and 12 degrees nose up. The shaft that is in the boat now sits at 12 degrees. That leaves enough room for a 20 inch wheel on the shaft. The ZF V drive transmission I am planning to buy is a 12 degree transmission. I would like to use a 20 inch wheel for this repower. If I need to lift the nose of the engine between 3 and 12 degrees that means I need to loose diameter on the wheel. I am going from a 210 HP Cat engine to a 315 HP Cummins. I really want to have the option of at least the same diameter wheel. I am in the planning stage and have the engine. I need to understand some options before I start to order trans. for this application? Thanks for any ideas.

Topic

[Darren Kinvig]

X tank

Thanks Tony
Is it possible for you to modify or supply an X tank that will work in my application? If I could get some of those fittings and water line I could do it myself. Your explanations to these questions sure helps to clarify allot of questions that come up in the planning stages. It can be difficult to understand where to start and what parameters to plan within. there is no written installation manual pertaining to each particular engine/ trans combination Some installation manuals are written in a way that restrict installation options. thanks again

[Tony Athens]

Remote Mount your X-tank and vent the engine properly

Look at these pics..This how you ignore the nose down thing

[Darren Kinvig]

Tilting engine

Thanks Tony.
To be clear you are saying It is okay to tilt the Cummins engine “Nose down” in order to get the proper angle to get clearance for prop? That is what needs to be done in this case. When the boat is running onto step the rear of the boat will drop more, resulting in more nose down attitude of the engine. The Issue I imagine could arise in a nose down attitude:
Air would be trapped in the cooling system at the opposite end of the expansion tank on the engine. This can be dealt with proper coolant tank venting? How costly and complex is this?
You say the oil pan angle does not care in this case. When the boat is trying to get on step at what point, or at what angle does the oil pan angle matter. Oil pan angle to me means at what point does the oil pick-up have no oil to pick up due to oil running to opposite end of oil pan.

Thanks again Tony.

[Tony Athens]

Just “tilt” the engine / v-drive package to get the clearances you need.. Forget about the engine to “Mother Nature” angle as all of that can be dealt with with the proper coolant tank venting.. The oil pan angle does not care in this case.

Tony

[Darren Kinvig]

sketch of engine room

The PDF drawing shows the original Prop shaft angle and the theoretical prop shaft angle using the cummins/ZF repower. The front of the Cummins engine is set in the same location as the front of the original Cat 3208.
The drawing shows the engine mounted at zero Degrees. At zero degrees I lose 3 inches between prop shaft center and bottom of hull due to transmission angle differences. If the front of the cummins is raised higher I would lose more space. My goal was to continue to run a 20″ prop.
Is moving the Cummins toward the bow of the boat an option to gain space between prop shaft and bottom of hull? Where does a person Start?

[Tony Athens]

Forget about “recommended installation angles”– Again, forget them..

Send me a simple sketch of what YOU need to do and I’ll sort it out.. This is “high school drawing 101” using a ruler and a tape, a protractor, a straight edge and common sense , not CAD stuff……….. Old fashioned “quadrille” paper helps to scale all.. For 2 decades +. that’s all I did….

[Darren Kinvig]

V-drive/ cummins installation guidlines

Thanks for the reply. I have spent countless hours on your website. it is the most helpful/informative collection of material I have run across on the internet. The very basic part of this issue is the fact that if the nose of the engine goes up facing the stern of the boat the shaft also goes up toward the bottom of the hull. I lose the space between the shaft and the bottom of the hull. As long as the recommended “installation angle” is not too rigid I feel more confident I can make a 12 degree down angle V-drive fit and have the dia. prop. I want. Scale drawings are not my forte’ but will do my best. I realize it needs to be down prior to starting the re-power.

[Tony Athens]

Darren,

The Cummins installation guidelines on this subject is only a guide as to the most “basics” and leave much to be desired.. At this point, just “totally ignore” that part……………..Spend some time and both post and send me direct what I need.

A good but simple drawing of what you are planning, IE, a good side view of your engine / v-drive/prop shaft layout in relation the Mother Nature ( AKA the LWL)……………………………………….

BTW, “v-drives” is what I do and a passion of mine, so I can sort it out as long as you help me help you..

All About Marine Transmission V-Drives

Why V-Drives, and then again, Why REMOTE?

Tony

[donald roth]

Your motor angle may change some due to its lighter weight.
Move batteries, water, fuel, whatever you can to compensate.
I know of a couple of 6bs with slight nose down angle that are doing just fine, although finding correct oil level took some fiddling.

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Darren Kinvig

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