Hino WO4CTI in a 26' Tollycraft

Hello everyone,

I have a 1973 26' Tollycraft that I am in the process of restoring. Currently, it has a Chrysler 360 with only about 70 hours on it. It runs well (it replaced a 318 and whoever did the swap did some... questionable... things that I had to fix). It's rated at 275hp and brings it to about 21-22kts WOT. This engine has a good amount of power and brings the boat up on plane quickly, however, I really, really, prefer diesel engines. I've been around boats all my life, my grandparents owned a 1989 Bayliner 3288 for about 27 years with twin 135hp Hino diesel engines, and I feel that the turbo-intercooled model (210 hp) of this engine would be perfect for this boat, but I'd like to run some of my math to see if it sounds right.

My current drive setup is at an 18° angle, 1:1, direct drive (not v-drive like most of these 26 footers are) with a 14x11 prop and 1" shaft. I am very restricted in engine length, with a maximum of about 47" from the coupling to the pulleys. Width and height aren't a major issue. They actually had to cut into the bulkhead a bit to fit this V8 in.

The reason why I picked the Hino was simply because of size. From the coupling to the end of the pulleys, it comes in at around 43" (based on dimensions, correct me if I'm wrong) so not only would it fit, but it would fit better than the Chrysler. From Mercruiser/US Marine, it came equipped with a ZF 63A 1.5:1 gear ratio, but they do have the same gear with 1.2:1, which is closer to the original gear ratio.

I believe I will also need to change prop shafts, as, according to the prop shaft safety factor calculator, a 1" shaft would have a safety factor of ~2.5 at 3k engine RPM with a 1.2:1 gear ratio, and with a 1.25" shaft, it bumps up to about 5. Another constraint I have is the prop diameter. I am restricted to about 15-16" without slicing through the hull, so I would probably need a 4-blade prop with a reasonable pitch.

The only place I can find Hino engines for sale is at Doug Russel Marine, which is all the way across the country for me. Those are not guaranteed to run, but they look okay from the photos on their website. Let's assume I purchased one from them for the sake of simplicity.

Here's a list of big-ticket prices, correct me if I am off the ballpark for these estimates.
Hino engine: $6,000 + tax + freight
Hino manicooler ceramic coat: ~$1000
Hino SS exhaust riser: ~$2000
New prop shaft: $1,000-2,000
New prop strut: $500-1,000
New prop: $500-1,000
New exhaust: $300-600
Total: ~$11-15k
Selling Chrysler +2-3k
Total: ~$9-13k

Is it worth it? Of course not. I will never make this money back, but it would be a fun experience. I don't have the funds to do this now, maybe in the next couple of years.

Doesn't seem too bad for a diesel swap. Do all the numbers sound about right? Am I missing anything?

 

As I read it, you are proposing swapping the existing engine for one that is heavier, has less power, and will use a less efficient propeller. Further, you are buying an engine "as is", which is advertised as being good for parts or rebuilding. The cost should include the labor and parts to rebuild it. The boat may not be able to get over the hump and plane with the added weight and reduced power. Unless you spend all your time at low speed, it seems like a bad idea.

 

Yanmar 4LHA-STP
4LHA-STP (Z) - YANMAR Marine International https://www.yanmar.com/marine/product/engines/4lha-stp/

The newer 4LV engine is an inch longer, 60 pounds lighter, and turns 3800 rpm. It's probably a better choice if access is acceptable. You are going to want rpms given your small prop aperture.
https://www.yanmar.com/marine/wp-co...-STP_KMH50A_right-side_wtext-768x614.jpg.webp

 

There’s a lot of issues with your proposal, the main one being the budget!
18* drive angle is far from ideal, the boat’s designers obviously favored interior accommodations over intelligent driveline engineering.
Have you thought about Vdrive Transmissions?

 

There's a geometry trick when you are getting into higher shaft drop angles like this, and I haven't seen it published anywhere. You want the meaty part of the blade, normally 70-75% of radius, to have about the same geometric angle as the shaft drop angle. This reduces one of the primary vibration modes of a skewed shaft. So let's look at this - take a 14" prop - the radius is 7". Seventy+ percent of that is 5 inches. Now 2*pi*5" is about 31.4". The sin of 18 degrees is 0.31, so you get a prop pitch of about 10 inches, which is mighty close to the 11 inches you are starting with. I would make an effort to maintain the prop geometry you currently have if you don't have any vibration issues. That means delivering the same engine power at the same prop rpm in the new installation.

I also wouldn't switch blade count if you currently have a 3 bladed prop. That also affects the vibration modes. A meaty, high AR, correctly cupped 3 blader may be your best choice if the old one is working and you aren't increasing power. But I'm not prop guy. So I'd consult with a manufacturer before changing stuff up.

 

just curious, what is the shaft length on the 26? also how many ft is it from the front of the engine room to the transom?

 

Terrible, terrible idea clutz, don't do it, you'll come around soon, hang in there...

 

The shaft length on this model is around 4ft, the v-drive models are I believe around 68". I decided to convert to a v-drive which would allow for a less steep shaft angle of 12 degrees with a ZF 68IV. I already purchased the Hino and it's almost ready to run. It was overall in very good condition, it just needs some repair to the Manicooler (typical). I found a good deal on 18x16 bronze prop and an 18x17 nibral prop. I need around a 7ft 1.5" propshaft and a new shaft strut to accommodate the v-drive. So far, this conversion is still around the budget I allocated, only a couple thousand more than expected due to the cost of the v-drive swap.

 

Hey, nice job for not listening to criticism, i think its a cool project, thanks for the reply.