New 2018 20hp 4 stroke tohatsu power

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nytebyte
Posts: 103
Joined: 18 Jan 2016, 11:23
Location: ND

New 2018 20hp 4 stroke tohatsu power

Post by nytebyte » 22 Feb 2018, 10:56

Have you had a chance to try the new prop to see how that does?

turbotodd
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Joined: 24 Dec 2011, 22:06
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New 2018 20hp 4 stroke tohatsu power

Post by turbotodd » 22 Feb 2018, 23:08

scoobeb wrote: My question is can it be possible or to need a 11.5-12 pitch prop on a 20hp 4 stroke outboard?

Anyone think this is crazy to need such a big prop on this small an engine?

No, not at all. Remember-there's more to prop selection than RPM, speed. There's also that magical gearcase ratio.

For instance a 2.33 gearcase can turn a bigger wheel than a 2.08 can assuming the same horsepower, torque, and boat rigging. There's a lot more to a gearcase and it's ratio too than just propping. The engine and it's power characteristics come into play as well. BUT-in our little motors, there ain't much you can do with the gearcase because unlike the bigger motors (150+) there aren't many-if any-options as far as changing it. So you use the prop to "correct".

Some of the modified outboards (400hp+) are using real low ratio gearcases, and one reason is that the gearcase can be smaller in diameter-which=less drag.

As a general rule (and take this as a generality), the higher the gearcase number, the faster the engine can develop RPM. Thus, if a motor already has a 2.00 gearcase, going to, say, a 2.50 will let the engine spin up faster, but it'll also require more pitch in the prop to get the engine RPM back down. That's the generality of it-and there is a lot to play with such as where the engine makes it's peak power, how peaky it is, how the torque curve is (flat vs peaky), etc etc. And again, most of the time you can't change your gearcase ratio's unless another motor of the same family has a slightly different set of gears in it that will retrofit. A lot of the 150's had that and people oft interchange them to gain performance according to what they're goal is.

This subject is where folks can get into trouble, especially reading forums. So-and-such might have a 20hp with a 11" and it runs 6000 RPM at 26mph, which is about average for a 20 on a good hull. But not every motor has the same gearcase. So another guy might read that and think hey my 20hp Honda should go 26mph with an 11", but doesn't think about the gearcase difference and it can come back and cost him a few props and quite a few cuss words. Sometimes I see this stuff at the shop and people will spend a lot of money because of internet forums. I'm at the point where I don't even bother arguing anymore. I'll just advise, educate, and the person on the other end of the conversation can take it for what it's worth, or go spend some more money, their choice. For a while the 40hp Yamaha's were an issue because back in the 90's the 3 cylinder C40's were real popular which only had a 1.75 foot. Then came the 4 stroke, which was originally a 4 cylinder (same block as a 50) and had a 2.33. So guys were putting 11" props on them and wondering why they were overheating and slower than their old 40's. Because the RPM was higher'n a cat's back, on the limiter constantly. Then the foots changed again when they went back to a 3 cylinder 4 stroke carb, then again when they went EFI. So guys who had 25's with 13" props running close to 40mph were putting 15's and 16's on their 40's and lugging the poo out of 'em, overheating, sluggish, 28mph pigs running 4000 RPM max. My recommendation was to drop to an 11". They aruge and said well so and so runs a 40 with a 16 and mine should so, something's wrong with my brand new motor, so fix it under warranty. If one won't listen, I can't fix that.

scoobeb
Posts: 875
Joined: 29 Aug 2011, 04:59

New 2018 20hp 4 stroke tohatsu power

Post by scoobeb » 23 Feb 2018, 01:33

What amazes me is my buddy has the older model tohatsu 20hp which is a 351 cc engine which i sold him brand new by the way,lol and the same 2.15 gearcase,the new tohatsu /merc has a yes efi compared to carb engine at 333 ccs and the 2.15 gearcase but just amazingly so much more power and wot speed than its last production model. That blows my mind. I've had the 20hp mer/tohatsu, 20hp suzuki, ran a 20hp yamaha and honda and I never had one over rev with a 11 pitch prop except this engine. It actually almost threw me out of the back of the boat when I nailed the throttle with a full load of 3 full adults,engine ,boat, gear,gas,etc were over 1000 lbs total and it still almost tossed me out of the boat, I'm being extremely serious to,I wasn't expecting that at all. My 25hp 2 stroke merc was the only engine to have this type of power and while it was much faster than this 20hp it has close to the same type of power which is absolutely mind boggling for a 20hp 4 stroke. The place I bought it from told me I would be amazed after running it and I trust him very much and it did not dissapoint me one bit.

I loved my suzuki 20hp but this tohatsu is way more superior to the suzuki. I mean night and day. I tested it on my local lake and I finally stayed under rpms and with a full load I hit near a steady 27.5 mph and hit 28.5 a few quick times. I never got more than 24-25mph with any other 20hp 4 stroke. Just a well put together engine ,super,I mean super quiet at wot,the suzuki had a loud scream at wot that was ear piercing and drove me nuts. At idle it is so so quiet and idles way down to near nothing and almost 0 vibration on the tiller handle with the way the motor mounts are designed on this engine . The only thing I regret is not waiting to buy the merc version due to the state of the art tiller handle on it,same powerhead as it's basically an upgraded tohatsu. I'm selling the tohatsu and getting the merc in mid march when they come in. I'm so picky about outboards and haven't been completely satisfied with a 20hp outboard till I got this minus the new tiller,finally I found my keeper for yrs motor until I decide to sell my whole rig and go to a fiberglass skiff. I'm planning on possibly keeping this merc for a very long time I love it that much.

scoobeb
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Joined: 29 Aug 2011, 04:59

New 2018 20hp 4 stroke tohatsu power

Post by scoobeb » 27 Feb 2018, 15:26

So now I'm contemplating on whether to keep the tohatsu instead of dishing out another $300-$500 on the merc. I'm wanting to buy the 20hp efi mercury now as it's the same exact engine just a way better state of the art tiller handle I'm in love with. I wished I would have waited till the merc came out because I would of bought that asap instead. Now I must sell the tohatsu and then buy the merc. I had no idea it was coming out so soon. Oh well, we live and learn. It's also nice you get a 6 gallon gas tank instead of a 3 gallon. I really like the design to of the merc a but better. I first am waiting on pricing and my discount from the place I buy my outboards from before I do anything. I'm thinking the new 20hp mercury short shaft, manual start tiller will be near $3k. If they give me near 10% off that I will sell mine and then turn around and buy the merc . So pricing depends on all this.

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wmk0002
Posts: 673
Joined: 17 Apr 2014, 15:39
Location: Cullman, Alabama

New 2018 20hp 4 stroke tohatsu power

Post by wmk0002 » 10 Jul 2018, 11:15

scoobeb...any update? You ever get the Mercury?

And I may have missed it but why are you getting 20hp motors vs 25hp+?
2016 Alumacraft 1648 NCS - 1992 Johnson 9.9 HP Tiller
http://www.tinboats.net/forum/viewtopic ... 21&t=40764

Duramacr
Posts: 21
Joined: 16 Sep 2016, 00:43

New 2018 20hp 4 stroke tohatsu power

Post by Duramacr » 26 Jul 2018, 23:05

Im happy for you bro and I’m not surprised. I had
A 2015 Mercury 20hp and it was running 30mph with
me solo on a 1542 tracker . It ran 28 with 2 adults and
Ice chest, gear, etc . The total weight was about 1000lbs
with 2 people . You have a bigger heavier boat that’s why your
going a bit slower. I’m sure that engine is better as it is 30lbs
lighter and EFI . Try a 12 pitch and see what happens. Also a jackplate
really helps. Good choice on the tohatsu . Fastest engine out there . I sold
the 20 and bought a 30hp tohatsu and now I’m doing 37-38 solo
but chinwalking badly . Too much motor for the boat but I’m thinking
of getting a bigger boat anyway. Tracker is [Censored] . They make a good
Welded boat but it’s too heavy.

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