New 2018 20hp 4 stroke tohatsu power

[scoobeb]

Ok fellows I need some advice here if possible. I just bought a new 2018 20hp efi tohatsu and I love the engine. I had used it with the original 10 pitch prop and it's on a 1648 alumacraft. The total weight in the boat was over 1000 lbs and the motor had so much power it over revved with the 10 pitch prop which is amazing in itself. So I went to a 11 pitch prop and again at wot to my surprise it over revved,same weight in the boat.

My question is can it be possible or to need a 11.5-12 pitch prop on a 20hp 4 stroke outboard? This seems like to big of a prop but I'm hitting the Rev limiter with the 10 and 11 pitch prop. Can this outboard have that much power to need a prop that big? Seems kinda crazy. The red light on the front was going on and it started to sound like it was missing until I just let off the throttle a bit,then red light off and ran perfectly the whole way home at around 3/4 throttle or just above that. So to make sure it was me hitting the Rev limiter I did wot a few more times and again every time it did the same thing and once I let off the throttle it ran perfect. I also read in the manual this is what it will do if it over revvs,the red light and sounds like it's missing until you back off the throttle and get under the rpms. I just find this amazing with so much total weight in the boat that this engine runs with that much power that it still over revvs with a 11 pitch prop.

The only thing so far I don't like about this motor is being efi it should start easy and it takes 5 pulls every time and it shouldn't. My 20hp suzuki was efi and it started every time on one to 2 pulls. It runs unbelievable when it gets going,the most powerful 20hp 4 stroke I've ever used or owned . My suzuki topped out at 24 mph steady,I had the older carbed tohatsu and it was near 24mph,the Yamaha 20hp the same. This tohatsu at 333 CCs hits 26mph steady which is extremely impressive. So if I need to go 11.5 to a 12 I may get a mph or 2 more but my main thing is to stay under the Rev limiter.


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

 

[richg99]

There are a lot of smart guys/gals on this group. However, if you don't get the answer that you are looking for here...try

https://forums.iboats.com/forum/engine-repair-and-maintenance/honda-tohatsu-nissan-outboards

 

[Jim]

Thanks Rich!


Sent from my iPhone using Tapatalk

 

[scoobeb]

I posted in both so hopefully I get an answer soon before I buy another prop,I'm leaning towards the 12 pitch prop.

 

[nytebyte]

Was there problems with the Suzuki to make you switch to the Tahatsu? I like the idea of the easy starting.

 

[scoobeb]

The suzuki had such a high pitch ear piercing whistle or scream from slow to wot and it drove me crazy,the older tohatsu/merc 20hp carb models also did the same thing. This tohatsu is a night and day outboard imo. The power alone is well worth having to pull it a couple extra times to start it. It's got no high pitch sound ,runs extremely quiet from slow to wot and the power will throw you back compared to the suzuki. The suzuki is a great running engine but I will take this tohatsu all day over it and I'm glad I did. Also near no vibration in the handle is a big difference imo. The way they designed this new tohatsu eliminates almost all vibration which is awesome,my hands don't go numb anymore,lol.

 

[nytebyte]

I still have a couple weeks before I will be ordering so I'll keep a eye on how you do. Hope it works out for you. Any better deals out there than Cummberland for Suzuki or Tahatsu that anyone knows of?

 

[okgene]

Where are you located? Want to sell the Suzuki?

 

[Crazyboat]

If you don't get your answer go to bandofboaters.com look up member Ken or propgods. They are one in the same and he can get you an answer as well as a prop if needed.

 

[scoobeb]

I still have a couple weeks before I will be ordering so I'll keep a eye on how you do. Hope it works out for you. Any better deals out there than Cummberland for Suzuki or Tahatsu that anyone knows of?

Believe me I'm a huge bargain shopper. Now maybe you can look up port a bote and they are good to. Ask for a quote or better yet call them and they usually do better then their advertised price.


https://www.google.com/url?sa=t&source=web&rct=j&url=https://store.porta-bote.com/&ved=2ahUKEwi0w66x7ZXZAhWss1kKHTKaD7MQFjABegQIBRAB&usg=AOvVaw1j1tq0xZVlziby-NL4Hdm4

 

[Mike Redmond]

Not shure about this,friend had same problem,hed bought a 15hp honda,he didnt know much about ob motors,his problem was that hed bought a short shaft engine,n he needed a long shaft one,twas a pricy mistake,hope this is not your case,,,wishing you good luck in solving your problem

 

[scoobeb]

Not shure about this,friend had same problem,hed bought a 15hp honda,he didnt know much about ob motors,his problem was that hed bought a short shaft engine,n he needed a long shaft one,twas a pricy mistake,hope this is not your case,,,wishing you good luck in solving your problem

No ,definitely not my issue. I just ordered a new 12 pitch prop so that should take care of the problem. I'm very knowledgeable about smaller outboards but again I've never in my life seen a 20hp 4 stroke outboard have this much power. I've had near every 20hp there is on the market except a Honda which are absolutely excellent outboards but for over $1000 more than any other brand is rediculous spending that type of money. There all made in japan and with the same darn parts.

Anyway, I just can't believe how this engine pushes my 1648 loaded down faster than any other 20hp 4 stroke I've ran. I'm absolutely not complaining, I'm just in complete shock and amazement and can't be happier that I bought this engine,I love it.

 

[Unter]

I have the same motor on a 14-42. It is raised on a manual jackplate about 3.5" . I am 200+ over rev so i ordered a 12 pitch prop based on your history. Before raising the motor the rpm's were similar.

Should have it on in a week or so...

 

[Unter]

Btw, at 116#, the electric start and power trim are cool.

 

[scoobeb]

It amazes me how much power this motor puts out,no 20hp 4 stroke I've ever had or ran comes close.

 

[nytebyte]

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

 

[turbotodd]

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]

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]

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.

 

[wmk0002]

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

And I may have missed it but why are you getting 20hp motors vs 25hp+?