60 merc vs 40 tohatsu

[Gumcove]

Debating between a 60 4 stroke mercury or a 40 2 stroke tohatsu, what's your opinions. I will be running it on a 18x42 south Fork tunnel. Will I gain that much if any with the 60 merc?

[Montauk17]

I would go with the tohatsu on that boat. Will have a better holeshot than the merc and weighs less. It is also hard to beat jap motors when it comes to reliability.

[homerun]

Cajun Christian will know if he chimes in. I think he said before he runs the 4 stroke on his 18 tunnel.

[Rippinlips55]

40 Merc with motor upgrades would be ideal! Have a buddy with the same setup and his will scoot.

[marshrunner757]

I've got a 40 merc/60 carbs and pirated on an old heavy marshrunner. I've pushed it 52mph.

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[scott craft]

If we're talking a newer four-stroke 60 mercury I don't think it comes in a short shaft, but the 40 does. Just something else to think about.

[Dink]

Go with the 40.....remove the restrictor plate.....hello 50!!!

[marshrunner757]

Originally Posted by marshrunner757

I've got a 40 merc/60 carbs and pirated on an old heavy marshrunner. I've pushed it 52mph.

Sent from my SAMSUNG-SGH-I727 using Tapatalk

*ported* not pirated....

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[keakar]

Originally Posted by Gumcove

Debating between a 60 4 stroke mercury or a 40 2 stroke tohatsu, what's your opinions. I will be running it on a 18x42 south Fork tunnel. Will I gain that much if any with the 60 merc?

have you looked at the Hondas yet? they aren't expensive like they used to be and are lighter and IMO much better motors then most

also Nissan and tohatsu are the same like Johnson and evinrude so compare them to each other before you purchase if that's your choice. in some models there are price differences just in the name.

also I cant understand how you can be deciding between a 40hp and 60hp of different brands? choose the hp you want then compare brands of the same hp so you are doing a fair comparison and get the best fit and deal

offhand I always go with the max hp the boat is rated for since most boats are already under rated for hp.

Originally Posted by Dink

Go with the 40.....remove the restrictor plate.....hello 50!!!

restrictor plate ???

I thought that was just for nascar?

do all 4 stroke motors have restrictor plates?

does my 2002 Suzuki df40 have one?

[jldsc]

dont believe they were on the df's...just the newer tohtsy...fuel infected


Sent from an Apple Tree..

[keakar]

Originally Posted by jldsc

dont believe they were on the df's...just the newer tohtsy...fuel infected


Sent from an Apple Tree..

thanks

mine has good top end but a hole shot like im draggin something lol.

[CajunChristian]

Originally Posted by scott craft

If we're talking a newer four-stroke 60 mercury I don't think it comes in a short shaft, but the 40 does. Just something else to think about.

The 3 cylinder, 45ci, efi, 4 stroke, 40hp merc comes in short or long, the 4 cylinder 40hp, efi comes only in long shaft with a big foot. The same in a 60hp comes only in long shaft with a standard or big foot gear case.
I have one of each. I love the lit,tle 3 cylindr efi on the tunnel, it is not a rocket, but it has a water pump from hell, it will hydroblast pumping mud.
That is the weakness of the Tohatsu, the water sytem. Both of my Mercs will pump 25 pounds water preure at 6000rpm, the tohatsu is lucky to see 9 pounds.
For a marsh tunnel, the TLDI Tohatsu is a beter choice. Pull the retrictor and you have 50hp at 150 pounds. The 60 merc is 60hp at over 250 pounds. The 2 mph gain of the extra 10 hp would be negated by the extra weight, not good on a shallow water boat. The hole shot goes to the tohatsu. I run 4 difernt props, that's why I get great performance in the marsh or river, prop swapping. In the marsh I run a 4 blade 14 pitch prop that planes the boat in 10 feet distance and hits the rev limiter within 50 feet, I also run a Bob's hydraulic lift plate. In deep water I run a highly modified 16 pitch , pitched up, Yamaha semi cleaver.
D

[CajunChristian]

Originally Posted by keakar

restrictor plate ???

I thought that was just for nascar?

do all 4 stroke motors have restrictor plates?

does my 2002 Suzuki df40 have one?

The tohatsu is a 2 stroke direct injected motor, the 40hp has a restrictor plate on the intake. Just like the 4 cylinder 4 stroke Merc and the 50hp 4 cylinder, 4 stroke merc has a restrictor plate in the intake. Intake restrictors is an old trick used by manufacturers for 25 years Some even use exhaust restrictor plates. Just a small steel plate with a hole drilled in the center, the plate was inserted into the exhaust pipe on some outboards.
D

[CajunChristian]

Originally Posted by keakar

thanks

mine has good top end but a hole shot like im draggin something lol.

Then you need to play with props. The 3 cylinder, EFI, 4 stroke 40hp Merc has a 2/1 gear ratio. I propped mine to run loaded, it will bang the rev limiter empty. BUT, it pushes an 1844 Alweld marsh tunnel with 3 men, dog, and hunting gear 30 mph. Gets on plane in about 15 feet distance loaded. I run loaded 90% of the time, so I don't care how fast it runs empty.
For my 1556 with the 4 cylinder, 4 stroke Merc, I run 4 different props. I run a 14 pitch 4 blade prop in the marsh, gets on plane in the length of the boat, then hits the rev limiter in about 50 feet. In the river, I run a highly modified, pitched up 16 pitch Yamaha semi cleaver, average pitch is 18.
Just for giggles and dares, I run my old short course race prop, a 12" diameter, 20 pitch Quicksilver cleaver. Takes 30 yards to get on plane, then put the cat outside and hang on.
First thing to get is a tach, otherwise you are guessing.

[keakar]

Originally Posted by CajunChristian

The tohatsu is a 2 stroke direct injected motor, the 40hp has a restrictor plate on the intake. Just like the 4 cylinder 4 stroke Merc and the 50hp 4 cylinder, 4 stroke merc has a restrictor plate in the intake. Intake restrictors is an old trick used by manufacturers for 25 years Some even use exhaust restrictor plates. Just a small steel plate with a hole drilled in the center, the plate was inserted into the exhaust pipe on some outboards.
D

thanks, im always looking for more power if I can get it. I have direct fuel injection and no sign of any restrictor plates I can remove

Originally Posted by CajunChristian

Then you need to play with props. The 3 cylinder, EFI, 4 stroke 40hp Merc has a 2/1 gear ratio. I propped mine to run loaded, it will bang the rev limiter empty. BUT, it pushes an 1844 Alweld marsh tunnel with 3 men, dog, and hunting gear 30 mph. Gets on plane in about 15 feet distance loaded. I run loaded 90% of the time, so I don't care how fast it runs empty.
For my 1556 with the 4 cylinder, 4 stroke Merc, I run 4 different props. I run a 14 pitch 4 blade prop in the marsh, gets on plane in the length of the boat, then hits the rev limiter in about 50 feet. In the river, I run a highly modified, pitched up 16 pitch Yamaha semi cleaver, average pitch is 18.
Just for giggles and dares, I run my old short course race prop, a 12" diameter, 20 pitch Quicksilver cleaver. Takes 30 yards to get on plane, then put the cat outside and hang on.
First thing to get is a tach, otherwise you are guessing.

I have a tach and a gps for speed and ran some tests.

on take off it seams to have too much bow lift making the stern dig in yet everything I could find says I have the right prop on it now and even the powertech props tech support suggested the SRD3R13P (which is what I have) is the right prop but he just suggested I could buy the 4 blade version of the same prop SRD4R12P and that could help lift the stern and give better hole shot.

that makes no sense to me since the 3 blade prop tends to dig in on take off so I don't see how a 4 blade of the exact same shape and design would do any different just by adding a blade and dropping 1 pitch size. to me that seams to negate each other and bring me right back to where I started. if the blade design is exactly the same (which he said it was) wouldn't a 4 blade prop give the exact same bow lift and stern digging in that the 3 blade does if not worse?

I am thinking I need a prop with less bow lift and more stern lift but because of the Suzuki gear ratio no one is willing to take the prop back if they recommend anything that doesnt work. that's the key, im not willing to spend $300-$500 buying props until I luck into one that works well or maybe spend that and still not find one.

the prop I am using right now is a PowerTech SRD3R13P SS and my Suzuki lower unit has a gear ratio of 2.27:1 and im getting 28 mph top end

here are the speed and rpm numbers I have for the boat:

first test condition:
fully loaded boat with 2 batteries (one in bow storage), one full 6 gallon plastic portable gas tank, two tackle boxes and 4 rods, one ice chest and a 25lb. bag of ice, 2 people weighing 450 lbs. with one of them sitting on the bow deck to balance the load. test was done from idle on smooth protected saltwater (1" ripples no chop).
from idle:
rpm - mph
1000 - 2.8
1500 - 4.5
2000 - 5.6
2500 - 6.5
3000 - 7.6
3100-3200 started to lift out of water, took 3500 rpms to finally reach true plane and loses plane below 3500 rpm
3500 - 14.6
4000 - 17.9
4500 - 22.3
5000 - 25.1
5500 - 27.6
5600 - 27.8

second test condition:
unloaded boat with 2 batteries (one in bow storage), one full 6 gallon plastic portable gas tank, 1 person weighing 230 lbs. in protected freshwater canal (no ripples no chop).
from idle:
rpm - mph
1000 - 3.1
1500 - 4.6
2000 - 5.6
2500 - 6.5
3000 - 7.9
3050-3100 started to lift out of water, still took 3500 rpms to finally reach true plane and loses plane below 3500 rpm
3500 - 16.5
4000 - 20.5
4500 - 23.5
5000 - 26.0
5500 - 28.0
5600 - 28.6

you will notice that in both tests, the numbers for rpms 1500-3000 are close to the same for the loaded and unloaded conditions (given a small margin of error) because its hard trying to judge the needle position to determine exact rpms since i don't have a digital tach.

[SuperDave]

Are y'all takin about a TLDI 40 Tohatsu?

[keakar]

Originally Posted by SuperDave

Are y'all takin about a TLDI 40 Tohatsu?

no, that post was a response about my df40 Suzuki from post #9 above

by the time I realized I failed to mention that it was too late to edit it in

[SuperDave]

I just found a 40hp Suzuki 2 cylinder for 250. It comes with all the controls but it has a blown head or some type of major issue. I was highly debating on putting it on the back of my B60 Riverhawk but I'm not sure it can handle the weight. But it would haul some arse!!!!

[jldsc]

the 2cyl.'s are nothin spectacular..


Sent from an Apple Tree..

[keakar]

Originally Posted by SuperDave

I just found a 40hp Suzuki 2 cylinder for 250. It comes with all the controls but it has a blown head or some type of major issue. I was highly debating on putting it on the back of my B60 Riverhawk but I'm not sure it can handle the weight. But it would haul some arse!!!!

you sure its a 40? as far as I know all the 40's are 3 cylinders