HP vs HP

GOB

Cadet
Joined
Oct 30, 2008
Messages
14
I'm looking at purchasing a new 6hp 4 stroke motor. In my research I have found most 6hp 4 strokes weigh in at about 55lbs and are 1 cylinder motors. With the exception of the Yamaha which weighs in at 82lbs and is a 2 cylinder.

So the question is, do the 2 motors put out the same hp or is the Yammy a stronger motor.

I like the lighter motor as it won't on a trailer and I'll be carrying it around everywhere. But If the Yammy is a stronger motor I'll have to sacrifice the old back for it.

John
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: HP vs HP

Horsepower is what folks talk about, torque is what moves a boat.
 

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,500
Re: HP vs HP

6 hp is 6 hp.

2 cyl will likely be a bit smoother at slow speeds.

The Tohatsu/Nissan/Merc (same motor, different decals) 5/6 hp (same block, different aspiration) weighs in at 55 pounds (15" short) through 59 pounds (ultralong 25"). 6 hp WOT fuel consumption is 2L/hr.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: HP vs HP

and i beleive the 2 cylinder would have more torque. i could be wrong. the one cylinder is going to be like your lawn mower idling.
 

coolguy147

Commander
Joined
Jul 14, 2008
Messages
2,817
Re: HP vs HP

welll id go with 2 stroke and even at that level fuel consumption isnt really a big factor
 

marquette

Petty Officer 1st Class
Joined
Apr 18, 2006
Messages
372
Re: HP vs HP

why a 4 stroke? do you need it for the lakes you go to? i would think a good clean used 6hp 2 stroke would be lighter and cost less.
 

TOHATSU GURU

Admiral
Joined
Jul 22, 2004
Messages
6,164
Re: HP vs HP

At WOT they do the same job. The Yamaha, however, has decidedly more hole shot. But, if you have to carry them around....You would appreciate the weight of the Tohatsu. The torque of the engine is meaningless except as a factor of the prop shaft hp at a given RPM. Since there is no published data for power head torque at given RPM's and since outboard engines have fixed gearing that do not allow them to take advantage of any unique advantage at an RPM, a discussion of "torque" is pointless...Except as to point out one engine's probable(in this case certainty) advantage over another for initial acceleration. IE Torque exists, it's real, it makes a difference at a set RPM in comparison to another engine at the same RPM, but the fixed gearing takes away it's relative importance and no one outside of the design engineers has the data(with rare exception) so....
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: HP vs HP

Unless you are dealing with local bans on carbed 2 strokes I agree with going for a nice JohnnyRude 6HP 2 stroke. Much lighter, smoother and quieter (than the single cylinder 4 strokes). I don't know if you can still buy them new, but I would take a good used JohnnyRude 6 over a new 4 stroke 6 of any make.

Making 4 strokes that small means vibration and weight and only trivial fuel usage and pollution advantages. Those small 4 strokes are carbureted, so they don't have all of the efficiency and cleanliness benefits that the big EFI 4 strokes and DFI 2 strokes offer.
 

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,500
Re: HP vs HP

In this size range, if buying new, in the US, it will be a 4-stroke, as the 2-smokes don't meet CARB and EPA numbers.
 

GOB

Cadet
Joined
Oct 30, 2008
Messages
14
Re: HP vs HP

Thanks everyone for your replies. Here in British Columbia Canada, the government is leaning towards banning the older 2 strokes on our fresh waters in the future. I believe they will still be allowed in the salt water though.

I'm leaning towards the Nissan 6hp 4 stroke as this will be easier on the back in the coming years. The 2 cylinder 4 stroke Yammy would be nice but a bit too heavy for my liking.

John
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: HP vs HP

At WOT they do the same job. The Yamaha, however, has decidedly more hole shot. But, if you have to carry them around....You would appreciate the weight of the Tohatsu. The torque of the engine is meaningless except as a factor of the prop shaft hp at a given RPM. Since there is no published data for power head torque at given RPM's and since outboard engines have fixed gearing that do not allow them to take advantage of any unique advantage at an RPM, a discussion of "torque" is pointless...Except as to point out one engine's probable(in this case certainty) advantage over another for initial acceleration. IE Torque exists, it's real, it makes a difference at a set RPM in comparison to another engine at the same RPM, but the fixed gearing takes away it's relative importance and no one outside of the design engineers has the data(with rare exception) so....
Yes, yes, yes!!!!! The only thing I will add is that the reason "The Yamaha, however, has decidedly more hole shot" is because it has more torque at low RPM . . . I am sorry that I seem to always find these torque comments, but the assertion that torque is all you care about is absolute nonsense!!! You can make 400 lb/ft of torque with your flippin' arms and a paddle, but you're not going to get even the lightest aluminum boat on plane . . . You buy horsepower, you pay for horsepower, it is what moves your boat. All of the torque in the world will not do anything for you unless it includes some RPM and that my friends results in . . . Horsepower.
 

TOHATSU GURU

Admiral
Joined
Jul 22, 2004
Messages
6,164
Re: HP vs HP

"a discussion of "torque" is pointless...Except as to point out one engine's probable(in this case certainty) advantage over another for initial acceleration"

I'm glad you agree. I think most people just use the word "torque" as a generality rather than as a specific event in an engines power curve. It bothers me, just enough, to where I point it out. I have to admit though, I've said "this engine has a lot of low in torque" often enough that I do feel guilty when I explain why it's not a good term to use most of the time. In fact, the reason the feds mandated PSHP was to get away from the power head torque/hp misnomers as usable data for model/brand comparisons. PSHP isn't perfect either, but at least it puts everyone in the same boat...Although some seats in that boat are better than others.
 

Howard Sterndrive

Rear Admiral
Joined
Nov 5, 2008
Messages
4,603
Re: HP vs HP

Here in British Columbia Canada, the government is leaning towards banning the older 2 strokes on our fresh waters in the future.

Those bans will never apply to existing motors.

I'd like to see them telling this taxpaying voter he has to throw his fishing buddy in the scrap bin:
58%27%20Johnson%20side.jpg



Bans will only ever be on the sale and registration and even that will likely never happen out there.
 

GOB

Cadet
Joined
Oct 30, 2008
Messages
14
Re: HP vs HP

Those bans will never apply to existing motors.

I'd like to see them telling this taxpaying voter he has to throw his fishing buddy in the scrap bin:
58%27%20Johnson%20side.jpg



Bans will only ever be on the sale and registration and even that will likely never happen out there.

You obviously don't know British Columbia my friend...I am a transplant American living in BC for 20 years now. They WILL put this law in place and good for them for doing so in FRESH waters.

John
 

mthieme

Captain
Joined
Oct 6, 2007
Messages
3,270
Re: HP vs HP

Yes, yes, yes!!!!! The only thing I will add is that the reason "The Yamaha, however, has decidedly more hole shot" is because it has more torque at low RPM . . . I am sorry that I seem to always find these torque comments, but the assertion that torque is all you care about is absolute nonsense!!! You can make 400 lb/ft of torque with your flippin' arms and a paddle, but you're not going to get even the lightest aluminum boat on plane . . . You buy horsepower, you pay for horsepower, it is what moves your boat. All of the torque in the world will not do anything for you unless it includes some RPM and that my friends results in . . . Horsepower.

Thank you.
There is a direct relationship.
HP = (Torque X RPM) / 5252
 

Howard Sterndrive

Rear Admiral
Joined
Nov 5, 2008
Messages
4,603
Re: HP vs HP

You obviously don't know British Columbia my friend...I am a transplant American living in BC for 20 years now. They WILL put this law in place and good for them for doing so in FRESH waters.

John

BC is the least likely province to ban 2 strokes. That's why there are large distributors of Sail and other offshore brands of Yamaha copy 2 strokes all based in BC.
IIRC, BC is the only province to back down on the regulation of PWC's. In 2002 (?) I served on an industry panel that made some recommendations to a Canadian senate regarding the enactment of that law - it was to give cottager's associations and municipalities greater authority over their waterways and who and what types of boats could use them. I seem to recall reading that BC's provincial cabinet did NOT pass their private member's bill due to all of the red tape involved in amending federal shipping acts. Ontario passed it, but BC was smarter. Ontario would just waste a lot of taxpayers money trying to enforce it and a charge would never hold up in court.

Same with emissions. BC hasn't banned old cars and trucks. Just the opposite. They are exempt from emissions testing.

BC does indeed have a lot of self-proclaimed environmentalists that like to flap their gums about anything with an exhaust pipe, but the taxpayers want their police and MNR focusing on criminals, grow ops and gangs..... not grampa's tin boat

A 4 stroke is better for the environment. And social pressures will eventually take care of any manufacturer making 2 strokes. Old motors will be dealt with by salt air, corrosion and father time.
 

GOB

Cadet
Joined
Oct 30, 2008
Messages
14
Re: HP vs HP

BC is the least likely province to ban 2 strokes. That's why there are large distributors of Sail and other offshore brands of Yamaha copy 2 strokes all based in BC.
IIRC, BC is the only province to back down on the regulation of PWC's. In 2002 (?) I served on an industry panel that made some recommendations to a Canadian senate regarding the enactment of that law - it was to give cottager's associations and municipalities greater authority over their waterways and who and what types of boats could use them. I seem to recall reading that BC's provincial cabinet did NOT pass their private member's bill due to all of the red tape involved in amending federal shipping acts. Ontario passed it, but BC was smarter. Ontario would just waste a lot of taxpayers money trying to enforce it and a charge would never hold up in court.

Same with emissions. BC hasn't banned old cars and trucks. Just the opposite. They are exempt from emissions testing.

BC does indeed have a lot of self-proclaimed environmentalists that like to flap their gums about anything with an exhaust pipe, but the taxpayers want their police and MNR focusing on criminals, grow ops and gangs..... not grampa's tin boat

A 4 stroke is better for the environment. And social pressures will eventually take care of any manufacturer making 2 strokes. Old motors will be dealt with by salt air, corrosion and father time.



How mis-informed you are...That was 2002. Now is different. You almost had me interested in your post until I read "Same with emissions. BC hasn't banned old cars and trucks. Just the opposite. They are exempt from emissions testing" and then I realized you are very mis-informed. Not trying to rag on you but you really need to be up to date on your information and not go by your experience from 5 years ago. Perhaps you are confused about freshwater vs. saltwater. (see my original post regarding this).

I LIVE here and keep an eye on what is happening NOW.

Besides this has nothing to do with the original post for information and so I will leave it at that.

John
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Re: HP vs HP

Its always nice to carry a light motor, but I think the bigger issue is how you are going to use the motor.

The singles are lighter, but they also vibrate a great deal and tend to be louder, plus from the ones I've had or used they seem to be made with light weight and a low price as a goal with less thought into durability.

The twins are much smoother, quieter, and seem to last almost forever.

If you just need a small motor to go short distances and then anchor or beach the boat like for some types of fishing or as a dingy for a large boat, then the singles work great. If you want a motor that will be pleasant to troll with for hours on end, or need to run a long distance and last for decades, the twins are much better.
 
Top