True or false a 4stroke has better low end torque

[fishrdan]

Re: True or false a 4stroke has better low end torque

I think you better look at the video again. The operators push to WOT on the count of three and the Yamaha powered boat actually moves before the ETEC powered boat, which is a clear indication that the Yammy oeprator actually pushed the power on, before the ETEC operator.

I did, many times,,, and still have the same opinion

Sure the Yamaha bumps the throttle a bit to straighten out, but he didn't go WOT. You can't even see what the operators are doing with the throttles, especially the Yamaha, it's completely obscured.

- Yamaha bumps throttle to straighten out (jerks stern of boat a bit)
- The Etec goes WOT
- Etec sends 30' of prop wash towards the Yamaha
- Etec's boat starts moving forward....
- ...Then the Yamaha goes WOT (but it's too late)

Eh, I guess it's up to interpretation

 

[boater1234]

Re: True or false a 4stroke has better low end torque

Totally agree fishrdan.That dvd is as rigged as you can get.Everyone knew before they even got there what was gonna happen and what to do.It was so well done i wonder how many times they had to practice to get it right.

Ok getting back to what this is about.The 2stroke hands down will have better low end torque from what i gather here.I guess until they get the perfect proper gearing or get the 4strokes much lighter the 2stroke will win everytime.

I have seen a ton of videos on you tube that show 2strokes and 4strokes taking off from an idle and from what i can see the 4strokes are not to far behind.The 20hp 4stroke yamaha/merc/tohatsu have extremely great power from what i can see.Now i don't know if the people had to fool around with the engine to do so like trying different props etc...There is a great video were it shows the 20hp tohatsu planing out a like a 450 lb wooden boat with unreal power,according to what the guys are saying in the video they are in the mid 20's which is great for a 20hp outboard,also the motor gets that boat on plane in seconds from a very slow idle to full blast.There is also a few videos were it shows the 20hp merc that just flat out gets it on an inflatable.

The 2strokes and 4strokes i have seen on you tube don't look to far away from eachother as far as power for hole shot.There is like a ton of videos with 15hp 4strokes and 15hp 2strokes and i have to tell ya it looks like they both are pretty darn close to one another when it comes to hole shot.Ok lets get some more info going here.I don't really know about the bigger engines as i will never be able to afford one so i don't really check them out.

Thanks guys for all the info so far keep it coming as i like learning.

 

[RRitt]

Re: True or false a 4stroke has better low end torque

It's like the ghosts in the movie "6th sense"......

I thought the OP wanted to compare 2 stroke and 4 stroke torque. Isn't that what's happening in this goofy test? Why do you want to compare a 2 stroke to 2 stroke now? I don't see how anyone could make the statement that the 4-strokes make more low end torque.
They have to put different pitch props and gear ratios on the 4 strokes just to give them any resemblance to a 2 stroke's low end power.
The 2-stroke has to have more torque---after all, it's a 2-stroke!
Wouldn't the 4-stroke also wear out faster, just like the 4-stroke automotive type engines in a stern drive, since they're always running high rpm's under a high load????? I was thinking that the motors in an inboard/outboard only last a small percentage of hours vs. an engine in a car for that reason. Shouldn't this result in a similar problem with 4-stroke outboards?
JMO,
JBJ

okay, I'm going to type this slowly. Maybe that will help.

The 2 strokes idle higher and rev faster. It is at 2000rpm while the four stroke is still at 1000rpm. The 2 stroke definitely puts out more torque at 2000rpm than the four stroke at 1000rpm. With that advantage it pulls against the transom of the four stroke and causes it to bog down.

All this video really shows is that 2strokes can rev faster. It doesn't even mean that 2 strokes have a better hole shot because everything beyond the first 1/10th of a second is removed from the result.

 

[pootnic]

Re: True or false a 4stroke has better low end torque

RRitt,are you trying to say 4 strokes have a better hole shot then a 2 stroke,or just on that video?
Idles higher revs faster...yup, because it makes it's power quicker.
Pretty sure even if the weights were the same the 2 stroke should have a jump on the 4,unless gears and prop were changed a bit.
Guess I'll have to google how a 2/4 stroke make there power,thought the difference was pretty simple.
I don't think I'd own a 4 stroke under 40hp,the few I've been in don't have the jump a 2 stroke has,maybe they weren't idling fast enough

 

[RRitt]

Re: True or false a 4stroke has better low end torque

RRitt,are you trying to say 4 strokes have a better hole shot then a 2 stroke,or just on that video?
Idles higher revs faster...yup, because it makes it's power quicker.
Pretty sure even if the weights were the same the 2 stroke should have a jump on the 4,unless gears and prop were changed a bit.
Guess I'll have to google how a 2/4 stroke make there power,thought the difference was pretty simple.
I don't think I'd own a 4 stroke under 40hp,the few I've been in don't have the jump a 2 stroke has,maybe they weren't idling fast enough

I'm trying to say that the e-tec as shown revs faster than a yamaha. BTW, a kawasaki dirt bike revs faster than a harley. That's all I'm saying. That's all the video is demonstrating.

Try this test.
Tie a rope on the back of a big 2 stroke motorcycle and the other end on a harley. On "GO" drop both bikes into gear and gas it. The guy on the rice burner should be able to jerk the harley right out from under the rider before he can get it up out of its deep idle. According to this video that would prove that the 2 stroke bike is more powerful than the harley.

 

[QC]

Re: True or false a 4stroke has better low end torque

I'm trying to say that the e-tec as shown revs faster than a yamaha. BTW, a kawasaki dirt bike revs faster than a harley.

They rev faster if there is more power against the same load. If the load is different (kawi vs. harley) then the comparison means nothing.

We need to clarify something. Revving (accelerating) against a load is what an engine does (if it can). Revving faster than some other engine means it has more power AT THAT POINT. It is not something to dismiss as "it just revs faster". That's what it is supposed to do if there is more power available than power required. Focus on that: Power Available vs. Power Required, it accounts for so much of what people discuss here regarding power. There is not some unmeasurable rev factor . . .

You might say "but hey man, turbo engines don't rev fast, but they might have more power". And you would be correct, but the only reason it doesn't rev fast at the beginning is that it needs time to boost the air then make the associated power, but the reason it doesn't rev is because POWER IS LOW at that point, not because there is some slow rev factor.

There is no such issue with a naturally aspirated engine, When you open the throttle, air is there for the next firing event whether it is a 2 stroke, 4 stroke or Wankel. If the air is there, it burns the fuel, if the fuel is burning she is making power and will rev happily until something stops it. Period. The turbo takes time to build air, so it takes time to build power. Only other significant example worth discussing, and it still is the same thing, if she can, she revs up.

 

[jay_merrill]

Re: True or false a 4stroke has better low end torque

Well, here's one for y'all to beat ..... the W?rtsil?-Sulzer RTA96-C. Its not exactly a "trailer boat" type engine, though.

14 cylinder, inline, 2-stroke turbocharged diesel. 90 feet long, 44 feet feet high, with a weight of 2,300 tons! It puts out a "measly" 109,000 horsepower.

I think it beats both the Yammies and the ETEC!

 

[RRitt]

Re: True or false a 4stroke has better low end torque

We need to clarify something. Revving (accelerating) against a load is what an engine does (if it can). Revving faster than some other engine means it has more power AT THAT POINT. It is not something to dismiss as "it just revs faster". That's what it is supposed to do if there is more power available than power required. Focus on that: Power Available vs. Power Required, it accounts for so much of what people discuss here regarding power. There is not some unmeasurable rev factor . . .

Wow, thanks for the tip. I never realized all I need to do to have a much more powerful engine was adjust up the idle speed. Cool. Thanks for the tip.

 

[QC]

Re: True or false a 4stroke has better low end torque

How in the flyin' flip do you glean that ^^^^^ from my post?

 

[Bob_VT]

Re: True or false a 4stroke has better low end torque

How in the flyin' flip do you glean that ^^^^^ from my post?

LOL I am wondering as I read this which coffee tastes better.....mountain grown, valley grown, picked in a "fair trade" area ........ wow I love commercials

 

[RRitt]

Re: True or false a 4stroke has better low end torque

How in the flyin' flip do you glean that ^^^^^ from my post?

the evinrude has a higher idle rpm from the factory. If i jack up the idle rpm on the yammy to 200 more than e-tec and give both boats same prop then it will pull the evinrude under. Would that prove the yamaha is better? No, it wouldn't. It would just prove that - as configured - the yammy revs faster.

 

[QC]

Re: True or false a 4stroke has better low end torque

Also assumes they have the same gear ratio, and it proves one thing. That the Yamaha is idling 200 RPM faster. How in heck does that prove it revs faster? Maybe I'm confused. When you say "revs" what do you mean?

 

[thaphillips]

Re: True or false a 4stroke has better low end torque

I am going to take my comparison to motorcycles. In Motocross they primarily race 2 stroke engines because they have more torque for the jumps. There is an ocassional 4 stroke in the field and 4 strokes are improving.

A 2 stroke will cost you more on a daily basis.
A 4 stroke costs you in lump sums.

Most 4 strokes are more expensive to purchase than there 2 stroke counter parts.
4 strokes also have more parts and mechanical failure is potentialy more expensive to repair.

2 stroke oil isn't cheap and with a big gas tank (mine is 30 gallons) it can get expensive.
2 strokes in general have more torque. For a 4 stroke w/ comparable torque it will be quiet a bit more expensive.

With the correct prop you can always adjust your torque vs top speed.

 

[thaphillips]

Re: True or false a 4stroke has better low end torque

You could also just ask yourself ...... "Would I save the money I am not spending on 2 stroke oil?".

If you not saving the money it doesn't matter.

Most people waste it on chips, sodas, beer, or just plain crap.

 

[boater1234]

Re: True or false a 4stroke has better low end torque

I have been interested in buying a 20hp 4stroke merc but i have a 15hp 2stroke merc that i'm positive will have great low end torque.There is a fellow who just bought the 15hp 4stroke merc basically the same motor just carbed differently.He said he has it on a aluminum boat as i want to do and it planes him out in under 4seconds and even has a ton of power to spare so that makes me feel a little better,plus he tops out at 27mph which isn't to shabby for a 15hp outboard.He sent me a home video of it and from what i can see it gets up fast.I know it's not going to be a rocket ship but i fish very shallow with tons of rocks and it is very important i get up on plane fast.I live on the west coast of fl and it is shallow.For some reason people think i'm worried about speed when in all my posts i'm just worried about planning fast.I know the 15 or 20 will give me good top end so i'm not even close to worried about that.

I have been going through almost all the 15 to 20 hp 4stroke videos on you tube and from what i can see they get up pretty quickly especially the merc/tohatsu 20hp 4stroke.Even the 20hp yamaha looks pretty powerful itself.I just like the idea of a slightly better gear ratio at 2.15 instead of 2.08 on the yamaha.Is there a [big] noticable difference in a 2.15 gear ratio compared to 2.08 gear ratio?If not that will open my options to even more motors and better deals.I have just heard that the merc/tohatsu 15/20hp has better get up and go compared to the 15/20hp yamaha,is this true?

I have a 14ft alumacraft that is 63" wide and has no center seat with a 42"floor,plus it weighs in at 230lbs,it's front heavy with a big front deck which is a good thing as it will help distribute the weight better for a heavier motor.I can't see the 20hp not being able to get the job done,plus it may have some power to spare i hope.I would think the 15 would do the job but i will take that extra 5hp for the extra minimal money.The boat is max rated for a 25.The guys here at the marina i bought the boat at say they sell the boat as a package with 15hp on them all the time and from what they here do very well.Ah maybe what i will do is buy a new 20hp 4stroke and if i don't like it i will keep the 2stroke and sell the 4stroke.

 

[seahorse5]

Re: True or false a 4stroke has better low end torque

the evinrude has a higher idle rpm from the factory. If i jack up the idle rpm on the yammy to 200 more than e-tec and give both boats same prop then it will pull the evinrude under. .

Actually the F150 Yamaha idles about 200 rpm faster than the 150 E-TEC. The Evinrude has a fixed idle of about 500 rpm and the Yamaha is about 700 or so.

 

[jbjennings]

Re: True or false a 4stroke has better low end torque

.There is a fellow who just bought the 15hp 4stroke merc basically the same motor just carbed differently.He said he has it on a aluminum boat as i want to do and it planes him out in under 4seconds and even has a ton of power to spare so that makes me feel a little better,plus he tops out at 27mph which isn't to shabby for a 15hp outboard.He sent me a home video of it and from what i can see it gets up fast.QUOTE]

He either has the fastest, lightest, tiniest aluminum boat hull in history, or has the fastest/most powerful 15hp 4-stroke merc ever constructed, or........... his or my GPS is inaccurate. I don't have a 15hp of any brand with any prop that will go that fast on any of my boats. My 18hp motors don't even go but about 26mph. If it were me, I'd have to ride in that boat with that motor and be looking at the GPS in order to believe it. Then again, he may weight a lot less than my fat rear at 225lbs., which could make the difference.
JMO,
JBJ

 

[boater1234]

Re: True or false a 4stroke has better low end torque

JB if you look at alot of threads in here there 15hp outboards move them close to 30mph.Go to you tube there are tons of people people who have the camera on just the gps after showing what motor they are running and over 75% of all those videos show the gps going close to 28mph and yes there are some that go slower.There is a guy there who does nothing but test small outboards and he has a tinny and with him and his wife on the boat they hit over 28mph everytime.I think you under estimate the power of these motors.Also i had a 9.8 2stroke tohatsu yrs ago and my buddy had a hand help gps and with me and him on a 12ft alumacraft flatbottom we hit over 20mph a ton of times,but it was glass calm out.Plus i was close to 75lbs lighter.Also what yrs are your 18's.There is a ton of videos on you tube check them out and you will see it's very possible.These flatbottom aluminum jon boats don't need much to get them going fast.Most of the people on there say they hit anywere from 25-30mph depending on the conditions outside.I know these motors are powerhouses i just have never run a 4stroke and i will be soon.

 

[jay_merrill]

Re: True or false a 4stroke has better low end torque

the evinrude has a higher idle rpm from the factory. If i jack up the idle rpm on the yammy to 200 more than e-tec and give both boats same prop then it will pull the evinrude under. Would that prove the yamaha is better? No, it wouldn't. It would just prove that - as configured - the yammy revs faster.

Sorry, but I have to strongly disagree with that assumption. Neither engine is developing much torque at idle speed, but the two stroke will develop more than the four stroke all along, which allows it to accelerate (in terms of rpm) faster and hit its optimum powerband.

You can bet if Yamaha thought it could perform the same test and sink an ETEC powered boat, they would have done so a long time ago.

 

[oldandintheway]

Re: True or false a 4stroke has better low end torque

Evinrude has a very interesting DVD that touches on this subject. They pitted a pair of identical boats against one another, by putting a two-stroke ETEC 150 on one and a four-stroke Yamaha 150 on the other. They then tethered the boats stern to stern.

Upon a signal, both operators slammed the throttles into the wide open position. Within a few moments, the ETEC literally pulled the stern of the boat with the Yamaha under water and sank it.

Yeah, but I got a great deal on the used Yami...

Sorry, I didn't realize this was an old thread.