Torque question

[River - Runner]

For manufactures, it's common to build different hp. motors that share the same cubic inch engine block. With the lesser hp. motor there is more cubic inch displacement for the hp. Is there more torque for the hp. with this motor?

 

[JB]

Re: Torque question

No, Runner.

The differences that make peak HP less also make peak torque less.

However, a 70 ci., 70hp engine may make more low speed torque than a 55ci, 70hp engine. It would give a better hole shot.

 

[River - Runner]

Re: Torque question

Thanks JB, I also figured as such.

A manufacture will brag when their motor has more ci. displacement than their competitors. There is a limited advantage. It's like the adages, "There is no substitute for cubic inches" and "There is no replacement for displacement".

 

[Scaaty]

Re: Torque question

Torque is a factor of stroke length (the old lever action principle). Most motors with the same block has been tuned different with exhaust tuners, intake/reed plates, different carbs and jets. ALL motors have an equal torque/horsepower number of 5252rpm, and not much more than that is where most motors run anyway. More torque will get ya there faster though, so more bottom end torque is the ticket. But with the same Bore/Stroke, it shouldn't matter. Need to see a Dyno graph to really tell the diff. I would think if they tossed smaller pistons in there for lower HP, your torque will be much more.

 

[Texasmark]

Re: Torque question

Interesting. I have been interested in the application of torque in 2 cycle OB engines for a long time.

Must be something to it as Merc had a 2 liter 150 and for the bassers they uped the cubes to 2.5 liters for the better hole shot. Obviously the bigger cubes relates to better low end torque.

And lo and behold, if you saw the recent Evinrude E-Tech commercials they mention torque......but don't give you any numbers or show any curves. How about that.

Mark

 

[Scaaty]

Re: Torque question

See next post.

 

[Scaaty]

Re: Torque question

It also depends a LOT on where the ports are located...if I remember correctly, the old Merc150 and the XS150 was just a matter of moving the ports down the bore a touch, and cranked out an extra 15hp.

 

[Frank Acampora]

Re: Torque question

2 cycle porting aint that simple. It's witchcraft and esoteric art. Seriously, it takes a lot of study. The factory can devote years and multiple engines to it; we can't.
And while we are talking cubic inches, lets remember the maxim: Too much horsepower is never enough!

 

[Scaaty]

Re: Torque question

2 cycle porting aint that simple. It's witchcraft and esoteric art. Seriously, it takes a lot of study. quote]

 

[Scaaty]

Re: Torque question

2 cycle porting aint that simple. It's witchcraft and esoteric art. Seriously, it takes a lot of study. quote]

Actually its a very simple...as long as you have a flow bench and the right instraments...but I still agree with more HP aint enough..!

 

[Texasmark]

Re: Torque question

Well, I'm going to say yes and no on looping (I realize it's not hp per se, but does affect it).

How many years did OMC have a 3 cyl looper out before they figured how to exhaust tune their V4 and loop it. I'm assuming exhaust tuning was the reason for the delay as everything I read said that 3 cylinders was perfect for the reflection.............course that doesn't explain the little 2 cyl looped 50. :%

Mark