Which motor would last longer. The long or the short? Also which motor works harder?

 

Shorter short will put less side loads on a piston, lower piston speeds etc.
This is one of the reasons why big stroked motors cant rev high.

 

I was just wondering Because my dad and i were arguing about this months issue of Dsport. They were talking about most of the population (and my dad) believe that the long rod would make more power. Because the long rods would have reduced side loading on the cylinder walls and thus have reduced friction horsepower loss. A few others people (and myself) believe that the short rods would make more power. Because it has less piston dwell at TDC and BDC. After reading the artical and finding out that the shorter rods DID make more power. My dad (because he was wrong) said the short rod motor would not last as long because it worked harder. I need to shut him up so i thought i would ask you guys.

 

shorter rods are used on longer strokes... more like drag racing

longer rods are used on shorter strokes... more like endurance racing

 

A longer stroke will make more power from simply sheer leverage. The friction isnt really strong enough to slow a motor down. I thought you were talking about longevity of a motor. The advantage of a short stroke is the ability to rev higher. Theres volumes of information about this argument.

 

Short stroke, high rpm, less torque.
Long stroke, shorter rpm, more torque.

There's ups and downs with both..... then came the B18C and the problem was solved.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slomofo &raquo;</TD></TR><TR><TD CLASS="quote">Short stroke, high rpm, less torque.
Long stroke, shorter rpm, more torque.

There's ups and downs with both..... then came the B18C and the problem was solved. </TD></TR></TABLE>


unless you add a deck plate w/that stroke and run a long rod.....how many motors
have a 97mm stroke and a r/s of 1.65

harv

https://honda-tech.com/zerothread?id=1282519

 

Short stroke motors rev quicker.

 

both motors would make kinda the same amount of power; its not as much of a difference as you think.
torque production ability will be same; the torque would just shift up or down.
the long stroke will work better with big port heads since it has more ''initial'' vaccume.
short stroke favors high rpm, more dwell helps high rpm cyl. filling.

 

the tq WILL NOT BE THE SAME......the LONG stroke will produce more tq
at lower rpms...as to where the shorter stroke will have to rev higher to make the tq.there is a night and day difference.


harv

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1700anddroping &raquo;</TD></TR><TR><TD CLASS="quote">the tq WILL NOT BE THE SAME......the LONG stroke will produce more tq
at lower rpms...as to where the shorter stroke will have to rev higher to make the tq.there is a night and day difference.


harv</TD></TR></TABLE>

Im meaning this keeping the stroke the same . only change is long vs. short rod.

should of explained myself better.
thought the conversation was more of long rod vs. short rod.
by changing the RS the power band shifts a little. higher up or lower.

of course changing the stroke changes powerband and torque produced.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller &raquo;</TD></TR><TR><TD CLASS="quote">thought the conversation was more of long rod vs. short rod. </TD></TR></TABLE>

It's hard to tell, it's gone back and forth, and stroke and rod have been used interchangably in this thread... They are not neccessarily linked; you can choose whatever you want when designing an engine. Someone should decide on whether we are talking about rods or crank shafts, and we can get something done.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller &raquo;</TD></TR><TR><TD CLASS="quote">

Im meaning this keeping the stroke the same . only change is long vs. short rod.

should of explained myself better.
thought the conversation was more of long rod vs. short rod.
by changing the RS the power band shifts a little. higher up or lower.

of course changing the stroke changes powerband and torque produced.

</TD></TR></TABLE>


yes that is correct...i must of misread it sorry buddy.


harv

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Skinny_REX &raquo;</TD></TR><TR><TD CLASS="quote">Which motor would last longer. The long or the short? Also which motor works harder? </TD></TR></TABLE>

The short stroke would last longer and work less hard. In fact, if you decreased the stroke to 0, the motor would last almost indefinately (and do no work at all).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos &raquo;</TD></TR><TR><TD CLASS="quote">

The short stroke would last longer and work less hard. In fact, if you decreased the stroke to 0, the motor would last almost indefinately (and do no work at all).

</TD></TR></TABLE>

do you work for NASA.......

harv

 

In the automotive industry it is common to use long stroke engines for creating torque, such as diesel engines in 18 wheelers. These motors are well lubricated and they last over a million miles. Short strokes are used for higher rev, quicker motor acceleration and rapid increase of horse power (which is really a derivative of tq) through hig revs. However, if the motor is built well it can also last a very long time. There are so many variables that I would think that it would be hard to say for sure...simply because we are comparing oranges and apples.

 

Your dad is caught up on displacment, yes it makes more power but there is different ways to increase displacment yeilding different outcomes. Your shorter stroke motor is going to make more PEAK horsepower. Your are multiplying RPM to make more power, so the higher the rev (is the flow is there) the more power, until u get catistrophis piston speeds. kinda like when u had ur bicycle in 1rst gear going down a hill and u legs couldnt keep up. The longer stroke will have more piston speed at at lower rpm, but like stated will make more TQ and RAW power. Drag racing. Now the short stroke with a big piston is like what they run in indy cars. like 55mm stroke with 105mm piston or some ****. BUT a shorter stroke motor will last longer because if u have a 77mm stroke in motor A and a 95mm stroke in motor B, and then have the motors at say 5,000RPM....motor B has to travel 18mm more distance every stroke 5000 times per minute. Do the math, it adds up. Thats like 50,000mm or something more distance in the same amount of time. Think about that next time you do 20 5th gear pulls on the highway in an hour. Its late im tired.