This is a general engine question, but definitely applicable to the DS. How does bore/stroke factor into engine design?

To clarify... if an engine has a long stroke, would it rev faster or slower then a shorter stroke motor? Same question but regarding bore, if an engine has a bigger bore, would it rev faster or slower then a smaller bore motor?

I know there are alot of factors that dictate the torque/HP of an engine. If overall displacement was kept the same, how would the following two motors compare when looking at torque/HP? Would one have more hp and the other more torque? Which one would be faster revving?
1. small bore - long stroke
2. large bore - short stroke

I have heard of terms such as square engine, I believe when stroke is equal to bore. What other terms are there?

 

Longer stroke = more torque = slower revving. This is for engines with the same displacement.

"Over-square" means bore is bigger than stroke.

That's about all I know.

 

It is my belief that a Stroker will always out perform a big bore. Being that you accomplish the same size in the end. I believe that gaining CC's buy sroking is a more efficient way of producing HP/TORQUE. JMO.

Example: If you bore the DS to 700cc you will gain HP and torque, but the "Power curve" will resemble a stock engine on the dyno.
Example2: if you stroke a DS up to 700cc you will gain HP and Torque, but the "power curve" will be alot longer and flater,and will allow you to pull longer. Thus resulting in a faster QUAD. PLUS you wont have to worry about head gaskets holding up.


JMO


Bigger.

 

rod ratio plays a big part in how an engine revs. if you have an engine with a crappy rod to stroke ratio it is not going to like to rev, and generally it would make more torque then horsepower. If you have an engine with a good rod to stroke ratio it will like to rev higher and generally make more horsepower then torque, and do i say "generally" it is not always the same in every case. i like big bore motors with a short stroke and the longest rod possible so it will rev good, other people may like a longer stroke to make more torque. displacment plays a big part in the motor will make , horsepower or torque, as cams and heads do also. So to answer your question about the 2 motors you have provided. small bore - long stroke = more torque, large bore -short stroke = more horsepower, and i use the word generally. Hope that kind of helps..

 

what about being bigger bore and being stroked.....how could u make that rev quickly?

 

By using a long rod, the better the rod to stroke ratio the better it will rev.[img]i/expressions/face-icon-small-smile.gif[/img]

 

LMAO!!!!

 

just remember to keep the stroke to rod ratio right and you shouldn't get hurt

 

Why does rod length matter? Wouldn't the length of the stoke be the same with a short rod or long rod?

 

On a stroker with long rod & shorter pin piston location has less friction than & stroker with short rod & longer pin location has more fiction I think is the diffrence & the amount of time time piston stays @ TDC. I can't remember everything that I learned 15yrs ago. I'm sure some one will correct my info. I tried. LOL