Gentlemen, which is more important - Bore or Stroke?

[hobbit.]

ok, so a two stroke goes faster than a four stroke, but what about bore? a big bore with a shorter stroke or a small bore quick repeating stroke?

should none males who suffer a stroke be shot or drowned?

 

[John Doe]

[Insert pun on Wankel engine here]

 

[butters]

*puts on gauntlets and strokes hobbit*

 

[Saint Peter]

A big bore allows the use of big valves.

Big valves = better flow.



Just don't be a pussy about it.

 

[bronzeage]

A big bore allows the use of big valves.

Big valves = better flow.



Just don't be a pussy about it.

Not as critical as it once was. Four valve systems and variable cam timing allow better low end flow without sacrificing high end, or the loss due to the excess overlap. When this is combined with roller lifters and a steeper ramp, big valves just aren't the solution.

 

[Saint Peter]

Not as critical as it once was. Four valve systems and variable cam timing allow better low end flow without sacrificing high end, or the loss due to the excess overlap. When this is combined with roller lifters and a steeper ramp, big valves just aren't the solution.

I am old school.

I am also grumpy.

 

[Squibbs]

ok, so a two stroke goes faster than a four stroke, but what about bore? a big bore with a shorter stroke or a small bore quick repeating stroke?

should none males who suffer a stroke be shot or drowned?

My four stroke can blow most 2 strokes away.

Especially on hills.

 

[parodyluvr75]

*puts on gauntlets and strokes hobbit*

*puts on sandpaper gloves and helps*

 

[gearhead73]

Bore and stroke are both important, as the old saying goes, there is no replacement for displacement.
Advancements like using multiple valves and variable cam timing have increased fuel economy without sacrificing power, but when they make the transition to solenoid valves, everything will change. Allowing an unlimited range of lift and duration based upon engine demand will change the way people 'tune' their cars.
Just my $.02.

 

[imalickin]

Back in the day...

Stroke was increased along with bore. The further you could bore an engine out the more power could be extracted. And it was all about air flow. That's why the first thing you did was port and polish your heads. then you bought headers, replace the stock ones. then you increased the size of the carb you were wearing and replace the intake manifold with one that had straighter through put. then you put in a hotter cam.

Or...

You went out an bought a crate motor. Why go though all that above when they are ready on an instants notice, "hot outa the box" so to speak.

 

[Wat_Tyler]

It's always about breathing. It's never not about breathing, and don't believe the misinformed who say things aren't as crucial as once were. That's a bit like saying that the wheel is less important for rolling along.


Big bores allow for the use of bigger valves. In some cases, valve size relationships can be changed based on cam events and potential RPM of the engine.


Piston speed is the limiting factor in RPM potential, and an engine with a larger bore and shorter stroke (oversquare) has the ability to keep piston speed lower than a square or undersquare engine.


All this shit works together, or against itself, and changing one variable can have a couple of different effects.

 

[M. Jordan]

The relationship between bore and stroke is hugely important but, with the new turbos coming out, a smaller displacement can be vastly augmented with turbos. So, even if you have a little piston it can be a big performer.

 

[Wat_Tyler]

Some of the hot new engines are undersquare.

 

[John Doe]

Or you could just use a Wankel. Then you have no valves or stroke at all to think about. Not even a crankshaft. Fewer moving parts in general so it's more reliable. Much smaller for the same power output compared to a reciprocating system and smooth at high-rpm. There are trade-offs though, such as a more complex seal system.

And as we all know, keeping a good seal is very important when you're Wankeling.

HA! There's my pun.

 

[colddiesel]

Alternatively, for heavy work you could go for a two stroke diesel - with a Roots blower.

 

[hobbit.]

*puts on gauntlets and strokes hobbit*

Awesome action there wench

*puts on sandpaper gloves and helps*

are you sure those are gloves?

Alternatively, for heavy work you could go for a two stroke diesel - with a Roots blower.

Steam is good!!!

 

[parodyluvr75]

Yes, the latest in fashion.

 

[BotanyBoy]

My four stroke can blow most 2 strokes away.

Especially on hills.

My no stroke blows most 4 strokes away....M3's and ZO6's are my favorite prey to toy with on the highway. The look on some rich kid or old man's face when you pull away and spit fire balls across their hood never get's old. ESPECIALLY if they have a hot woman with them....that's the ultimate.

It's like having a fast civic but not nearly as ricer....no one ever expects it.

[Insert pun on Wankel engine here]

 

[about_average]

Neither is more important. The bore to stroke ratio is what's important and where you want your power band vs engine speed.

 

[hobbit.]

Yes, the latest in fashion.

poppycock.

 

[parodyluvr75]

poppycock.

Would I lie to you?

 

[hobbit.]

Would I lie to you?

yes. but I would be able to tell when you were lying and thereby take appropriate steps.