ive done a search but frankley im to stupid to quite understand.

I know what bore and stroke is, but what are the advanteges and disadvantages of having a larger bore and a shorter stroke or visa versa to make the same displacement?

Anything would help im just trying to understand a little bit better.

Thanks, Option

 

BORE= There is no replacement for displacement

- Larger bore means larger engine. Means more power to similar smaller engine.
- CONS- To me there really aren't any.


STROKE= Increases displacement as well.
-More low end torque
-CONS- Increased piston speed. Narrower power band.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Option &raquo;</TD></TR><TR><TD CLASS="quote">ive done a search but frankley im to stupid to quite understand.
I know what bore and stroke is, but what are the advanteges and disadvantages of having a larger bore and a shorter stroke or visa versa to make the same displacement?
Anything would help im just trying to understand a little bit better.

Thanks, Option</TD></TR></TABLE>

if you change bore and stroke Volume will change becuz you can't compensate the exact amount of each..

Volume displacement of Engine inline 4 (honda) V= [pie x stroke x bore^2]/4, so total displacement = V x 4

advantage of larger bore = improve volumetric efficeincy of piston and reduces some frictions therefore improve performance power, but too much bore will decrease velocity of air intake, decrease pressure, inside engine lead of restarted compustion and power lose instead of gain.

stroke doesn't really increase displacement (well i does because of its lenght that it travels), stroke is the distance traveled by the piston from zero degrees to 180 degrees is called the stroke, stroke of piston as you will. Now longer-stroke make more torque at lower rpm than higher rpm than shorter stroke ones because, longer strokes travels closer to cylinder pressure with shorter time and has a greater distance from crank and is producing more torque and power. Cylinder pressure remain the same long strokes complete the TDC first and power make faster than shorter strokes with the same cylinder pressure + long stroke. So it kinda opposite with to shorter stroker....the down side of the shorter strokes are you might sacrified some low end power...but since ur bore is bigger that might prevent the lose of low end

well this concept is complicated i might not explain good enough...

but the basically theory is that long-stroke with small bore help high end power, bigger bore shorter stroke give low end power......

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by yeegsr &raquo;</TD></TR><TR><TD CLASS="quote">
but the basically theory is that long-stroke with small bore help high end power, bigger bore shorter stroke give low end power......</TD></TR></TABLE>


please tell me you know you got this backwards.

 

Back to the real world...

There are no consequences to a larger bore, except the possibility of Head Gasket issues if yu go too large.

 

big bore The only bad thing about big bore is that they need big blocks, EX. the b16 is big compare to a d15, the big bore+wide damn engine.

 

Ok so let me ask this. What would putting LS connecting rods and crankshaft with Dart 85mm sleeves and forged 85mm pistons?

What sort of advantages or disadvantages would i get from this?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LsVtec92Hatch &raquo;</TD></TR><TR><TD CLASS="quote">
please tell me you know you got this backwards.</TD></TR></TABLE>

oh jesus god...i explain everything and concluded backward, my bad man...i guess i wrote too much....let me say that again lol...

but the basically theory is that long-stroke help low end power, shorter stroke give high end power.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Suprdave &raquo;</TD></TR><TR><TD CLASS="quote">Back to the real world...
There are no consequences to a larger bore, except the possibility of Head Gasket issues if yu go too large.</TD></TR></TABLE>

who told you that....? headgasket thickness can increase/decrease compression true...but volumetric efficiency does effect hp curve if you dont bore properly on the basic of how much hp you want....big bore need to have big power...or else it wont work.....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by yeegsr &raquo;</TD></TR><TR><TD CLASS="quote">who told you that....? headgasket thickness can increase/decrease compression true...but volumetric efficiency does effect hp curve if you dont bore properly on the basic of how much hp you want....big bore need to have big power...or else it wont work.....</TD></TR></TABLE>

Big bore needs to have big what?????

Are you quoting out of one of those honda performance books you can pick up at your local Borders/ Barnes and Noble again?

Big bore does not need anything to be effective. It is already more effective because it is bigger, regardless of compresion ratio. As I said earlier there really are no drawbacks to a big bore.
Superdave is saying with a large bore, like say 86+ mm it is challenging to get the head gasket to seal on such a small amount of cylinder surface area.

 

An easy way to see the diference between bore and stroke on a powerband, compare a S2000 block (89mm bore vs 84mm stroke -high end power) dyno graph with a CRV B20 block (84mm bore vs 89mm stroke- low end torque) and keep in mind what were they built for.

 

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

Are you quoting out of one of those honda performance books you can pick up at your local Borders/ Barnes and Noble again?

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

Busted.

 

The only real disadvantage to a larger bore is that detonation resistance starts to decrease as the distance the flame has to travel increases. But in all honesty, if we are talking about a typical B-series powerplant, you will probably run out of room for a larger bore before this becomes a concern.

 

Yeah, I think 86mm is the unofficial max.
&lt;who's going 85mm

 

what about stroking the motor ??? if you stroke a 2.0 (84 mm) b18c1 sleeved block with an ls crank and rods (aftermarket) then wont you runinto problems with reving the motor higher ?? ( at like 9k rpms of the like)

i ask because im looking at a 2.0 gsr block sleeved and i wanna get the most power out of my daily driver by using an a bigger mm crank and aftermarket rods

 

A longer stroke (with everything else being identical) will shift the powerband down. And if you dont get cams that make power up high, its useless to rev that high anyway.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by asubennett &raquo;</TD></TR><TR><TD CLASS="quote">
Big bore needs to have big what?????
Are you quoting out of one of those honda performance books you can pick up at your local Borders/ Barnes and Noble again?
Big bore does not need anything to be effective. It is already more effective because it is bigger, regardless of compresion ratio. As I said earlier there really are no drawbacks to a big bore.
Superdave is saying with a large bore, like say 86+ mm it is challenging to get the head gasket to seal on such a small amount of cylinder surface area. </TD></TR></TABLE>

wether from reading or not...eorodynamic is the basic knowledge to engine...therefore eorodynamic also work with internal engine...your body is eorodynamic too...your nose is ur intake...big nose breath better but too big and breath in too much does help...because you ended up with some o2 coming out and CO2 anyway

if you bored out ur throat to make it bigger with bigger nose true you will get more air in but you will need a bigg lung and diaphram to store and convert.....air and power is and fuel have ratios ......same as hp vs tq..they same a certain ratios cant not have too much...

and no it not from all the reading i did...it mostly from car mechanical engineer i been studying...i like car stuffs so i going with car major in machanical engineering

well to me and this is me...i think air and fuel will make certain power out of certain compression...over volume of each result in interferance and volumetric disturbance this results in losing hp over all range...you dotn think it makes sense?

lol peace...this is discussion so dont get mad or anything...

 

oh talking about those honda book...sometime i think theyre misleading sometime...not information to a productive explaination...

and those dyno results too....yet dyno is more or less very accuate to determine hp & tq curve but upgrading stuffs from before effect on the upgrade later you do...and if you dyno the stuffs you upgrade later with the stuffs you upgrade before then the result tend to be more aggressive

just liek dyno an intake with stock engine and resutl of increased in 4hp &2tq,,, the same intake with the same engine but now it has camsshaft. If you dyno the cams with stock intake gain is 13hp's, then dyno again with intake and see the gain is another 5, now u got 13 + 5, notice the result before with stock is 4, later is 5..., in the dyno book they didn't say that the engine has cams already...or other stuffs..so that kindda misleading power

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LsVtec92Hatch &raquo;</TD></TR><TR><TD CLASS="quote">A longer stroke (with everything else being identical) will shift the powerband down. And if you dont get cams that make power up high, its useless to rev that high anyway.</TD></TR></TABLE>

i have skunk2 stage2

 

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

wether from reading or not...eorodynamic is the basic knowledge to engine...therefore eorodynamic also work with internal engine...your body is eorodynamic too...your nose is ur intake...big nose breath better but too big and breath in too much does help...because you ended up with some o2 coming out and CO2 anyway

if you bored out ur throat to make it bigger with bigger nose true you will get more air in but you will need a bigg lung and diaphram to store and convert.....air and power is and fuel have ratios ......same as hp vs tq..they same a certain ratios cant not have too much...

and no it not from all the reading i did...it mostly from car mechanical engineer i been studying...i like car stuffs so i going with car major in machanical engineering

well to me and this is me...i think air and fuel will make certain power out of certain compression...over volume of each result in interferance and volumetric disturbance this results in losing hp over all range...you dotn think it makes sense?

lol peace...this is discussion so dont get mad or anything...</TD></TR></TABLE>

????? I lost that link to universal translator.... ????? I think you got volumetric right... the spelling, I mean.

 

Seriously.

This guys analogy is way off to. He compared boring out the engine to boring out your throat and nose, where, if you did want to make that kind of comparison, it would have to be said that boring your cylinders is like boring your lungs. Make the intake pathway flow better would be like boring your nose and throat. Still, thats a completely assinine comparison.

Big bore, short stroke. Thats the way to go.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rjay8604 &raquo;</TD></TR><TR><TD CLASS="quote">Yeah, I think 86mm is the unofficial max.
&lt;who's going 85mm</TD></TR></TABLE>

you're WAY off

 

YOu can take a sleeved B series out to 87mm max. 86mm is my personal max. I am currently running 85mm.

YEEGSR:

I am not mad at you. I just don't understand you at all. Perhaps there is a language barrier preventing your english from coming across in a way I can understand it? If that is the case, then I apologize for all previous comments.

If English is your first language than man, I think engineering school is a far reach.

 

you can go over 87mm

for the street...86mm is safe for the most part, wiht a good tuner (n/a obvioulsy)

 

Im in engine class right now so this is what i got from it. You have a formula to calculate voume displacement. VD=Bore^2(stroke).7854*Cylinders. So for instance, we have a 4 inch bore, 3 inch stroke, 8 cylinders. You end up with 301.6 or 302. So bore the engine .030, pretty standard. We end up with 306.13 CI. Instead of boring, we increase the stroke by a quarter of an inch to 3.25 and end up with 326.7 or 327. Stroking offers a better advantage, but like people say, stroking a motor does have its downsides. You have more force on the cylinder walls and revving as high as we do, it can cause a few problems. I am looking at the LS stroking kit on here, and it lowers the weight of the pistons and rods i believe, so it helps us rev a lil better. Boring +stroking seems to be nice, but I don't know too much about all of this, just letting you in on what I know. Hope that helps.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NAstreetEH2 &raquo;</TD></TR><TR><TD CLASS="quote">

you're WAY off </TD></TR></TABLE>
Well, I'd say 86mm is the max for a mechanically sound street engine.