stroke: does more make the engine weaker?
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From: Houston, TX, USA
stroke: does more make the engine weaker?
it would be common sense that increased stroke would make an engine weaker, but maybe it doesnt apply here. that would basically make the b16 the strongest b series if this was true.
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From: tallafizzy, FL state
Re: stroke: does more make the engine weaker? (JimBlake)
all things being equal, giving an engine more stroke it would make the RS ratio worse and would make the engine not as rev happy....but that's not that important anyways..
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From: Greetings From Asbury Park,, NJ
Re: stroke: does more make the engine weaker? (ragerized)
If I recall correctly a long stroke engine is called "undersquare". And all other things being equal, will produce more torque than a more "square" engine of the same displacement. Check the differences in torque output say between a D and a B engine. Most Detroit V-8's are notoriously "undersquare" and look at the huge torque nubers they produce. No one says V-8's are inherently "weaker" , beacuse of their rod- stroke ratio do they?
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From: tallafizzy, FL state
Re: stroke: does more make the engine weaker? (4crx4me)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4crx4me »</TD></TR><TR><TD CLASS="quote">If I recall correctly a long stroke engine is called "undersquare". And all other things being equal, will produce more torque than a more "square" engine of the same displacement. Check the differences in torque output say between a D and a B engine. Most Detroit V-8's are notoriously "undersquare" and look at the huge torque nubers they produce. No one says V-8's are inherently "weaker" , beacuse of their rod- stroke ratio do they?</TD></TR></TABLE>
undersquare engines will make more torque at a lower rpm....since they cant breathe good at a higher rpm.With shorter rods, the piston will accelerate out of TDC faster than a ''long rod'', thus improving low rpms efficiency; but not good for high rpm
and as i sayd all things being equal in a HONDA engine, taking a b16 for example; you stroke a b16 to lets say 89mm and it will not be as reliable in high rpms as a stock 77mm, keeping in mind im saying if you for the longer stroke you use a shorter rod, simple. the RS ratio will be worse, putting more side loads on the cyl. walls.
And as you say, in one perpective iron V8 is weaker; try reving one of those puppies to 9k rpms, even if the valvetrain allowed so, the block would not last
but then again rs ratio is not all that important..
undersquare engines will make more torque at a lower rpm....since they cant breathe good at a higher rpm.With shorter rods, the piston will accelerate out of TDC faster than a ''long rod'', thus improving low rpms efficiency; but not good for high rpm
and as i sayd all things being equal in a HONDA engine, taking a b16 for example; you stroke a b16 to lets say 89mm and it will not be as reliable in high rpms as a stock 77mm, keeping in mind im saying if you for the longer stroke you use a shorter rod, simple. the RS ratio will be worse, putting more side loads on the cyl. walls.
And as you say, in one perpective iron V8 is weaker; try reving one of those puppies to 9k rpms, even if the valvetrain allowed so, the block would not last
but then again rs ratio is not all that important..
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From: Greetings From Asbury Park,, NJ
Re: stroke: does more make the engine weaker? (mmuller)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller »</TD></TR><TR><TD CLASS="quote">
undersquare engines will make more torque at a lower rpm....since they cant breathe good at a higher rpm.With shorter rods, the piston will accelerate out of TDC faster than a ''long rod'', thus improving low rpms efficiency; but not good for high rpm
and as i sayd all things being equal in a HONDA engine, taking a b16 for example; you stroke a b16 to lets say 89mm and it will not be as reliable in high rpms as a stock 77mm, keeping in mind im saying if you for the longer stroke you use a shorter rod, simple. the RS ratio will be worse, putting more side loads on the cyl. walls.
And as you say, in one perpective iron V8 is weaker; try reving one of those puppies to 9k rpms, even if the valvetrain allowed so, the block would not last
but then again rs ratio is not all that important..</TD></TR></TABLE>
Weaker would be relative term, HERE.
I would not say a Detroit V-8 is weaker than a Honda B16. IF the V-8 is used within it's rev limit. At what point would you NEED to rev a V8 to 9k, anyway?
You can use an undersquare V8 to pull a tree stump (with the correct tranny, of course). At 3K-4K. But you could NEVER get enough torque out of a B16 to pull around more than a 150lb. passenger or two in the backseat, IF you are lucky, no matter how high it can rev or how reliable at high rpm it is. That all I was trying to say.
And as you said rod-stroke ratio ain't all it's cracked up to be.
undersquare engines will make more torque at a lower rpm....since they cant breathe good at a higher rpm.With shorter rods, the piston will accelerate out of TDC faster than a ''long rod'', thus improving low rpms efficiency; but not good for high rpm
and as i sayd all things being equal in a HONDA engine, taking a b16 for example; you stroke a b16 to lets say 89mm and it will not be as reliable in high rpms as a stock 77mm, keeping in mind im saying if you for the longer stroke you use a shorter rod, simple. the RS ratio will be worse, putting more side loads on the cyl. walls.
And as you say, in one perpective iron V8 is weaker; try reving one of those puppies to 9k rpms, even if the valvetrain allowed so, the block would not last
but then again rs ratio is not all that important..</TD></TR></TABLE>
Weaker would be relative term, HERE.
I would not say a Detroit V-8 is weaker than a Honda B16. IF the V-8 is used within it's rev limit. At what point would you NEED to rev a V8 to 9k, anyway?
You can use an undersquare V8 to pull a tree stump (with the correct tranny, of course). At 3K-4K. But you could NEVER get enough torque out of a B16 to pull around more than a 150lb. passenger or two in the backseat, IF you are lucky, no matter how high it can rev or how reliable at high rpm it is. That all I was trying to say.
And as you said rod-stroke ratio ain't all it's cracked up to be.
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From: Greetings From Asbury Park,, NJ
Re: stroke: does more make the engine weaker? (4crx4me)
Someone should define "weaker".
Diesels by their design are long stroke-undersquare engines because they need the long stroke to force spontaneous combustion from compression alone.
And I don't think anyone would call a diesel "weaker" in the power to pul department. But then you might say diesels can't rev past 5 or 6K so, therefore they ARE weaker than a B16 because IT can rev to 9K.
Diesels by their design are long stroke-undersquare engines because they need the long stroke to force spontaneous combustion from compression alone.
And I don't think anyone would call a diesel "weaker" in the power to pul department. But then you might say diesels can't rev past 5 or 6K so, therefore they ARE weaker than a B16 because IT can rev to 9K.
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From: tallafizzy, FL state
Re: stroke: does more make the engine weaker? (4crx4me)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4crx4me »</TD></TR><TR><TD CLASS="quote">Someone should define "weaker".
Diesels by their design are long stroke-undersquare engines because they need the long stroke to force spontaneous combustion from compression alone.
And I don't think anyone would call a diesel "weaker" in the power to pul department. But then you might say diesels can't rev past 5 or 6K so, therefore they ARE weaker than a B16 because IT can rev to 9K.</TD></TR></TABLE>
you dont get what im saying..you are comparing apples to oranges
Diesels by their design are long stroke-undersquare engines because they need the long stroke to force spontaneous combustion from compression alone.
And I don't think anyone would call a diesel "weaker" in the power to pul department. But then you might say diesels can't rev past 5 or 6K so, therefore they ARE weaker than a B16 because IT can rev to 9K.</TD></TR></TABLE>
you dont get what im saying..you are comparing apples to oranges
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From: Greetings From Asbury Park,, NJ
Re: stroke: does more make the engine weaker? (mmuller)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller »</TD></TR><TR><TD CLASS="quote">
you dont get what im saying..you are comparing apples to oranges</TD></TR></TABLE>
I guess, I don't. I thought YOU were the one comparing apples and oranges, though.
But, I'm willing to learn, though. Imagine I'm retarded.
What are you trying say?
All I'm saying is...."all else being equal, a longer stroke MIGHT be a waekness at 9K, compared to a shorter stroke, but the point is moot, because a long stroke engine can't rev to 9K. Due to limits placed on it by virtue of it's longer stroke"
Cause in the REAL world, 99.9% of all engines built don't spend too much time at 9K, even IF they could.( excluding F1's 19K-20K's, perhaps)
"One man's weakness might be another man's strength" So to speak.
Sorry if this sounds condescending, I don't mean to be.
I really would like to know why I seem to be missing your point.
Modified by 4crx4me at 1:38 PM 5/19/2004
you dont get what im saying..you are comparing apples to oranges</TD></TR></TABLE>
I guess, I don't. I thought YOU were the one comparing apples and oranges, though.
But, I'm willing to learn, though. Imagine I'm retarded.
What are you trying say?
All I'm saying is...."all else being equal, a longer stroke MIGHT be a waekness at 9K, compared to a shorter stroke, but the point is moot, because a long stroke engine can't rev to 9K. Due to limits placed on it by virtue of it's longer stroke"
Cause in the REAL world, 99.9% of all engines built don't spend too much time at 9K, even IF they could.( excluding F1's 19K-20K's, perhaps)
"One man's weakness might be another man's strength" So to speak.
Sorry if this sounds condescending, I don't mean to be.
I really would like to know why I seem to be missing your point.
Modified by 4crx4me at 1:38 PM 5/19/2004
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From: Greetings From Asbury Park,, NJ
Re: stroke: does more make the engine weaker? (ragerized)
From a wesite of automotive terms, I found on google:
Turbocharger--Device that compresses air for forced induction, much like a supercharger, but instead of relaying on power from the crankshaft, it runs off the pressure of exhaust gases. While turbochargers are far more efficient than superchargers in that they have less parasitic drain, their operation and mechanics is less straight-forward than with supercharging. Turbocharging was very popular in the 80s, but is relatively uncommon today, even in ultra-expensive exoticars. The extremely fast Porsche 911 Turbo is one of the few exceptions. One problem of turbocharging is that it requires a substantial volume of exhaust gases to generate boost. This either has to come from a larger motor, such as a V-8, or a smaller motor operating at high RPMs. The need for high RPMs leads to turbo lag, and a generally unsatisfactory solution for street driving. While turbocharging is a very impressive technology that will likely regain its popularity at some point, a real awareness of its strengths and weaknesses are in order. While it far surpasses most other methods in obtaining optimal horsepower from a motor, it won't give a 4 cylinder engine the torque characteristics of an 8 cylinder
Turbocharger--Device that compresses air for forced induction, much like a supercharger, but instead of relaying on power from the crankshaft, it runs off the pressure of exhaust gases. While turbochargers are far more efficient than superchargers in that they have less parasitic drain, their operation and mechanics is less straight-forward than with supercharging. Turbocharging was very popular in the 80s, but is relatively uncommon today, even in ultra-expensive exoticars. The extremely fast Porsche 911 Turbo is one of the few exceptions. One problem of turbocharging is that it requires a substantial volume of exhaust gases to generate boost. This either has to come from a larger motor, such as a V-8, or a smaller motor operating at high RPMs. The need for high RPMs leads to turbo lag, and a generally unsatisfactory solution for street driving. While turbocharging is a very impressive technology that will likely regain its popularity at some point, a real awareness of its strengths and weaknesses are in order. While it far surpasses most other methods in obtaining optimal horsepower from a motor, it won't give a 4 cylinder engine the torque characteristics of an 8 cylinder
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From: Greetings From Asbury Park,, NJ
Re: stroke: does more make the engine weaker? (ragerized)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ragerized »</TD></TR><TR><TD CLASS="quote">
</TD></TR></TABLE>
And your point IS?
</TD></TR></TABLE>And your point IS?
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Re: stroke: does more make the engine weaker? (4crx4me)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4crx4me »</TD></TR><TR><TD CLASS="quote">From a wesite of automotive terms, I found on google:
Turbocharger--Device that compresses air for forced induction, much like a supercharger, but instead of relaying on power from the crankshaft, it runs off the pressure of exhaust gases. While turbochargers are far more efficient than superchargers in that they have less parasitic drain, their operation and mechanics is less straight-forward than with supercharging. Turbocharging was very popular in the 80s, but is relatively uncommon today, even in ultra-expensive exoticars. The extremely fast Porsche 911 Turbo is one of the few exceptions. One problem of turbocharging is that it requires a substantial volume of exhaust gases to generate boost. This either has to come from a larger motor, such as a V-8, or a smaller motor operating at high RPMs. The need for high RPMs leads to turbo lag, and a generally unsatisfactory solution for street driving. While turbocharging is a very impressive technology that will likely regain its popularity at some point, a real awareness of its strengths and weaknesses are in order. While it far surpasses most other methods in obtaining optimal horsepower from a motor, it won't give a 4 cylinder engine the torque characteristics of an 8 cylinder
</TD></TR></TABLE>
That goes for the whole b16a turbo pulling out a tree stump think.
Turbocharger--Device that compresses air for forced induction, much like a supercharger, but instead of relaying on power from the crankshaft, it runs off the pressure of exhaust gases. While turbochargers are far more efficient than superchargers in that they have less parasitic drain, their operation and mechanics is less straight-forward than with supercharging. Turbocharging was very popular in the 80s, but is relatively uncommon today, even in ultra-expensive exoticars. The extremely fast Porsche 911 Turbo is one of the few exceptions. One problem of turbocharging is that it requires a substantial volume of exhaust gases to generate boost. This either has to come from a larger motor, such as a V-8, or a smaller motor operating at high RPMs. The need for high RPMs leads to turbo lag, and a generally unsatisfactory solution for street driving. While turbocharging is a very impressive technology that will likely regain its popularity at some point, a real awareness of its strengths and weaknesses are in order. While it far surpasses most other methods in obtaining optimal horsepower from a motor, it won't give a 4 cylinder engine the torque characteristics of an 8 cylinder
</TD></TR></TABLE>
That goes for the whole b16a turbo pulling out a tree stump think.
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Re: stroke: does more make the engine weaker? (4crx4me)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4crx4me »</TD></TR><TR><TD CLASS="quote">... it won't give a 4 cylinder engine the torque characteristics of an 8 cylinder</TD></TR></TABLE>What about a 4-cyl vs an 8-cyl when they're both the same displacement?? Way up on top mmuller said something about 'all things being equal'. Well, it's really hard for EVERYTHING to be equal. But I gotta think that when you're comparing Honda 4's against a V-8, it's probably all about displacement. I bet a square (bore=stroke) inline 4 with 5.7 liters of displacement would pull stumps.
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From: Greetings From Asbury Park,, NJ
Re: stroke: does more make the engine weaker? (JimBlake)
I was not trying to compare honda 4's against detroit V8's!!!!! 
Like mmueller said..... apples and oranges.
I WAS using them as EXAMPLES.
I WAS trying to SHOW people, that their simple "theories" are WRONG!!!!
Physics and mechanical laws aren't CHANGED by how WE PERCIEVE things.
Longer strokesDO NOT= WEAKER engines
Higher redilinesDO NOT= STRONGER engines.
Higher redlines DO NOT = MORE TORQUE
Turboe'd 4's do = other turboe'd 4's
Turboed 4'sDO NOT= N/A V8's
There ARE more important considerations when building an engine than if "it's R/S ratio is perfect!!!" Who cares!!!! it's just one of many perameters USED.
Engines are designed the way they are to accomplish design goals, and how the engine is designed and made has alot to with how they perform and if they perform well.
Which again "performance" is relative. And NOT ALWAYS THE ULTIMATE GOAL.
Engine designing/building is a compromise of many different factors.
Any ONE, none more important than any other, see my point yet?
Have I clarified myself?
Like mmueller said..... apples and oranges.
I WAS using them as EXAMPLES.
I WAS trying to SHOW people, that their simple "theories" are WRONG!!!!
Physics and mechanical laws aren't CHANGED by how WE PERCIEVE things.
Longer strokesDO NOT= WEAKER engines
Higher redilinesDO NOT= STRONGER engines.
Higher redlines DO NOT = MORE TORQUE
Turboe'd 4's do = other turboe'd 4's
Turboed 4'sDO NOT= N/A V8's
There ARE more important considerations when building an engine than if "it's R/S ratio is perfect!!!" Who cares!!!! it's just one of many perameters USED.
Engines are designed the way they are to accomplish design goals, and how the engine is designed and made has alot to with how they perform and if they perform well.
Which again "performance" is relative. And NOT ALWAYS THE ULTIMATE GOAL.
Engine designing/building is a compromise of many different factors.
Any ONE, none more important than any other, see my point yet?
Have I clarified myself?
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Re: stroke: does more make the engine weaker? (4crx4me)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4crx4me »</TD></TR><TR><TD CLASS="quote">I was not trying to compare honda 4's against detroit V8's!!!!!
Like mmueller said..... apples and oranges.
I WAS using them as EXAMPLES.</TD></TR></TABLE>Exactly. I didn't really mean to argue against you or anyone in particular. I was just throwing out another comment.
I thought I saw your point, along with the others. I don't think anyone's WRONG, exactly, but everyone's looking at it a different way. What I really want to say is that it's nearly impossible to change something & have everything else the same.
Take the same bore, same head, same camshafts, with a longer stroke. You've made the displacement bigger, and THAT gives you more torque. But the piston speeds are now higher, so it probably has to have a lower redline. Then you'd really want to use a different cam to take advantage of the longer stroke. But now you've changed several things.
Take the same displacement, the same bore/stroke ratio, but compare 4cyl vs. 8cyl engines. Now you've got much shorter stroke, lower piston speeds, so the tiny V-8 can probably have a higher redline. Also, shorter distance between valves & BDC so cam timing is less influenced by speed-of-sound. So you wouldn't want to use the same cam profile here either.
If you look at first-order effects only, & pretend there's no differences in cam profiles or any of that stuff, torque depends on displacement & cylinder pressure ONLY. Bore & stroke cancel out, number of cylinders cancels out, everything else cancels out. Do the math...
In real life you can't ignore 2nd & 3rd order effects like breathing, cylinder/ring friction, all that other stuff. And THAT'S what makes different engines -um- different from each other.
Like mmueller said..... apples and oranges.
I WAS using them as EXAMPLES.</TD></TR></TABLE>Exactly. I didn't really mean to argue against you or anyone in particular. I was just throwing out another comment.
I thought I saw your point, along with the others. I don't think anyone's WRONG, exactly, but everyone's looking at it a different way. What I really want to say is that it's nearly impossible to change something & have everything else the same.
Take the same bore, same head, same camshafts, with a longer stroke. You've made the displacement bigger, and THAT gives you more torque. But the piston speeds are now higher, so it probably has to have a lower redline. Then you'd really want to use a different cam to take advantage of the longer stroke. But now you've changed several things.
Take the same displacement, the same bore/stroke ratio, but compare 4cyl vs. 8cyl engines. Now you've got much shorter stroke, lower piston speeds, so the tiny V-8 can probably have a higher redline. Also, shorter distance between valves & BDC so cam timing is less influenced by speed-of-sound. So you wouldn't want to use the same cam profile here either.
If you look at first-order effects only, & pretend there's no differences in cam profiles or any of that stuff, torque depends on displacement & cylinder pressure ONLY. Bore & stroke cancel out, number of cylinders cancels out, everything else cancels out. Do the math...
In real life you can't ignore 2nd & 3rd order effects like breathing, cylinder/ring friction, all that other stuff. And THAT'S what makes different engines -um- different from each other.
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From: henderson, nv, usa
Re: stroke: does more make the engine weaker? (4crx4me)
stroke makes an engine weaker, meaning it cant handle high rpm's.
detroit v8's are NOT Undersquare, they are in fact, Oversquare, as most engines were after world war II.
Chevy 350 for example has a 4" bore, 3.48" stroke, and r/s of 1.74:1.
diesels have long strokes so the turbocharger can cram more air/fuel into the engine. diesels are NOT comparable to gasoline engines. Diesels dont have pistons, they have slugs, which have a point as near center in the combustion area as possible to create the most centered detonation point possible, allowing for the most complete burn of the air/fuel mixture.
"There ARE more important considerations when building an engine than if 'it's R/S ratio is perfect!!!'"
assumptions are a pain in my ***. the main goal of I4 builders is to achieve higher thermal and mechanical efficiency. an engine with a r/s closer to perfect would immediately gain mechanical efficiency.
detroit v8's are NOT Undersquare, they are in fact, Oversquare, as most engines were after world war II.
Chevy 350 for example has a 4" bore, 3.48" stroke, and r/s of 1.74:1.
diesels have long strokes so the turbocharger can cram more air/fuel into the engine. diesels are NOT comparable to gasoline engines. Diesels dont have pistons, they have slugs, which have a point as near center in the combustion area as possible to create the most centered detonation point possible, allowing for the most complete burn of the air/fuel mixture.
"There ARE more important considerations when building an engine than if 'it's R/S ratio is perfect!!!'"
assumptions are a pain in my ***. the main goal of I4 builders is to achieve higher thermal and mechanical efficiency. an engine with a r/s closer to perfect would immediately gain mechanical efficiency.
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From: Greetings From Asbury Park,, NJ
Re: stroke: does more make the engine weaker? (RABHonda)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RABHonda »</TD></TR><TR><TD CLASS="quote">stroke makes an engine weaker, meaning it cant handle high rpm's.
detroit v8's are NOT Undersquare, they are in fact, Oversquare, as most engines were after world war II.
Chevy 350 for example has a 4" bore, 3.48" stroke, and r/s of 1.74:1.
diesels have long strokes so the turbocharger can cram more air/fuel into the engine. diesels are NOT comparable to gasoline engines. Diesels dont have pistons, they have slugs, which have a point as near center in the combustion area as possible to create the most centered detonation point possible, allowing for the most complete burn of the air/fuel mixture.
"There ARE more important considerations when building an engine than if 'it's R/S ratio is perfect!!!'"
assumptions are a pain in my ***. the main goal of I4 builders is to achieve higher thermal and mechanical efficiency. an engine with a r/s closer to perfect would immediately gain mechanical efficiency.</TD></TR></TABLE>
Ok I'll continue this theoretical diatribe.
Long strokes DO NOT make an engine weaker, you are entitled to your wrong opinion. It does make it less effecient at high rpm, though. Higher revs do not make an engine stronger, as revs rise volumetric effeciency declines. Hence the need for turbos.
The Chevy 350 was an evolution it didn't start life as a 350.
And I'm sure when the GM designers built the 265 they said... "oh ****. look at the rod ratio. Better change that...... and they did,.......... 13-14 years later......
Diesels HAVE pistons! Youre "assumption" is to CALL them 'slugs'.... but they are pistons just them same.
Not ALL diesels have turbos, AND/OR superchargers OR BOTH!!!! (Detroit Diesel, FYI, ...BTW)
And turbo chargings not the reason for the long stroke.
Diesels had long strokes long before turbos were invented.
Turbos DO make diesels more effecient, though.
Diesels ARE comparable to gas engines in "an internal combustion kind of way"
And there isn't a gas engine of equal displacement on the planet that will equal the torque output of a diesel by vritue of it's longer stroke. ( yes, amongst many other reasons.)
And YOU make the assumption that YOU KNOW what engine designers goals are, as if designing an engine is a theoretical college project.
I don't think the ULTIMATE goal of an engine is "mechanical and thermal effeciency"
The goals are more concrete than theoretical.
Engines must do "work" in the "real world", not in an engineers head.
detroit v8's are NOT Undersquare, they are in fact, Oversquare, as most engines were after world war II.
Chevy 350 for example has a 4" bore, 3.48" stroke, and r/s of 1.74:1.
diesels have long strokes so the turbocharger can cram more air/fuel into the engine. diesels are NOT comparable to gasoline engines. Diesels dont have pistons, they have slugs, which have a point as near center in the combustion area as possible to create the most centered detonation point possible, allowing for the most complete burn of the air/fuel mixture.
"There ARE more important considerations when building an engine than if 'it's R/S ratio is perfect!!!'"
assumptions are a pain in my ***. the main goal of I4 builders is to achieve higher thermal and mechanical efficiency. an engine with a r/s closer to perfect would immediately gain mechanical efficiency.</TD></TR></TABLE>
Ok I'll continue this theoretical diatribe.
Long strokes DO NOT make an engine weaker, you are entitled to your wrong opinion. It does make it less effecient at high rpm, though. Higher revs do not make an engine stronger, as revs rise volumetric effeciency declines. Hence the need for turbos.
The Chevy 350 was an evolution it didn't start life as a 350.
And I'm sure when the GM designers built the 265 they said... "oh ****. look at the rod ratio. Better change that...... and they did,.......... 13-14 years later......
Diesels HAVE pistons! Youre "assumption" is to CALL them 'slugs'.... but they are pistons just them same.
Not ALL diesels have turbos, AND/OR superchargers OR BOTH!!!! (Detroit Diesel, FYI, ...BTW)
And turbo chargings not the reason for the long stroke.
Diesels had long strokes long before turbos were invented.
Turbos DO make diesels more effecient, though.
Diesels ARE comparable to gas engines in "an internal combustion kind of way"
And there isn't a gas engine of equal displacement on the planet that will equal the torque output of a diesel by vritue of it's longer stroke. ( yes, amongst many other reasons.)
And YOU make the assumption that YOU KNOW what engine designers goals are, as if designing an engine is a theoretical college project.
I don't think the ULTIMATE goal of an engine is "mechanical and thermal effeciency"
The goals are more concrete than theoretical.
Engines must do "work" in the "real world", not in an engineers head.
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From: tallafizzy, FL state
Re: stroke: does more make the engine weaker? (RABHonda)
ok, lets compare the SAME engine family.
4crx4me, if you have the same engine, and you stroke it; using a shorter rod, it WILL make the engine ''weaker'' to revs..
Its all math.
rod ratio= lenght of connecting rod divided by stroke
piston speed in fpm = stroke in inches x rpm / 6
lets see some examples:
B16
rod lenght:134mm
maximum rod angularity: 16.7 degrees
mean piston speed @ 8400 RPM: 4266 fpm
1.74:1
B18A/B
rod lenght:137mm
maximum rod angularity: 18.95 degrees
mean piston speed @ 8400rpms:4905 fpm
1.54:1
B18C
rod lenght:137.9mm
maximum rod angularity: 18.49 degrees
mean piston speed @ 8400rpms:4806 fpm
1.58:1
so if you for example grab a b18c and stroke it with a 92mm crank
B18C(stroked to 92mm)
rod lenght:135.5
rod angularity: doesnt matter and dont feel like doing the math
mean piston speed @ 8400rpms: 5070 fpm
1.47:1
so to put it in perspective, the piston's speed of the stroked b18c to 8400 is the same as a b16 revving to 10034 rpms....or a stock b18c to 8860 rpms
This is not how we percieve things, this is facts.
So a stroked engine will be ''weaker'' to revs, i know is not much of a difference, but i was trying to state a point.
The stroked engine WILL NOT last as long when stroked and revved to same rpms as before.
Modified by mmuller at 11:20 PM 5/20/2004
4crx4me, if you have the same engine, and you stroke it; using a shorter rod, it WILL make the engine ''weaker'' to revs..
Its all math.
rod ratio= lenght of connecting rod divided by stroke
piston speed in fpm = stroke in inches x rpm / 6
lets see some examples:
B16
rod lenght:134mm
maximum rod angularity: 16.7 degrees
mean piston speed @ 8400 RPM: 4266 fpm
1.74:1
B18A/B
rod lenght:137mm
maximum rod angularity: 18.95 degrees
mean piston speed @ 8400rpms:4905 fpm
1.54:1
B18C
rod lenght:137.9mm
maximum rod angularity: 18.49 degrees
mean piston speed @ 8400rpms:4806 fpm
1.58:1
so if you for example grab a b18c and stroke it with a 92mm crank
B18C(stroked to 92mm)
rod lenght:135.5
rod angularity: doesnt matter and dont feel like doing the math
mean piston speed @ 8400rpms: 5070 fpm
1.47:1
so to put it in perspective, the piston's speed of the stroked b18c to 8400 is the same as a b16 revving to 10034 rpms....or a stock b18c to 8860 rpms
This is not how we percieve things, this is facts.
So a stroked engine will be ''weaker'' to revs, i know is not much of a difference, but i was trying to state a point.
The stroked engine WILL NOT last as long when stroked and revved to same rpms as before.
Modified by mmuller at 11:20 PM 5/20/2004
Honda-Tech Member
Joined: May 2003
Posts: 2,329
Likes: 1
From: Greetings From Asbury Park,, NJ
Re: stroke: does more make the engine weaker? (mmuller)
Oh LORD, I'm tired of playing these "SEMANTIC" games.
If that's the phraseology you wish to use or the terminolgy with which you express it.
Fine I conceed. YOU WIN.
I don't care... I can no longer be bothered trying to expain ....."weakness" is in the eye of the beholder!!!
Yes, LONGER stroke engines ARE WEAKER than short stroke engines by virtue of their inability to rev to 11K
There is more than one way to skin a cat....and.
I was just trying to show another perpective is all, and I FAILED.
Believe what you want.
If that's the phraseology you wish to use or the terminolgy with which you express it.
Fine I conceed. YOU WIN.
I don't care... I can no longer be bothered trying to expain ....."weakness" is in the eye of the beholder!!!
Yes, LONGER stroke engines ARE WEAKER than short stroke engines by virtue of their inability to rev to 11K
There is more than one way to skin a cat....and.
I was just trying to show another perpective is all, and I FAILED.
Believe what you want.
Mad Scientist
Joined: Nov 2002
Posts: 5,827
Likes: 1
From: tallafizzy, FL state
Re: stroke: does more make the engine weaker? (4crx4me)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4crx4me »</TD></TR><TR><TD CLASS="quote">Oh LORD, I'm tired of playing these "SEMANTIC" games.
If that's the phraseology you wish to use or the terminolgy with which you express it.
Fine I conceed. YOU WIN.
I don't care... I can no longer be bothered trying to expain ....."weakness" is in the eye of the beholder!!!
Yes, LONGER stroke engines ARE WEAKER than short stroke engines by virtue of their inability to rev to 11K
There is more than one way to skin a cat....and.
I was just trying to show another perpective is all, and I FAILED.
Believe what you want.
</TD></TR></TABLE>
mmmm god....
i tried to state a fact before and you questioned it, so i just showed you what i was trying to say; thats all
After all we are talking about hondas... right? thats why this is called honda-tech and not diesel-tech or archaic pushrod V8- tech.
Sorry if i couldn't explain what i ment by ''weak''....
I understand what you were saying..
Dont be mad
If that's the phraseology you wish to use or the terminolgy with which you express it.
Fine I conceed. YOU WIN.
I don't care... I can no longer be bothered trying to expain ....."weakness" is in the eye of the beholder!!!
Yes, LONGER stroke engines ARE WEAKER than short stroke engines by virtue of their inability to rev to 11K
There is more than one way to skin a cat....and.
I was just trying to show another perpective is all, and I FAILED.
Believe what you want.
</TD></TR></TABLE>
mmmm god....
i tried to state a fact before and you questioned it, so i just showed you what i was trying to say; thats all
After all we are talking about hondas... right? thats why this is called honda-tech and not diesel-tech or archaic pushrod V8- tech.
Sorry if i couldn't explain what i ment by ''weak''....
I understand what you were saying..
Dont be mad
Joined: Apr 2004
Posts: 196
Likes: 0
From: henderson, nv, usa
Re: stroke: does more make the engine weaker? (4crx4me)
4crx, arent you the same guy who said detroit v8's are "notoriously undersquare?"
"Most Detroit V-8's are notoriously 'undersquare'"
oh snap, you did, with the 4th response in this post.
you mention a 265, which had a stroke of 3", 3.75" bore, and a r/s of 1.9:1. so tell me, how did they improve the 265 with the 350? i wont wait for that answer because it will be wrong because you DO NOT know what youre talking about. they improved the 265 by not only stroking it more, but boring it just a bit more. by stroking it they dropped the r/s ratio to 1.74:1, increasing piston speed and widening the torque curve of the engine.
"And YOU make the assumption that YOU KNOW what engine designers goals are, as if designing an engine is a theoretical college project.
I don't think the ULTIMATE goal of an engine is 'mechanical and thermal effeciency'"
i am an engine builder. im not talking about automotive engineers who design daily driver cars, im talking about guys who build engines for hp, increased efficiency.
"Long strokes DO NOT make an engine weaker, you are entitled to your wrong opinion. It does make it less effecient at high rpm, though."
isnt that what i said, that undersquare engines are weaker, meaning they cant handle higher rpm's. i did.
Honda engines that start life Undersquare;
d16a/z/y, b=75mm, s=90mm
b18c, b=81mm, s=87.2mm
b18a/b, b=81mm, s=89mm
b17a, b=81mm, s=81.4
b20b, b=84mm, s=89mm
h22a, b=87mm, s=90.7mm
Oversquare/Square Honda engines;
b16a, b=81mm, s=77.4mm
k20c, b=86mm, s=86mm
Domestic v8's
Chevy
327 cu in, b=4", s=3.25"
350 cu in, b=4", s=3.48"
Ford
352 cu in, b=4", s=3.50"
427 cu in, b=4.23", s=3.78"
Mopar
354 cu in, b=3.94", s=3.625"
426 cu in, b=4.25", s=3.75"
"Most Detroit V-8's are notoriously 'undersquare'"
oh snap, you did, with the 4th response in this post.
you mention a 265, which had a stroke of 3", 3.75" bore, and a r/s of 1.9:1. so tell me, how did they improve the 265 with the 350? i wont wait for that answer because it will be wrong because you DO NOT know what youre talking about. they improved the 265 by not only stroking it more, but boring it just a bit more. by stroking it they dropped the r/s ratio to 1.74:1, increasing piston speed and widening the torque curve of the engine.
"And YOU make the assumption that YOU KNOW what engine designers goals are, as if designing an engine is a theoretical college project.
I don't think the ULTIMATE goal of an engine is 'mechanical and thermal effeciency'"
i am an engine builder. im not talking about automotive engineers who design daily driver cars, im talking about guys who build engines for hp, increased efficiency.
"Long strokes DO NOT make an engine weaker, you are entitled to your wrong opinion. It does make it less effecient at high rpm, though."
isnt that what i said, that undersquare engines are weaker, meaning they cant handle higher rpm's. i did.
Honda engines that start life Undersquare;
d16a/z/y, b=75mm, s=90mm
b18c, b=81mm, s=87.2mm
b18a/b, b=81mm, s=89mm
b17a, b=81mm, s=81.4
b20b, b=84mm, s=89mm
h22a, b=87mm, s=90.7mm
Oversquare/Square Honda engines;
b16a, b=81mm, s=77.4mm
k20c, b=86mm, s=86mm
Domestic v8's
Chevy
327 cu in, b=4", s=3.25"
350 cu in, b=4", s=3.48"
Ford
352 cu in, b=4", s=3.50"
427 cu in, b=4.23", s=3.78"
Mopar
354 cu in, b=3.94", s=3.625"
426 cu in, b=4.25", s=3.75"
Honda-Tech Member
Joined: May 2003
Posts: 2,329
Likes: 1
From: Greetings From Asbury Park,, NJ
Re: stroke: does more make the engine weaker? (mmuller)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller »</TD></TR><TR><TD CLASS="quote">
Sorry if i couldn't explain what i ment by ''weak''....
I understand what you were saying..
Dont be mad
</TD></TR></TABLE>
Not mad.
I just don't agree.... that an engines inability to rev to X rpm means that it is "weaker" in comparison to one that CAN.
Just a different perspective is all it is.
My definition of "weak" would include "an error of design, or manufacture that would cause a failure in normal operation" ........But that's just me.
Sorry if i couldn't explain what i ment by ''weak''....
I understand what you were saying..
Dont be mad
</TD></TR></TABLE>
Not mad.
I just don't agree.... that an engines inability to rev to X rpm means that it is "weaker" in comparison to one that CAN.
Just a different perspective is all it is.
My definition of "weak" would include "an error of design, or manufacture that would cause a failure in normal operation" ........But that's just me.
Joined: May 2004
Posts: 5
Likes: 0
From: Lilburn, Georgia, USA
A V8 doesnt NEED to rev to 8k beacuse its not designed to make power that high. Nost V8's make more power in the first 3k rpm than a 4-cyl makes throughout the whole engine. Saying a V8 is weaker cuz it cant rev as high is bullshit. learn what youre talking about before you make comments...