long rod short piston vs short rod long piston
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long rod short piston vs short rod long piston
okay i was thinking about something that i cant figure out.
if you have a rod and piston combo that from the center of the crank journal of the rod to the top of the piston, does it matter if you use a tall piston and short rod compared to the long rod and shallow piston. what i am getting at is if they are the same length, what is the advantage. how does horespower or durability react to the setups. say a 6.1 rod attached to a piston that overall has the same length as a 6.0 rod attached to a piston.
i hope my question makes sense because i am getting ready to build a lq4 and want to know the trade off.
also, is a longer stroke with a shorter rod better than a short stroke and long rod setup. i noticed that the new ls9 has a sub 4" stroke and yet makes bad *** power. does this change the rules as far as big stroker motors being the way to go, or is that for NA motors.
thank you in advance for helping me out.
if you have a rod and piston combo that from the center of the crank journal of the rod to the top of the piston, does it matter if you use a tall piston and short rod compared to the long rod and shallow piston. what i am getting at is if they are the same length, what is the advantage. how does horespower or durability react to the setups. say a 6.1 rod attached to a piston that overall has the same length as a 6.0 rod attached to a piston.
i hope my question makes sense because i am getting ready to build a lq4 and want to know the trade off.
also, is a longer stroke with a shorter rod better than a short stroke and long rod setup. i noticed that the new ls9 has a sub 4" stroke and yet makes bad *** power. does this change the rules as far as big stroker motors being the way to go, or is that for NA motors.
thank you in advance for helping me out.
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These are design questions that have different answers for different situations. You need to fist specify what your application is going to be and then we can give you a better direction. There will be no right or wrong answer, there will only be different answers from different people that have had different results.
So, give us a little background about your project and we will help out the best we can.
So, give us a little background about your project and we will help out the best we can.
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well i was thinking about my 408 build i am starting and was wondering if a 6.00 rod is better than a 6.1 rod. also is a 6.1 rod with a 4.00 stroke going to give the same cubic inch as a 6.0 rod with a 4.1 stroke. what is better.
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Rod length has nothing to do with displacment. It's main function is simply to connect the piston to the crank. The longer the rod, the shorter the piston compression height will be.
Are you planning on doing this yourself, or having one of the engine builders here do it?
Are you planning on doing this yourself, or having one of the engine builders here do it?
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I Havent Decided Yet. I Have A Lq4 Block That I Want To Biuld To 550 Rwhp Na ( Wishing For 600na Rwhp W/tf 225cc). I Want The Motor To Rev Well And Be Reliable. People Told Me My T-rex 346 Would Not Live Long And It Has Worked Flawlessly. I Can Build Motors On My Own But If The Price Is Right, Who Knows. Just Curious Why People Use A 6.125 Rod Instead Of A 6.000 Rod Or Like Lt1 5.700 Rods.
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Schwanke, Can You Pm Me A Price On A Stroker Kit And What Manufactor Of The Parts You Use. I Have To Piece This Motor Because I Dont Have Bulk Cash To Buy One Already Done Yet.
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I may be wrong here, but doesn't the traditional "small block" Chevy have a standard nominal deck height of 9.025", while the standard LS1's (GenIII's) come in at 9.250" If correct, and I know this IS a bit off topic, but want to make sure I have MY facts straight, wouldn't subtracting 9.025" from 9.250" leave you with a difference of .225", NOT .035"?
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okay i was thinking about something that i cant figure out.
if you have a rod and piston combo that from the center of the crank journal of the rod to the top of the piston, does it matter if you use a tall piston and short rod compared to the long rod and shallow piston. what i am getting at is if they are the same length, what is the advantage. how does horespower or durability react to the setups. say a 6.1 rod attached to a piston that overall has the same length as a 6.0 rod attached to a piston.
i hope my question makes sense because i am getting ready to build a lq4 and want to know the trade off.
also, is a longer stroke with a shorter rod better than a short stroke and long rod setup. i noticed that the new ls9 has a sub 4" stroke and yet makes bad *** power. does this change the rules as far as big stroker motors being the way to go, or is that for NA motors.
thank you in advance for helping me out.
if you have a rod and piston combo that from the center of the crank journal of the rod to the top of the piston, does it matter if you use a tall piston and short rod compared to the long rod and shallow piston. what i am getting at is if they are the same length, what is the advantage. how does horespower or durability react to the setups. say a 6.1 rod attached to a piston that overall has the same length as a 6.0 rod attached to a piston.
i hope my question makes sense because i am getting ready to build a lq4 and want to know the trade off.
also, is a longer stroke with a shorter rod better than a short stroke and long rod setup. i noticed that the new ls9 has a sub 4" stroke and yet makes bad *** power. does this change the rules as far as big stroker motors being the way to go, or is that for NA motors.
thank you in advance for helping me out.
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There are a lot of variables involved. But for most applictions, the longer the rod the better. It reduces cylinder wall loading and increases piston dwell time at TDC. I think NASCAR motors use like a 6.5" rod or close to it.
Re'
Re'
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Just want to confirm something I already believe to be true.If the longer rod has more dewel time doesent that also increase an engine chance to detenate as opposed to a shorter rod.
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I may be wrong here, but doesn't the traditional "small block" Chevy have a standard nominal deck height of 9.025", while the standard LS1's (GenIII's) come in at 9.250" If correct, and I know this IS a bit off topic, but want to make sure I have MY facts straight, wouldn't subtracting 9.025" from 9.250" leave you with a difference of .225", NOT .035"?
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I may be wrong here, but doesn't the traditional "small block" Chevy have a standard nominal deck height of 9.025", while the standard LS1's (GenIII's) come in at 9.250" If correct, and I know this IS a bit off topic, but want to make sure I have MY facts straight, wouldn't subtracting 9.025" from 9.250" leave you with a difference of .225", NOT .035"?
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If this is the general thought as to not buying a shortblock, then I guess we better raise our price.
You have to remember that is just the shortblock, no covers, cam, lifters, nothing but the block, main caps and bolts, crank, bearings, rods and bolts, pistons, rings and cam bearings with assembly.
Sorry for the thread hijack
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the LS9 may have < 4" stroke but don't forget it's supercharged which is a big reason it makes more power.
i agree with what grinder said, only thing else i can think of is a longer rod will have more mass for a given material but that may be a mute point depending on the material you use a lighter material to begin with such as titanium.
and I don't know if a difference in rod length would have any affect on balance of the rotating assembly regarding reciprocating mass vs rotating mass... whether a shorter or longer rod is beneficial or detrimental.
For longer vs shorter pistons, would a longer piston be more durable from a heat standpoint but worse because it would be more massive?
check this out http://rustpuppy.org/rodstudy.htm
i agree with what grinder said, only thing else i can think of is a longer rod will have more mass for a given material but that may be a mute point depending on the material you use a lighter material to begin with such as titanium.
and I don't know if a difference in rod length would have any affect on balance of the rotating assembly regarding reciprocating mass vs rotating mass... whether a shorter or longer rod is beneficial or detrimental.
For longer vs shorter pistons, would a longer piston be more durable from a heat standpoint but worse because it would be more massive?
check this out http://rustpuppy.org/rodstudy.htm
Last edited by 1 FMF; 03-13-2008 at 01:00 PM.
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wow, if was a dead topic for awhile but then got some good stuff. i know i should think about other things also, just curious. those are some good prices 3200= short block. i just want to build it myself, stupid pride.