connecting rods length + piston size?
connecting rods length + piston size?
I dug up an old post by SSP- Ralliart who says that although we are able to use the 7-bolt 4G63 connecting rods they are about 0.050" shorter than our rods which unless using a piston with increased height, will result in lower compression/increase in quench area/incomplete combustion
I am wondering if Wiseco makes a taller piston, or if buying the +6.0mm Manley connecting rod would fix this? Being that 0.050" equates to just 1.27mm, is the 6.0mm longer rod Manley makes going to be too long now? To offset this, perhaps I can go with a slightly thicker gasket (which for boost isn't a bad idea anyway...)??
Curious to know what others have done
I am wondering if Wiseco makes a taller piston, or if buying the +6.0mm Manley connecting rod would fix this? Being that 0.050" equates to just 1.27mm, is the 6.0mm longer rod Manley makes going to be too long now? To offset this, perhaps I can go with a slightly thicker gasket (which for boost isn't a bad idea anyway...)??
Curious to know what others have done
ok to start off both the 2nd gen 7 bolt 4G63 and EVO 8/9 Rods will work in our block but there is one catch. They are both .050" shorter in length then our rods. The 2nd gen rod length is 5.900" and EVO's 5.906" (stock) 150mm. Ours are 5.950". So you will be .050" shallow in the bore. Wrist pin diameter is the same at .866". Rod Big end bore are all 1.88" and Big End width of 1.036-1.038". Now being shallow .050" compared to stock 4g69 rods can lead to less compression, increase in quench area, incomplete combustion, etc. I would suggest either increasing the pistion height. Even with turbo all the above is still an issue. If you have any questions feel free to write.
Thank you for your time.
Steve
Thank you for your time.
Steve
I suppose, assuming SSP-Ralliart's measurements of the EVO8/9 rods against ours are correct, and by using a +6mm longer connecting rod, I need a head gasket that is 4.73mm thicker than stock.
Ideas?
Ideas?
it'll still be fine, you're over thinking it...+6mm on the rod is getting crazy, you're looking at custom pistons...
i would revisit the rod measurements....was it measured in total? or was it measured from center of main bearing to the center of the wrist pin, that's what's important...if the evo rods have a little extra bulk, it's not an issue...
i would revisit the rod measurements....was it measured in total? or was it measured from center of main bearing to the center of the wrist pin, that's what's important...if the evo rods have a little extra bulk, it's not an issue...
Last edited by CrAnSwIcK; Jul 19, 2013 at 12:13 PM.
it'll still be fine, you're over thinking it...+6mm on the rod is getting crazy, you're looking at custom pistons...
i would revisit the rod measurements....was it measured in total? or was it measured from center of main bearing to the center of the wrist pin, that's what's important...if the evo rods have a little extra bulk, it's not an issue...
i would revisit the rod measurements....was it measured in total? or was it measured from center of main bearing to the center of the wrist pin, that's what's important...if the evo rods have a little extra bulk, it's not an issue...
I spoke with someone at Wiseco and they said it'd be no problem to make me a custom pistonn 0.050" taller so I think that's the best way to go.
Trending Topics
you sure?
i got 7.2cc
anyway, using that, if you can figure out the combustion chamber displacement, you can calculate compression ratio. then we'll see if it will make much of a difference, but if you're going turbo, why worry about it. it will likely be lower, even though the change of max and minimum volume is he same amount...
i got 7.2cc
anyway, using that, if you can figure out the combustion chamber displacement, you can calculate compression ratio. then we'll see if it will make much of a difference, but if you're going turbo, why worry about it. it will likely be lower, even though the change of max and minimum volume is he same amount...
you sure?
i got 7.2cc
anyway, using that, if you can figure out the combustion chamber displacement, you can calculate compression ratio. then we'll see if it will make much of a difference, but if you're going turbo, why worry about it. it will likely be lower, even though the change of max and minimum volume is he same amount...
i got 7.2cc
anyway, using that, if you can figure out the combustion chamber displacement, you can calculate compression ratio. then we'll see if it will make much of a difference, but if you're going turbo, why worry about it. it will likely be lower, even though the change of max and minimum volume is he same amount...
(3.142)(43.5mm^2)(1.27mm) = 7550.72mm^3 = 7.55cm^3
i'm likely overthinking it, you are right...for turbo it doesn't make a difference, but i want to make sure if i was to shut boost off, i won't experience any adverse side effects to general motor operation
in any case Wiseco has already confirmed that they can easily make the pistons 1.27mm taller which will solve this problem.
Last edited by doncarbone; Jul 20, 2013 at 10:09 PM.
perfect..
and the answer is in cm cubed, so you have to convert all your mm variables to cm
and low compression N/A will work, and you can't "shut boost off" you have to remove most of the turbo kit from the motor. and return to stock...i mean you could just leave it spooling an not connect the compressor to the motor at all, but that's just wearing the turbo and not using it which is silly, i can't imagine why you would want to "turn off" boost anyway, it's as simple as not stepping on the throttle enough to spool.
and the answer is in cm cubed, so you have to convert all your mm variables to cm
and low compression N/A will work, and you can't "shut boost off" you have to remove most of the turbo kit from the motor. and return to stock...i mean you could just leave it spooling an not connect the compressor to the motor at all, but that's just wearing the turbo and not using it which is silly, i can't imagine why you would want to "turn off" boost anyway, it's as simple as not stepping on the throttle enough to spool.
Thread
Thread Starter
Forum
Replies
Last Post
doncarbone
04-06 Ralliart Engine/Drivetrain
9
Feb 23, 2014 10:07 AM