What is the benefit of running a 5.7 to a 6.0 rod? I know they move the location of the wrist pin up on the piston for the 6'' rod but do you get more torque with a 6'' vs a 5.7"?and 5.565 rods which was the first 383 chevy, till piston manufactures started making the 5.7 and 6.0 rod compression heights
Ummmm, well.........:no:What is the benefit of running a 5.7 to a 6.0 rod? I know they move the location of the wrist pin up on the piston for the 6'' rod but do you get more torque with a 6'' vs a 5.7"?
Rod length is, basically, irrelevant.
As far as the CHP kits...the reason I did that (originally) was because the only 5.956 rod that was available was stock. Using the 6.200 allowed a decent piston and a lot of options for upgrading the rod.
Probably the best reason for using it now is the comparative weights of the 1.350 C/H piston and the 1.600 C/H piston.
If you already have the crank and rods....changing the piston is probably the way to go if you wish to save money.
It's what I'd do. You can always build a different short block for the future, especially since the heads will outperform the combination.
Originally Posted by CHANMADD
The ratio between the crank stroke and the rod length is ,my friend, very important.
If the angle of the rod is to acute the rod will go through the cylinder wall at great speed and leave you on the side of the road!!!...
Oh horse poop, my friend.
you carry any argument to the ridiculous extreme you can prove anything.
This, I think, is a reality based board. No one in the industry has a piston forging long enough to allow that scenario.....so I won't sweat it.
Rod ratio is not a consideration when designing a combination unless there is a serious mismatch between the engine and cylinder head sizes.
351C and BB Chevy have short rods....big head, little motor. BB Chrysler has a long rod.......big motor, little head.
I doesn't really matter even then but the rest of the time, pick a rod, it's all good.
Rod ratio is the least important piece of folklore to consider when building an engine.
I think this is another one of those issues that have only a tiny, tiny impact on performance. People refer to “piston acceleration” when they really mean “piston speed”. It’s the moving piston that pulls in the intake charge and regardless of rod length, piston speed is zero at TDC.
I plotted piston speed versus crank angle at 7,000 RPM for 6.500”, 7.000”, 7.500””, and 8.000” long rods, keeping everything else constant.
Notice that at TDC or zero degrees all the lines converge. There's no difference. At maximum speed, which is at around 75 degrees, there's a slight difference in speed, but I can't believe it's going to have much impact on the incoming charge.
The idea that the piston is going to accelerate away from the advancing flame front is preposterous.
The correct rod to crank ratio is 8:1. Eight rods....one crank.
Unless there is an rather severe imbalance between cubic inches and cylinder head size rod ratio is irrelevant.
You better go back and re-do your math.....a 383 is a .030" over 350 block, a 388 is .060" over........350 block + 400 crank = 383
400 block + 350 crank = 377
.030 overbore add approximately 5 cubic inches
i.e. .030 over 383 = 388,
.030 over 377 = 382/383