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Author Topic:   6.0 rods
PBR
Dirt Roller

Total posts: 23
posted January 20, 2001 07:58 AM
Are 6 inch rods worth the added expense.Would it be better to half a point more compression or use the longer rods. Do they really give you that much more toruqe. This is a 350 flat top motor. Thanks for any help.

Earl Parker II
Dirt Roller

Total posts: 17
posted January 21, 2001 11:08 PM
To get a better feel for the effect of various rod lengths, go to http://www.parkercarburetion.com/freedownloads.html. Assuming you have Microsoft Excel, the Engine Analysis v. 1.0 spreadsheet will allow you to "construct" the bottom end of an engine and let you try out various combinations. This spreadsheet will only show you mechanical relationships but it might help you out.

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Earl Parker II
www.parkercarburetion.com
704.482.7588

Limited5
Dirt Maniac

Total posts: 141
posted January 22, 2001 08:31 PM
Isn't the biggest benifit of 6.0 rods is that it takes some angle out of the movement of the rod? I also believe it holds the piston at top dead center for a longer period of time, correct?

awkwardjeff
Dirt Freak

Total posts: 219
posted January 23, 2001 11:57 AM
I'm not trying to argue with limited 5, I just need to ADD to what he said.....the duration of the piston being at top dead center is longer in degrees of crankshaft rotation.....this IS because of the angle of the rod, the angle change was from the longer rod......The piston stays at BOTTOM DEAD CENTER longer also.........since every thing we are talking about is in degrees of crankshaft rotation..........let us assume you start with the piston at TDC and zero a degree wheel, when you get to .050 down the bore you may have moved say 15 degrees with a 5.7 long rod.........with a 6 inch long rod that .050 may take say 20 degrees ......
the same thing happens at BDC also.......what a loner rod does is speed up the piston when then valve timing is critical. because it's duration is longer at TDC and BDC it will need to travel faster than with a 5.7 long rod during it's travel.
this changes the velocity of the air inside the bores and intake and exhaust when the valves are opening and closing.....this relates to cylinder pressure......
there is a great article in a recent circle track and if I can find this I will post the publication date............Jeff

awkwardjeff
Dirt Freak

Total posts: 219
posted January 24, 2001 03:46 PM
The article I was referring too in the last post is in Circle Track June 2000 publication date........Pages 70-77 This is a long article and has great information for someone trying to decide which length rods they should run in a motor.........or Maybe it will just add to your confusion?????
But it has great information, on they why's and hows of long rods......Jeff

PBR
Dirt Roller

Total posts: 23
posted January 29, 2001 10:31 PM
I couldn't find the mag. Just want to know if it is worth it in a 355 with double humps and 11.5 comp. flat top motor. holley 2-barrel and headers solid lift cam midwest motorsports #8. It will be in 3200lb street stock.

awkwardjeff
Dirt Freak

Total posts: 219
posted January 30, 2001 11:56 AM

okay, you want a answer to the question,NO.
I wouldn't put a 6 inch rod in that motor for that car. The reasons are many but as you increase the length of the rod you move the torque curve up in the motor. Also with that heavy of a car it would be hard to get a cam to pull it off the corner while having the proper gear for the rpm range of the motor with 6 inch rods. Some people will argue about this all day long...........If you ran a better intake and fuel system, along with lighter weight rule.........my advice would be to run the 6 inch rod.........
If this was a mod I would say yes to running the 6 inch rods..........If you ran a cheater intake and cheater carb and all kinds of other stuff that would allow you to utilize the benefits of the 6 inch rod I say go ahead..........
Any motor is a package of parts that need to work together........without the rest of the package the 6 inch long rod hurts the performance of this motor........Jeff

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