What are the pros and cons of running a 6" rod over the 5.7"? My new 383 has them, just wanted everyones opinion on them, because I know some people don't like them.

 

Do a search, this has been discussed many many times. But i think the general consensus is that they dont really make a difference save in a max effort racing engine thats turning high RPM. Though some seem to think it makes more torque.

 

Not to be an *** or anything, but there are literally tons of info on this subject if you use the search function. I personally am using 6" rods in my 355 and like them a lot.

 

There is not a nickel's worth of difference in using either.

 

A 6" rod is a great way of connecting a piston to a crankshaft.

Yep... do a search.

-Mindgame

 

 

The veterans of this site strongly encourange the use of the search function, in case you hadn't figured that out

 

I'm guessing this won't be a max-effort race engine spun within a micron of its life, so I would say... price out the options. Now I'm going to guess that the cost difference will be minimal (if any), so I guess I'd go with longer rods because people will think you're cool. In reality, the difference in a street application is probably so small that it's barely even measurable (and I'm talking about wear, not HP).

 

It is not measurable ya are right. Ya can take a 6" motor and run it on the dyno and max it out. Then take that same motor and put in 5.7 and max it out. If there were big frictional differences it would show as HP loss. Which both engines will HP within the error factor of the dyno. If ya change heads and cam to make the 5.7 spot on it will in most cases out HP the long rod. The LONG rods Smokey talks about in his book at indy gave that engine a 2.6+/1 RR at ??? a bunch of RPM's
Now when ya start talking big cubes (long stroke 4"+) or 85-9000RPM's it's different.

On a 347 Ford stroker out of a 302 if ya run 5.400 rods in it it will burn oil due to the pin being in the oil ring. If ya put a 5.300 rod in it
,it stops the oil burning without the pin in the oil ring. Side load? Don't know,but I think it has to do more with the pin in the oil ring groove and they don't run any different.

 

Look, here's the thing about 6" rods.

They have an effect on the way the piston moves..

Whether the particular effect is something that is going to be either noticable in practical terms or of benefit to you; depends on the interplay of many complex factors.

As a General rule of thumb, Smokey said that "Longer is Better"

I think Paris Hilton said that too, but that's a different subject.

My next build is going to use 6" rods, but a big part of the reason for that is because I am going to be using Alcohol for fuel. (Actually E85, but that's not the point.)

The point IS that the proper question is not; "Are 6" rods good or bad?".

The question is; "Will 6" rods benefit me in my particular situation?"

Which is why you need to go through the rather long process of reading up about them.

You might want to buy Smokey's book too; Power Secrets. Amazon has it used for less than ten bucks.

 

Forget the rod lenght of 6.0". The real nity grity of this chat should be what is the best rod/stroke ratio.
Generally a r/s ratio in the 1.7-1.8 area give the best high rpm breathing potential in a race engine.
If your only reving the engine to 6500RPM then attaining the R/S ratio this high is not all that important.
The longer rod lenghts generally are easier on the side walls of the cylinder in theory.
If you have to put the wrist pin into oil ring land for the longer rod to fit in the block then I would not recommend it at all as oil consumption will be an issue after short number of miles. (daily driver of course)
If strictly a race engine then you may not care if it needs a rebuild sooner.

 

The search function is your friend. Many of us are talked out on this issue.

Rich