Ok I ask this question in LS1 Engine Tech and got no answers, so im going to try it here.

I was wondering if there is any advantage in going with 6.125 rod length over the stock 6.098 for an LS1?

Is there more of a possiblity of the piston rocking with one of the lengths than the other?

I was thinking with longer rods and matching pistons that the pistons would be less top heavy, than having shorter rods and taller pistons.

Is my thinking right? What do you professionals say? Whats the best length to go with?


Joel

 

If you do a search you will find a lot (too much?) discussion of this very topic.

Rich

 

With regard to a 'top heavy piston' , a difference of 0.027" in wrist pin position, would be negligible (my novice opinion).

The longer rod will benefit a naturally aspirated motor that doesn`t have the
advantage of a boosted plenum and higher cylinder charging efficiency.

With the extended duration of the piston sitting near TDC, the intake charge
has more time to build pressure on the piston face.

This will allow for more force to be transmitted to the crankshaft resulting in
higher torque values per power stroke.

Using a longer rod in a boosted application is not recommened because of the
increased chance of knock as the pressure builds, while the piston maintains a
relavtively small combustion space for a longer period of time.

 

Yes rskrause I know about the search button and use it often. And I did not find an answer to my question. Its really starting to bother me seeing so many people getting told to use search to find an answer to there question. Specially new people. Yes using search is a very good idea and I have found many answers to my questions doing a search. People need to understand that sometime the answer to someones question may just need to be answered differently than what they have found by doing a search.

Sorry for having to bring this up but I see it happening to people eveyday and its getting really annoying. So when everyone reads this please think twice before telling people to use search to find all there answers. Because when people ask questions it helps the forum grow for futrue members to find answers to there questions. Just my 2 cents. ANYWAYS.


Thanks for the help Zero_to_69. Im not sure if your answer means its not worth getting 6.125 length rods or not. Im not going to be boosting my engine so I don't need to worry about that part. Im just trying to find out if 6.125 rods have any greater chance of causing problems over the stock 6.098. Are there possible problems I may run into down the rod? I hope to get more post on this topic.


Joel

 

Joel,

A few minutes with the search button netted these interesting threads. If you read and understand what the posters say, you'll have a better idea of what changing the rod length pros and cons are.

Rather than just having a few people tell you something which you may not grasp immediately, spend some time reading. Active learning beats the hell out of passive learning as far as understanding goes.


http://web.camaross.com/forums/showthread.php?t=336800

http://web.camaross.com/forums/showthread.php?t=325807

http://web.camaross.com/forums/showthread.php?t=322754

Oh, yeah, these also showed up:

http://web.camaross.com/forums/showthread.php?t=307727

http://web.camaross.com/forums/showthread.php?t=339727

Here's my opinion: IF you plan to replace the stock rods, you may find a better choice in 6.125 than in 6.098 long ones. Of course you'll need special pistons, rather than stock replacements. The rod lengths you talk about have a negligible effect on piston mass. Piston design is a much bigger factor.

Perhaps the .127 difference is the "yawn factor" that limits responses. .300 difference doesn't even generate much excitement. Don't get too lost in the details if you really plan to do an LS1.

FWIW, you are going to get a lot more help being "nice" than coppin' a 'tude.
Well, maybe that works, because it got me to respond.

Rich (rskrause) is too nice to reply. However, if you ever get busted up around Buffalo, he's the doc you want putting you back together.

My highly-opinionated change for a nickel.

 

You have to look at it from the point of view of the people who have the in-depth knowledge to answer your question correctly and in detail. Many of them have been here for years. They know the information is out there, and that if you take the time to do a search, you will find it. It is not reasonable to expect multiple members to repeatedly type a multi-page, high-tech answer for each individual who asks the same question, when they know they have done it before. It would be easy to give you a quick answer like "it doesn't really make any difference, don't worry about it", but your question appeared to seek a bit more thought than that.

Please try to look at the problem form both sides. "Use the search button" is not an "excuse" or an "admonishment", its a positive statement that the knowledge is there waiting to be found.

 

the longer rod increases dwell time at tdc and bdc like the other's said it also increases piston speed up and down bore. this increases the vacume signal and pulse strength in an engine. the longer also give a more direct angle on the piston helping reduce piston slap but the custom pistons usualy used in long rod aplications have extreamly short skirts which tend to have more piston slap. so that could be a catch .22 depending on the brand of piston. if you do use a long rod on a boosted application cam timing is very important because of stated reason. I'm curently using a 6.2 in rod in my 350. I like long rod engines. I have my cam is 256 @ .050 and it still work my power brakes and idles at 800 rpm's