Any benifits of smaller rod journals?
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Teching In
Joined: Jul 2011
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Any benifits of smaller rod journals? I'm getting ready to build my bottem end and I'm wondering what the pros and cons are?
It seems you reduce the linear speed of the bearing by about 5% if you go from a 2.100" to a 2.000", but what if any down sides are there?
It seems you reduce the linear speed of the bearing by about 5% if you go from a 2.100" to a 2.000", but what if any down sides are there?
Other than reducing journal overlap, nothing really. The rod big end will be smaller (more clearance) and lighter (smaller bobweight), plus the reduction in bearing speed (less friction) so the pros really outweigh the cons in most applications .
On The Tree
Joined: Aug 2010
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From: Melbourne
Pro : less parasitic loss Katech has an awesome video on you tube showing the c5r engine developing and the use of smaller bearing diameters which increased horsepower.
Con: will wear out faster due to have less bearing surface.
IMO: unless your building a high rpm sprint engine that your gonna year down and freshen up often if stick with the larger.
Con: will wear out faster due to have less bearing surface.
IMO: unless your building a high rpm sprint engine that your gonna year down and freshen up often if stick with the larger.
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TECH Apprentice
Joined: May 2005
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From: toronto
just ran up on this dilmia /cough cough !! 2 in they dont build this rod for much more then 1000 hp soooo 2 1/2 is the way to go for bigger hp more choices ..in rods if your motor only ya there is always more power in less rotating 
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Teching In
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Thanks for the feedback guys! I think I'm going to go for the smaller 2.000 journals and just check the bearings at the end of the "season" to see if they need to be replaced. Callies Compstar has all the goods to support it rod wise and Clevite makes the bearings. I'm not planning on huge power, ~525 BHP or so and would like it around 6800-7200 rpms so I think I'm on the right track.
