Hi, I searched (Phrase rod and ratio) and got over 1000 hits...
I think search just does not work right...I cant figure it out...

Anyways...
What is the optimum rod ratio for a type 4.
I would like to hear lots of opinions on this one.

Rich

Try

+rod +ratio

Skip

According to BrettW in this thread the optimal type IV ratio is 1.70 to 1.80.

http://www.914world.com/bbs2/index.php?sho...c=4964&st=0

Hmm . . . this graph migh interest you, as well as the article I bookmarked it in a while ago.

http://www.e30m3performance.com/tech_artic...ratio/index.htm

What are you looking for as far as HP / TQ..????

And at what RPM will this engine be living in most of the time?

Clayton

Optimum rod ratio is dictated by the RPM range goal for the engine as well as the cam and head work as well as the longevity goal...

For engines I design I shoot for 1.75:1 for street engines, but I have some powerful combos that run as little as 1.55:1. Our race engines that sustain RPM use 2:1 or more

There is no perfect rod ratio for the engine.

"Its all in the combo". as always.

Dema Elgin (local SF Bay area cam grinder) has an interesting article on engine design including rod ratios. lElgin Cams