Ok, ive heard because of the long ratio that its not good to rev to 8k on a regular basis. Can anyone explain this to me? Also, is there anyway to reduce the probability of problems in the future? bottom end balance/blueprint?
Thanks
Kamin

 

Well according to some people on the board including sgT, rod to stroke ratio isn't everything. I have asked this question before because I am in the process of building a b20/vtec myself and was also interested. From what people say it isn't a really big problem so I decided my motor should be fine no matter how I drive it. As long as you have some nice aftermarket products on your bottom end and built corretly then you shouldn't run into any problems.

Here is the link to the thread I made about rod to stroke ratio. This was when I was still thinking between the b18c5 and b20. In the end I went for the b20 all the way.

https://honda-tech.com/zerothread?id=135946

 

i am sure you read this but, http://www.crvtec.com/index.php?section=crankshaft. also, i think (i am no expert) it might also have to do with the weight of the whole rotational mass. if you use light weight aftermarket rods and pistons that will help in this weight reduction and the revability. if you use a different crank, ie b17, then you lose torque, defeating the purpose of the b20 in b20vtec.

 

thanks maximus! ill read through that. i tried a search but that didnt come up (yes archives too)
and yea, im sure the entire weight of the rotating assembly takes alot of stress off it. and i will be using the b20 crank.

 

To put it simply, having a lower rod ratio will 'want' to push the piston through the cylinder wall MORE THAN a motor with a higher ratio. And I believe that stress rises exponentially with RPM.

If you can picture a triangle:

Draw a line vertically, then draw a line horizontally...the lengths should be equal (just for this example). Now connect the 2 lines and NOTICE how slanted this line is....this would be your rod. Now, having a lower rod ratio would mean extending the horizontal line (the stroke). In doing this, you can see that the angle of the 'rod' becomes more horizontal.