I am plannig on build an Ls/Vtec but I've been reading on the web that the B18B has a bad R/S ratio.
I would like to know what is R/S ratio, and how can I improve it?

 

rod lengh/stroke
The LS r/s ratio isn't really something to worry about. The LS r/s ratio is 1.54:1, and the GSR/ITR is only 1.58:1, not a very big difference. Ideal R/S ratio is 1.75:1, the b16a has a 1.74:1 r/s ratio, almost perfect. You can make your r/s ratio better by destroking the motor, but at the cost of lost displacement.

 

The reason a GSR bottom end can out-rev an LS bottom end is because it has a girdle which connects all of the main bearing caps together. So to say that an LS bottom end can rev almost as high as a GSR one based on the similarity of r/s ratio from one to to the other is a tad misleading.

 

I never stated that the r/s ratio was the determining factor of revving an LS bottom end. All I said was that it's not much worse than a GSR, which is what he was concerned with. He didn't ask about crank girdle, crank balancing, oil squirters, rod bolts, etc More so than the crank girdle, the stock LS rod bolts are a weak point in the bottom end. They tend to stretch under the stress that 8k rpm creates.

 

How can I, or what does it takes to install a GSR or B16a girdle into a B18B block?

 

z10 makes a billet block girdle that will fit. But you also need the GSR main bolts, windage tray, oil pickup, and oil pan. You can take a stock GSR girdle and have it machined to fit, but you still need all the above parts.

 

http://honda-tech.com/zerothread?id=263598