This is about to get interesting.
Rocker ratio changes are very popular way to increase performance in many makes of cars when guys hot rod them.. even with VW, but from what I've seen, only air cooled. I can't say that I've ever seen anyone change the rocker ratio on a water cooled car yet. Not that I've looked very hard..
For several months now I have been talking with a couple engineers at Schaeffler about our rocker arms. The reason is that I want more than the 11mm lift that all the aftermarket cams have for the 24v VR6.
Today I was happy to receive the following email-
"found one that MIGHT be beneficial to you and it has a slightly higher ratio. There is
no guarantee that it will fit or operate successfully without running a
full analysis on it. These calculations take weeks, unfortunately my
boss wont let me do side jobs like that. Buy a set (or one) and try it
out on the bench to see how things line up.
Good luck! Let me know how it works"
Sounds like typical engineer disclaimers to me. They have the full specifications of both right in front of them, I'd imagine they would bother telling me about them if they didn't think they were going to work. I'm stoked!
The 'slightly higher' ratio he is talking about is roughly a 14% increase over stock.
They should jump the lift on the Schrick cams from 11mm to a hair over 12.5mm.
I can't find my old email file from Willy @ Supertech with the specs on the stock valve springs, but if I remember correctly somewhere around 12.5 was the coil bind limit on them. I should have that info again tomorrow when he responds again. Looks like I might need to change them out if this rocker is indeed functional in this application.
I also sent an email to the Schrick engineer I converse with to see what his thoughts are just for fun.
While these rockers would be a cheap way to gain power on any of the 24v regardless of cams or head, I am especially looking forward to them as my ported head is capable of decent peak CFM over stock.
aprox .430 VS .490 with the stock rockers and these new ones..about a 15cfm gain intake side at peak lift.
For those of you wanting to know more about changing rocker arm ratios, here is a quick page with a nice graph showing area under the curve. By opening and closing the valves at a faster rate, the engine flows more air for the same number of degrees of valve duration. It is for old American iron, but the concept is the same.