[DeTomaso] Intakes {rocker arms}.

[cengles at cox.net]

Dear Daniel,

You wrote:

" We ran the gold Crane 351C 1.73:1 ratio rockers for
those tests. Subsequent tests showed a shorter 1.65:1
ratio on the exhaust side helped pick up torque:"

$$$$$$$$$ I am so ignorant I do not understand how a 1.65:1 shorter ratio rocker arm on the exhaust helps increase torque. I am so ignorant I thought that in terms of the combustion chamber torque was related to efficiency of fuel-air mixture. I also thought that increased 1.73:1 ratio exhaust rocker arm would enhance and improve exhaust gas egress, which should improve, due to overlap, increased filling of the CC with more fuel-air mix. It would seem that on the surface that a 1.65:1 rocker arm would be detrimental to efficient intake and exhaust function and therefore detrimental to torque. The dyno results seem to refute my remedial understanding of such things.

Can you explain how the short ratio exhaust rocker arm improves the torque? Is the answer that the mysterious and mostly unknown world of superhot explosive exhaust gas flow dynamics causes the 1.65:1 to just plain work better than the 1.73:1 rocker in this particular combination??


Puzzled, Chuck Engles, rookie engine builder