Now hear me out. With hydraulic lifters, as soon as the cam lobe starts to push the lifter, the plunger inside the lifter starts to collapse. With higher oil pressure acting on the plunger, the less it is going to compress. Less plunger displacement equates into more valve lift. Hence the claim of more HP.

Is this or am I in :lala: land.

 

Im gonna go ahead and call on this one....the lifter isnt going to compress any less with high oil pressure than with low oil pressure....if you look at the design this should be obvious. High oil pressure will merely cause parasitic drag by the pump and rob a few ponies.

sorry '73. just had to knock you off your podium

 

I never was on my soapbox until now.



Power loss from high oil pressure comes from work that drives the pump, which is the integral of (PdV) or pumping losses. Double the pressure, you double the work. With an increase of pressure, volume will also increase and increase work.

Power is the rate of work. So at the same RPM, we have the same rate, more pressure, and more volume. And yes there is an increase of parasitic losses also.

I did look at the design of the hydraulic lifter. With more oil pressure, more force is acting on the plunger (~0.5" diameter, 0.2 sq. in).

At 40 psi, we have 8 pounds acting on the plunger. With 80 psi, we have 16 pounds acting on the plunger.

This may be a mute point because at max lift, spring pressure is about 300 pounds and thru the rocker arm and on the lifter is 450 pounds. I'll the 100 or so pounds of force from inertia.

So 600 pounds of force is acting on the plunger, 8 pounds won't matter much.

 

parasitic loss (general)= power that is not going to the rear wheels that should be..... Whether the power is lost through the pump or the friction of the parts moving within it is a mute point....its still power you didnt need to give up. Next time Ill use a bunch of technical jargon so everyone understands better.

Since we are the only ones on this thread I think we should both go back to

:lala: land