Higher ZDP in a roller camshaft engine

[buster]

Quote:
. Not so much on the lifter anymore but both pushrod ends are contact points as well as the valve stem. So a roller motor can still benefit from a zinc additive but a flat tappet much more so.


Do you think there are any benefits of higher ZDP levels in engines that have roller cams? The consensus seems to be no. Engine wear has been reduced to a minimum on most modern engines using API oils which have continually lowered the ZDP levels.


Quote:
The advantages of a roller cam include: no need to break-in the cam on initial startup, the lifters can be reused if you change cams, the open and close ramps of the lobes are faster, giving you more torque and horsepower for any given grind, roller cams wear at a fraction of the rate of standard cams, and roller cams can use the latest blends of motor oil with out the zinc, so no additives are needed.


Link


RP's take:

Quote:
Yes. All Royal Purple engine oils contain the zinc/phosphorous compound zinc dialkyl dithiophosphate (ZDDP). Royal Purple HPS and XPR lines of engine oils are formulated with a higher concentration of these elements and are suitable for both roller and flat tappet valve trains

 

[A_Harman]

High zddp may not be needed to protect the cam interface, but more couldn't hurt. ZDDP also protects the ring pack from wear and is an oxidation inhibitor as well.

 

[friendly_jacek]

ZDDP is also important for controlling timing chains wear. this is the main reason we didn't see ZDDP banned yet.

 

[buster]

Thanks for the info guys.

 

[mechtech2]

What about the INSIDE of the roller?
Some have needle bearings, and some slide on pins.
Very different needs.

 

[A_Harman]

In needle roller bearing assemblies, the highest stress is on the bearing axle, and that is the life-limiting component. People here spend most of their time obsessing about how the cam and roller look, but they never get to see the bearing axle, which is the components that starts pitting first. The ID of the roller is the lowest-stress part of a needle roller bearing assembly.

On rotating cam followers, the contact stress is very low, but since the motion is pure sliding between the axle and roller ID, wear can occur. These types of cam followers are used a lot in heavy duty diesels, using steel rollers on pressure-lubricated bronze axles. I worked with these a lot at Cummins.

 

[Brigadier]

My 06 Colorado 3.5L has rollers, and I have debating on trying RP HPS[no warranty] 5W30 just for the extra measure of protection.

 

[buster]

RP HPS looks like a very nice oil.