Hyd. roller lifters to solid roller lifters?
 

I have a hyd. roller cam at present and thinking about going with solid rollers on it. It has .660 lift on it and is steel billet. Has any body done this and what kind of results did you have?

I did on a pair of motors a few years back, picked up approx. 30 HP in the upper RPM scale

FBC,

In most cases hydraulic roller lobes can be run as tight lash solid rollers. Given a .006” lash ramp and a 1.7 rocker ratio a HOT lash (iron block/aluminum head) figure for this application would be .010”.

Now for the liability side, a 250°/.390” HR lobe will decrease ~4° in effective duration to 246° and the gross lift at the valve will drop .010” from .663” to .653”. Putting this into a more comparative light, with the lobe design remaining the same you would need a 254°/.396” T/L SR to maintain the equivalent lobe area to the 250°/.390” HR.

In the asset column, the elimination of the hydraulic mechanism in the valve train reduces compliance in the system allowing a more accurate translation of rotary motion (cam lobe) to valve path at the seat. (Valve)

Developments in hydraulic roller technology have significantly reduced the delta in competency between the HR and SR systems in many applications. Let’s use a naturally aspirated 540 CID making 700 hp at 6000 RPM with a properly matched valvetrain as an example. Keeping all else the same, with only a lifter change, and a spring pack that’s designed to stabilize the dynamic mass the valvetrain, you would likely see an increase of around 10 hp at peak, maximum. If you saw more than that, it would likely be due to a deficiency somewhere in the valvetrain of your baseline engine.


Now things start to really change when you’re dealing with forced induction applications at horsepower levels above 1000 HP. We’ve looked over data amassed from literally dozens of forced induction applications ranging from 1000 to 1400 hp. I can tell you unequivocally that the dynamics of maintaining stable valvetrain with hydraulic rollers at those levels becomes considerably more challenging. The Morel .903” hydraulic roller lifter, with a .810” wheel, is arguably the most competent piece of hydraulic roller valvetrain available today. I have the results of A/B testing evaluations (Hyd vs Solid) performed by Haxby Speed and Marine at levels above 1200 hp. Let say the results were enlightening, to say the least.

Bob

Thanks Bob for the reply. I am going to have some manifold work done I though while I had the manifold off I might go to solid rollers. This is one of your cams. Just trying to get some opinions. Thanks . Fred

Are you having problems with the hyd roller lifters, or just looking for more power? From what Bob has said, sounds like minimal power gains and negligible durability increase for the cost of new lifters and pushrods, as well as the potential extra maintenance of checking valve lash.

No problems,I was wondering since I spin it to 6000 rpms what I would gain by going to solid rollers.