Most people here want aggressive cam lobes. Why? Because someone told them they are better. So what is an aggressive cam lobe? To take the most advantage of the LS Chevy engine design the cam lobe must be smooth and stable. Generally in this LS Chevy engine, the smoother and more stable the cam lobe, the more power and RPM capability the engine will have. So generally the less aggressive lobe will make for the most aggressive (powerful) engine.

There is no need in having 8 different lobe styles or variations for the LS Chevy hydraulic cams. Most of the engine combinations I see on here run from idle to 6500 RPM with a valve lift from .550” to .650” lift and with spring seat pressure 130lbs to155lbs with 350lbs to 400lbs open pressure. The measurable differences in these lobes are very slight, the real difference is that some of them operate very well and others do not. The “hard” or “aggressive” lobes may make a small amount more vacuum at idle and may show a two pound gain in torque at 4000RPM but will cause more valve noise and float the valves sooner plus having a destructive affect on valve train parts and valve seat sealing. The “softer” lobes will have a little less vacuum at idle but provide quite valve train operation and extend the valve “float” RPM 300-500 RPM and do not destroy valve train components.

What do you call “aggressive? Is it high acceleration or high velocity? Which is harder on the valve train? The cam with higher lifter acceleration rates will be harder on the valve train.

Let us compare technical data on two lobes both with 230 degrees duration at .050” with .350” lobe lift. One lobe we’ll call “hard” the other “soft” even though I don’t like to use the word “soft”, but it is soft compared to the hard lobe. I prefer to call it the correct lobe for your engine.

Compare:

HARD SOFT

MAX ACCELERATION: .00037 .000323

MAX VELOCITY: .0073 .00775

NOSE ACCELERATION: .00023 .000212



So which one is more “aggressive”? The soft one moves the valve FASTER or higher speed. So what is aggressive? One of the reasons the hard lobe floats the valve sooner is because it has higher “nose” acceleration, which is negative acceleration at the top of the lobe.

 

Thanks for sharing!!

 

Good info Kip!
I still think to many people relate a higher lift cam to automatically being the more aggressive cam, when it's sometimes quite the opposite. Like comparing Comp Cam LXL and XER lobes.

 

Interesting

 

I have the EPS lobes ground by Cam Motion. Would you classify them as soft? Using the above comparison?

 

^^ That question.

 

I would call them correct for your application. They would be called soft. They would have less acceleration but more velocity/speed. What that means is the lifter/valve will move more per degree of rotation.

 

My pet peeve is when someone uses only lift to describe the size of their cam.

 

This, or when they think that lift is going to be the determining factor regarding piston to valve clearance.

 

Excellent. They seem to work pretty well!

 

Stable doesn't sound tough and powerful while aggressive does. I think that since the ls1 has a lighter valvetrain than previous pushrod engines people were pushing the intensity of their cams. Common sense is coming back around so people are seeing better results.

 

Are Cam Motion lobes asymmetrical ?

Quoted from the cam guide sticky.

Most people here want aggressive cam lobes. Why? Because someone (JRP) told them they are better.
But that was then (2005). Now we look at the rate from .050 to .200 also. Are you calling the number from .006 to .050 the acceleration and the number from .050 to .200 the velocity ? I can understand how a fast rate from .006 to .050 would be hard on parts, especially springs but wouldn't a fast rate from .050 to .200 float a valve easier ?
Comparing your Titan V to your Penetrator , one would guess the 230* lobe used on the Penetrator is more aggressive because of the .637 lift compared to the .612 of the Titan. Do both of these cams have the same .006 to .050 rate ?

 

Velocity is the speed in which something is travelling. Acceleration is the rate by which the velocity is increasing.

A smooth lobe achieves its velocity by accelerating at a controlled, steady rate.

A well designed lobe can still reach high velocities while maintaining controlled acceleration rates.

I am betting Kip will agree that too aggressive of a .050"-.200" intensity does indeed lead to an earlier valve float RPM.

 

You are absolutely correct Sir.

 

Our lobes are asymmetrical, or as I say non-symmetrical. Symmetrical lobes would be OK for this type of application. Unfortunately, there are many myths about cams, cam lobe design, and cam lobe separations that have been passed down over the years. One of the most famous pioneers in NHRA pro stock engine building called me when we were heavy into making pro stock camshafts. He wanted to try one of our cams. We started talking about different combinations and he said “I have tried a cam on a 114 lobe separation and that does not work”! I knew then we were not going to be able to work together.

Someone came up with this statement and it stuck, “THE MORE AGGRESSIVE THE RAMP RATE, THE MORE OVERALL AND UNDER THE CURVE POWER”. It was probably some cam lobe designer trying to BS people. Ramp rate? What is that? Velocity? Acceleration? Degrees from .006” to .050”? You must have high acceleration and jerk to have a lobe that has a low .006” to .050” number like 49 degrees, and that will beat the snot out of the lifters and be noisy. We use a smoother ramp of about 55 degrees. The .050” to .200” can be pushed if you want a high duration @.200”, but you will have higher accelerations before and at the nose which will float sooner. If you have two cams, both having 230@.050”, one with .340” lobe lift, one with .360” lobe lift, the lobe with the higher lobe lift (.360”) will always have a higher .200” duration.
Why does everyone want to know the .200 number? because some said the higher the .200 number the better the lobe? Or is it more power it will make?

 

Kip I talked to you yesterday. Name is Zach if you remember, I assume you would cut that cam asymmetrical?

 

You diving off into the deep end and getting a new cam?

 

 

"Comm-on man"!

 

Yes sir it sure would. I see you may ad Nitrous soon? When we make cams for Nitrous,Blown or Turbo charged engines we use a little different Exhaust lobe because of the opening presser. A softer lobe make it easer to open the exhaust valve.