Lobe separation

I'm not twisting. I have done nothing other than quote you and ask you to clarify your statements and pick which one is a lie. Still waiting.


Zach
 
This thread is about camshaft lobes.....Lots of people could learn about the subject since not many people here have spent hours watching a valve train work, and noting the changes made when the camshaft is degreed differently.

That said...

Put your damn petty differences aside about your products in this thread and actually put up relevant information. We're all tired of this rock throwing garbage. No one learns anything from it and we go from a good, useful thread to a heap of garbage. If you can't say something useful about the subject or ask a relevant question then please, by all means, stay out of it.
 
partsguy662 said:
This thread is about camshaft lobes.....Lots of people could learn about the subject since not many people here have spent hours watching a valve train work, and noting the changes made when the camshaft is degreed differently.

That said...

Put your damn petty differences aside about your products in this thread and actually put up relevant information. We're all tired of this rock throwing garbage. No one learns anything from it and we go from a good, useful thread to a heap of garbage. If you can't say something useful about the subject or ask a relevant question then please, by all means, stay out of it.
Click to expand...

thanks.
 
You Go Boy!!!!

Opened up a can, didn't ya!!! lol



partsguy662 said:
This thread is about camshaft lobes.....Lots of people could learn about the subject since not many people here have spent hours watching a valve train work, and noting the changes made when the camshaft is degreed differently.

That said...

Put your damn petty differences aside about your products in this thread and actually put up relevant information. We're all tired of this rock throwing garbage. No one learns anything from it and we go from a good, useful thread to a heap of garbage. If you can't say something useful about the subject or ask a relevant question then please, by all means, stay out of it.
Click to expand...
 
I have actually never seen a diesel pro cam. Any good, I don't know.

This is all I know, they use regrinds and they don't release specs. Maybe they can chime in on their lobe separations.

Zach
 
Here is some exhaust lobe data from 2004 testing I just pulled out of my files on 3 cams. A stock marine cam, a stock CR cam and a Helix 2.

This will help show ramp rates to anyone interested.

EX Duration .003"_____.006"______.020"______.050"

Marine............318.........295.8.........237.1..........202.4

CR Stock.........319.........294.2.........225.8..........191.6

Helix 2............342.........319.3.........235.5..........208.2

The lower lift areas between .003" and .020" is where the better part of the ramp lies on the lobe. The higher the number on the table above, the longer the valve is open and the faster it is opening. Although this does not mean the wear HAS to go up. It can be much less if the lobe is designed properly. This clearly shows a very fast acceleration of the lobe on the Helix 2.

I have files on most of the popular cams available. Including all the stock lobes and many prototypes we have yet to use or release.
 
There are a lot of parameters that go into designing a cam shaft. It is hard to look at any one of them by themselves and be definitive about the effect it will have.

As a general rule a narrower LSA will increase valve overlap, and a wider one will decrease it. Traditionally turbocharged engines will run a wider LSA to decrease the amount of time that both the intake and exhaust valves are open at the same time (valve overlap). Supercharged engines will often run narrow LSA's to increase cylinder scavenging. Normally aspirated will generally run a wider LSA for lower engine rpm, and a narrower LSA for high rpms.

These are all just general rules, that really don't mean much by themselves. All of the cam specs must be taken into consideration. Keep in mind though our trucks are normally aspirated until they produce boost.

Paul
 
Here is the intake data from the same 3 cams

Intake Duration.. .003"_____.006"_____.020"_____.050"

Marine.................270...........240.9.........202.7.........175.2

CR Stock.............281.4........252.1.........187.6.........161.6

Helix 2................301.2........271.2..........219.6.........189


The marine cam lobe used by several vendors for their intake side is actually giving less duration than a stock CR cam at the low lift areas. You will actually get less airflow using these "mileage" or "towing" cams.

The Helix 2 has 30 degrees more than a towing or marine cam and 20 more than a CR stock cam at the low lift area of .003" of lobe lift.

There is a ton of mis-information about the Cummins cams out there. Dont look only at the .050" duration values. These are helpful, but far from the whole story.
 
Cam i just purchased to put in my 03 CR is a 174/215 with a LSA 112, how is it going to work spooling a S400 71mm with a .90 exh housing. whats your guys thoughts.
 
jordanjames81 said:
Cam i just purchased to put in my 03 CR is a 174/215 with a LSA 112, how is it going to work spooling a S400 71mm with a .90 exh housing. whats your guys thoughts.
Click to expand...

It could be worse than a stock cam if it what I think it is.

The 174 lobe is most likely a 175 marine lobe that was copied. Typically a grinder will lose a degree of duration and even some lift when they copy the lobe over. If this is the 175 marine lobe, it has less duration at low lift than your stock cam had.

The 215 is most likely a copy as well. I have seen this lobe copied by 2 vendors. I have the specs here and will post them below.

The best way to know what you have is to have it measured to get the lift and duration numbers from .001" all the way through the complete cycle.

Here is the 215 exhaust lobe I see all the time.

Ex Duration.......003"____.006"_____.020"____.050"

215 lobe............319.____290______238______215

As you can see the 215 degrees @ .050" value given seems so much better than the stock 191.6 on its face, but it is no better at low lift and slightly worse at .006"
 
Wow....The Holidays has got Don in a giving mode!!

Keep it coming!! for those who understand it better than I do..lol

Thanks Don...Trying to learn..
 
here's numbers off the cam card
intake exhaust
Duration at .50 174 215
lobe lift .2870 .3050
lsa 112 op -cl op-cl
timing event.050 -15 9 49.5 -14
duration at .20 220 260
gross lift .431 .458
vavle lash .012 .014
degree intake lobe to 102​
hope this helps, I hope i havnt purchsed a cam that not gonna help me with the hp mark im looking for. i purchased this from a vendor on here but not saying any names.
 
jordanjames81 said:
here's numbers off the cam card

intake exhaust​

Duration at .50 174 215
lobe lift .2870 .3050
lsa 112 op -cl op-cl
timing event.050 -15 9 49.5 -14
duration at .20 220 260
gross lift .431 .458
vavle lash .012 .014
degree intake lobe to 102​
hope this helps, I hope i havnt purchsed a cam that not gonna help me with the hp mark im looking for. i purchased this from a vendor on here but not saying any names.
Click to expand...

It certainly is not a marine lobe or the 215 lobe I was thinking it was. I wonder what the low lift numbers are?

There is not enough info there to tell the whole story. It has more duration than a stock cam.
 
how about this one?

intake exhaust
@.050 180 200
@.020 200 228
@.006 214 240

valve lift .442 .501

lash .008 .008

lobe sep 108

installed @ 100
 
Soup Nazi said:
Here is some exhaust lobe data from 2004 testing I just pulled out of my files on 3 cams. A stock marine cam, a stock CR cam and a Helix 2.

This will help show ramp rates to anyone interested.

EX Duration .003"_____.006"______.020"______.050"

Marine............318.........295.8.........237.1..........202.4

CR Stock.........319.........294.2.........225.8..........191.6

Helix 2............342.........319.3.........235.5..........208.2

The lower lift areas between .003" and .020" is where the better part of the ramp lies on the lobe. The higher the number on the table above, the longer the valve is open and the faster it is opening. Although this does not mean the wear HAS to go up. It can be much less if the lobe is designed properly. This clearly shows a very fast acceleration of the lobe on the Helix 2.

I have files on most of the popular cams available. Including all the stock lobes and many prototypes we have yet to use or release.
Click to expand...


If you subtract duration at .003" from .020" of all three cams which is the most common method used to determine lobe intensity/acceleration rate you will find that the helix exhaust lobe is the slowest of the bunch. Sure it has more duration but the degrees it takes to get from .003" to .020" is 106.5 vs 93.2 degrees for the stock cam and 80.9 degrees for the marine cam.

Are you contesting the Helix 2 cam has a more agressive opening rate from .003" to .020" or are you just saying that the valve will be open farther due to more duration built in this cam? Some clarification would be appreciated.

From .003 to .006 the fastest to slowest is: Marine, Helix, Stock. This number is more indicative of beating up the lifter though given at .010" or close to a setting of lash the lifter won't even be loaded at this point or not loaded by spring pressure.

From .006 to .020 the fastest to slowest is: Marine, Stock, Helix. Is this to soften the initial hit?

From .020 to .050 the fastest to slowest is: Helix, Stock, Marine. Seems the Helix begins agressive lift in this region which is more important to opening the valve sooner. Is the difference between .020 to .050 why you say "This clearly shows a very fast acceleration of the lobe on the Helix 2"?

Not trying to argue only wishing to understand where you're coming from. From what I see in the lobe intenstiy numbers it seems the Helix exhaust lobe is easier on the lifter during the initial opening phase which would promote an easier life for the cam/lifter and then off to the races from .020 to .050!
 
I thought that this was supposed to be about LSA's only. Do we need to start another thread for Helix ramp rates?

Why must you use such slow ramp rates? If you used faster ramps, you could get better bottom end spool with tighter LSA's and better top end as well. Glad to see you have changed your profile up a bit though, the old one was pretty rough.

Zach
 
There you go again. Another snipe. These are the same lobes the Helix used since 2004.

Anyone can understand that a lobe with less duration VS a lobe with more will almost always have a faster rate of lift as long as the lobe lift is similar in height. In other words a longer duration cam is more round, less peaky.

The CR cam has a short duration and has nearly .300 lift. The Helix is much longer duration and roughly the same lift. This is an easy mental picture to understand when compared to a mountain range. A peaky mountain with a fast rate of climb will have less real estate ( so to speak ) between its sides. A fatter mountain will have more real estate and will take more time to climb to the other side. The duration of time the Helix lobe spends lifting the tappet is simply longer. Clearly the duration figures I gave are longer.
 
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