Advanced Engineering Tech - @@ Lobe Dynamics @@

Hello there, I've been searching for a thread or post on LS engine lobe tech. And it seems there nothing out thread, so I figured I start one.

For me, I'm some what tech savvy but could still stand to learn more about the secrets of lobe dynamics. I'm freshening my top end and getting the heads worked. So in doing so I'm considering a cam change to take advantage of the new higher CR and improved flow.

And thats what is propting my curiosity in the lobe designs. There are so many to choose from, I will be using a top engine/ cam guy but still would like to be educated on the parts going into my engine.

1)LSL
2)LSK
3)LSR
4)XE
5)XER
6)XFI
7)EPS
8)HUC
9)ect...

Just to be clear, I'm only interested in hydr. roller cams.

My question is; has any one put these different lobe designs (with same; INT Open, INT Close,EXH Open, EXT Close, and with all other specs being equal ) in a cam doctor to check ramp rates at specific areas (.006, .050, .200, ect..).

I'm really interested in the new HUC lobes but theres not much info floating around.

Thanks...and I'm looking for an education..

Bump. I'd like to pay close attention to this thread, as I also would like to understand more about the ramp profiles, and lobe designs. If I read them I understand, but sometimes its just better to have "real-world" experience from some guys that have tried one or the other and might have dyno printouts to show changes in RPM band or so on. Good post. Looking forward to info. generated on this one.

HUC lobes, hello.....anyone outthere ??

I thought this was the advanced section ?? I'm just trying to understand ramp rates and lobe profiles not string theroy or quantum physics. :nod::nod:

Ha I've noticed on here that a lot of the folks that know a lot don't wanna share their knowledge, they just wanna say "do a search" or just don't post. I wouldn't mind to know about this either. I can understand your frustration. I saw a thread on lobe designs somewhere but I can't remember if it was on here or another site.

Check out this thread, I can't copy and paste on my phone, but search for this thread, Camshaft Theory: Lobe Design. I don't know if it will completely answer your question, but it'll be a start I think.

Thanks for the lead...the lobes I'm reffering to (HUC) are some what new, I think. FYI, they are in the back of the new Comp. catalog.

And just FYI, I did a search but theres nothing definative on lobe tech (at least not in one thread). IMHO, there should be a sticky on ongoing data pertaining to lobe tech. Because inevitably thats what seperates the players from the wannabes (in terms of camshafts).

Thanks....and I truly understand how propriatary this info can be. But just wanting.....a little :D.

Why only hydraulic lobes???

Some people run solid lobes with hydraulic lifters. :D

Don't even think about doing it they other way around.

Admittedly I'm not familiar with the new HUC lobes, however the trend of
agressivness continues. More rise over the run (faster lifter acceleration)
I would imagine that at some point the hydraulic lifter will become the
limitation. Apparently the LS engines intake valve closing point finds it's
sweet spot @ 43-45 degrees ABDC. My thought is this has alot to do with the
intake manifold and port design which GM tried to duplicate a stepped cross
sectional area similar to racing headers only on the intake side. It starts large
and gets smaller(area-wise) as it approaches the bowl to enhance velocity
and promote a blend of tumble and turbulance but not too much of either.
This is to keep the fuel molecules more like mist than droplets since until direct-injection becomes common the port has to flow air AND fuel.
Also the LS cam cores were a unique diameter 15yrs. ago it required retro
fitting other lobes like from Ford cams. However as this engine continues it's
hot-rodding popularity these companies are designing lobes specifically for the
application. Geoff @ EPS is very informative with describing how .050, .200,
duration #s and the smooth control of opening and closing rates (which can
differ on the same lobe) all plays a vital role in making power as well as
extending valvespring life.....hope some of this helps

That was great info. That makes a lot of sense. I need to do some very extensive research looks like.

Whats going on Kevin ?? And thanks A.R. Shale Targa for the detailed break down.

Its been a interesting day, I've talked to Bullet, Cam Motion, LSM and Comp. about my current cam and lobes. After talking to Comp about lobes it seems the HUC is not really what I expected. They say it was designed for a lazy valve train, something that has heavier valves and in a marine application. The way the ramp designed was explained to me is, the lobe allows for the valve and springs to be "gently" sat down. A way of controlling a heavy valve train at higher rpm's. Sound like the opposite of the LSL's if you ask me, but I'm not a cam expert.

The reason I started this thread was to get a little insight into the lobe tech to see if it was worth a cam upgrade while the top end is off the motor. After talking to these gentleman it seems there would not be much gain if any from my current combo.

If anyone is interested I would be more than willing to spill the beans about the cam data to see if you guys think I should change cams to accommodate the new found CFM.

Again, thanks..

HUC lobes are not new. They work pretty well if the valve train is setup well. ;)

OK.....whats not new ?? If I remember right Comp said they have been out like a year or something. Is there a newer lobe design out since the HUC's ??

Hey, Stage 7 whats your take on the HUC lobe as described to me by Comp. ??

OK.....whats not new ?? If I remember right Comp said they have been out like a year or something. Is there a newer lobe design out since the HUC's ??

Hey, Stage 7 whats your take on the HUC lobe as described to me by Comp. ??

I guess it's perspective. 1+ years isn't new to me. The engine in my sig uses HUC lobes. These lobes are very stable. I'm not sure what you were told regarding ramp rate, etc, but they were intended for marine based apps.

Stage 7...you have a PM.

what did Cam Motion say about their lobes when you spoke to them?

Why only hydraulic lobes???

Some people run solid lobes with hydraulic lifters. :D

Don't even think about doing it they other way around.

:secret2:

I don't really dabble in the 55mm stuff, but just off the seat .050 .200 values, the HUC doesn't look to have that much area especially when you consider the base circle it will run. I've been running hydraulic lifters on solid lobes for the last 3 years with good success.

OK.....whats not new ?? If I remember right Comp said they have been out like a year or something. Is there a newer lobe design out since the HUC's ??

Hey, Stage 7 whats your take on the HUC lobe as described to me by Comp. ??

HUC is not new at all like Stage 7 said, it just wasn't in the catalogue till recently.

Most of the faster lobes in that list are not that good unless you have ultra light stuff and don't turn too much rpm.

LSK for instance is one of the worst in general. I have seen that lobe lose over 40 hp across the top of some engines.

HUC is not new at all like Stage 7 said, it just wasn't in the catalogue till recently.

Most of the faster lobes in that list are not that good unless you have ultra light stuff and don't turn too much rpm.

LSK for instance is one of the worst in general. I have seen that lobe lose over 40 hp across the top of some engines.

Erik, Is the 40hp loss you're refering to, generally when an LSK is used on a large intake valve AND over 7000 rpm? In your experience are the LSK fine on exhaust side under 7000 rpm?

I would not use the LSK unless you have light valves and a really good spring.

Ya'll are making start to wonder. I was spec'd LSL's with a stock LS3 valvetrain just upgraded springs.

The hollow stem LS3 stuff will work with that fine with good springs.

I remember reading somewhere on here that EPS lobes while ground by comp
were uniquely designed by Geoff and Pat G....can any one verify this ????
I looked real closely @ my baby EPS to see if I could understand what was
different about it and the opening flank looks aggressive and fast like a LSR
shape, but then the closing side sorta looks gentle so as to set the valve on
the seat and not drop it....perhaps a HUC shape. Geoff reitterated many times
about "smooth control...like a stalled auto; not an M6 snap"......then I remembered all the threads I read when cam searching about quiet valvetrains
and killer power w/beehives, etc....I know I'm just rambling but relative to this
thread kinda makes me go Hmmmmm.

The LSG lobe is EPS's lobe. G stands for Geoff I suppose :jest:

I remember reading somewhere on here that EPS lobes while ground by comp
were uniquely designed by Geoff and Pat G....can any one verify this ????
I looked real closely @ my baby EPS to see if I could understand what was
different about it and the opening flank looks aggressive and fast like a LSR
shape, but then the closing side sorta looks gentle so as to set the valve on
the seat and not drop it....perhaps a HUC shape. Geoff reitterated many times
about "smooth control...like a stalled auto; not an M6 snap"......then I remembered all the threads I read when cam searching about quiet valvetrains
and killer power w/beehives, etc....I know I'm just rambling but relative to this
thread kinda makes me go Hmmmmm.

As far as I understand it, the only person that actually designs lobes at Comp is Billy Godbold. When you want your own lobes made you just tell Comp what kind of properties you'd like them to have and he engineers them for you. Definitely not cheap.

Hello there, I've been searching for a thread or post on LS engine lobe tech. And it seems there nothing out thread, so I figured I start one.

For me, I'm some what tech savvy but could still stand to learn more about the secrets of lobe dynamics.

Just to be clear, I'm only interested in hydr. roller cams.

My question is; has any one put these different lobe designs (with same; INT Open, INT Close,EXH Open, EXT Close, and with all other specs being equal ) in a cam doctor to check ramp rates at specific areas (.006, .050, .200, ect..).

I'm really interested in the new HUC lobes but theres not much info floating around.

Thanks...and I'm looking for an education..

There really aren't any "secrets" per-se in our experience. The overwhelming majority have nothing to go by other than claimed durations in a lobe catalog. Those claimed or design specs are so vague as to be nearly useless when it comes to making comparisons. That being all most have to work with tends to create a great deal of speculation, misinformation, and perceived mystery. Claimed catalog specs are so ambiguous that the common interpretations based on them are often 180deg opposed to the reality of the lobe or series. As it pertains to the common GM LS1/LS2 valved, stock rocker, OEM lifter, & 5/16" PR setups there are lobes assumed to be mild that are actually anything but, and lobes assumed to be aggressive that are better choices than the "mild" lobes in that particular application. It only takes a few guys repeating a talking point they feel sounds correct or realistic for it to become a viral assertion and thus an internet "fact." :)

Most guys asking questions like this are attempting to determine what they are trading for performance, but with only vague generalities to go by it is rare that they manage to choose an appropriate grind based on forum claims. There are so many ways a lobe can be aggressive or mild depending on the remainder of the valve train system that your best bet is typically to do as you mentioned & find someone to determine what is appropriate for your specific setup & intended use. Lobe "aggressiveness" not only varies from lobe family to family, but also between various areas of the individual lobe. That is compounded by the fact that often times not all lobes in the family exhibit equivalent velocity/accels/jerk/etc, have slightly different operating ranges, etc. Furthermore, "aggressive" and "mild" are also relative terms and require a point of reference to be meaningful.


Ha I've noticed on here that a lot of the folks that know a lot don't wanna share their knowledge, they just wanna say "do a search" or just don't post.
Very few have actual data on various lobes/systems/etc. It also helps sell cams if you perpetuate the myth that lobe design & cam selection is akin to black magic. :D


IMHO, there should be a sticky on ongoing data pertaining to lobe tech. Because inevitably thats what seperates the players from the wannabes (in terms of camshafts).

Lobe 'technology' is largely a marketing idea/term IMO. I have begun to put together some cam info on our revised site that attempts to point out what we think the average consumer should consider vs. the common vague talking points. It touches on the common "technology" talking point: http://www.advancedinduction.com/LSX/AiLSxBilletCams.php

Why only hydraulic lobes???

Some people run solid lobes with hydraulic lifters. :D

Don't even think about doing it they other way around.

While it is certainly common to run a hydraulic lifter on a "solid" lobe, it is also common to run a solid lifter on "hydraulic" lobes. It is no more inherently precarious than the former situation - both require careful selection & application in our experience. :)


When you want your own lobes made you just tell Comp what kind of properties you'd like them to have and he engineers them for you. Definitely not cheap.

Generally that is how new designs are come up with. A customer will typically request something be made either for a specific application, or a line of lobes be made so they have something unique to sell. You can specify particular limits to specific characteristics, but very few have the data to even begin to do that. More often than not new lobes are only minutely different from existing catalog designs. While the performance value is often low, the marketing value of something new is typically high. That being the case, paying for "new" or proprietary lobes can be worth doing.

Beyond that, one can employ some of the same tools & software to come up with profiles for a particular system that do offer a performance advantage. Our proprietary grinds were refined/created based on simulations & testing w/ existing known good cam grinds. I used 4sthead which many cam companies, race teams, etc. utilize. There isn't a great deal of info on their site, but http://www.profblairandassociates.com/index.html does have some tech articles you may enjoy.

In the end, there being thousands of lobes out there, it is rare that it is actually worth creating a new lobe design. Additionally, getting a theoretical system "perfect" is simply beyond the point of diminishing returns for cams sold to the public. With no control over their implementation I personally ended up with so much headroom (safety margin) that almost invariably there was a readily available suitable lobe for a given application. We are typically supplying camshafts with our heads, and with a superior head design it does make it easier to simply back things down a notch & rely on the head to get the results. The power is in the head/manifold & machinework... while your valve train will largely determine the reliability/longevity of a given setup IMO. In the end, almost all common lobes can be made to run reliably if the rest of the VT is appropriately selected, installed, and adjusted.

Erik's comments are a good example of what I am talking about - the LSK's work OK for many people, but a milder lobe sacrifices little if anything considering the longevity, rpm headroom, etc. it may gain. That is the kind of mentality you want your builder to exhibit when it comes to engines that have to live awhile.


I think most would be surprised at how similar most of the commonly run LS lobes are. I realize this is tough to really read, but it illustrates the point:

http://www.advancedinduction.com/Cam/graphs/AiComparison-CommonCCLSLobes.jpg

Still, there are distinct advantages and disadvantages to them. To further muddy the waters, consider that those graphed are all similarly styled. There are many different styles of lobe out there. :)

In the end I think you'll find that the only truly useful info for the consumer is the link to our cam page. However, these discussions are certainly engrossing. :)

-Phil

How do you argue with a graph like that? Why would anyone run a cam that is so much mroe agggressive, yet yields little gain.

I like my valve springs to stay in one piece for a long time.

How do you argue with a graph like that? Why would anyone run a cam that is so much mroe agggressive, yet yields little gain.

I like my valve springs to stay in one piece for a long time.

Well, some people don't mind the trade off for a few extra hp, or the same power w/ slightly less low rpm trade off. I believe the most likely explanation is that many simply don't know what the trade off will be. Dyno #'s at 0 miles sell parts. It's all a compromise & this being the aftermarket, there are no guarantees. :)

I hope this question is not to generalized;

If my valve train is relatively light....

1)Intake valve..high 70's...grams
2)Exhaust valve..high 50's...grams
3)PRC .675...Install Height: 1.800"
Closed Spring Pressure: 157lbs @ 1.800"
Open Spring Pressure: 471lbs @ 1.125"
Maximum Spring Lift: .675"
Coil Bind 1.060"
Spring Rate: 483lbs/in
4)Comp Ti retainer..high 50's...grams
5) stock locks..3...grams (x16)
6)stock rockers..low 80's...grams + weight of trunnion....with the rocker arm trunnion supported and the tip of the rocker on the scale. Scale zeroed prior to measurement it measured 8.3 grams.


Is this cam optimal considering what was said about the LSL/HUC lobes ??

CAM
(LSL) INT. 235@.050 (HUC) EXH. 247@.050
Lift INT.=.620 w/1.7 EXH.=.632 w/1.7


Or would I be better with a "faster" ramp considering the lightness of the valve train ?? Or maybe I should first ask if you consider this a light setup ??

Thanks.....

I hope this question is not to generalized;

If my valve train is relatively light....

1)Intake valve..high 70's...grams
2)Exhaust valve..high 50's...grams
3)PRC .675...Install Height: 1.800"
Closed Spring Pressure: 157lbs @ 1.800"
Open Spring Pressure: 471lbs @ 1.125"
Maximum Spring Lift: .675"
Coil Bind 1.060"
Spring Rate: 483lbs/in
4)Comp Ti retainer..high 50's...grams
5) stock locks..3...grams (x16)
6)stock rockers..low 80's...grams + weight of trunnion....with the rocker arm trunnion supported and the tip of the rocker on the scale. Scale zeroed prior to measurement it measured 8.3 grams.


Is this cam optimal considering what was said about the LSL/HUC lobes ??

CAM
(LSL) INT. 235@.050 (HUC) EXH. 247@.050
Lift INT.=.620 w/1.7 EXH.=.632 w/1.7


Or would I be better with a "faster" ramp considering the lightness of the valve train ?? Or maybe I should first ask if you consider this a light setup ??

Thanks.....

What is your intake valve?
I would think you would be just fine on the LSL lobe.

I hope this question is not to generalized;

If my valve train is relatively light....

1)Intake valve..high 70's...grams
2)Exhaust valve..high 50's...grams
3)PRC .675...Install Height: 1.800"
Closed Spring Pressure: 157lbs @ 1.800"
Open Spring Pressure: 471lbs @ 1.125"
Maximum Spring Lift: .675"
Coil Bind 1.060"
Spring Rate: 483lbs/in
4)Comp Ti retainer..high 50's...grams
5) stock locks..3...grams (x16)
6)stock rockers..low 80's...grams + weight of trunnion....with the rocker arm trunnion supported and the tip of the rocker on the scale. Scale zeroed prior to measurement it measured 8.3 grams.


Is this cam optimal considering what was said about the LSL/HUC lobes ??

CAM
(LSL) INT. 235@.050 (HUC) EXH. 247@.050
Lift INT.=.620 w/1.7 EXH.=.632 w/1.7


Or would I be better with a "faster" ramp considering the lightness of the valve train ?? Or maybe I should first ask if you consider this a light setup ??

Thanks.....

Your masses appear off to me. You can run any lobe with any spring for the most part, the question is what kind of RPM will it control the valve train to, will it be hard on specific parts etc. That is quite a bit of spring load - the LSL's are typically controllable to 6800-7200rpm with far less spring & the HUC's even more so. If you were staying with Comp, you could move to one of their higher lift series lobes, but if they're in the same duration range it won't likely make a large difference in output vs. the LSL.

What is your intake valve?
I would think you would be just fine on the LSL lobe.

Just your typical 243...2" hollow stem intake 73 gram valve.



Thanks....

Your masses appear off to me. You can run any lobe with any spring for the most part, the question is what kind of RPM will it control the valve train to, will it be hard on specific parts etc. That is quite a bit of spring load - the LSL's are typically controllable to 6800-7200rpm with far less spring & the HUC's even more so. If you were staying with Comp, you could move to one of their higher lift series lobes, but if they're in the same duration range it won't likely make a large difference in output vs. the LSL.


LS6: intake = 73 grams, exhaust = 65 grams ....not sure if that is what you were refuring to...and about the RPM..I'm spinning it to 6800-6900ish.

Thanks...

Some good discussion here.

FWIW, I ran a 223/227 Comp LSK cam in my H/C LS1, which made approximately 295rwkW (395hp) on an Australian dyno. When I changed lifters at around 40k miles of (mostly) highway use - steady 60-70mph - I found it had become a bit pitted on a couple of lobes. I was using Patriot Gold duals with Ti retainers and set up properly, etc and was revving it to 6800rpm.

I put a 223/227 Comp LSL cam in to replace it and made 3rwkW (4hp) less at peak and a little less torque, so not a great deal of difference - certainly not to a purely street-driven car. So, in my application, not a large trade-off, for a slightly milder lobe.

I think the LSL is a good compromise lobe, not as aggressive from .006 - .050 as the XE-R and not as aggressive from .050 - .200 as the LSK, but a fairly good compromise between the two.

In my current car, I'm using a 215/223 LSL camshaft and it is making some great numbers (better than the larger cams did!) and peaks at 6250rpm, with the rev-limiter set at 6600rpm - no need to wring it out at all.

cheers

Pitted lobes sound like a faulty cam....

Pitted lobes sound like a faulty cam....

Not always, especially with lobes like the LSK.

Well I know Comp has had some quality issues in the past.

HUC lobes on my cam. 7200rpm shift point. Good enough to make my 4000lb heavy beast go 11.5004 @ 118.8mph with a 4200ft DA.

http://i4.photobucket.com/albums/y121/jonschwenn/IMAG0445.jpg

Found some interesting reads....that I thought you guys might like.....of course valve train based.

http://www.cds-valvetrain.com/Doku/Valve%20Train.pdf

http://www.tech.plym.ac.uk/sme/desnotes/valvet1.htm

And here is an interesting thread on the bullet about increasing base circles...and the effects.

http://www.yellowbullet.com/forum/showthread.php?t=420668




Thanks...........

Very good reading!