Racer Brown Cam

[olie05]

My position makes perfect sense. The cam lobe is either symmetrical in shape or it is not. If I weren't talking about the cam lobe, and were actually talking about valve speeds or cam timing, I might refer to that as "valve speed symmetry" or "valve timing symmetry" but that is not what people are talking about when they say "asymmetrical camshaft." While your description of valve timing events might be more accurately called "symmetric", that has no bearing on the common meaning of the term asymmetric cam. The common definition refers to the shape of the lobe and the ramps. Some evidence follows. This took about a few minutes to look up on google. You can try and find some that say that asymmetric cam refers to valve speed or valve timing, but based on what I just found I think you'll be looking for a while.

 

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Here's one that even refers to what you and Tony are talking about.

http://www.metricmechanic.com/catalog/dual-profile-asymmetrical-cam.php

"If you look at the BMW intake and exhaust cam lobes, they will appear to be a mirror image of one another and ground with an asymmetrical profile. When you plot out the lift curve on a piece of graph paper, you'll discover that the asymmetrical BMW lobe looks like a symmetrical bell shaped curve. The reason this phenomena occurs is because as the nose of the cam wipes across the curved foot of the rocker arm, the rocker arm ratio changes from a low of 0.9:1 to a high of 1.6:1 (with an average of 1.25:1). So, if we combine a fairly symmetrical lobe with BMW's variable rocker arm ratio we end up generating an asymmetrical cam map."

 

Is everybody else wrong, or are you and Tony wrong?

 

Jon,

 

Almost all the links you posted to the definition of asymmetrical cams are referring to cams that would be used in engines with relatively fixed/constant rocker ratio, which would also result in a symmetrical cam giving symmetrical valve opening/closing.

 

Maybe the nomenclature doesn't agree from one source to the next, but I would have to agree that almost all L6 cams would have to have asymmetrical "cam profiles" to optimize the changing rocker ratios for valve velocity/acceleration (as mentioned in your BMW quote.)

 

For the Original Poster,

 

Why not buy some v-blocks as Jon mentioned earlier, get a dial indicator and a degree wheel and measure the cam all the way around. Then model the valve movement as the cam acts through the rocker arm, and check out what the lift is.

 

At that point you would have more information than the original cam card had. (might be more work than you signed up for though.)

 

Also, if anyone is willing to take measurements of their cam (don't care if it's stock or regrind) and send them to me, I would be happy to model the resultant lift at the valve.

Edited November 8, 2010 by olie05

[JMortensen]

People who use the term "symmetric cam" are talking first and foremost about the shape of the lobe, I think that is clear based on the links I posted. You're partially right though Tim. I assumed that the shape of the lift curves when plotted would be roughly analogous to the shape of the lobe. So when I said I had two cams that were asymmetric, I made that distinction based on the shape of the lobe, because "everyone knows how to tell an asymmetric cam". I learned something about my erroneous assumption about how the cams really act from your post and I appreciate the education. Regardless, the cam that acts like we are all describing with regards to timing is still going to have an asymmetric profile, with a fast lift ramp and a slow close ramp.

 

Tony's assumption that Delta, Sunbelt, and Isky make asymmetrically timed cams for the L series and "others" use "old tech bumpstick profile" still strikes me as wrong and if I were one of those "other" cam manufacturers I'd be insulted by it. As you pointed out Tim, virtually every cam that you can find for an L series is asymmetrical. Don't you think it would be a strange thing to assume that every cam manufacturer had gone through and found the proper profile to get equal timing events on the open and close of the valve, and then make all of their cams a variation of that basic profile to maintain their symmetry, especially while simultaneously advertising that their asymmetric cam profile opens the valve quickly and closes it slowly? Are they all liars, or are they all too stupid to figure it out, while simultaneously being smart enough to ensure the symmetry of all of their L cams? No customer with a race car ever plotted it out and came back and said: "Hey, this thing actually opens and closes pretty evenly"? And no cam manufacturer ever cared enough to put their cam in a car with a degree wheel and a dial indicator and check what the thing actually does on the engine and then thought to himself: "Hey, what if we modified this thing to actually open the valve quickly and close it slowly, in the same way that works with our cars that don't have the curved rocker contact surface throwing the cam timing off?" None of those cam grinders ever put it through a computer model? Really? I dunno. It seems like you have to have an awfully low estimate of a lot of peoples' integrity or intelligence to believe such a thing.

Edited November 8, 2010 by JMortensen

[Tony D]

I dunno, in the pushrod realm, and assymetric cam was quite a revolutionary thing.

 

To discuss what a cam manufacturer does or doesn't do when you aren't one seems arrogant and presumptious, IMO.

 

Ron seemed straightforward about their R&D: "We copied a BMW profile just to have something to offer initially. It's amazing to see our profiles from back then directly copied on other people's cams, even to this day! They make power I guess, but they aren't right. When we were working with Electromotive ten years later, Nissan wouldn't give us ANY information, so we had to shadow-profile their stock cams and that's when we realized they were doing things quite a bit different from what BMW did, the profile was all wrong for the Nissan Engine and I had to totally re-engineer the ramps to get an assymetric valve action. From that, we changed everything we did on the L-Cams."

 

Like I said before: Plenty of IMMITATORS, but few INNOVATORS. If it runs and makes power, and you can just rip it off from someone else, why ENGINEER it? Yeah, the Chinese are the only ones that do that, right? It would NEVER happen in the USA with something as complex as a camshaft...

Edited November 8, 2010 by Tony D

[JMortensen]

To discuss what a cam manufacturer does or doesn't do when you aren't one seems arrogant and presumptious, IMO.

 

Like I said before: Plenty of IMMITATORS, but few INNOVATORS. If it runs and makes power, and you can just rip it off from someone else, why ENGINEER it? Yeah, the Chinese are the only ones that do that, right? It would NEVER happen in the USA with something as complex as a camshaft...

Glad we cleared that up.

[Tony D]

Concentrate on that which doesn't blow your argument out of the water? Interesting that's your only comment now...

 

I can delete those portions if that makes you feel better John, but they both bring out two salient points to your ad hominems about my comments from earlier. What, is this a goose-gander situation?

 

I mean, facts of the matter are that many cam manufacturers simply rip off profiles. Isky did it, and admits it. And they also went back to revisit the design when it became obvious they needed to. And the evidence remains clear today that many other cam manufacturers HAVE NOT done this.

 

Which directly addresses your sarcastic comment about assuming other manufacturers being competent enough chack what their designs do on an engineering level. Well perhaps THEY HAVEN'T...the evidence exists that some still have the SAME grinds they stole back in the 70's. Perhaps it's simply as Ron said: "they make power I guess, but they aren't right"---so their criteria may simply be limited to functionality, defined as power production. For many people that is all that matters.

 

Never ASSUME total competence from a guy simply because he has a shingle hung out. Limited competence, or performance is one thing, engineering backed knowledge of what is going on is something totally different. I limited my comments to what I have actually seen in my own investigations, or gained from discussions directly with people who design and manufacture the product, not off some website. From what I have seen, Ron's assessment seemed valid, so that is probably a bit more indicative of the state of the manufacturing environment regarding camshafts. I only know people from three manufacturers, Erson, Crane and Isky, perhaps you know more and have more insight than I do...I don't know. But from what I've seen and discussed over the past 15 or so years I belive my statements to be based on fatual conversations and evidence from my own investigations and not supposition and wild-arse guessing based on assumptions.

 

The last point in your quote punctuates that: Finding a competent engineer to actually start something from scratch is exceedingly difficult. To assume simple human nature to imitate is not applicable or done in something as complex as camshaft design seems foolish to me, it's often been said that China rips off things...but they are simply human and cam manufacturers in the USA are the same humans (as far as I know) and that they would have the same tendencies to 'save work'.

 

That it addresses things salient to the discussion is a separate, additional benefit.

[JMortensen]

I've conclusively proven you wrong about cam asymmetry. Do I now need to show you how cam manufacturing might have changed since 1980? Can you really not come up with the one tool that I'd bet $1000 that every cam manufacturer has in their shop which would make cam design a whole lot easier? I'll give you a hint. You're sitting at one.

 

Again, took 2 minutes to search "camshaft design software"

 

this link has 4 different suggestions for software

http://www.eng-tips....d=163889&page=4

 

This one looks to be for large businesses.

http://www.designofmachinery.com/Cam/

 

And here is a machine that can (among other things) measure the lift and duration of the cam at the valve on the engine.

http://www.audietech...m-pro-plus.html

 

EDIT- Here is a list of companies using this machine, I've bolded the ones which from memory make L series cams. There very well might be more:

 

Bordeaux Dyno Cams

Boubis Cams

Brian Crower, Inc.

Bullet Racing Cams

Cam Motion

Cam Tech - Australia

Camcraft Performance Cams

Camshaft Engineering Co.

Camshaft Machine

Colt Cams

Crane Cams

Crower Cams

Demos Cams

Dougherty Racing Cams

Elgin Cams

Erson Cams

ESTAS - Germany

Howards Cams

Huggins Cams

Hyperformance Camshaft

Integral Cams

Kent Cams - England

Kelford Cams - New Zealand

Kiwi Cams Ltd.

Lunati Cams

Megacycle Cams

Precision Cams

Schneider Racing Cams

Spiros Cams

Sure Cam

Universal Crankshaft

Wade Camshaft

Web Cam

 

 

I don't know what you've convinced yourself of regarding people and their relative stupidity as compared to you (although I've got a pretty good idea), but I'm convinced that there are a large number of people out there pursuing speed, and ones that get really serious about it will use their brains and sometimes their engineering degrees to much greater effect than you seem to want to give them credit for. In the meantime, I've got just a few minutes into proving my point about asymmetry, and just a couple more into showing how all those troglodytes that you show so much disdain for might have managed to figure out a little bit more about cam design than you're giving them credit for. If you're going to come back to this argument again, can you please provide some actual proof of something?

Edited November 9, 2010 by JMortensen

[CarolinaTZ]

I love a heated debate and I appreciate all the information you've brought to my question about cam lobe repair which I may or may not need. I just wanted to jump in for a second and say "Thank you" to dapiper for the cam card specs for my cam.

 

Racer Brown SS-56 SS-54 110

Intake .487 lift / 244 dur.

Exhaust .478 lift / 236 dur.

 

While I understand much of the information you guys have shared, it's mostly above my head but, I'm learning.

[Tony D]

"I've conclusively proven you wrong about cam asymmetry."

 

Have you now? I think Tim has addressed your vague webreposting of contradictory information well enough that I don't have to revisit it. When all else fails, change the definition of the question or answer the question nobody asked. I knew it before I clicked on it.

 

Thanks for that list, I have to add Web Cams so that makes four. Their shop is about 3-5 miles from the house, but I deal with them more on VW cams. Though now I will have to go an ask Mr. Weber about some interaction between the species...

 

This should prove enlightening. I'd never even considered WebCam for my L-Grinds. It would save gas not having to drive down to have a chat with Ron and Ed. I should probably stay closer to home, my freeway exposure is less then.

 

Though I've talked with the Schneider boys, I don't really 'know' anybody there, so they are discounted off my list. I'll work on that.

 

Is the sole intent of your post to expose my unfamiliarity of other cam grinders Jon? Is that your big expose here? Because I stated that "I only know of two" (which now may be three, since I never asked the Webers about their cam line for the L-Series) grinding assymetric profiles (and not the damn cam lobe profile, which is NOT what was referenced originally and what you went off on your tangent about...) which was quickly appended to "O.K. three then" (And maybe now by proxy four[/b]...)

 

Is it YOUR contention that EVERY manufacturer on this 'comprehensive list from memory' is the only ones making L-Cams? Where's Isky on that list? That they have the means is somehow an indication that they are actually applying it to existing designs? You've confirmed this personally...right? You wouldn't be reposting mere internet 'proof' as you seem wont to do.

 

As freakin' TERRIBLE as my offense was for not knowing from my memory, and personal experience I would think leaving Isky off such a list FAR more egregious. Obviously they make cams. The produce cams for the L-Engine. But because they haven't bought this equipment (have they---they aren't on the list, so they musn't be good, they don't have the latest technology to apply...)

 

And is it your contention that EVERY manufacturer on that listing is making assymetric cams for the L---in valve action, not merely lob profile?

 

Like I said...sometimes I wonder what your purpose is posting this swarf. It has no point sometimes. What exactly is the offense here, not knowing the capabilities of each and every cam manufacturer on the face of the planet? Of only making recommendations to people based on reputable people I have dealt with for an extended period and who make good product?

 

WOAH! GUILTY!

 

You win again Jon, irrefutable logic as usual.

 

 

Oh, and with the "obvious" availability of cam software (as I think is the point of your last post) and all this whatever-it-was you posted about...what does that make the manufacturers who have not updated their profiles from when they originally stole them from Isky? What does that say about their application of technology to existing product line? Does that support your 'I would assume' stance...

 

Or does it support a 'Lowest Common Denominator' stance?

 

The SR71 was designed by sliderule. Got something faster? A sliderule got us to the moon. Just because someone has the means doesn't mean they use it in every case. Just because someone doesn't have the latest and greatest software and computer manufacturing capabilities, doesn't make them bad, wrong, or inferior. If they know how to operate what they got, I'll take a 65 year old with a sliderule redesigning something he has worked with successfully for 45 years every day...to some kid on a computer guessing by FEA as to what the computer says will be the next great ticket. I see it too much in my line of work.

Edited November 9, 2010 by Tony D

[JMortensen]

Read my last post again. The list has nothing to do with cam asymmetry.

[Tony D]

Neither did mine.

It was 'what is your point'?

As usual, no response to the hard questions.

[JMortensen]

My points were that the computer does make it easier to design a cam, and that the bolded companies on the list make cams for L series and also own a machine which lets them easily check valve timing and valve speeds right at the valve, so they could easily make the changes necessary to get asymmetric valve timing if they didn't already have it on their stolen cam profiles. ISKY was not on the company's list. Maybe they use slide rules, but I doubt it. They're probably using some other software.

 

For the last time, I think it's unlikely that every company that makes a cam with an asymmetric lobe and sells it as "opens quick closes soft" would have had one attempt at stealing someone else's design and then never bothered to update since the 1970s, especially since all of this technology has become available. With the knowledge that 6 of the common suppliers (common enough that I recognize their names from the list) have the technology to easily understand the effect of changes to the lobe shape at the valve, I just don't see them all sitting around trying to keep selling the cam profiles that they stole 40 years ago. I have no idea why you are so dead set on the notion that nearly all cam manufacturers are thieving morons, but I do not share your analysis, and I think the fact that they are buying this technology supports my argument.

 

CarolinaTZ, I'm glad you got your cam identified.

Edited November 9, 2010 by JMortensen

[Tony D]

Welllllll one on that list is still selling the same profile Jon, why don't you call them and ask if it's the case. I'm sure you will get a resounding "no"...

 

I am not here to sully someone's reputation, but I know better than to make generalizations, and your list contains someone who is to my CURRENT knowledge engaged <EDIT>(IS ENGAGING)<EDIT> in EXACTLY what I said was happening.

 

And I'm leaving it at that.

 

 

 

BTW, it's YOUR characterization that they are theiving morons. I simply stated that this is deriguer, and that in industry EVERYBODY SEALS EVERYBODY ELSES IDEAS (if they are good ideas and WORK, why do the legwork add cost to get the same result?) I didn't make a value judgement other than to say people seem to thinkg it's bad when China does it, but when American companies do it (as long as we don't know about it or deny it happens) then it's O.K.

 

I called nobody a moron---you did that. Perhaps that is your thought on them. I simply said the market realities in a market driven economic system is that if you can rip off a design (even if it is wrong) and it WORKS then marketing will push to adopt it without further refinement.

 

Are you so obtuse to think I am calling Ron Iskendarian a thieving moron? GO READ MY POST: Ron admitted where they got their original profile. He admitted it was market based 'get into the segment' logic that drove it. That it was close to 10 years and EXTERNAL MARKET FORCES that had him re-evaluate their position on the cam profiles.

 

And it was Ron that expressed SHOCK that competitive cams (as of this past year) were STILL running their original BMW-Based L-Cam Profiles. He ASSUMED anybody else in the business would have re-evaluated the grinds simply as a matter of course. APPARENTLY NOT.

 

Don't put words in my mouth, they are a transferrence of your own prejudices and inferences. I don't know why you have such a problem with believing market realities. It's been my experience if something works, there is GREAT resistance to changing it, especially on a theoretical argument. This does not make someone a moron. It makes someone a slave of the business and market situation they are in, nothing more.

 

I reiterate my previous comment about misstating what I say. You only make it more clear this is the case now.

Edited November 9, 2010 by Tony D

[JMortensen]

"We're gettin nowhere mighty fast, Cap'n!"

[TimZ]

"We're gettin nowhere mighty fast, Cap'n!"

You've proven that conclusively.

 

...Now back to our original programming.

Edited November 10, 2010 by TimZ