Cam profile design 10

[EngJW]

Hello,

Just discovered this forum. I have been searching for a forum on camshaft design. That is, actual design like ramps, profiles, materials, machining, and so on, as opposed to "what cam should I use?" I found a gear forum but no cam forum. Anyone know of one, or is this forum the appropriate place?

Thanks,
John Woodward

 

[PFM]

Well ShaunT,

I will not disagree with your reply, a hydraulic cannot keep up with a flat tappet or solid roller. This post originated about cam design and I am shure you could provide input to that as well. I will take up the "other cam grinders not knowing the duration" at other lift numbers. Two come to mind Iski, lists the duration at all lift points up to max lift right in the catalog, second is WebCam, they may not publish the numbers but call and talk with them or in my case stop in and they have that and more.

My question to you is if I call your shop on Monday one week, Tuesday the next week and Thursday the following and ask for a cam recomendation for the same motor: How many different cams will be recomended and why?? What I have not found in cam companies is any remote shred of consistancy in cam recomendations.

This makes me question anyone that claims to know "all the answers". Cam design the original thread still seems to be a black art, some no doubt do it better than others. Some continue on old reputations and others on truly new designs but none seem to have resolved all the questions.

Regards

D Friedeck

 

[EngJW]

Hello Shaun,

I have a request to ask of you. If we could go back to my original questions at the top of the thread, I wonder if you could share some of your cam design experience with us. Your comments about cam performance are very interesting, but I would like to learn more about the actual design and manufacture. For example, do you design your own profiles, and what tools do you use, such as computer programs or good old intuition. Do you grind your own cams? Please understand, I would in no way ask you to give away any trade secrets that you have worked so hard to learn.

Thanks,
John Woodward

 

[ShaunT]

We design and manufacture all of our profiles. We use a program that we created that uses for the most-part, 6,7, or 8 decimal place polynomial equations. We can do this by hand with a calculator, but the computer allows us to do it millions of times faster. In the old days, using a desk-top calculator would many times give a design that might not show up flawed untill it was ground. A couple weeks lost.
Our cams are 6 or 7 different sections, each section can contribute up to 10 million different cams at any given lift in the section. Some would be too big,others small, some could not physically be made, and others might only be different in millionth of an inch increments. Engines react to different curve families and do not notice differences in millionth's of an inch. We have a very slow initial opening to minimize reversion, then we open it fast. We are able to catch cams at .050 lift that are 6-10 degrees bigger at the seat. We also slow the closing down for two reasons. 1:we build so much more port velocity than others because even though we may open the valve later, we start flow sooner because a reversion in the port costs valuable time. A port that starts flow late, will never catch up. Due to our higher percentage of clean air flow, we get to #2: The more velocity I build, the longer cylinder filling will continue to RAM the cylinder after BDC. So, why hurry and shut the valve? Take advantage of inertia! Close it slowly unlike conventional Symmetrical designs. It gives you extra time and it also shuts gentle enough to stay shut taking advantage of ALL of the charge, and (here is the good part) Your intake port does not have a reversion due to a valve bounce during the compression stroke. So when the intake valve opens again, It will fill instead of having several crank degrees try to reverse the reversion. The proof that we pick up the flow is the increased fuel required at high RPM since an increase in air flow demands an increase in fuel also. This is why many Blowers are blowing the burst panels. Years ago, We were the only ones that did not cause this to happen in a test of a Nitro Hemi conducted by a really big name.(Almost a house-hold name to racers) We also picked the motor up nearly 500 HP with ten LBS less boost than any other cam they tried.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[camshaft]

I love this stuff.

Shaun T ULTRADYNE Arl,TX

 

[ShaunT]

There are also manufacturing processes involved. One simole one is the immersion of flat tappet cams into a hot tank of phosphorus. This is the Black stuff on the cam lobes. I have had many cams come back to me for a freshen up. Once i check every lobe for wear and they all check out good as new, I re-phosphate the cam and send it on its way. There are on occasion people who will say they had a cam and it sucked because it broke in two pieces in the first 5 minutes. This is not the fault of a cam grinder accept in one area. He dropped or hit the cam core which fractured it. Usually though, the cam is damaged in transit. There are only Two cam core manufacturers for American V8's in America. Incidentally Crane owns one of them. They are cheaper than others largely because of that and the fact that they "Gang Grind" cams. For ALL of you Ford 5.0 fans out there, Crane also produces the Private labeled Ford Motorsports cams.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[furious70]

>>>I have half a mind just to give it away to anyone that >>>wants it. Trouble is, I am not sure it will run on >>>another computer without VB being installed.

If you have the full version of VB, you can create an executable out of your program for us all to use. I have the full version and could try to do this for you if you don't.

 

Shaun,

I basically understand your theory of cam profiles. One thing I have a question about however, is why we could not open the valve quickly at first? Could not the duration be decreased with a faster initial opening? Or are there other requirements (like peak lift?) that need to be considered?

Thank you!

 

[ShaunT]

You can't open it with a high jerk if you want to engineer a cam to live long enough to win and win again. It also will induce valve float due to the inertia load. You will also spit roller bearings out in every direction. When you open it fast before TDC, you induce a ton of unnecessary reversion and hence delay cylinder filling. In terms of power, reversion is the enemy. A port that starts flow late will never catch up. The port with the higher velocity will continue to ram the cylinder after BDC and that is the origional reason for the long and slow closing. It buys time to take advantage of the inertia ram from the port. It also shutsa so softly that it stays shut keeping ALL of the mixture in the cylinder and therefor ALL of that power capability there. The best part is not putting a reversion in the intake port from the flow valve opening on the compression stroke, and hence starting flow sooner on the next intake cycle.


Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

So let me see if I understand.

The slow initial opening (prior to TDC) is to take up clearance and get the valve moving in a smooth manner. Once past TDC, you want to open the valve as quickly as possible (short of mechanical problems).

Did I interpret that correctly?

 

[ShaunT]

You have most of it down. The other reason for slow movement is to minimize port reversion. Virtually all cams open the initial opening much faster than US. We all understand that having no reversion would mean opening at or after TDC. Then we would have to explode off the seat to move any air. All of us here also understand what that would do to our valve train.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[naknorm]

Not sure what engine types you are refering to but I would suggest contacting KAMS inc in Oklahoma email: jeff@kamsinc.com. They design and build special cams for large diesel engines

 

[ShaunT]

Yeah. Some one here in Dallas that I know uses them.After looking at one, I told him I can make one for him that will beat it badly in economy, power, and valve train reliability. But, you know, not a priority with the slow economy now.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[ShaunT]

There are different acceleration families that are intended by design to do different things. The really fast opening cams are very effective in limited breathing stock cylinder headded motors such as Super Stock class drag racing. They also would be well in lift rule restricted Stock class drag racing that are usually limited to flat tappet cams. The really fast lobes I mention here are very good at making torque and horsepower, but are not stable at 9000+RPM's like a slower opening big lobe lift piece. Such pieces are found in Road Race engines, Endurance, Super Gas, Pro Gas, Comp Eliminator, and of course Pro Stock. Many of the slower cams with big lobe lifts are teamed with high ratio rocker arms to achieve "big" net lifts. when a motor has a big port and one that flows very well, it can hurt power with a very fast ramp because it gents into a situation of having the ability to keep up in terms of port velocity.

We consistently shock the Pro Stock engine builders with the gains in peak and total torque plus the dramatically increased valve spring life and stabilized pressures they discover when using our cams. Most of them find they need to run some rediculous (in my opinion) spring pressures to stop float and bounce associated with many cams. when they are used to throwing away at least half the valve springs every 2-3 runs, you can imagine their satisfaction at keeping them for at least an entire national event race. At upwards of $500.00+ per set, who wouldn't be satisfied?

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[Windsor377]

Shaun,

I hate coming across like a testimonial, but I guess I have to. For those that don't know, I run Ultradyne rollers. Although not big block Pro Stock engines, they are very potent N/A and Nitrous small block engines capable of comfortable 7 second 1/4 mile ETs.

A recent combination went an entire 20 event season on a single set of valve springs. True, valve lift was only .778" and rpm was only 8500, but I still think that is pretty remarkable. Another surprise was, the springs were only 255# on the seat and 715# open.

The valve job looked new at the end of the season as did the entire valve train.

There has to be something you guys do at the "transistion points".

 

[ShaunT]

Oh yes indeed!

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[ShaunT]

How many of you have seen the brass colored evidence in the oil form pulverized needle bearings? I have seen this even when the bearings are still in tolerance. If you practice inspecting lifters and rockers in a race engine on a regular basis, you will pay yourself big dollars through avoidable disasters. You can also significantly increase the needle bearing life by using a full synthetic oil such as MOBIL1 or ROYAL PURPLE(not too heavy.) One of the areas you can help to minimize roller lifter tracking on the cam lobe is to throw out lifters with excessive bearing clearance. Some will say "they are about wore-out but they will be okay for a few more races." Then I get a call or Email from someone asking for help in a hurry because the roller lifter came apart and hurt a lobe. I will also tell them to pull the oil pan and inspect rod and main bearings because I am very confident that the trash from the lifter and cam ended up in your oil system and consequently some bearings. I have to re-do their bottom end about half the time.
Guys, It doesn't pay and it usually costs you Big Time, so don't gamble, especially whti the valve train.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[ShaunT]

First sentence should say "from pulverized needle bearings",
not form pulverized needle bearings. TYPO, sorry!

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[ShaunT]

Here is an example of two cams with the same seat or advertised durations, but intended for different purposes.

310@.020 vs 310@.020

282@.050 vs 275@.050

203@.200 vs 192@.200
One is quite bigger everywhere after.020 Obviously, it will make more power EVERYWHERE, but it will need more spring, and will not be very dynamically stable above 7500-8500 RPM's (depending on rocker ratio)

One is an NHRA Super Stock national event winner, and the other is a 24 Hour Lemans and 24 hour Daytona winner.
Big difference in environments here.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[EngJW]

Do excessive jerk pulses tear up the needles, or is it just high spring loading? Are needles in rocker arms also affected?

Thanks,
John Woodward

 

[ShaunT]

Yes and Yes. Excessive lash settings, higher rocker ratios, and bad rocker arm geometry hurt things too. If you have to run the lash loose to go faster, you are likely lacking in the fuel department, and/or the cam is too big for your needs/RPM range. I have stated before that running solid roller cams with 300+LBS seat pressures in anything other than forced induction(and serious boost at that) is bad. I stand firm in the belief that a cam that has to have that much seat pressure to control the valves in a typical American V8 needs to go in the trash can.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)