Kip Fabre

Question ramp rate speeds. OK lets look at it this way on any lobe you have 1. lift how for the lifter is open at each degree of rotation. 2. Speed or what we call it Velocity of the lifter it’s measured in thousands per degree 3. Acceleration of the lifter is the change of the Speed or Velocity of the lifter. 4. Jerk rate which is the change of the Acceleration. So a 236/360 lobe we make may will a max Speed or Velocity of the lifter .00786 per cam degree and Acceleration rate of .0000305 with a Jerk rate of .000018. So your question how much difference with a lobe of 236/350 not much difference. Velocity .007638 Acceleration .000301 Jerk .000018. The problem is when you try to make a lobe with low .006 number and high .200 number with a certain lobe lift you get into rushing the lift up that is when you get into trouble and an unstable lobe profile that is noisier and hard on parts. High Speed and Acceleration on a lobe do not cause the problem it is when you try to achieve them to soon. Look at it this way if you were in your car sitting there in neutral and your buddy in his car came up behind you just touched your bumper now he starts pushing now you are up to 45 MPH and he backs off now put your brakes on and stop. No damage to you are your car. Now your are sitting in your car and your buddy is coming at you going 25 MPH he runs into the back of you and accelerates up to 45 MPH now put on your brakes start stopping but before you stop there is a wall now you hit it at 25 MPH any damage done? This is the best way I know of the explain lobe profiles. If you have 2 lobes one with .360 one with .380 with the same Duration @ .05 or any other Duration the higher lift will always have higher Speed and Acceleration it can be almost as smooth. One more thing you asked about .006 durations so you can calculate DCR. Cams with a soft ramp or cams with a longer duration at .006 will not make that much difference while running because of preload deflection meaning the valve may not come off of the seat until .004 or .006 lifter rise.
Our Web Site is not finished we are adding to it weekly. We will have shelf cams available soon.
You asked about the difference between IN lobes and EX lobes I will get back later on that.

99Bluz28

iTrader: (35)

So would you say the valve spring life with a Cam Motion cam with .310" lift lobes would be very similar to a identical cam under the same conditions except for using .350"lift lobes..., and I wouldn't need to use stiffer valve springs for equal control with the .350" lift lobes, compared to the .310" lift lobes?

I'm really just trying to get a feel for how they compare to other cam lobes I'm more familiar with.

Rise of the Phoenix

iTrader: (27)

Kip, I know Futral and Geoff have proprietary lobes through Cam Motion, but do any other big name LS guys do too? I know many have proprietary lobe profiles with Comp Cams.

Kip Fabre

If we make a .310 lobe with a 1.7 Rocker that is .524 a .350 lobe would be .595 so if you set the spring height the same lbs at the seat for both cams you will have more open presser on the higher lift cam. Now even if both lobes are stable witch they are always the higher lift will not last as long as the lower lift you will be working it harder. The ramps on our .310 lobe and our .350 lobe are the same only difference is later on the ramp the Velocity is higher on the .350 lobe and a little more - acceleration at the nose. Open presser is more important than closed presser. Let me know if I did not answer your question well enough.

Kip Fabre

Some use our lobes and some use theirs it's up to them. When someone likes something it's hard to make them change.

99Bluz28

iTrader: (35)

Okay, just one more question on the same hypothetical cams. If both of these cams have their valve springs shimmed to .05" of coil bind at max lift would the valve spring life of the 2 different lift cams be fairly close...?

Kip Fabre

I would say fairly but the one with more lift will work the spring harder it is taking more stress so it's life I think would be a little less.

99Bluz28

iTrader: (35)

Thanks Kip, I appreciate your replies.


So will the .006" lift numbers be available on the website, in a lobe catalog, or by request...?

01ssreda4

iTrader: (96)

Describe your lobes. I order a cam straight from your website, how do these lobes compare to others in the industry? Why did your website change? There are no "shelf" grinds for LS engines anymore.

Ari G

iTrader: (25)

Great to get feedback from the source

Could you explain the process of desining a lobe and what effects it has using the wrong lifter wheel diameter,weak pushrods,To low or high of a spring pressure and rocker material?

Why dont cam companys specify what components it was desinged for like Valve weight,Spring Frequency(what springs to use) and RPM limit?

Kip Fabre

I will make them available on the web site soon. Or you can email or call.

Kip Fabre

We design our lobes to be smooth what that means is they have low Acceleration rates and low Jerk rates so it makes a smooth lobe that will not make noise or brake parts and rev much higher. Most of these cams for the street/ strip are for HYD lifters. So the lobe are from 220@ .05 to 260 @.05 with lobe lists of .300 to .390 some smaller some larger. These are easy to design. For some reason some cam guy or engine builder came up with the idea that all cams with low .006 numbers and high .200 numbers were the best lobes. So if my 230/360 lobe has more .006 duration and less @.200 it is not as good as Joe Blows 230/360 that has less @.006 and more @.200. That is all a bunch of BS sales gimmicks. The MOST important numbers are opening and closing events not the lobe design . Not the .006 or .200 numbers. Now on some lobes for Turbo, Super Charged or Nitrous engine we will make a different EX lobe design. If it has high boost or a big shot of Nitrous we will make the EX opening ramp softer the reason is it is easier to open the EX valve with high presser with less Velocity on the opening ramp. WE will be putting some shelf cams on the web site soon for now just order what you want. I hope this helps

Rare96LT1Formula

iTrader: (32)

Kip,

Can you discuss the Pro's vs. Con's of running a cam ground on XE-R lobes (99.9% street driven F-body). I've been debating switching cams due to a number of reasons, and the lobe profile is right at the top of what I'm concerned.

Cam is a Comp 232/240 .595/.609 112+2 LSA. Running this cam on a stock bottom end 346 c.i LS1 with hand ported 241 casting heads (said to flow .315+ @ .600). LS6 intake as well.

Thoughts?

poltergeist 02

iTrader: (65)

Just make sure you have your valvetrain set up correctly and check your springs regularly (every 8K or so).

Kip Fabre

All lobes are designed for a loft profile let’s say I make a Hyd Roller lobe for your SBC I want 230 @.05 with 350 lobe lift and we are using a .842 lifter with a .750 wheel. In the old days and still now when we made a lobe like this it was made on a mill by hand it was call a model lobe now after making it you have to make a master for the grinding machine and it worked fine for a designed base circle size. This lobe for a SBC would be made on a 1.158 base circle. If we ground the new cam with this base circle it would come out with the correct specs. If we used the same master for a LS1 cam the base circle would be 1.455 now if you measure the dur @.05 with this big base circle it will come out to be about 6 degrees larger 236@.05 because of the geometry. Now all of our lobe are made on the computer and feed into the CNC grinding machine. So this lobe file is just a lift data file before we grind the cam we need to tell the grinding program or machine what we want to end up with. For a lobe to come out what we want like a 230/350 we program 1 Base circle finish size 2 roller wheel diameter and grinding wheel size. If we grind a cam lobe that is 230/350 for a roller lifter with a .700 wheel and you put in lifters with a wheel size of .750 the duration will be a little bigger. Going from .700 to .750 is not much difference but going from .700 to .850 is a fair amount. Now for the week pushrods & spring pressers. No one can made a valve train to stiff the larger the cam core the stiffer the pushrods the most sturdy the rocker stands the lighter the valve retainers the better the system will work and live. On spring presser you only need as much as it takes to not have valve float for your RPM range. Most drag racers over spring because they think more is better. Rockers can fool you. A good expensive set of rockers may work as well as stock or another set that are not expensive. On components like springs and valve spring Frequency can get complicated because a spring can be good for this engine and not for this one so if they work use them if they done try some others there is a lot more to this but I will leave it for now.

Kip Fabre

Sorry I know nothing about XE-R lobes. I see the cam you are running here the question is how does it run? What would you want it to do that it is not doing now? More on top more on the bottom? Why are you running more EX lift than intake lift?
Question I have after looking at your specs are.
How much compression do you have?
Stick? automatic? Stall?
How much lift can your heads handle?
How do you want it to run?
I see it is street driven mostly if it is do you want the best cam for the street? Or one for the best ET at the track?

VerdeZ28

Kip,

I appreciate you taking time to enlighten some of us on cam geometry and characteristics. A few months ago I came on here asking what would be a good cam for road racing and autocross. I own a 2002 Z06 and have recently done a cam swap on it along with head swap as well. While doing this swap I found many on corvette forum who regularly road race saying that if you want the car to be dependable on the road coarse your better off staying with stock cams, since they are not so rough on the valvetrain. Considering this I decided to go with what I understood was a slower ramp rate cam, which ended up being a Comp Cam XE lobed cam. the specs were 228/230 .571/.573 on 112 LSA and 110 ICL. I also opted for titanium retainers and turned down LS3 valves with PSI 1511ML springs. Its seems to me that your mentality on cam design falls along the lines of what I was looking for. Reliability first, power second. Id like to know what you think of my setup choice and what cam specs would you have done?

Kip Fabre

Thanks for the question. We have made cams for road racing for some times one of the biggest problems with road racing and keeping the engine and valve train together is not the cam lobes. Don’t get mad at me but it is the driverJ the engine builder can put a chip in, but the problem is I am sure you may know about this it is the DOWN SHIFT. They will have a 7000 chip in the engine but on the down shift the bad driver will send it to 9000. Just thought I would though that in. In a road race you must finish to finish first I am sure you have heard that. You do want lobes and a valve train that will stay together I do not know any thing about the lobe you spoke about but if they work that is fine. As far as soft lobes go they will most of the time make more power than the so call hard lobes. The HARD LOBES will most of the time make a little more TORQUE at a given RPM but will float sooner and loose power. But in road racing you need a good torque curve more than just power. Now on your combination I will need more information for a cam recommendation . I can send you a sheet to fill out for a cam rec but I still would need to talk to you about this combination.

99Bluz28

iTrader: (35)

Kip, the 006" lift #s on those lobes is 281 for the 228 lobes and 283 for the 230 lobes. These are considered soft lobes for Comp Cam lobes.

Kip Fabre

That is 53 degrees the ones we make are 55 degrees but the Acceleration rates could be different. But I think 53 degrees should be fine for the lower part of the cam that would be so a call soft lobe. How high do turn the engine? How about valve spring life?