XE 3100 lobes, will engine rev lower?

Will the 3100 series lobes, vs 3300, cause the engine to make peak power lower and therefore not having to rev the engine to 6500?

Thanks,
Jeremy

Don't know about the lobes you mentioned but using a cam with a tighter LSA will keep the rpm in the lower range. Of course, that's not emmisions friendly but what exactly is the application here??

-Mindgame

Well the xe 230/236 with 3300 series lobes will have .510/.520 lift whereas the 3100 series lobes will have .585 on both i/e.

Originally posted by mastrdrver
Will the 3100 series lobes, vs 3300, cause the engine to make peak power lower and therefore not having to rev the engine to 6500?

Thanks,
Jeremy

If you mean Comp Xtreme Energy hyd. rollers, the 3100's are more aggressive (more lift for the same duration) than the 3300's, so most likely you can get power at lower rpm. I've seen it done.

Of course, the 3190 series lobes are VERY aggressive, and 6500 is probably about as high as you should run them, unless you get into very high load (and high cost) springs. They are very effective lobes when used at reasonable speeds, with good flowing heads.

I dont know the answer for sure, but i would maybe shoot a PM or email to Rich as he runs one and knows quite a bit about them.

Who's Rich?

rkrause-username

A very knowledgeable cam dude.

I can't find that member name. It say that it doesnt exsit. :confused:

Try this for rskrause

http://web.camaross.com/forums/member.php?s=&action=getinfo&userid=2101

hehe sorry i get too comfortable refering to people by first name on here :)

I am also thinking about using the 224/236 3100 Xtreme lobes and Im wondering what to do about the lifter end. You cant get the Comp R's anymore and I cant get a definite answer if the 850-16 Comps will hold 6200 to 6300 on these lobes. I called Comp about getting some earlier linkbar type R's and mill my lifter bores down to use these, oh gawd guess what they are out of them also. So what is everyone else using? The springs I already have in order for the lobes, Thanks for anybodys input

p.s. Thanks to Bret Bauer for helping me so far in this, thanks again

Originally posted by mastrdrver
Will the 3100 series lobes, vs 3300, cause the engine to make peak power lower and therefore not having to rev the engine to 6500?

Thanks,
Jeremy

I think that it's the usual "it depends" answer. In general, a higher lift cam with the same duration will have more hp everywhere (low, middle, or high). However, that's partly dependent on heads and the actual amount of lift. But no matter what, the peak revs without valve float will be lower with the higher lift cam. So you could get into a situation where you have to stop revving the higher lift cam (or experience valve float), and the lower lift cam will keep making power to higher revs. But up to that point, the higher lift can only help.

That's why the XE lobes make such great street lobes, who want's to rev the snot out of a motor on the street to make hp?

Hope this helps.

Rich Krause

What is the main difference between the 3300 series and the 3100 series?

Is the 3300 series better than a CC 305- or cc 306 cam up to 6krpm?

Originally posted by The Highlander
What is the main difference between the 3300 series and the 3100 series?

Is the 3300 series better than a CC 305- or cc 306 cam up to 6krpm?

Now you are on track! The XE lobes are indeed a better choice for a lower revving setup, though the lobes on the 306 are also pretty steep. The XE lobes are (in)famous for being very "steep", IOW they have high lift/degree of duration. You can get a feel for how steep a lob is by looking at 0.050" duration and comparing lifts at 0.200" and total lift.

For example, compare the 306 intake lobe #3112 with XE lobes 3315 and 3194.

3312
230 @ 0.050"
143 @ 0.200"
.3400" lobe lift

3315
230 @ 0.050"
151 @ 0.200"
.3400"

3194
230 @ 0.050"
157 @ 0.200"
.3890"
So as you go down the list, the lobes get steeper (reach 0.200" lift sooner). In fact 3312 and 3315 have the same lift, but 3315 is "steeper", ie reaches that peak lift sooner.

More lift (sooner) is better, to a point ;)

Rich Krause

I guess the point would be spring life...
Too much lift soon will decrease significantly spring life and can cause valvetrain failure...

I'm a grave robber. I'm bringing this thread back to life! :D

Instead of using the XE 3100 lobes, what do you think of the higher lift magnum lobes?

XE 3314 vs Mag 3119 (224@.050)
XE 3315 vs Mag 3111 (230@.050)
XE 3316 vs Mag 3122 (236@.050)

Magnum lobes here -> http://www.compcams.com/catalog/229.html
XE lobes here -> http://www.compcams.com/catalog/230.html

These seem to be some of the more common durations used today.

The XE lobes have short advertised duration for their dur.@.050, more dur@.200, but they are lacking in peak lift.

The Magnum lobes have more advertised duration and more lift, but they aren't as big @.200 (very close though.)

I'm assuming the XE lobes would help the car idle smoother. True/False?

I'm assuming the XE lobes would produce more torque. True/False?

I'm assuming the XE lobes would make more vacuume. True/False?

I'm unsure which type of lobe would be easier on spring life. Which would be more detrimental; the quickness of the XE ramps or the greater peak lift of the Magnums?

Would you recommend a cam with fast ramps on the intake but slower on the exhaust, slower intake/fast exhaust, or what?:confused: :bow:

:EDITED to correct the lobes:

The XE lobes are very similar to the more agressive Magnum lobes, so any differences are subtle. What's more interesting is to compare the XE lobes to the solid roller lobes of similar duration. While the diference between advertised duration and duration @ 0.050" is greater for the XE lobes, indicating a less rapid lift off the seat, they have equivalent or even a bit more difference between duration at 0.050" and 0.200", indicating ramps that are as steep or steeper! It's amazing how far hydraulic rollers have come.

Anyway, to get back to your questions, the answer is "it depends". In general, the XE lobes will do what you suggest. The main limitation, compared to the comparable duration Magnum lobes, is peak rpm. If you are using the same springs, valve float will occur earlier with the XE lobes. There may not be enough pressure to keep the lifter on the abrupt "shoulder" of the lobe as it transitions to the "plateau" area or the valve may bounce off the seat if the seat pressure isn't high enough. The slightly more "rounded" profile of the Magnum lobes will delay these events by a couple of hundred rpm.

Why not just use more spring pressure? First, most people like to keep open pressures less than ~350lbs with hydraulic rollers. The basic issue is life of the valve train components. The higher the open pressure, the shorter the life of the whole valve train. If you need to go as high over ~350lbs, it becomes more important to use the best quality components you can get. A practical maximum even with excellent parts (and careful setup) is in the 400-450lb range. You want to use as much pressure as needed, but not more. Seat pressures in the 120-150lb range are adequate to control the valve on the seat.

The weight of the valve train components has as much influence as rpm on the spring pressure needed to avoid valve float. The heavier the components, the more inertia, and the more pressure needed to control them. Of course, since in general stronger parts are heavier, there is a trade off. The way out of this dilemma is to use more costly parts, that are both stronger and lighter due to better design and materials. An example is titanium valve retainers and aluminum rocker arms. If you are using, by necessity, higher spring pressures it is important to use a good pushrod. Stock type pushrods will flex excessively at high pressures. Of course, stronger pushrods are also heavier.

I really am going on here. So to cut to the chase, the conclusion is that which lobe type is better depends primarily on how high you want to rev the motor, how much you want to spend on the valve train, and how long you are willing to go before the need for component replacement or a failure mode occurs. All other things being equal, use the XE lobes for a lower revving setup and the Magnum lobes for higher revs.

FWIW, my current (and as yet untested) setup uses the #3192/3196 XE lobes with seat pressure of 120lbs and 310 open on the intake and 330lbs on the exhaust side. I am only going to rev it to ~6,200rpm though. If it were setup to run higher rpm, more open pressure would be needed. This illustrates why I am such an advocate of the XE type lobes for a SC setup. You don't need to rev ths piss out of a blower car to make power, you can just pulley up the blower. This allows the use of very steep lobes without excessive spring pressure.

BTW: I am not a shill for Comp Cams. There are other fine cam and valve train parts out there. It's just that I am most familiar with their stuff. The discussion of the shape of opening and closing ramps on the intake v. the exhaust side, using different springs on the intake and exhaust, etc. is beyond me. I know that there are issues worthy of discussion there though. If some of the gurus want to chime in, that would be great.

Rich Krause

Originally posted by AdioSS


Instead of using the XE 3100 lobes, what do you think of the higher lift magnum lobes?

XE 3192 vs Mag 3119 (224@.050)
XE 3194 vs Mag 3111 (230@.050)
XE 3196 vs Mag 3122 (236@.050)

Magnum lobes here -> http://www.compcams.com/catalog/229.html
XE lobes here -> http://www.compcams.com/catalog/230.html

These seem to be some of the more common durations used today.

The XE lobes have short advertised duration for their dur.@.050, more dur@.200, but they are lacking in peak lift.

The Magnum lobes have more advertised duration and more lift, but they aren't as big @.200 (very close though.)



Rich said it very well. Re-read it a couple of times.

Unless I read the charts wrong, all of the XE 319X lobes you mentioned have more lift than the equivalent Magnum, not less. Compare both at 1.6 rocker ratio, or just compare lobe lift numbers.

Bottom line is that the XE 319X have higher opening and closing rates, and have "inverted flank" or "hollow" flanks on the lobes to achieve this. Higher rates equal more forces needing more spring and stiffer parts, etc. There's no free lunch especially in valvetrains.

With very similar durations (a couple of degrees difference between rated and .050 duration is inconsequential) idle vacuum and idle quality will be similar if LCA is the same.

If the heads can use the lift, the XEs with more lift should make more torque and power. The entire engine design should be considered when choosing any cam profiles; let the engine tell you what it needs, not the other way around. High end simulation programs are a good way to start if you have enough engine data.

Dangit, at 5am I tend to make mistakes when trying to post something usefu. Please see the corrected post above..

I MEANT to put the less aggressive XE 331X lobes instead of the XE 319X ones.

This should change your replies, right guys? :D

Originally posted by AdioSS
Dangit, at 5am I tend to make mistakes when trying to post something usefu. Please see the corrected post above..

I MEANT to put the less aggressive XE 331X lobes instead of the XE 319X ones.

This should change your replies, right guys? :D

Yeah, just reverse the numbers, but the results are about the same: more agressive flanks (not "ramps") with the same duration equals more lift and more area under the curve and more output.

All of this depending on what the engine wants, of course! (Audrey II comes to mind)

IMO, engines are a lot like women (or men, if you are a lady), they are happier getting what they want rather than what you want them to have.

My $.02