Lobe centers

[bajaruner]

James2
FYI the DTD in my experience seems to be quite accurate. I find it approx 10% over reality, but still accurate on power and torque curve. Still it gives you the best combo possible in most cases before you build it. One other thing to bring up, I have been learking on this thread a while, and something to consider most cams of higher LC's are also dual pattern, this is why a higher LC is the best of both worlds, and yes LC's around 112 on a dual pattern cam are awesome! Hope all goes well at the strip.

STEVE

[michael gideon]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Plastermaster:
<B>Some time ago I saw a link on this forum to a good article on cams. Most info I have come across cover lift and durration but not much on lobe centers and the effects different lobe centers have on the engine.
I did a search for lobe centers and didn't find much. Anyone refer me to an article/s?
What got me interested was while this forum was down I came accross a post on the Calook forum about 112 making a good bit more power over the commonly used 108. There was not info though as to what other changes the cam might like, or its effect on engine temps and so on. Its a big enough subject that my questions could go on an on, so any info out there?

Thanks
Ron </B><HR></BLOCKQUOTE>

First, I would suggest that you find out this information on your own. Most of what you find on forums, while well intentioned, is not based on actual science. Often, the VW parts industry prints things that are just wrong in their catalogs. I would start to read Racecar Enginering and Race Tech magazines. Check out Elgin Cams website. Also, look on the Society of Automotive Engineers Website. (sae.org) They have lots of good technical studies. Try "Design of Racing and High Performance Engines." (# PT-35)

Here is my two cents on the subject based on research done by Crysler on 2 valve engines. The Lobe center separation doesnt control the cams characteristics itself. The intake valve closing is the single most improtant timing issue. The later the valve closes the more "high RPM" cam it will be. So you could have a cam with a lot of duration but a small lobe center have similar performance to a smaller duration cam with a larger lobe center. Intake Valve opening has little to do with cam performance. The importance of valve overlap is over stated in the performance industry. Hope this helps, Michael Gideon.
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[firebeetle]

interesting but i always thought vw camshafts are outdated
regarding to lobecenters i tried 113 on a camshaft considered similar grind to a fk8 im doing EFI with throttle bodies when moved from 108 to 113 idle gets better with 108 your intake ports end up black sothed black dirt i mean did 113 and works cleaner idle improves but i still not satified enough so im widening even more i calculate 116 to 118 should be enough for me map readings are more stable and the most incredible part is that engine asks for more fuel at upper rpm still pulling hard when you cant and never will get that from a 108 lc you just get a peak on fuel consuption and power then it stops pulling also that valve float sound will never dissapear and 108 tend to be pulling hard at mid rpms and requires less fuel also i cant explain the results but im more glad getting 150 hp as a flat line and not peaky instead of getting a a short peak of 180 hp also i cant make it ping advancing timing at 35 degree as NA doing turbo i still dont know about ping but in my opinion after testing overlap is my enemy so i make my camshafts high duration and kill overlap to a measure that i like because in my case peaky or wide power wide power or pulling even at high rpms lets me pass my competition slowly say good bye to him and win this is impossible with 108 wich is what my competition has same combo at heads and he has a bigger engine than me still i can pass him slowly smile at him blink my eye and good bye.
Thats what it does for me and does it really well but im doing efi and using map reading not maf or map get any benefit from overlap as signal gets pulses from overlap so again nothing good comes from overlap when using a good set of cilinder heads.
Any one got this same results or no one has done testing on this interesting subject?
Thanks.

[Piledriver]

Welcome to the STF!!!

It IS a very interesting subject, and had been covered many, many times since this thread from 2002.

Short consensus is that any LC will work for some definitions of "works" but it must work with the heads/intake and exhaust tuning as a system.

You should check out the engine management forum and sub forums for EFI related discussion as well.

[firebeetle]

Wow i ve just checked the engine managment forums every kind of trouble can be found, mostly regarding to megasquirt , just have to say i wont fit in any of those because i designed my own hardware and software around motorola MPC tricore processors family. But regarding to Lobe centers i already did testings with stock heads kind of restrictive for 108 lc and cb perf heads and in both cases overlap just makes engines peaky power at midle range and drops as an anchor to the deep ocean doesnt help adding more fuel engine stops moving air and air intake starts to pulse even worse either map or maf reading none makes a difference this lets us see how bad overlap harms us and if we talk turboing an aircooled with a big cam and lots of overlap just gonna get pinging , need to turn the boost screw all in to get some boost and around past 22 pounds of boost almost every fuel avaiable will ping and will get a cracked head and got this same results with carb and efi after changing the lc i ve solved my troubles this is all i have to say, but regarding exact cam numbers that solved my trouble i wont share ,took too much time to find, and lot of cam grinds and sorry i will not answer that question never so dont ask me about that. The fact is that it has to do a lot with Lobe center angles and watching the effects with map or maf electronics dataloggings that when 108 lc cams where designed didnt exist, now that we have that instruments i feel new cams should be designed for aircooled engines any one has done testings about this?
please PM me. As i dont want to loose time discussing just making the perfect camshaft for every application adjusting to ideal Lobe centers.
Thanks

[Piledriver]

If the engine combination doesn't work together as a system, you will see peaky performance if you are lucky.
With the right combination of parts, a 102LC cam can pull like a truck from near idle to redline, and it will give up little if anything at the top end.

PM sent, but probably not what you had in mind.

[Buggsy]

Hey Firebird, this "." is a period. Your post would be much easier to understand if you would use some of these in the appropriate places.
Thanks