The Camshaft Spec "lobe Center" What Does It Mean As Far As "effect" On Performa

gtsr515 · 06-10-2002, 12:53 AM

I "understand" what and how "Duration, Lift, Rocker ratio, intake and exhaust events, and lifter type", effect (affect?) the performance of an engine as far as camshafts work, but I must admit I just don't get "Lobe Center" and how it effects performance?

Screw it, I'll just do the Pneumatic valvetrain thing.....(inside joke for those of you who remember

)

Thanks!

ballistic_331LX · 06-10-2002, 01:10 AM

Hey man whats up...please read....i dug deep for this and have read it several times in the past...good luck
LOBE CENTER LINE
Lobe center line, or lobe centers, is the number of degrees between the theoretical center line of the exhaust and intake lobe for a given cylinder, measured in camshaft degrees. On automotive applications the average lobe center is 110°, but will vary between 118° and 100° depending on the application.
The lobe center line of the American automotive camshaft is determined at the time the camshaft is ground and cannot be changed except by regrinding the camshaft.
Contrary to what some cam manufacturers say, very minor changes in lobe centers can alter the power range of an engine sufficiently to make a winner out of an also ran. Subtle changes in lobe centers are one of the top secrets of the successful cam designer. To decrease the lobe centers of a given camshaft, the exhaust lobe would be retarded and the intake lobe advanced. This would cause the exhaust to open later and close later and the intake to open earlier and close earlier.
A camshaft with closer lobe centers will have more overlap (valves
open more at TDC at start of intake stroke) and higher cylinder
pressure due primarily to the earlier closing. The camshaft with the closer lobe centers will always produce more power in the mid range than a cam using the same profile and wide lobe center, and in many applications will produce more power all throughout the range depending on many variables such as the induction system, rod angularity and flow capacity of the ports.
The full potential of lobe center changes can only be appreciated by someone who has had the opportunity to work with an engine that is equipped with a separate cam for intake and exhaust such as the Offy, Jag, four cam Ford, etc. Until a person has been able to change lobe centers at will, he cannot fully appreciate the affects on performance.

Stroked408 · 06-11-2002, 11:26 PM

LOL wow very technical there Ballistic,in simpler terms a lobe center of 108-110 is good for NA motors,112 and higher is usually reserved for your power adder engines,noticed I said usually this is not the rule,but most street cams are in the area of 108-114 and I say most NA cams that run good are in the area of 108-110 a serious drag race cam might be 104-106,so it all depends on your combo

Unit 5302 · 06-12-2002, 01:25 AM

LCA is very close to LSA. LSA is figured as the angle in degrees of camshaft lobe seperation. In other words, how far apart the center of the cam lobes are. LCA is how far off center the cam lobes are. Typically, cams are installed straight up, and the LCA and LSA are the same. The alphabet cams do not follow this pattern. E303 is 107/117 B303 is 109/119. Since the alphabet cams have already been setup with an unequal LCA, they are almost always best when installed straight up. Some other cams, including the stock HO cam are better advanced or retarded in particular applications.

I don't know who came up with the idea the average automobile application has an LCA of 110*? That's what most high performance cams have. The stock HO cam, which is fairly aggressive is 116 or so. Most street cams are between 110-114 for the 5.0, anyway. Going below 110 generally begins to lead towards manual brakes, and causes idle problems with the EFI systems due to poor vacuum. On a stock EEC-V 5.0 computer system, the car probably wouldn't run for crap. Newer cams have bumped LCA and LSA up in an attempt to sacrifice a little very high rpm performance for a good idle and stronger bottom end/mid range power.

Stroked408 · 06-12-2002, 07:35 AM

Have had a E303 cam for 6 years with a 110 centerline no problems,if you are not willing to accept a lumpy idle then why change cams,especially any of the alphabet cams,I seen on a post elsewhere in here how great the F303 cam is and it idles rougher than a E303 and it's centerline is 114,so back to what I always say "it is your preference and how much loss of a smooth idle you can tolerate"

Unit 5302 · 06-12-2002, 07:12 PM

Quote:

Originally posted by Stroked408
Have had a E303 cam for 6 years with a 110 centerline no problems,if you are not willing to accept a lumpy idle then why change cams,especially any of the alphabet cams,I seen on a post elsewhere in here how great the F303 cam is and it idles rougher than a E303 and it's centerline is 114,so back to what I always say "it is your preference and how much loss of a smooth idle you can tolerate"

LSA and LCA are NOT the only indicators of overlap. You need to go back to school. The B303's idle is lumpier than the E303, yet the B303 has more LSA and LCA. I agree with you on the point of making high end power. Sacrificing idle quality usually pays dividends above 5500rpm, but most EFI combos don't make their peak power much higher than that, anyway. For a carbed car, yes. The reason I don't like cams that try to overcompensate is another topic altogether. The Comp Cams XE series has very high LSAs, but they also have a very lumpy idle. It's just that they actually generate vaccum, which most SN95 cars need to run worth a crap.

The idea that your E303 has given you no problems so it's a good cam is asinine. There are more posts about problems related to vacuum and idle quality with the E303 cam than all other cams combined. The SN95 cars revised computers do not deal well with the poor vacuum created by the E303. This has been well known for a while now.

Your "Engine Guys" seem to be failing you again in the real world 5.0 knowledge department. I'm not suprised.

Stroked408 · 06-12-2002, 08:10 PM

so Unit5 I would really like to know,what makes you an expert? Does sitting behind your computer and searching websites make you an expert? I am not trying to start any crap but I would really like to know? I have had (4) 5.0 Mustangs all of varying degrees of modifications and all have ran great and I have gotten out of them what I wanted to get out of them,I have built many a 5.0 Mustangs to varying degrees of mods and the customer has been happy,so let me see just because I just joined this little forum makes me not know anything about 5.0 Mustangs,you have over 1000 posts.......where did you get the info from? You read it,you study it,you call a speed shop,I have in no way built a car for NMRA or FFW or NMCA or any other sanctioning body but obviously you have,so I would really like to hear your credentials on what makes you an expert on the 5.0 Mustang,and building a car for either of those sanctioning bodies does not make you an expert either,but I would really like to hear what makes you an expert,I have only been following the 5.0 Mustang since 1982 and learning something new about them every year,so the one thing is you never stop learning,but obviously you have,so once again what makes you an expert?

06-10-2002, 12:53 AM	#1
gtsr515 Registered Member Join Date: Nov 2001 Location: Sunny, Hot, Sebring, Florida Posts: 725	The Camshaft Spec "lobe Center" What Does It Mean As Far As "effect" On Performa I "understand" what and how "Duration, Lift, Rocker ratio, intake and exhaust events, and lifter type", effect (affect?) the performance of an engine as far as camshafts work, but I must admit I just don't get "Lobe Center" and how it effects performance? Screw it, I'll just do the Pneumatic valvetrain thing.....(inside joke for those of you who remember ) Thanks! __________________ Remember...2nd place is 1st place for losers!

06-10-2002, 01:10 AM	#2
ballistic_331LX Registered Member Join Date: Jun 2002 Posts: 28	lobe center.....you gotta comprehend this.....or it will lose ya!!! Hey man whats up...please read....i dug deep for this and have read it several times in the past...good luck LOBE CENTER LINE Lobe center line, or lobe centers, is the number of degrees between the theoretical center line of the exhaust and intake lobe for a given cylinder, measured in camshaft degrees. On automotive applications the average lobe center is 110°, but will vary between 118° and 100° depending on the application. The lobe center line of the American automotive camshaft is determined at the time the camshaft is ground and cannot be changed except by regrinding the camshaft. Contrary to what some cam manufacturers say, very minor changes in lobe centers can alter the power range of an engine sufficiently to make a winner out of an also ran. Subtle changes in lobe centers are one of the top secrets of the successful cam designer. To decrease the lobe centers of a given camshaft, the exhaust lobe would be retarded and the intake lobe advanced. This would cause the exhaust to open later and close later and the intake to open earlier and close earlier. A camshaft with closer lobe centers will have more overlap (valves open more at TDC at start of intake stroke) and higher cylinder pressure due primarily to the earlier closing. The camshaft with the closer lobe centers will always produce more power in the mid range than a cam using the same profile and wide lobe center, and in many applications will produce more power all throughout the range depending on many variables such as the induction system, rod angularity and flow capacity of the ports. The full potential of lobe center changes can only be appreciated by someone who has had the opportunity to work with an engine that is equipped with a separate cam for intake and exhaust such as the Offy, Jag, four cam Ford, etc. Until a person has been able to change lobe centers at will, he cannot fully appreciate the affects on performance.

06-11-2002, 11:26 PM	#3
Stroked408 Registered Member Join Date: Jun 2002 Location: Southwest Posts: 131	LOL wow very technical there Ballistic,in simpler terms a lobe center of 108-110 is good for NA motors,112 and higher is usually reserved for your power adder engines,noticed I said usually this is not the rule,but most street cams are in the area of 108-114 and I say most NA cams that run good are in the area of 108-110 a serious drag race cam might be 104-106,so it all depends on your combo __________________ Deeper,Harder,Faster Stage Deeper Launch Harder Go Faster

06-12-2002, 07:35 AM	#5
Stroked408 Registered Member Join Date: Jun 2002 Location: Southwest Posts: 131	Have had a E303 cam for 6 years with a 110 centerline no problems,if you are not willing to accept a lumpy idle then why change cams,especially any of the alphabet cams,I seen on a post elsewhere in here how great the F303 cam is and it idles rougher than a E303 and it's centerline is 114,so back to what I always say "it is your preference and how much loss of a smooth idle you can tolerate" __________________ Deeper,Harder,Faster Stage Deeper Launch Harder Go Faster

06-12-2002, 08:10 PM	#7
Stroked408 Registered Member Join Date: Jun 2002 Location: Southwest Posts: 131	credentials so Unit5 I would really like to know,what makes you an expert? Does sitting behind your computer and searching websites make you an expert? I am not trying to start any crap but I would really like to know? I have had (4) 5.0 Mustangs all of varying degrees of modifications and all have ran great and I have gotten out of them what I wanted to get out of them,I have built many a 5.0 Mustangs to varying degrees of mods and the customer has been happy,so let me see just because I just joined this little forum makes me not know anything about 5.0 Mustangs,you have over 1000 posts.......where did you get the info from? You read it,you study it,you call a speed shop,I have in no way built a car for NMRA or FFW or NMCA or any other sanctioning body but obviously you have,so I would really like to hear your credentials on what makes you an expert on the 5.0 Mustang,and building a car for either of those sanctioning bodies does not make you an expert either,but I would really like to hear what makes you an expert,I have only been following the 5.0 Mustang since 1982 and learning something new about them every year,so the one thing is you never stop learning,but obviously you have,so once again what makes you an expert? __________________ Deeper,Harder,Faster Stage Deeper Launch Harder Go Faster

06-12-2002, 01:25 AM	#4
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	LCA is very close to LSA. LSA is figured as the angle in degrees of camshaft lobe seperation. In other words, how far apart the center of the cam lobes are. LCA is how far off center the cam lobes are. Typically, cams are installed straight up, and the LCA and LSA are the same. The alphabet cams do not follow this pattern. E303 is 107/117 B303 is 109/119. Since the alphabet cams have already been setup with an unequal LCA, they are almost always best when installed straight up. Some other cams, including the stock HO cam are better advanced or retarded in particular applications. I don't know who came up with the idea the average automobile application has an LCA of 110*? That's what most high performance cams have. The stock HO cam, which is fairly aggressive is 116 or so. Most street cams are between 110-114 for the 5.0, anyway. Going below 110 generally begins to lead towards manual brakes, and causes idle problems with the EFI systems due to poor vacuum. On a stock EEC-V 5.0 computer system, the car probably wouldn't run for crap. Newer cams have bumped LCA and LSA up in an attempt to sacrifice a little very high rpm performance for a good idle and stronger bottom end/mid range power.