I don't know if anyone saw this before. J-ROD posted it on Tech back maybe over a year ago but, it serves its purpose really well of showing you the differences between a slow and fast lobe. Everyone is familar with the XE-R line of lobes from Comp and how they are 'quicker' correct... Well, what does this mean???

1. Less duration @ lower lift values
2. More peak lift
3. More duration @ higher lift values due to #2
What else can you see?

The blue curve is lobe # 3726 (XE-R)
The green curve is lobe # 3356 big block journal, marine lobe

#3726
.006'' = 281
.050'' = 232
.200'' = 153
PL w/ 1.7 = .595''

#3356
.006'' = 298
.050'' = 242
.200'' = 153
PL w/ 1.7 = .566''



Now, take a stock 5.3L head. Lets look at the intake side. Where is the largest portion of flow occuring... Higher lift correct. So what these quicker lobes are doing is popping the valve up quick off the seat and getting it to this area where flow is higher. Like mentioned above, more peak lift is more duration @ higher lift. It's all about bringing the charge into the chamber and when looking at lobes, this is one way that definetly works.

 

Here are some other comparison for you now that you probably have a better grasp of what is going on.


X-E 220* -.563''
.006'' = 273
.050'' = 220
.200'' = 138


TR 220* -.564''
.006'' = 272
.050'' = 220
.200'' = 141

XE-R 220* -.581''
.006'' = 269
.050'' = 220
.200'' = 143

 

GREAT info there.... someone's been doing their homework

 

DEFINETELY worth a look and keeping it in memory....

 

Great info Sport Side !!!!!, a visual comparison is always nice to have !!!

 

what does this mean though in terms of making power? its great for comparisons but for someone like me an average joe with very little cam knowledge how can I use this to be able to see what matches up best as far as lift goes and head flow rates to create greater power?

 

The visual doesn't tell you anything but instead, gives you an idea of different lobe profiles and ramp rates. If you have an understanding of how the head flows, and the other parts of your motor, what they are doing... Then, you can decide what type of lobe you will need for the job. Whether it is a quicker ramp like the XE-R or a slower one... All combination specific sorta stuff!

 

once you figure out what type of ramp rate you are dealing with how can you then use that to find out how much flow you need to create power?

 

damn kyle, you got this stuff down packed.
how bout a new cam for the tired old tr220? i'm sure there are better out there.

 

Kyles got friends in high places. Its amazing how much help someone will give you when you got some brains and want to use them.