Effects of Change in LSA discussion
03-21-2006, 03:36 PM
#11
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MJ, what do you think about this.
We take a TR220 112/108 cam w/ a 38* IVC.
Put it on a 120* seperation and place the ICL at 116*. Now, we have a 46* IVC. So, the high end has increased.
If you spread the LSA (and keep the ICL/ECL at the same placement from the LSA) then, the intake duration must come down to maintain the same RPM range.
220/220 112/108 = 210/210 117/113 (same 38* IVC)
Which one offers a stronger, mid range curve?
We've totally forgotten about one thing however.
Shaun Perry explains here.
We take a TR220 112/108 cam w/ a 38* IVC.
Put it on a 120* seperation and place the ICL at 116*. Now, we have a 46* IVC. So, the high end has increased.
If you spread the LSA (and keep the ICL/ECL at the same placement from the LSA) then, the intake duration must come down to maintain the same RPM range.
220/220 112/108 = 210/210 117/113 (same 38* IVC)
Which one offers a stronger, mid range curve?
We've totally forgotten about one thing however.
Shaun Perry explains here.
These motors are intake limited and therefore it is RPM limited. Installing a camshaft that is meant to peak at 6800RPM is a waste of lobe. With the LS1/LS6/Truck intake manifolds, these motors can not make power at this high of a RPM. So, tightening the LSA will boost power in the mid-top end and keep the motor in a more usable RPM range.
I tighten the LSA to do just that. This keeps the power below 6200RPM and this is favorable since this is where the LS1 makes peak power, regardless of the camshafts specifications.
I tighten the LSA to do just that. This keeps the power below 6200RPM and this is favorable since this is where the LS1 makes peak power, regardless of the camshafts specifications.
03-21-2006, 03:53 PM
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Originally Posted by KySilverado
I just bought a darn cam with 121LSA.
03-21-2006, 04:20 PM
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Great discussion topic, lol this has been what i have wanted to know since i got to these forums... all i want is great lower and midrange torque, im not gonna be racing my truck... i want more grunt down low. but sportside i am cam illiterate like many here and dont know how to answer the question you asked in your last post..
which one of these would offer stronger mid range? or would they be the same due to the same IVC? im still trying to grasp alot of these terms and how they relate... 
i think i need to find a beginners cam term library....
220/220 112/108 = 210/210 117/113 (same 38* IVC)
Which one offers a stronger, mid range curve?
Which one offers a stronger, mid range curve?
i think i need to find a beginners cam term library....
03-21-2006, 04:43 PM
#15
Originally Posted by Sport Side
Yeah but your intake duration is probably small and also... The Radix doesn't use the same intake.
03-21-2006, 08:29 PM
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Originally Posted by Sport Side
MJ, what do you think about this.
We take a TR220 112/108 cam w/ a 38* IVC.
Put it on a 120* seperation and place the ICL at 116*. Now, we have a 46* IVC. So, the high end has increased.
If you spread the LSA (and keep the ICL/ECL at the same placement from the LSA) then, the intake duration must come down to maintain the same RPM range.
220/220 112/108 = 210/210 117/113 (same 38* IVC)
Which one offers a stronger, mid range curve?
We've totally forgotten about one thing however.
Shaun Perry explains here.
We take a TR220 112/108 cam w/ a 38* IVC.
Put it on a 120* seperation and place the ICL at 116*. Now, we have a 46* IVC. So, the high end has increased.
If you spread the LSA (and keep the ICL/ECL at the same placement from the LSA) then, the intake duration must come down to maintain the same RPM range.
220/220 112/108 = 210/210 117/113 (same 38* IVC)
Which one offers a stronger, mid range curve?
We've totally forgotten about one thing however.
Shaun Perry explains here.
Now that I have made that clear; What exactly do you mean with the specs you are giving above?... (220/220 112/108 = 210/210 117/113 (same 38* IVC)
Which one offers a stronger, mid range curve?)
What is the 112/108 and the 117/113? Is that the lsa/icl?
Second - I have no clue who Shaun Perry is, but that quote is either not giving all the info in respect to cam or he is just wrong IMO. What I am thinking is he is saying that he either moved the icl or decreased the duration to bring the power band down yet kept the lsa tighter to allow it to peak higher where he wanted it. This is just a hunch. Otherwise, I am saying he is wrong.
03-21-2006, 08:44 PM
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Yep, pretty much... I've taken two single pattern camshafts. One with a 112LSA + 4* and the other with a 117LSA + 4*. Duration adjusted for the IVC point.
I figured this was your main idea that given the same RPM spectrum, one with a wider LSA will have a broader power curve.
No disclaimers needed... I know. 
I figured this was your main idea that given the same RPM spectrum, one with a wider LSA will have a broader power curve.
Ok. Lets start out with this. I don't claim to know everything about a cam. That is why I started this thread, to learn. Not to say everyone is idiots and i'm right because I said so. I hope i'm not that shallow or stupid.
03-22-2006, 12:24 AM
#18
Ok, so I'm thoroughly confused now. A tighter lsa like a 112 will have a narrower power band and something wider will have a broader powerband. What I'm wondering is how you tell when a cam is gonna kick in, i.e. which lsa is better for bottom end? Like say the same cam such as a tr 220 on a 112 vs. one on a 114.
03-22-2006, 06:08 AM
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Originally Posted by Sport Side
MJ, what do you think about this.
We take a TR220 112/108 cam w/ a 38* IVC.
Put it on a 120* seperation and place the ICL at 116*. Now, we have a 46* IVC. So, the high end has increased.
If you spread the LSA (and keep the ICL/ECL at the same placement from the LSA) then, the intake duration must come down to maintain the same RPM range.
220/220 112/108 = 210/210 117/113 (same 38* IVC)
Which one offers a stronger, mid range curve?
We've totally forgotten about one thing however.
Shaun Perry explains here.
We take a TR220 112/108 cam w/ a 38* IVC.
Put it on a 120* seperation and place the ICL at 116*. Now, we have a 46* IVC. So, the high end has increased.
If you spread the LSA (and keep the ICL/ECL at the same placement from the LSA) then, the intake duration must come down to maintain the same RPM range.
220/220 112/108 = 210/210 117/113 (same 38* IVC)
Which one offers a stronger, mid range curve?
We've totally forgotten about one thing however.
Shaun Perry explains here.
03-22-2006, 06:17 AM
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Originally Posted by StrokerAce03
Ok, so I'm thoroughly confused now. A tighter lsa like a 112 will have a narrower power band and something wider will have a broader powerband. What I'm wondering is how you tell when a cam is gonna kick in, i.e. which lsa is better for bottom end? Like say the same cam such as a tr 220 on a 112 vs. one on a 114.
Confused
I have been for years! 