Ummm no

 

Can you explain.

 

Yeah, definitely explain. I'm just quoting stuff I learned from you guys!

I always thought a wide LSA had a broad power band and vice versa.


Maybe one of us is misunderstanding the other?

 

When comparing cams with identical duration, a narrow LSA will cause a narrow powerband. A wider LSA will cause a wider powerband generally speaking. At least this is the way I've told by several different people.

 

What I understand is that tighter LSA equals to more overlap which means the powerband will shift to higher RPM's.

 

Tighter LSA does equal more overlap. I'm not gonna comment on the power peak again! I must be confused!

 

I'm sure most of us have seen this chart before.\\


The first three are what's making me confused about Bret's reply to me.



Varying Lobe Separation Angle
...........Tighten................................ .......Widen
Moves Torque to Lower RPM.........Raise Torque to Higher RPM
Increases Maximum Torque...........Reduces Maximum Torque
Narrow Powerband......................Broadens Power Band
Builds Higher Cylinder Pressure......Reduce Maximum Cylinder Pressure
Increase Chance of Engine Knock..Decrease Chance of Engine Knock
Increase Cranking Compression.....Decrease Cranking Compression
Increase Efective Compression.....Decrease Efective Compression
Idle Vacuum is Reduced Idle........Vacuum is Increased
Idle Quality Suffers....................Idle Quality Improves
Open Valve-Overlap Increases.....Open Valve-Overlap Decreases
Closed Valve-Overlap Increases....Closed Valve-Overlap Decreases
Natural EGR Efect Increases.........Natural EGR Efect is Reduced
Decreases Piston-to-Valve Clerance.....Increases Piston-to-Valve Clerance

 

Why did you pick those as choices? I think you could use more lift.

Rich

 

Cause I am looking for top end performance. Would like to rev it higher. Not sure if I can go with more lift without PTV issue unless the valve events are carefully designed to help that.

 

What pistons are you running? Why not an SR cam if it's for racing?

Rich

 

JE Pistons (-16 cc dish). I am talking my self of going that route.

 

these all ***-U-ME a lot of things....

...........Tighten................................ .......Widen
Moves Torque to Lower RPM.........Raise Torque to Higher RPM

only if you are moving the ICL earlier does this happen, you can keep the same LSA and ICL and move the ECL (because of the move in the LSA) and Widen the LSA and lower the peak TQ RPM and value.

...........Tighten................................ .......Widen
Increases Maximum Torque...........Reduces Maximum Torque

Well the RIGHT LSA will improve the peak TQ value and usually the whole cruve, above and below that value will reduce the peak/max TQ.

...........Tighten................................ .......Widen
Narrow Powerband......................Broadens Power Band

Uhhh, actually if you do it correctly you can broden the powerband with the right LSA, which is USUALLY narrower but it's all in connection with a lot of things.

...........Tighten................................ .......Widen
Builds Higher Cylinder Pressure......Reduce Maximum Cylinder Pressure
Increase Chance of Engine Knock..Decrease Chance of Engine Knock
Increase Cranking Compression.....Decrease Cranking Compression
Increase Efective Compression.....Decrease Efective Compression


All of those are totally dependant on the ICL and duration and have NOTHING to do with the LSA.

...........Tighten................................ .......Widen
Idle Vacuum is Reduced Idle........Vacuum is Increased
Idle Quality Suffers....................Idle Quality Improves
Natural EGR Efect Increases.........Natural EGR Efect is Reduced
Decreases Piston-to-Valve Clerance.....Increases Piston-to-Valve Clerance

Generally yes, but if you don't account for duration it doesn't matter.

...........Tighten................................ .......Widen
Open Valve-Overlap Increases.....Open Valve-Overlap Decreases
Closed Valve-Overlap Increases....Closed Valve-Overlap Decreases

Uhhhhh, WTF is closed valve overlap? OVERLAP is when BOTH VALVES ARE OPEN so like the idle examples you still need to take into account duration.

Bret

 

Damnit...I guess I gotta throw everything I thought I knew about cams out the window!

What about "in general"? Are some of them right then?!!