KB

iTrader: (4)

I've been trying to learn how to read camshaft specs because I'm such a newb to all of this and I want to try and understand on a basic level what I'm doing before I swap out for the LQ4. Anyway I understand LSA is the distance in degree (measured on the cam itself) between the point of peak lift on the intake lobe and the peak lift on the exhaust lobe right? What I'm having a hard time understanding is what effects does LSA contribute to power output. Does it affect the powerband? What would the affects be for two cams ground exactly the same except for one having a narrow LSA and one having a wider one? Any other info I'm missing is appreciated.

Thanks

02sierraz71_5.3

iTrader: (2)

The tighter the lsa(lower number) the more narrow the power band, the wider more the power is stretched over an rpm range. The lsa icl and ecl are all byproducts its the valve events that come first. All the factors play against one another for example if you want an early IVC you need to keep lowering the ICL the more you increase duration but then that increases overlap its a give and take. There are obviously other factors and Im simplifying it.
DO NOT PICK A CAM BASED ON LSA,ICL look at the valve events.

The best way to really learn about whats going on is too readup on cam theory and what different valve events do. Then download pianoprodigys spreadsheet or desktop dyno and start punching in numbers. After playing with it for a while youll see whats going on

KB

iTrader: (4)

Thanks for the info/tips. I'm definitely going to look into that!

TurboBerserker

iTrader: (1)

Some basic cam stuff Grippy dug up a while ago:

.........................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
-------------------------------------------------------------------------

Lobe Separation Angle
-----------------------------------
Above 114 Deg. = Extremely Wide
114-112 Deg. = Wide
112-110 Deg. = Moderately Wide
110-108 Deg. = Moderate
108-106 Deg. = Moderately Tight
106-104 Deg. = Tight
Below 104 Deg. = Extremely Tight
-----------------------------------

.........................Advancing/Retarding Cam Timing................................
...............Advancing.......................... ........Retarding
*Begins Intake Event Sooner...................Delays Intake Event
*Open Intake Valve Sooner...............Opens Intake Valve Open Later
*Builds More Low-End Torque..............Builds More High-End Torque

*Decrease Piston-Intake........................Increase Piston-Intake
...Valve Clearance................................... Valve Clearance

*Increase Piston-Exhaust........................Decrease Piston-Exhaust
....Valve Clearance.....................................Valv e Clearance

KB

iTrader: (4)

Thanks for that Turbo. That really puts things in layman's terms for me to understand lol.

Mark Johnson

iTrader: (1)

How can I tell the events of the cam with say; lift, duration and LSA?