What Is Lobe Separation Angle (LSA)?

Lobe Separation Angle (LSA) is the angle in degrees between the peak of the intake lobe and the peak of the exhaust lobe on a camshaft.

In simple terms:

• It controls how much the intake and exhaust valves overlap.
• It affects idle quality, vacuum, torque curve, and peak power.
• It changes how aggressive or smooth the engine feels.

LSA is usually between 100° and 120° in most performance engines.

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Why LSA Matters

LSA directly changes how an engine behaves.

Tight LSA (104°–106°)

• More valve overlap
• Rough idle
• Strong mid-range power
• Popular in oval track and aggressive NA builds

Moderate LSA (108°–112°)

• Balanced idle and performance
• Strong street performance
• Common in muscle cars

Wide LSA (114°–116°+)

• Less overlap
• Smoother idle
• Better for forced induction (turbo or supercharged)
• Stable vacuum

The calculator classifies the result so you can quickly see where your cam falls.

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How the Lobe Separation Angle Calculator Works

The calculator has three modes:

1. Calculate LSA from Centerlines
2. Calculate from Duration and Timing Events
3. Calculate Valve Overlap from Known LSA

Let’s break them down.

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1. Calculate LSA from Lobe Centerlines

If you already know:

• Intake Lobe Centerline (ATDC)
• Exhaust Lobe Centerline (BTDC)

The formula is:

LSA = (Intake CL + Exhaust CL) ÷ 2

Example

• Intake CL = 106°
• Exhaust CL = 114°

LSA = (106 + 114) ÷ 2 = 110°

That’s a strong street-performance LSA.

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2. Calculate LSA from Duration and Timing Events

If you know:

• Intake Duration at 0.050″
• Exhaust Duration at 0.050″
• Intake Opening (BTDC)
• Exhaust Closing (ATDC)

The calculator finds the intake and exhaust centerlines first.

Formulas Used

Intake CL = (Intake Duration ÷ 2) − Intake Opening
Exhaust CL = (Exhaust Duration ÷ 2) − Exhaust Closing
LSA = (Intake CL + Exhaust CL) ÷ 2

This method is helpful when reading cam cards or degreeing a cam during installation.

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3. Calculate Valve Overlap

Valve overlap happens when:

• Intake valve opens
• Exhaust valve has not fully closed

Overlap affects idle quality and cylinder scavenging.

The calculator uses:

Overlap = (Intake Duration ÷ 2) + (Exhaust Duration ÷ 2) − (LSA × 2)

More overlap usually means:

• Rougher idle
• Stronger high RPM power
• Lower vacuum

Less overlap means:

• Smooth idle
• Better drivability
• Stronger low-end torque

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Cam Installed Advance Explained

The calculator also accounts for installed advance.

Installed advance changes where the cam sits relative to the crankshaft.

• Positive number = cam advanced
• Negative number = cam retarded

Typical street engines use 2° to 4° advance.

Advancing the cam:

• Increases low-end torque
• Moves power band lower

Retarding the cam:

• Improves high RPM power
• Moves power band higher

The tool shows:

• Original centerlines
• Effective centerlines after advance
• Ground-in cam advance

This helps when degreeing a cam properly.

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LSA Classification Guide

The calculator automatically classifies LSA values:

LSA Range	Category	Typical Use
Below 104°	Extremely Tight	Racing only
104°–106°	Tight	Oval track
106°–108°	Moderately Tight	Performance
108°–112°	Moderate	Street
112°–114°	Moderately Wide	Cruiser
114°–116°	Wide	Turbo/Supercharged
116°+	Extremely Wide	Pro Stock

This quick classification helps match the cam to the engine application.

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Real-World Example

Let’s say you enter:

• Intake Duration: 230°
• Exhaust Duration: 236°
• Intake Opening: 15° BTDC
• Exhaust Closing: 15° ATDC

The calculator will:

1. Compute intake and exhaust centerlines
2. Calculate LSA
3. Determine overlap
4. Show cam advance
5. Classify the cam

Within seconds, you get a full camshaft timing analysis.

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Who Should Use a Lobe Separation Angle Calculator?

This tool is ideal for:

• Engine builders
• Camshaft designers
• Performance tuners
• Drag racers
• Oval track racers
• Street performance enthusiasts
• DIY mechanics degreeing a cam

If you are installing a cam or comparing cam specs, this tool saves time and prevents math mistakes.

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Common Mistakes When Calculating LSA

1. Mixing BTDC and ATDC values
2. Forgetting to divide duration by 2
3. Ignoring installed advance
4. Using advertised duration instead of duration at 0.050″
5. Confusing intake and exhaust centerlines

The calculator reduces these errors.

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How to Get the Best Results

• Always use duration at 0.050″
• Double-check timing events
• Confirm your cam card specs
• Measure centerlines accurately when degreeing
• Match LSA to engine compression and intended use

Remember, LSA alone does not determine performance. It works together with:

• Duration
• Lift
• Compression ratio
• Cylinder head flow
• Exhaust system
• RPM range