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Don't let the Harley heat monster ruin your riding.
Reduce  Engine Surging
Improve Throttle Response
Reduce Engine Ping


HD 2007/2008 Engines

High Heat on 2007/08 HD engines

HD 2007/08 Performance Recommendations

Cool your exhaust temperature with the Wide Band O2 upgrade for 2007/08 HD

Harley Camshaft Specification Tables

HD Twin Cam Engine Builds
TC 128 HP 95 CID
TC 100HP Street Engine

The basics of Fuel Injection explained

Rammer Performance Air Cleaners
TC Performance Heads 100+HP

Pro Tuning on a Shade Tree Budget


Camshaft Technology
Understanding Lobe Separation Angle (LSA)

If you look at enough cams, you might begin to notice that cams with the same duration and lift can have different performance characteristics when installed in similar bikes. At first glance, it may seem difficult to explain. A difference in the lobe separation angles (LSA) of the cams can explain the difference. Here is a summary of what general conditions you could expect for the engine if the LSA is made wider or narrower.
Condition Wide Separation Angle Narrow Separation Angle
Overlap Decreased Increased
Low End Power Higher Lower
High End Power Lower Higher
Detonation Potential Lower Higher
Intake Events Later Earlier
Exhaust Events Earlier Later
Overlap Decreased Increased
Manifold Vacuum Higher Lower

LSA is the Lobe Separation Angle or the number of degrees between the intake and exhaust lobe centerlines. The LSA has a direct relationship to amount of overlap on a cam. Cams with identical duration and lift specifications can have very different LSAs. Generally speaking, a wide LSA will produce greater low end torque and a narrow separation angle will produce better top end power. For any given LSA, an engine will give similar torque curves and peak torque RPMs even with different overlaps. Refer to the LSA table above to determine how an increase or decrease in LSA is expected to change the performance of the engine.

Intake Lobe Centerline is an imaginary line that passes through the camshaft rotation axis and the point of maximum lift of the intake lobe. Changing the lobe centerline without changing the duration can increase or decrease the point at which intake events take place during engines cycles. Increasing the intake lobe center line from 104 to 106 degrees is considered retarding. All events will take place later in the engine cycle. Retarding the cam causes the intake valve to open and close later. This will reduce cylinder pressure which reduce the low speed performance of the engine. Remember that advancing or retarding a cam effects both the intake and exhaust. Do not advance or retard a cam by installing the cam with the timing mark offset by one tooth. One tooth on the timing gear is about 17 degrees.

The cam can be offset by pressing off the timing gear and re-installing it. This should only be performed by experience performance mechanics or by the manufacturer. A better solution is to use Crane Cams High-Roller series of camshafts with an offset keyway timing gear than can be advanced or retarded 4 degrees.

Exhaust Lobe Centerline is an imaginary line that passes through the camshaft rotation axis and the point of maximum lift of the exhaust lobe. Changing the lobe centerline without changing the duration can increase or decrease the point at which exhaust events take place during engines cycles.


Table of Contents
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Modification, Installation, Maintenance and Tuning Index  will help you find most of the information you want on one page.

How to get Professional Tuning Results at home
Testing the Innovate Motorsport LM-1 portable air fuel meter

Profession Tuning on a Shade Tree Budget

Veypor VR2 Data Logger and Instrument Panel
Video Installation and Demo
Purchase VR2

Engine Performance
How to Build a
TC96 2007 Engines
TC88 70HP Stage1  
TC95 128HP Stage 3
TC95 100HP Street
TC96 2007 Stage 1/2
EVO 64 HP Stage 1
EVO 74 HP Stage 2
EVO 82 HP Stage 3
EVO 95 HP Stage 3
883 to 1200 Upgrade
Shovelhead Modifications

New EFI for EVO and TC

Performance Gallery
Horsepower Gallery
Evolution 80
Twin Cam 88/95
Evolution Unlimited
Sportster Unlimited
Drag Strip Gallery
Land Speed Racing Gallery
CV Carburetor
Modifying the CV carb
Tuning a CV carb
Selecting a cam
Install a TC 88/95 cam
Install a Big Twin cam
Install Sportster cams

Camshaft Specifications
Twin Cam

Exhaust Systems
EVO Exhaust Testing
TC Exhaust Testing
Khrome Werks AR100 test
Making Drag Pipes Work

Shop Manual
Carburetor Troubleshooting
Finding Manifold Leaks
Cylinder Heads
Pistons and Cylinders
Belt Drive
Shop Manual Appendix
$20 Bike Lift
Plug Wires
Spark Plugs
Engine Tuning
Nitrous Oxide
Motor Oil
Stutter Box
General Information
WEB Links
Buy Books and Manuals
Performance Calculations
Estimate Horsepower
Estimate 1/4 Mile Time
Estimate Top Speed

Engine Displacement
Exhaust Length
Gear Ratios
Air Density

The Nightrider Diaries
The ramblings of a genius a, a madman and something in between.

Where is Sifton Cams?

Autocom Active-7 tested

Harley-Davidson EFI
-EFI basics explained
-EFI modifications explained

183 HP, 2 carbs, 2680cc

Copyright 1997-2006  Stephen Mullen, Oldsmar, FL -+-