Get XiED(tm)! Performance Parts

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


Engine Development and Modification
Performance and Technical information on modifying engines for Harley-Davidson motorcycles.

Looking for high performance engine specifications for your Harley-Davidson motorcycle? Need to know what high performance equipment provides the best performance at the lowest costs for your H-D. Here you can look at performance modifications with the dyno runs of many different engine combinations, so you can pick your own equipment, horsepower rating and dollars to spend. An incremental approach to engine development has provided some good results on many engines. Find out what combination of carburetor, camshaft, exhaust systems, ignition systems, head work, pistons and the other high performance components work well. There are tests of some equipment that did not work well. Know what works and what does not. Compare the results of your current bike to those seen here. Are you getting the performance you paid for?

If you have had success in your engine development program, send a picture of the bike and your performance results (dyno sheets or time slips) to the V-Twin Café for publication. The V-Twin Café is always looking for good articles on motorcycle performance work. If you write performance oriented articles, contact us.

Twin Cam
88 and 95
cubic inches
Twin Cam Engines from Harley-Davidson have a good design and some nice upgrades available from the local Dealer including a 95 cubic inch big bore kit. What can you expect from this engine? Here are some engine configurations that have been tested.
45 to 50 HP Stock Evolution Engines are the starting point for all the modifications. The only way to validate what the performance gain was for any change is to have dyno runs before and after. These are the before runs of several bikes.
55 to 65 HP

Up to $750

Stage One Evolution Harley-Davidson engines involve no internal changes made to the engine. All modifications are made by changing or modifications to external components on the engine. These components include air cleaners, carburetors, exhaust systems and ignition systems. No special tools or training is required to perform stage one modifications.
These modifications will provide from 55 to 65 horsepower at the rear wheel of a late model 80 CID Harley-Davidson big twin Evolution engine.

If you want to build your own Stage 1 engine, here are the parts used to create a 64 HP engine.

60 to 80 HP

Up to $1,500

Stage Two Evolution Harley-Davidson engines involve any stage one changes plus changes to some internal "bolt-on" engine components. These "bolt-on" modifications include camshafts and milling of the heads to increase compression. Some special tools and knowledge of engines is required to perform stage two modifications.
These modifications will provide from 60 to 80 horsepower at the rear wheel of a late model 80 CID Harley-Davidson big twin Evolution engine.

If you want to build your own Stage 2 engine, here are the parts used to create a 74 HP engine.

70 to 120 HP


Stage Three Evolution Harley-Davidson engines involve any change to any component in the engine. These modifications should only be performed by experienced mechanics with knowledge of performance modifications and engine "blue printing". Special tools are required to perform stage three modifications. V-Twin Café will limit its Stage Three engine information to those combinations that are mostly streetable.
These modifications will provide from 80 to 120 horsepower at the rear wheel of a late model 80 CID Harley-Davidson big twin Evolution engine.

If you want to build your own Stage 3 engine, here are the part used to create an 82 HP engine that can be assembled over a weekend.

120 HP and more


Stage Four Harley-Davidson engines are "anything goes". If it can be stuffed into a motorcycle chassis, it is worth trying. Time, expert knowledge, special tools and lots of money are required to build stage four engines. The ability to run on the street is not a criteria when designing these engines. These are all out race engines, designed for drag racing and other forms of competition.
These modifications can provide 120+ horsepower at the rear wheel of a late model 80 CID Harley-Davidson motorcycle. For these engines, the horsepower is only limited by the available money and engineering skills.
Shovelhead Engines The Shovelhead engine has been around for a long time. While the combustion chamber design is not as good as the Twin Cam and Evolution designs, there is still good power potential available in these engines. A good Shovel engine should make about 10% less power than a comparable Evo. This means your 80 CID Shovel can make 70-80 horsepower without to much trouble.
The Horsepower Gallery provides an extensive list of bikes , the power they produced and the major engine components. This list covers Evolution, Twin Cam 88/95 and Shovelhead engines.


Table of Contents
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Ask us a Question

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 -+-