Technical information on highly modifed engines for Harley-Davidson motorcycles.
Stage Three 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.
The major difference between Stage Two and Stage Three
engines is in the heads. A set of 'ported' heads and higher compression rations are
considered essential to reaching Horsepower figures in excess of 80. A successful stage
three engine will be well thought out, with all components determined prior to rebuilding
the engine. As you view the Stage Three dyno sheets, notice the differences in the power
bands. Specifically note where peak torque and horsepower occur. The lower the RPM's are
on these figures, the more 'streetable' the engine will normally be.
Build an 82 HP Stage 3 engine
Build a 95 HP Stage 3 engine
EVO 77 HP
EVO 78 HP
EVO 81 HP
EVO 82 HP
EVO 85 HP
EVO 93 HP
EVO 95 HP
EVO 101 HP
XL 103.1 HP
EVO 112 HP