Paul,


My SeaWind friend just got his all alumium (except for the intermediate
housing) 20B with aggressive street ports and slightly enlarged exhaust
ports back from R.B.  He is considering the new PowerSport PSRU as it
is robust and three inches shorter than Tracy's combination.  I don`t
particularly like the reduction ratio of  2.42:1 as it would difficult
with his 76" to take advantage of the top rpm power.  Unless he pushes
his prop rpm over 2700 on T.O.  his engine will be hovering around 6500
rpm which is below peak hp.  Redline on a 20B was I believe was around
8000 rpm but max power was below that figure.

Do you or anyone have a dyno curve on a NA 20B at 6500 to 7000 rpm?   My
rough guess would be around  270 - 280 Hp.

We know turbocharged it put out max 320 Hp. As a contingency plan he
will slap a turbocharger on it.

Doug in Japan


It all depends on the intake manifold. What I have is on Al Gietzen's
intake manifold which is less than optimum. Notice haw the manifold air pressure starts to drop at 3000 RPM.

Paul Lamar