In a message dated 6/1/2007 3:02:35 P.M. Eastern Daylight Time,
eanderson@carolina.rr.com writes:
Given we know that some racers are restricted by the size of the
intakes permitted (is this true for the PP, Lynn?) perhaps that is why the VE
seems a bit on the low side. But, that's just a guess. Well, that
was my best crack at trying to determine the efficiency of a PP.
So anybody else having an idea or source of information or opinion - jump
in.
Ed
The GT-2 12A is allowed to use two 44MM Chokes in a Weber 48 IDA Carb. The
RPM is just about the heat load limit for road racing, since you have to keep
this insanity up for a minimum of 45 minutes. With lighter rotors and crank and
ceramic apex seals drag racers
can turn up well over 12,000 RPM for 8 seconds. The actual RPM they turn,
is not mentioned where I can find it. Plus the drag racers are not limited in
choke size. And they don't worry about cooling. Super light rotors fatigue and
crack often requiring frequent changes. Too heavy for paper weights, and they
never quite leaking oil.
Oil temps from added centrifugal loading are going up with RPM. Also
120 to 140 PSI of oil Pressure is used from an external pump. A Pport 13B with
44MM chokes can do 330 HP.
But are seldom turned up more than 10,000 without extensive rotor
lightening. Longer crank and more flex. So Racing Beat's 900 HP three rotor
airplane engine has been derated, a bit and runs 160 PSI oil pressure. You can
actually cool up to 300 HP per rotor.
These engines use extra dowel pins through the combustion area to keep the
rotor housings from flexing away from the rotor face. Ouch!!!!!
Over 700 HP from a boosted street 13B is not uncommon. They take the
controller hose off of the waste gate and stand on for long enough to get a HP
peak on a chassis dyno.
Chassis dynos are springing up across the country. Kids meet each weekend
at the dyno and "Race their cars" Even blowing one to pieces is a badge of honor
at the dyno.
So with 25 +pounds of boost and injecting water and alcohol from a 5th
injector in front of the TB, and the sky is the limit. But I run on as
usual.
Lynn E. Hanover