"Bass, Jerry" wrote:

Mazda class open wheel racers in the Spec Mazda, from Southern California,
run all season without opening the engine.

My son and his friend ran mostly road tracks and got third overall without
rebuilding the engine, in the late 80's. Transmission and tires were the
main work.

You ask, maybe first, if they did some engine work?  Perhaps, but rev
limiters and drivers ability also played into the mix.

Star Mazda claims they have one engine with about five years of racing.
Most have three years of racing.

Paul Lamar

Bill Freeman wrote:

  OK, it depends a LOT on what kind of racing we are talking about as to
the real duty cycle of a racing motor.  One example may be useful.

Porsche and Mark Donahue jointly developed the incredibly fast 917-30
turbo racer.  This is a flat-12 4.5 liter aircooled pure racing CanAm car
that absolutely OWNED the CanAm series (actually killed it, probably)
in the 72 or 73 timeframe, IIRC.  Anyway, when the  CanAm series
went kaput, Mark had this TOTALLY reliable and ultra fast car and
no place to play.  He and Roger Penske decided to take the world
record for a closed course since the car was capable of about 240+ mph.

They rented Texas Int'l Raceway or Talladega, (some huge banked oval) and
went out to EASILY win the record.  Broke the motor at about the
2 lap mark - hot oily, expensive pieces everywhere.  Well, you know,
these motors sometimes just fail unexpectedly, so put in a new $100K plus
powerplant and go again.---  BOOM!  What the heck??????? Donahue is
a really sharp [sanitary :-)] engineer, and it took (IIRC) two more motors before
they got the oil cooling system up to coping with more than 2 laps at
full power, with a pile of blown motors.   VERY expensive record.

The take home??   The duty cycle of road racing cars is *low*, they can't hold
full power for more than a few (like 5-10) seconds, then down the gears
for a corner at 0-25% power, then back on the power.  Not like climbing out
at 100% and cruising all day at 75%.

Bill

I wish my Mazda could make it down any of the straights at Road America in 12 seconds. I would be King. Its worse at Charlotte Motor Speedway, where we run nearly all of the oval and the infield course. Lynn E Hanover

Lynn and Bill, it is not full power all the way done the straight unless the car has reached
top speed, the RPM is at peak power and not changing. Is that the case with your 
car at Road America Lynn? That is undoubtedly true on the oval at Charlotte.  If so 
let me help you with the aerodynamics. Send me some pictures of the cooling system 
ducts and the under hood area. Subtle changes can make a big difference. Most high 
power race cars accelerate all the way down the straight. Do you have data 
acquisition so you can send me a plot of RPM around the track? 

Paul Lamar

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