the design engineer is factored out of the equation. Individual cars have the HP and car weight adjusted to make the performance equal. Unlike Formula 1 where good engineering design counts.

   Not really a car race at all. They should just let all the drivers run around the track using just their legs for 24 hours and see who wins :)

   Mazda has entered their silly carcinogenic diesel in this race and within an hour one is having problems.

   Another silly car entered is the so called delta wing with a billet block Mazda Miata engine.  The "engineer" that designed this car does not understand weight transfer in a corner. In the first hour it spun out once.

   Paul Lamar



   I thought the Delta Wing had an affiliation with Nissan. Trikes do not have exceptional stability.

   Dale Davies

   Last year.

   Nissan/Renault wised up :) This year it is a Mazda Miata based engine but the block is NC machined from a billet.

   Paul Lamar

   -------------------------------------------------------
   As of right now the Delta is 16 laps down and last in class.
   There is a difference between handling and cornering speed.

   Paul Lamar

   ------------------------------------------
   They interviewed John Doonan on TV and he mentioned torque and steel pistons. Steel pistons in a diesel is a drastic way to deal with piston over heating. That tends to limit RPM and HP because of increased piston weight and inertia forces on the connecting rods.

   I wonder if they tried oil squirter's on the bottom of the heads of the aluminum pistons?  Standard in most aircraft piston engines and probably truck diesel piston engines.

   They could also go with beryllium aluminum pistons, BeAl is .7 times the density of aluminum pistons and good to 750 F while aluminum pistons start failing at 500 F. Outlawed in F1 but the Rolex organizers might not know that.

   Cars accelerate and airplanes fly on HP with a good gear box and not torque.

   They could always try talking the Rolex organizers into allowing them to double the displacement of the diesel engine.

   Mazda won the last Rolex race in 2012 with a RX8 rotary engine.
   Now they are 12 laps down and running near the back.
   How the mighty have fallen.

   Paul Lamar




   Paul,

   Diesel engines are limited in their rpm by the delay time between the injection of fuel and the start of combustion. That's why car diesels have peak power around 4000 rpm and redlines around 5000. Even Mazda's racing diesel only revs slightly higher. Therefore any additional weight imposed by steel pistons has no effect on the engine's revving capability.

   Csaba Csere

   Do all diesel passenger cars use steel pistons? I don't pay too much attention to them.
   Are new diesel cars required to use urea anti pollution fluid in California like the trucks?

   ("The BlueTec system injects water-based urea solution into the exhaust system. The ammonia produced by the hydrolysis of the urea reacts with the nitrogen oxide emissions and is converted into nitrogen and water within the catalytic converter.")

   The BSFC of the rotary gets much better when they are leaned to 18:1 but the NO goes
   way up.

   I just found out that the Mazda diesel's are using cast iron blocks.  For some reason I got
   the idea that they were aluminum. Mazda are not very fourth coming with the tech.

   Last Daytona race info I have is they were 54th in a field of 67 OA. Even the delta is ahead
   of them :)

   Now that Form 1 is using turbo compound I hope Mazda wakes up and uses it
   with the rotary. IMHO  a potential 30% reduction in fuel burn without
   the pollution problems of the diesel and also without the exhaust valve problems
   of the piston turbo compound.


   Paul Lamar


   Steel is stronger than cast iron which is what some old diesels had. The steel pistons will be a lot lighter that cast iron.
   Ceramic coated Al may get the job done but may require detonation gun application. The 18:1 diesels may have iron blocks.
   The Skyavtiv blocks can be Al due to the 14:1 CR.
   NOx is fairly easy to deal with by EGR and add in turbo compound with variable geometry for the power recovery turbine
   and the rotary might kick crap out of knock-O-meters.

   Dale Davies


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