The thing about this so-called "race" is 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


I've been watching the Daytona race. Sort of sentimental; the
24-hour was the last time I drove in a race, in '94. And, this does
not make me a participant in the current diesel/Mazda/steel piston
debates, but something has gone wrong with the Mazda car or cars and
at least one of them is so slow it is dangerous and should be
black-flagged off the track. I have no idea why the organizers allow
it to continue to stay on the track, because it's a bad wreck waiting
to happen.

As for the Delta, it might feel nimble to the drivers but that's not
the same thing as cornering speed or exit speed. IMHO the jury is
still way out because no one has yet made the comparison of equal
weight and horsepower with a conventional four-wheel layout compared
to the Delta's modified three-wheel configuration. Until somebody
does that, who knows what the advantage or disadvantage truly is?
And I bet it has more than half the drag of a conventional car and
doesn't have anywhere near the downforce; after all, its frontal
area is not a lot less than a four-wheeler, it's just narrower at
the front. It's like the front end of a Bonneville streamliner and
the back end of a sports-racer.

And the organizer's efforts to have all the cars with essentially
very close top speeds seems to have resulted in them driving around
in packs and passing has to occur with dive-bomb moves through
traffic into crowded corners. I saw Jamie MacMurray make an
absolutely thoroughly professional move to avoid a wreck just
because some bonehead in a Ferrari waited too long to get on the
brakes as a crowd was getting into the chicane.

I hope Pruett wins. The very first time Scott Pruett ever drove in
an endurance race of any kind it was a three-hour end-of-season SCCA
enduro at Riverside, put on by the Cal Club. I believe he was still
a teenager, fresh out of go-karts. There were about 80 or so cars,
anything with fenders, from Showroom Stock C to TransAm Mustangs
and, if memory serves, a Porsche 935. The speed differentials on the
back straight might have been close to 2:1. His co-driver was yours
truly. We won our class. Taught the kid everything he knows.

The rest is history.

But they really ought to black-flag that Mazda and get it off the
track.

Hugs and kisses --

Uncle Don [Fuller]



Paul,

I'm not sure if steel pistons are common on passenger car diesels, but the urea fluid requirement seems to depend on engine size. The smaller cars, such as the VW diesels can meet the NOx requirements without the urea-catalyst. But as the vehicle gets larger, requiring the engine to develop more power and burn more fuel, NOx emissions rise and the more complex and expensive urea catalyst is required.

By the way, the other problem with diesel cars is that there isn't any spare diesel fuel. Over the past thirty years, global demand for diesel has grown faster than global demand for gasoline. That's why diesel has gone from being 15 percent cheaper than gasoline in 1980 to 15-20 percent more expensive today. If America really started to buy lots of diesels, this situation would simply worsen.

Already, diesels make little economic sense. You get 30 percent better fuel economy, but pay 20 percent more for the fuel. And you pay $5 grand upfront for the privilege. What a deal!


Csaba Csere