Slashdot Mirror
Computer Designed Car Sets Speed Record
amcdiarmid writes "Several sources are reporting that the first entirely computer designed car, the JCB Dieselmax, has broken the diesel speed record of 236MPH at a speed of 328MPH. From the article: 'The record attempt came after a string of trial runs on the runways at the airbase. But while testing went well, the team endured a troubled time in the US. The combination of the altitude (4,000ft) and the higher air temperatures affected the performance of the second engine, which was generating insufficient turbo boost pressure and led to days of work for the small team of engineering experts.'"
...on the next day of testing, it again bested the record. This time it was 350.092 MPH. http://today.reuters.co.uk/news/articlenews.aspx?t ype=topNews&storyID=2006-08-23T151359Z_01_L2331696 1_RTRUKOC_0_UK-TRANSPORT-DIESEL-RECORD.xml
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http://www.engadget.com/2006/08/23/diesel-powered- car-edges-on-half-the-speed-of-sound/
Apparently Slashdot isn't as fast as it used to be. That car has already hit 360+ mph. 320+ mph is now old hat.
As an aside, all these smaller blogs seem to be able to keep up with the news much better than slashdot these days. I often find myself with a feeling of deja vu when I'm on Slashdot, as I've no doubt read the clippings elsewhere a few days prior.
Ah, the problems inherent in scale.
IIRC, diesel engines generally produce less power output per pound of engine weight, which hurts them in speed contests against gasoline negines. Their advantage in many applications is that they are more cost effective in terms of the kind and quantity of fuel consumed to do their work.
Approx 528 Km/H or 881664 furlongs/fortnight
Women are like electronics: you don't know how damaged they are until you try to turn them on.
You're wrong about diesel. It is a more efficient design, giving much higher torque per pound of engine weight and often more horsepower. There is an interesting bit about a diesel race car needing to be handicapped to compete fairly with gasoline cars here.
Man, you really need that seminar!
I believe the fastest gasoline powered vehicle; was a single engined vehicle. This diesel is a twin engine. Aerodynamics play a HUGE HUGE factor in top speeds. It takes an enormous amount of horsepower just to increase the top speed by a small amount. Same reason why bikes suck so bad on the top end. Their power to weight ratios on paper show ridiculously fast acceleration numbers possible at higher speeds. But in reality; they are beaten by lower power/weight cars for higher speed runs; solely because of aerodynamics. That and power/weight means much less at higherspeeds. Its more about horsepower and gearing. Ok I'm talking to much now. PS. Ever seen a diesel drag racing vid of a semi-fast one? They blow huge columns of thick black smoke.
This particular diesel doesn't smoke - it's running a blended mix to help prevent that. Black smoke is unburned fuel and a sign of an improperly tuned diesel. The low sulphur fuel will help air quality and allow us to FINALLY get some of the better diesels here but I don't think it will change the exhaust smoke since if the car is running right it shouldn't smoke anyway. I've got a new TDI and I've yet to see any smoke but expect to see some come Winter...
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The black smoke hasn't been a problem for properly maintained engines ever, but much cleaner diesel's should be available in the US this fall. Refineries have been producing S15 Low Sulphur diesel since June and all retail outlets should have it by October 15th according to EPA requirements. This means that manufacturers can start importing designs from europe that are designed to run on ultra low sulphur diesel fuel. These designs are MUCH less polluting then engines designed for low grade diesel. For more info see link
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
One of the design factors for the original engine was to function as a backhoe counterweight. This made the engine block and other components so robust that the engine could easily survive the 2-stage turbocharging.
They used 200 liters of ice for cooling, had diesel particulate filters on the exhaust, and got 4 miles to the gallon. The car had only 2 gallons of fuel to start. They used a tractor with the same engine, untweaked, as a push vehicle.
Hey, Mom! Is it beer, yet?
For the more metrically inclined among us, 236 M/h equals 379 Km/h (105 m/s) and 328 M/h is 527 Km/h (142 m/s). While the imperial system does have its merits, 527 Km/h looks so much faster than 328 M/h :P
What's trying to be said on the site is that the car didn't undergo any physical testing or prototypes before the metal was cut for the production car. The mechanical parts were tested with Finite Element Analysis and, more notably, the Aerodynamics entirely with Computational Fluid Dynamics. Although most cars are designed entirely on computers these days (The Deiselmax on Unigraphics, incidentally), they'll invariably make a model of the car and test it in a physical wind tunnel. This is true of even ultra-high-end development like F1 - the Toyota team has three Wind Tunnels that run 24/7/365 when they're not down for maintainance.
This wasn't an option for the Dieselmax for two reasons. The first was the speed involved - most automotive wind tunnels with the 'rolling road' surface required for accurate results top out around 240mph, way short of 375mph. The second, much more important factor is size - this car is nine meters long! Normally high-speed road car models are tested at between 1/3rd and 1/6th scale, and to fit the Dieselmax onto a rolling road tunnel would require a very small model, and the results you got from it would be very nearly useless.
By default, really.
236mph, while indeed fast, isn't extrodinarily fast by today's standards in car performance. It will have simply been a lack of interest. If they break the broader "internal combustion" record of 409.3mph it would be more impressive, but then again that was set in 1965...
The diesel torque advantage (over the otto cycle) is due to the higher brake-mean-effective-pressure of that thermodynamic cycle.
The volumetric fuel efficiency (mpg) advantage is in part due to the higher LHV (lower heating value) of diesel fuel.
The energy efficiency advantage is, in part, due to the higher compression ratio typically used and in part due to the lack of induction throttling for power control (less pumping losses). The noise generated by diesels is mostly due to the fast cylinder pressure rise. Diesel noise reduction is partly effected by compromising the ideal diesel cycle (and some of the related efficiencies).
As for diesel in a personal car, well, a lot of people work on it, have prototype and even have scheduled to sell them in a couple of years. Just ask google for more...
Looked up this "bike" (3 wheels). Nice! but many bikes can beat most cars from a standing start, however some diesel cars (keeping on-topic) can actually go much faster than 140mph but there are very few places in the world that you can do this legally much less safely. I had a Subaru WRX (there are many cars that can beat this) that could easily reach this speed but you needed to go to a track to do it. Get caught by the cops and its by-by license and "watch your fingers" as the cell door closes.
Anyway back on topic.
A jet or rocket engine could easily beat any road vehicle in a straight line but what we are looking at here is a diesel powered car with mechanical linkage from engine to road wheels. I tried a Google search and this is definitely a first although they say they are going to try for 400mph. Should be interesting since to win as the fastest internal combustion engine car they have to beat the following.
For petrol internal combustion engine so far (note the date):
When: November 13, 1965
Where: Bonneville Salt Flats, USA
Who: Bob Summers USA
Car Name: Goldenrod
Speed: 409.277mph, 658.526kph (over 1 mile)
All other cars after this have been jet(turbo fan) or rocket. Then again none of them are street legal.
There ain't no such thing as proprietary standards only proprietary formats. Standards are by definition open.
The noise is not due to the fast cylinder pressure rise. The reason diesels are loud is because, unlike in a gasoline engine, the fuel detonaes rather than burns. The diesel "knock" is the sound of diesel fuel detonating because of the extreme temperatures created by very high and very fast compression ratios. The knock itself is the detonation of diesel. That's where the noise comes from. The same loud knock can be heard in gasoline engines that are overheating because the fuel instantaneously detonates when it enters an overheated cylinder, instead of deflagrating in the course of normal combustion. Diesel fuel detonates, gasolind deflagrates. That is why diesel engines are chracteristically louder in operation than gasoline engines. Also, diesels operate at a far lower speed than gasoline engines, so the pressure rise in the cylinders is slower. It is the extremely high compression ratios that allows for the fuel to detonate. I have an International Harvester Corporation "Navistar" engine that redlines at 3.5 krpm, and idles around 500 rpm. The cylinder pressure doesn't necessarily rise faster, it just rises more.
Diesel efficiency comes from the fact that it is an extremely rich-running engine that uses a fuel that is exceedingly higher in energy density and content per volume than gasoline. Average energy efficiency (percentage of the energy generated that is converted into useful work) is along the order of 25%, versus 12% for gasoline engines. Also, diesel engines can withstand higher turbo boost pressures, which means more air can be crammed into a larger cylinder, generating even more power. Efficinecy over gasoline engines also comes from the fact that the fuel detonates rather than burns. This, combined with the extreme compression ratios and energy-dense fuel, is what gives diesels a higher level of efficiency over gasoline engines. Also, since diesel contains far more energy than gasoline, a smaller volume generates more energy (both because of chemical composition and method of combustion), and therefore an engine that uses such a fuel is obviously going to be more efficient. The power generated by diesel engines is significantly increased when a 2-stroke engine is used, versus a four stroke engine.
However, the efficiency of an engine, regardless of fuel type, is relative to the application and environment in which it is operated in.
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Sig Sauer
Knowing Google's lust for data collection, the Soviet Union is still alive and well inside the psyche of Sergey Brin....
Duh, of course it should and it *does*. You'll note that COLDER temps actually cause LEANER Air/Fuel mixtures not rich which is what black smoke indicates. However colder temps also mean that the fuel doesn't atomize nearly as easily - even at the sick pressures the TDI uses. The result with a diesel, just like a gas vehicle, is rich mixtures in order to get combustion at all and that means some smoke from a diesel as unburned particles make it out the pipe. Warm it up quickly and the emissions impact is lessened.
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