Top Speed?

[kennyrayandersen]

7evin,

 

My personal Nitrous button has run out. This is the first thing I have ever owned, that within a few days I didn't know how fast it would go. That in the past could not have happened. Now from past experiences the thoughts of pain take over, and I have started to ask myself why. The chase has started to wind down for me.

 

The day after thoughts you speak of above, and my memories of the pain has already made me stop riding bikes. Hell, of all things I even own a Buick now!

 

 

Gary

 

 

It's called maturity...

[7evin]

According to the math I have done I will redline at 178MPH. Now if you consider that I can bury the speedo in the donor car and it weighs 3200 lbs at about the 150 mph mark. If I can keep the wheels on the ground I should be able to do it.

Tim

 

That is clickty clacking down the track....

What are the specs on your car?

Keeping it on the the ground will be a chalenge.... 1 word "wings"

[scannon]

According to the math I have done I will redline at 178MPH. Now if you consider that I can bury the speedo in the donor car and it weighs 3200 lbs at about the 150 mph mark. If I can keep the wheels on the ground I should be able to do it.

Tim

 

Aerodynamics are far more important at high speed than car weight.

 

150 in an S2000 or any modern high performance car is very different than 178 in a Se7en type car which has a higher Cd than a brick.

[gjslutz]

I out the big ugly flat plate heated windshield and heater back on the car. I can tell the difference as it isn't as crisp after around 6,800 in 4th. That windshield sure makes a difference.

[7evin]

Aerodynamics are far more important at high speed than car weight.

 

150 in an S2000 or any modern high performance car is very different than 178 in a Se7en type car which has a higher Cd than a brick.

 

A Brick probably has better aero than a 7..... smaller frontal area....

[scannon]

A Brick probably has better aero than a 7..... smaller frontal area....

Actually the brick has been proven to have a lower Cd than a Caterham by quite a bit.

 

There is a magazine article about some wind tunnel testing Caterham did a few years ago that shows some of the addons they used to try to get the Cd down some as well as negate some of the front end lift.

 

I tried to post them but they were too large. I sent them to Mazda who was going to shrink them and make them available, Mazda did you ever post them?

[7evin]

 

I tried to post them but they were too large. I sent them to Mazda who was going to shrink them and make them available, Mazda did you ever post them?

 

I guess not...

[scannon]

I guess not...

 

Someone posted the article a few weeks ago on this forum but I don't recall which thread it was.

[Ruadhd2]

Frankn7 is an aircraft without wings. 100 mph is just in the neighborhood to pick up a loaf of bread. I rode in it a couple of weeks ago and am still taking heart medicine to deal with it:willy_nilly:. Fun visit otherwise.

[snookwheel]

Actually the brick has been proven to have a lower Cd than a Caterham by quite a bit.

 

Here's a piece I saw on line. This one has the brick scoring worse than a Caterham, but I have seen one somewhere before that had the brick at a .6 CD. Can't find that one.

 

Drag coefficient - Cd in automobiles

 

The drag coefficient is a common metric in automobile design, where designers strive to achieve a low coefficient. Minimizing drag is done to improve fuel efficiency at highway speeds, where aerodynamic effects represent a substantial fraction of the energy needed to keep the car moving. Indeed, aerodynamic drag increases with the square of speed. Aerodynamics are also of increasing concern to truck designers, where a lower drag coefficient translates directly into lower fuel costs.

 

About 60% of the power required to cruise at highway speeds is taken up overcoming air drag, and this increases very quickly at high speed. Therefore, a vehicle with substantially better aerodynamics will be much more fuel efficient.

 

Drag coefficient - CdA

 

While designers pay attention to the overall shape of the automobile, they also bear in mind that reducing the frontal area of the shape helps reduce the drag. The combination of drag coefficient and area is CdA (or CxA), a multiplication of the Cd value by the area.

 

The product of the drag coefficient and area, called drag area, was introduced in 2003 by Car and Driver as a more accurate way to compare the aerodynamic efficiency of various automobiles. Average full-size passenger cars have a drag area of roughly 8.5 ft² (.79 m²). Reported drag area ranges from the 2005 Chevrolet Corvette at 6.1 ft² (.57 m²) to the 2006 Hummer H3 at 16.8 ft² (1.56 m²).

 

Drag coefficient - Drag in sports and racing cars

 

Reducing drag is also a factor in sports car design, where fuel efficiency is less of a factor, but where low drag helps a car achieve a high top speed. However, there are other important aspects of aerodynamics that affect cars designed for high speed, including racing cars. Notably, it is important to minimize lift, hence increasing downforce, to avoid the car ever becoming airborne. Also it is important to maximize aerodynamic stability: some racing cars have tested well at particular "attack angles", yet performed catastrophically, i.e. flipping over, when hitting a bump or experiencing turbulence from other vehicles (most notably the Mercedes-Benz CLR). For best cornering and racing performance, as required in Formula 1 cars, downforce and stability are crucial and these cars have very high Cd values.

 

Drag coefficient - Typical values and examples

 

The typical modern automobile achieves a drag coefficient of between 0.30 and 0.35. SUVs, with their flatter shapes, typically achieve a Cd of 0.35–0.45. Notably, certain cars can achieve figures of 0.25-0.30, although sometimes designers deliberately increase drag, in favour of reducing lift.

 

Some notable examples:

 

* 2.1 - a smooth brick

* 0.9 - a typical bicycle plus cyclist

* 0.7 to 1.1 - typical values for a Formula 1 car (wing settings change for each circuit)

* 0.7 - Caterham Seven

* at least 0.6 - a typical truck

* 0.57 - Hummer H2, 2003

* 0.51 - Citroën 2CV

* 0.42 - Lamborghini Countach, 1974

* 0.39 - Dodge Durango, 2004

* 0.38 - Volkswagen Beetle

* 0.38 - Mazda Miata, 1989

* 0.372 - Ferrari F50, 1996

* 0.36 - Citroën DS, 1955

* 0.36 - Ferrari Testarossa, 1986

* 0.36 - Opel GT, 1969

* 0.36 - Citroën CX, 1974 (the car was named after the term for drag coefficient)

* 0.34 - Ford Sierra, 1982

* 0.34 - Ferrari F40, 1987

* 0.34 - Chevrolet Caprice, 1994-1996

* 0.338 - Chevrolet Camaro, 1995

* 0.33 - Dodge Charger, 2006

* 0.33 - Audi A3, 2006

* 0.33 - Subaru Impreza WRX STi, 2004

* 0.32 - Toyota Celica,1995-2005

* 0.31 - Citroën GSA, 1980

* 0.30 - Saab 92, 1947

* 0.30 - Audi 100, 1983

* 0.30 - Porsche 996, 1997

* 0.29 - Honda CRX HF 1988

* 0.29 - Subaru XT, 1985

* 0.29 - BMW 8-Series, 1989

* 0.29 - Porsche Boxster, 2005

* 0.29 - Chevrolet Corvette, 2005

* 0.29 - Honda Accord Hybrid, 2005

* 0.29 - Lotus Elite, 1958

* 0.29 - Mercedes-Benz W203 C-Class Coupe, 2001 - 2007

* 0.28 - Toyota Camry and sister model Lexus ES, 2005

* 0.28 - Porsche 997, 2004

* 0.28 - Saab 9-3, 2003

* 0.27 - Infiniti G35, 2002 (0.26 with "aero package")

* 0.27 - Mercedes-Benz W203 C-Class Sedan, 2001 - 2007

* 0.26 - Toyota Prius, 2004

* 0.25 - Honda Insight, 1999

* 0.212 - Tatra T77, 1938

* 0.195 - General Motors EV1, 1996

* 0.19 - Mercedes-Benz "Bionic Car" Concept, 2005 (based on the boxfish)

* 0.137 - Ford Probe V prototype, 1985

[Mondo]

Worse than a Hummer;(

[pksurveyor]

I had one of the first Hummer H2 in Houston. It was a genuine POS. It got me stranded a couple of times and I had to replace just about everything (sometimes more than once) except for the floor mats. If I have known that the Hummer has such an impressive CD and outperforms the lowslung Cateham, I would have kept that hunk of scrap metal.

[jimrankin]

Holy Ceramics Batman!! At 2.0 was the brick tested standing up on its end with the flat side forward? Might as well have tested a parachute just to see where it came in. LOL. I can feel the wind drag start to matter at about half way down the main straight at Thunderhill but haven't really looked down to see what speed that is as it also starts to nose up a bit at the same point. 2.2L Honda in the S2K seems to really need the Vtec r's about then also.

[bball7754]

The Elite is impressive, but the Tatra's number seems amazing considering it was designed in 1938. Doubt there was a wind tunnel or CFD involved in that design.

 

There was an article about a Tatra T87 in the Times this past weekend.

 

http://www.nytimes.com/2010/07/25/automobiles/collectibles/25contest.html?_r=1&scp=1&sq=tatra&st=cse

 

Steve

[scannon]

There is a Tatra which I think is also a T87 in the Clive Cussler collection here in Denver. Cool car.

 

Check out the previous year's winner, the Marques de Soto. http://www.nytimes.com/interactive/2009/02/22/automobiles/collectibles/20090222-desoto/index.html

[Silk]

Just to add an interesting note to this discussion, John Meyers recently finished near the top of the heap at the '10 GRM Ultimate Track Car Challenge in his V8 Stalker. This from John:

 

"I just finished unloading the car and putting it away in my garage. The rear slicks measure about 71.5 inches in circumference. Review of the data logger showed max RPM at the end of the back straight on my quickest lap of 6469 RPM. This calculates to about 169.5 MPH. Now I know why I was not watching the tach more closely .

 

John

 

PS: If I could prove that the tire circumference grew 1/4" at speed and there was no slippage, the speed would equal the magic 170 MPH."

 

http://finishlineprod.net/nasa/index.htm

[jimrankin]

Was with HOD at ThunderHill friday 8-13 (yes Friday the 13th) and was getting a bit more comfortable with the cars set up and also brakeing points so was able to glance down at the speedo quite a few time at the end of the main straight. Was pretty consistant at about 120MPH, a little plus or minus depending if I wanted to avoid upshifting and just held the last bit at redline or if I wanted to upshift the last 1/4 of the straight and deal with both braking and down shifting into turn one. Since it's not a race and 120 was fast enough for my comfort and talent level I opted for just holding it near red line all but a few times. There was a lot of speed still left in the car, if not in the driver.

The car does seem to get quite a lot of air under it at speed and some of the chin spoilers/splitters posted here may be my next track day upgrade. Sure was a lot of fun and a lot of track time, since the advanced and "race car" groups got combined there were only three groups. I was in the combined group so got to be on track with some really fast cars.

[pi7ot]

106.8 mph in 4th at Black hawk Farms raceway front stretch.

125hp standard compression ZX1 in the Birkin with full front screen.

 

I have no desire to see what it does in public.

 

m

[MichaelD]

My car with a 216 hp Zetec and hits 132 on the front and back straights of VIR and the front straight at Summit Point. It is not redlined but almost.

 

It has clams and a splitter with 4 inch cannards on the front that keep the front planted and stable.

[mac w]

110mph at Road atlanta before turn 10 1700xflow with clam shells on a Westfield with passenger----90MPH in third!