26 replies to this topic

[peteepots]

Not sure if this has been covered before but does the difference between the body shape of the vx220 compared to the lotus make a slight difference aerodynamically? In other words, even though the two body shapes are contoured in their own way, are they just as good as each other because the speeds concerned legally are not fast enough to warrant any specific shape? Otherwise I would assume more cars would look similar than they do - especially the faster sportier types!

[techieboy]

I think both S1 and S2 Elises are more aerodynamically efficient than the VX. For the type of car it is, the VX has an awful Cd figure.

[SteveA]

I remember reading one of Chris Randalls threads and appartenly they are all rubbish due to the part after the passenger compartment. Exige/Europa is the way to go for aerodynamics. Nice smooth lines.

[rsg]

I remember reading one of Chris Randalls threads and appartenly they are all rubbish due to the part after the passenger compartment. Exige/Europa is the way to go for aerodynamics. Nice smooth lines.

There was an article in Racecar Engineering in the Aerobytes section with a Noble M12 being converted to a race car. The rear clam/roof area is similar to the VX (with flat back window and buttresses). The guys in the tunnel tried a panel to cover the area similar to an exiges and the figures produced were acutally worse! Not what was expected! I'll try and dig the article out and post it up if I get chance

[siztenboots]

VX and S2 are a lot better than S1 , but still compromised by the rear deck. Never seen actual Cda figures or frontal area ( arguably more important )

[peteepots]

That makes sense regarding the vx220 back window. I was reading in New Scientist about turbulent airflow at the rear end of trailers and trucks that end in a square can be a serious drag (excuse the pun) on fuel econonmy. The Exige/Europa is the 'way to go' but at the expense of limited visibility I suppose.

[SteveA]

That makes sense regarding the vx220 back window. I was reading in New Scientist about turbulent airflow at the rear end of trailers and trucks that end in a square can be a serious drag (excuse the pun) on fuel econonmy. The Exige/Europa is the 'way to go' but at the expense of limited visibility I suppose.

Not so in the Europa, It has a big window.

[peteepots]

Thanks rsg. If you get a chance to post that article up I would be most grateful! Also I wasn't sure about the Europa - but I presume it is aerodynamic in a different way ( smooth lines ) despite it's big window. I shall have a look. Thanks chaps.

[SteveA]

[Alex L]

That Europa is parked next to my new toy at Lipscomb Lotus...can't wait to pick it up tomorrow.

[peteepots]

Cheers SteveA. I see what you mean now. I do like the look of the Europa!

[southpaw]

That europa is

[starlight]

Heres a good technical data source:

Opel Speedster NA Technical Data

Opel Speedster Turbo Technical Data

Unfortunately it does not list all the Aerodynamic data for the Lotus Elises - I can only find a Cd of 0.42 for a 2004 111R & 2003 Exige, and a value of 0.434 for a 2006 Exige S but no frontal area

Comparing a Cd value is not valid as it is only a shape factor, you have to take into account the frontal area and compare CdA's (Cd x Frontal Area)

[Ouchie]

Frontal areas should be almost exactly the same. According to dubious internet research the frontal area is a cross section, the drag coefficient is what will change between the cars. So assuming the frontal area is 1.6 then the Elise and VX Turbo are not that different. The NA surprises me though, front splitters, big ears and a lip spoiler don't make "that" much difference do they?

Edited by Ouchie, 21 August 2009 - 05:40 PM.

[theolodian]

I remember reading one of Chris Randalls threads and appartenly they are all rubbish due to the part after the passenger compartment. Exige/Europa is the way to go for aerodynamics. Nice smooth lines.

There was an article in Racecar Engineering in the Aerobytes section with a Noble M12 being converted to a race car. The rear clam/roof area is similar to the VX (with flat back window and buttresses). The guys in the tunnel tried a panel to cover the area similar to an exiges and the figures produced were acutally worse! Not what was expected! I'll try and dig the article out and post it up if I get chance

Or read this. linky

[techieboy]

Heres a good technical data source:

Opel Speedster NA Technical Data

Opel Speedster Turbo Technical Data

NA = 850kg

vs

Turbo = 1005kg

[iceman]

Well, i distinctly remember seeing the figures and the vx was the best.

[starlight]

But, Power-to-weight

Turbo 196.02 bhp/ton

Vs.

NA 169.41 bhp/ton



Oh and not forgetting VX220 VXR

Vauxhall VX220 VXR Technical Data

VXR 233.33 bhp/ton

Edited by pjohn151, 21 August 2009 - 07:11 PM.

[Ben Cole]

NA = 850kg

vs

Turbo = 1005kg

When doing my research on what to buy the same two figures came up from lots of different sources.

na=870kgs
Turbo=930kgs

[starlight]

Yes, 930kg is quoted for the VXR on Carfolio. What makes a VXR lighter than a standard turbo?