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Capt_Gherkin
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Post subject: differences between cars that look fast, and cars that are!! Posted: Sat Feb 07, 2009 10:25 pm |
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Joined: Wed Sep 17, 2008 1:38 am Posts: 1039 Location: Hornsby
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Hi folks, As I have been researching and getting advice on track day preparation it has struck me that what I assumed was 'go fast' stuff such as low profile tyres, is actually slower!! So thought I'd start a list of the differences; Looks Fast ---------- low profile tyres big rims eg 17" wings, scoop, bodykit v. low suspension Actually is fast - Reason --------------- ------- higher profile tyres - bigger sidewall = more flex & less skipping small rims eg 13" - less rolling weight & gearing (I think!) minimalist bodywork - less drag, weight & FWD not needing rear downforce! moderate suspension height - better suspension travel for traction (& kidneys!) Anything else?! Love this new forum BTW - thanks Mods!! 
_________________ Cheers, James.
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tekkie
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Sat Feb 07, 2009 11:44 pm |
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Joined: Mon Aug 25, 2003 12:00 am Posts: 4479 Location: Brisbane
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bodywork kit is a broad term.
Basically its about reducing airflow here, and accelerating it there.
The basics of some aftermarket bodykits are sound. air dam, side skirt to reduce the side entry or airflow under the car and diffusers at the back of the car. But there is more to aero then how the look on the outside. And often apart from added weight contribute very little.
_________________
2008: Mk1 TAR car, stock engine, open diff - 1/4mile 14.774 @ 91mph
2006: Mk1- yeah well at some stage to go on track... 2003-2005 Mk3(retired)- EC 1:54.6 , Wakefield 1:13.14 , OP (short) 52.00 , OP GP 1:24.40
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Capt_Gherkin
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Sun Feb 08, 2009 12:12 am |
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Joined: Wed Sep 17, 2008 1:38 am Posts: 1039 Location: Hornsby
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tekkie wrote: bodywork kit is a broad term.
Basically its about reducing airflow here, and accelerating it there.
The basics of some aftermarket bodykits are sound. air dam, side skirt to reduce the side entry or airflow under the car and diffusers at the back of the car. But there is more to aero then how the look on the outside. And often apart from added weight contribute very little. True - I was generalising! Yes - I remember on Top Gear when they were racing that BMW that the car was several seconds a lap slower when the Diffuser came off! Does anyone have any experience of undercar aerodynamics for Swifts, or is it another thing that is very minor in the scheme of things?
_________________ Cheers, James.
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Dattman
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Sun Feb 08, 2009 7:59 am |
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Joined: Sat Feb 05, 2005 6:51 pm Posts: 1772 Location: Chch - Quake Capital
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Capt_Gherkin wrote: Does anyone have any experience of undercar aerodynamics for Swifts, or is it another thing that is very minor in the scheme of things? It's actually very important but is generally quite difficult for a lot of people to make/utilise. The most important thing is to get the car lower, using smaller wheels helps, a 185/60/13 is going to make your car sit 20mm lower than a 205/50/15 etc. A splitter on the front bar/bumper will make a huge difference, there are a few of us working on solutions for this at the moment, (but don't expect anyone to market and sell it), most involve plywood or aluminium attached to the front bumper extending back 400-500mm underneath the car. this helps split the air cleanly to go thru the radiator and reduces lift, helps turn in on high speed corners. Cutting part of the rear bumper/bar out helps trapped air under the car to get out and reduces lift, a rear diffuser helps too but is hard to build due to the shape of the swifts undercarridge.
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waylow
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Sun Feb 08, 2009 8:05 am |
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Joined: Mon Aug 25, 2003 12:00 am Posts: 6718 Location: Camden
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Dattman wrote: It's actually very important but is generally quite difficult for a lot of people to make/utilise. The most important thing is to get the car lower, using smaller wheels helps, a 185/60/13 is going to make your car sit 20mm lower than a 205/50/15 etc. A splitter on the front bar/bumper will make a huge difference, there are a few of us working on solutions for this at the moment, (but don't expect anyone to market and sell it), most involve plywood or aluminium attached to the front bumper extending back 400-500mm underneath the car. this helps split the air cleanly to go thru the radiator and reduces lift, helps turn in on high speed corners.
Cutting part of the rear bumper/bar out helps trapped air under the car to get out and reduces lift, a rear diffuser helps too but is hard to build due to the shape of the swifts undercarridge.
Not to mention some of us are restricted in what we can do with rules.
_________________ Swift gone.
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FlyingGrape
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Sun Feb 08, 2009 4:26 pm |
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Joined: Wed Apr 28, 2004 3:03 am Posts: 2063 Location: Canberra
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For aerodynamics I suggest you might look at some of what is being done on ecomodder.com
There is a guy (basjoos) there who has modded his civic to bring the Cd from 0.34ish to around 0.17 (also see it at aerocivic.com). While this was done for fuel economy (he now uses 3L/100km's not all due to the aero mods) it also resulted in the cars top speed going from 95mph to around 140mph.
A lot of this is not really practical for motorsport at entry level but look at most high end sports cars and you will see these aerodynamic processes are being applied to the cars as well.
Interestingly more sports cars are heading towards low drag higher downforce setups by using better undertray designs. What is often missed by the ricer crowd is that the wing they have is doing nothing except increasing their fuel bill at the speeds they travel.
You will also find that small geo metro's are a popular base for modding for the eco crowd and useful insights for the GTi.
There is also some practical stuff down about this on autospeed.com
Personally, I think stuff that could make the GTi feel a little more planted at speed would be nice!
_________________
ET 13.138 at 120.2mph
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4 banger
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Sun Feb 15, 2009 3:06 pm |
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Joined: Fri Oct 06, 2006 12:37 am Posts: 490 Location: Singapore
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FlyingGrape wrote: For aerodynamics I suggest you might look at some of what is being done on ecomodder.com
There is a guy (basjoos) there who has modded his civic to bring the Cd from 0.34ish to around 0.17 (also see it at aerocivic.com). While this was done for fuel economy (he now uses 3L/100km's not all due to the aero mods) it also resulted in the cars top speed going from 95mph to around 140mph.
A lot of this is not really practical for motorsport at entry level but look at most high end sports cars and you will see these aerodynamic processes are being applied to the cars as well.
Interestingly more sports cars are heading towards low drag higher downforce setups by using better undertray designs. What is often missed by the ricer crowd is that the wing they have is doing nothing except increasing their fuel bill at the speeds they travel.
You will also find that small geo metro's are a popular base for modding for the eco crowd and useful insights for the GTi.
There is also some practical stuff down about this on autospeed.com
Personally, I think stuff that could make the GTi feel a little more planted at speed would be nice! was wondering if anyone could design an undertray cover for our car cos THAT would definitely clean up the airflow and help us gain some top speed and @ the same time save fuel!! 
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tekkie
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Sun Feb 15, 2009 10:52 pm |
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Joined: Mon Aug 25, 2003 12:00 am Posts: 4479 Location: Brisbane
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yes saving fuel is important,  ......... stick your head under the back of your swift and you will soon realise how difficult it is to achieve rear splitter in a swift.
_________________
2008: Mk1 TAR car, stock engine, open diff - 1/4mile 14.774 @ 91mph
2006: Mk1- yeah well at some stage to go on track... 2003-2005 Mk3(retired)- EC 1:54.6 , Wakefield 1:13.14 , OP (short) 52.00 , OP GP 1:24.40
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FlyingGrape
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Mon Feb 16, 2009 12:11 am |
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Joined: Wed Apr 28, 2004 3:03 am Posts: 2063 Location: Canberra
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My aim is 250hp at the wheel and highway economy around 6L per 100km's... 
_________________
ET 13.138 at 120.2mph
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4 banger
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Mon Feb 16, 2009 9:18 pm |
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Joined: Fri Oct 06, 2006 12:37 am Posts: 490 Location: Singapore
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FlyingGrape wrote: My aim is 250hp at the wheel and highway economy around 6L per 100km's...  thats only possible in your dreams 
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tekkie
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Mon Feb 16, 2009 10:57 pm |
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Joined: Mon Aug 25, 2003 12:00 am Posts: 4479 Location: Brisbane
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4 banger wrote: FlyingGrape wrote: My aim is 250hp at the wheel and highway economy around 6L per 100km's...  thats only possible in your dreams  let me introduce you to the concept called sarcasm sar·casm Pronunciation: \ˈsär-ˌka-zəm\ Function: noun a mode of satirical wit depending for its effect on bitter, caustic, and often ironic language that is usually directed against an individual b: the use or language of sarcasm
_________________
2008: Mk1 TAR car, stock engine, open diff - 1/4mile 14.774 @ 91mph
2006: Mk1- yeah well at some stage to go on track... 2003-2005 Mk3(retired)- EC 1:54.6 , Wakefield 1:13.14 , OP (short) 52.00 , OP GP 1:24.40
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Steve
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Tue Feb 17, 2009 12:35 pm |
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Joined: Thu Oct 28, 2004 3:06 pm Posts: 271 Location: Ballarat
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tekkie wrote: 4 banger wrote: FlyingGrape wrote: My aim is 250hp at the wheel and highway economy around 6L per 100km's...  thats only possible in your dreams  let me introduce you to the concept called sarcasm sar·casm Pronunciation: \ˈsär-ˌka-zəm\ Function: noun a mode of satirical wit depending for its effect on bitter, caustic, and often ironic language that is usually directed against an individual b: the use or language of sarcasm  Keep it up guys. I am really starting to enjoy this series of posts. Steve
_________________ 1987 Swift GTI used in dirt track autocross competition
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itsdamo
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Wed Feb 18, 2009 12:14 pm |
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Joined: Fri May 28, 2004 12:18 pm Posts: 1403 Location: NSW
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FlyingGrape wrote: My aim is 250hp at the wheel and highway economy around 6L per 100km's...  It is possible to have a car that is powerful and economical but not both at the same time. You are not normally on boost when cruising on the highway. If you have electronic boost control and set a minimum TPS of say 50-60% before it turns on and increases boost beyond wastegate setting you can trundle around quite economically untill your right foot goes down and stays down.
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tekkie
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Wed Feb 18, 2009 3:21 pm |
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Joined: Mon Aug 25, 2003 12:00 am Posts: 4479 Location: Brisbane
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well of course on highway driving, thats why trucks use turbos. Economy (and torque). But to achieve 250bhp in a swift you are talking redline rpm stuff. At those RPM forget about economy.
Considering this is Motorsport section any mention of "economy" should be deleted by the mods as soon as it is posted. (Neo are you listening?) If economy is what you are after, feel free to petition the mods for your own separate section on this forum.
_________________
2008: Mk1 TAR car, stock engine, open diff - 1/4mile 14.774 @ 91mph
2006: Mk1- yeah well at some stage to go on track... 2003-2005 Mk3(retired)- EC 1:54.6 , Wakefield 1:13.14 , OP (short) 52.00 , OP GP 1:24.40
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Dattman
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Wed Feb 18, 2009 4:21 pm |
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Joined: Sat Feb 05, 2005 6:51 pm Posts: 1772 Location: Chch - Quake Capital
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tekkie wrote: Considering this is Motorsport section any mention of "economy" should be deleted by the mods as soon as it is posted. (Neo are you listening?) 
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fatboyz39
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Post subject: Re: differences between cars that look fast, and cars that are!! Posted: Wed Feb 18, 2009 4:56 pm |
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Joined: Sun Oct 31, 2004 9:38 pm Posts: 1309 Location: Sydney
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tekkie wrote: Considering this is Motorsport section any mention of "economy" should be deleted by the mods as soon as it is posted. (Neo are you listening?) If economy is what you are after, feel free to petition the mods for your own separate section on this forum. LOL!!
_________________ BYP Honda Civic Wakefield Park- 1.03.2Eastern Creek- 1.41.2
Mk3 Swift Gti - WP 1.13.8 EC 1.56.1
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