Amateur car aero modification is easy!

Think modifying your road or race car's aero is difficult and expensive? Think again! Buy my aero book at www.amazon.com/Vehicle-Aerody...

[@ShadowfaxIsAHorse]

For anyone reading this, I purchased the book and it is an excellent book. I highly recommend it. You also aren’t obligated to go from front to back as it lends itself to browsing back and forth as the ideas start flowing.

[@JulianEdgar]

Thank you. It's incredibly frustrating when people still think that aero modification is expensive, difficult, can't be measured, etc - and it's all in the book!

[@tcarter6462]

You need to do a series on how to assess a cars weaknesses as a means to guide us towards what modifications will have the best effects. For example... I'm not certain that aero would provide me a better balance for my handing issues over some other mod. To be honest, almost most my driving is below 45mph. I don't feel lift at those speeds not like the highway... so, how much aero do I need to stop pig understeer below 35mph?

[@JulianEdgar]

You don't use aerro changes to stop pig understeer at low speeds. You fix the suspension.... as covered in my suspension book.

[@4ssiduous]

I have observed a 5-6% improvement in fuel economy from fitting a 65mm deep airdam to a mid 90s japanese hatchback with a rough under body / partial aero undertrays, in good agreement with the findings of "EFFECT OF UNDERBODY STRUCTURE ON AERODYNAMIC DRAG AND OPTIMIZATION (ZHIQUN YUAN, YIPING WANG)". I've got twice the money back in fuel savings that I spent on the air dam over 5,000km of highway driving.

[@TestTest-eb8jr]

Where do I find the publication you mentioned??

[@JulianEdgar]

Be careful if following only one tech paper. Invariably, you'll find other papers that get different results. That's why in my book I always quote from a variety of sources (tech papers, text books, direct quotes from professional car aerodynamacists) before making recommendations.

[@michaelblacktree]

When people say it's too hard, I think it's because they don't want to put in the work (i.e. testing and development). Most people are looking for "easy button" solutions.

[@SoloRenegade]

yes!

[@JulianEdgar]

It's also a philosophy. If people don't realise that they can in fact do easy test and development, then they're not inclined to do so. I've always done my car mods in that way, so to me it's perfectly natural.

[@nsreid88]

Purchased the book. Been watching all your videos and I'm excited to learn

[@JulianEdgar]

Hope you enjoy it!

[@banovsky]

One of the best books on cars that I have (and I have many). Really accessible and cheaper than shipping on bolt-on car parts.

[@JulianEdgar]

Thank you.

[@dra911]

BTW, the book is 43% off at the Amazon US store right now, it's still full price in the EU (~106 Euro.) Wish it was like that when I bought the suspension book last week from the US!

[@JulianEdgar]

Buy from the US then?

[@dra911]

A lot of savings lost on shipping, so would have been good to combine the two. Still thinking about it.

[@Kurayami777]

The thing I do not get is why does the government/ police are against "after market/ manufacturer" improvements? If you fit better shocks than stock it means your car will handle better which makes it safer for you and others trying to avoid danger and maintaining control. Fitting better breaks is self explanatory. If earo dynamic improve a lot of things like handling etc the wats with the hate? there has been issues with cars out of the factory where they have to do recalls to rectify the issue but aftermarket usually have solutions before manufacturers have them and most of the time the aftermarket has better solutions. Note that is if you buy from a certified manufacturer that has tested and passed the qountries standards and that is of good reputation and quality.

[@GasoliniASMR]

the government and police are businesses that work for corporations not individuals!

[@tcarter6462]

Problem: most these mod makers aren't certified, they didn't fully test their products except in computer modeling. Julian addresses this numerous times and comments back it up.

[@pocketpc_]

The thing is, most of those aftermarket parts HAVEN'T met any kind of standard. Some of them probably could if they were put through all the requisite testing, but that's far too expensive for small aftermarket suppliers to do. The government doesn't care if the aftermarket parts are better if there's no paperwork to back it up, and getting the paperwork to back it up is where a lot of the cost of developing automotive hardware and software comes from.

[@836dmar]

Most mods are by the kiddies who would rather signal their clan than have a safer or better performing car. They are more concerned with acceptance by how they appear even if it is from those who know little about actual performance. Think Fast and Furious. It’s been this way since the second car was sold.

[@dukinse5198]

I am seriously thinking about buying this book when i afford it, my concerns are, if i can actually manufacture mock ups and final parts that can be safely attached to my car. I hope the book, covers that part too, recommending materials, attaching methods and easy crafting techniques for amateurs with a limited amount of machinery/tools and hands on experience.

[@JulianEdgar]

Yes it covers what materials to use for mock-ups and final parts, and has numerous examples, eg using plywood, plastic sheet, aluminium sheet, etc. Attachment methods are also covered.

[@dukinse5198]

@@JulianEdgar very nice thanks

[@aimbot0x01]

Very interesting! I'm gonna buy this book😄

[@JulianEdgar]

Hope you enjoy it!

[@C.I...]

Is this book a continuation of your earlier book "Modifying the Aerodynamics of your Road Car", or would you consider it the replacement of that book?

[@JulianEdgar]

It's a replacement for the earlier book - about twice the size; better measuring techniques; covers trucks, trailers and ultra low drag vehicles; has a lot more input from professional aerodynamicists.

[@jonathanang8740]

I am interested in having a forward swept wing in cars instead of the normal rectangular wings but i would like to have it functional as well. Do you have any research papers that might help me with this?

[@JulianEdgar]

Not sure I fully understand the question but if I am picturing the design correctly, I can't think of any advantages of a forward-swept wing (and I don't know of any tech papers on such a design).

[@MG1275cc]

Sadly, every added part without allowance from the german government is forbidden. That also counts undertray. No the less, just take it off bevor TÜV 😂

[@lemonpaper]

I disagree. Sure adding a wing that produces downforce isn’t difficult. But it has to earn its keep against the additional drag, and that’s a difficult justification which depends on how many straights are on the course, how many high speed corners, how powerful car is. If you produce 100lb downforce thats at best multiplied by the tire coefficient of friction which I’ll assume is 1.3. So 130lb increase for lateral acceleration which is a really small percentage of total lateral force. But thats only at some speed maybe 70mph. So now at 70mph your suspension is settling at a different place than at 30mph and 100mph. So what speed should your suspension be set up for? Significant downforce demands suspension revision. Well set up aero cars tend to handle poorly when they’re off the wing. Wing weight is also typically going to increase polar moment. Have you verified the aero is working properly in pitch, dive, and roll? And lastly it’s ugly lol Of course I agree with underbody changes and closing panel gaps and such.

[@lemonpaper]

All that to say I think amateurs really shouldn’t be worrying about wings until they can justify that adding aero will yield improved position in a race.

[@JulianEdgar]

There is a lot that is questionable (or simply wrong) in what you have written - a lot of 'paddock wisdom' I think. (1) A good wing has inconsequentially low drag. (2) The effect of downforce is not as you have described - I go into some detail on this in my book. In fact, even small amounts of downforce disproportionally change car behaviour. You also seem to assume that the car isn't developing lift - yet lift is very likely on any race car based on a road car. (3) Well set up aero cars do not handle poorly at low speeds - that's a definition of poorly set up aero cars! (4) Polar moment depends on actual inertial forces, of which aero downforce has none. (5) Pitch roll and dive will make very little difference to downforce values on cars at normal ride heights. (6) Closing panels gaps will make almost no difference to drag - 80-90 per cent of car drag is pressure drag, not frictional drag (the panel gaps are buried in the boundary layer). Maybe buy and read the book?

[@JulianEdgar]

Huh? Of course well-executed aero (all aero, why mention just wings?) will benefit track times.

[@lemonpaper]

@@JulianEdgar sorry to come at you like that. I follow you because i like what you said about sway bars and suspension tuning. i think agree to disagree here though. I come from a formula student perspective and so i know how much is involved in making a well thought out effective aero package and i’ve seen how small the gains can be. I also see so many people slap a wing on their car that is very clearly not effective. I’ll admit, most of these people are using the car primarily as street cars and not visiting the track at all. It’s just a personal pet peeve. But I do think a lot of track day folks would be surprised at how little they earn from having a wing.

[@JulianEdgar]

It's not a very strong argument. People haven't tested their aero adequately and so they don't get good results... because they haven't tested their aero adequately. The answer is obvious.