Five ways to reduce your car's aerodynamic drag
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- čas přidán 4. 07. 2024
- Forget the weird and wonderful theories - here's how to do things that actually work. Note that my most recent aero book (replacing the one shown in this video) can be found here - www.amazon.com/Vehicle-Aerody... or Amazon in your country.
- Auta a dopravní prostředky
"...won't make a bee's dick of difference". Whew, I sure got a kick out of that! Terrific info, and I loved the humor.
Currently marathoning all these videos. These are answering questions I've had/ thought about for so long without any clue where to start looking for answers. My birthday is comming up, I think I know which book to buy for myself :D
Harry Potter ?
Harry Potter?
Harry Potter?
Harry Potter?
Harry Potter?
Just a note on grill blockers.
Don’t forget about the fans.
If you have a mechanical fan that can’t be disconnected you will probably use more energy than you save spinning the fan against a restriction.
Yes, excellent point.
except that mechanical fans died just after the dinosaurs...
@@CosmicSeeker69 . You’d be surprised at the number of dinosaurs running around these days. Some even drive new vehicles.
Ever blocked the front of a box fan an listened carefully? The fan speeds up.
Finally someone who calls Coupé the way it should be pronounced.
5:37 Mercedes used completely enclosed hubcaps from 1968 until the mid-1980s without issue. My background is tier 1 brake system testing. You would need to subject the vehicle to absolutely extreme conditions, effectively hot laps for that open hubcap cooling to be a requirement
I can’t find even one Mercedes of that era that doesn’t have wheels with ventilation openings through the periphery of the hub caps.
Thumbs up for rear (roof) extension “spoilers” @7:25 for SUV-type vehicles. Reducing wake and possibly gaining a forward component aerodynamically should help with fuel consumption, especially in combination with an undertray w/ rear diffuser reducing lift over the top of the car...I’ve got to source some ABS sheeting...
I’ve got to source some ABS sheeting. #metoo
@@CosmicSeeker69 I got lucky - a regional distributor within 10mi of home, and one of my friends works there, so he gave me his discount, then helped me cut it on their machines and install it. It works quite nicely - gained about a gallon of more distance from the tank than before the addition…2-3% increase in mileage. Chase the parasitic stuff and it makes a difference in all cases, and can be impressive in others.
Practical and down to earth. Too much advice is spread around with sciency and hyping languange, but not here! Well done!
Glad you liked it!
Another thing to mention would be to prioritise using the lightest materials possible while keeping everything safe of course if your going for fuel economy. Added weight equals more fuel use and though it wont be massive drop in economy it would make aerodynamic mods pretty pointless if better fuel consumption was the goal
I received your latest book today. Im glad to be able to support you.
I hope you enjoy it
Great and well consumable content! Thanks. Would love to see your opinion on key differences when choosing right shape of roof cargo/box. What would work best? I own Subaru Outback 2016 and might need one for skis (so can be low profile and rather wider and longer to fit 185 cm skis). I know nothing about aerodynamics and not sure, what to buy to make the less impact possible. Thanks for any point, there is not much on the net about this topic
Now that I'm thinking about it, it seems weird that manufacturers aren't putting undertrays on themselves...
All current cars have at least some undertrays.
omg i have been lied to by all hollywood movies ; Thank you
I put a NASCAR style spoiler on my Monte Carlo. I was expecting lower mpg but went from 17 mpg combined to 21 mpg combined (through test of car’s odometer+ GAS PUMP.
At next tank fill up I’ll no longer be paying attention to the odometer in that sense and I’m going to just use an app on my phone that is a bit more accurate in most cases
This is interesting, because I'm currently planning on building a camper trailer for those overlanding trips and it's pretty much 95% DIY one. Haven't decided the shape yet, but this gives something to think about, because most driving will be on highways doing 80-100 km/h, so anything that'll help with fuel economy is worth doing I think (when deciding the shape of the trailer) 🤔
I suggest that you buy my books on car aerodynamic modification and on aerodynamic testing - you'll likely save their cost in the first correct decision you make re the camper trailer's shape! (My books are available from Amazon.)
@@JulianEdgar Was considering that, I'll take a look 👍
I’m curious about what material you used to make the rear spoiler. I’m interested in making one for my Golf R used for drag racing. I’d like to reduce wraparound/drag
Great Info!
Thank you, Julian, that's some great information, planning on an undertray and rear spoiler for my 04 Jeep Grand Cherokee. What are your thoughts about replacing the side-view mirrors with cameras?
Yes a good idea - it reduces both Cd and frontal area. But don't skimp on the cameras and screens - lots of people are disappointed at the results when they use cheapies. And check the legalities first.
@@JulianEdgar what do you think of this camera and screen? amzn.to/3dDfUf5
amzn.to/3nW4iIR
or what would you suggest?
@@martinbuilt I haven't done this so I am just guessing - but my guess is that camera would be nowhere near the required quality.
it can make sense to approach an aerodynamic form if you drive an open top car that has different hard top variants available. For example the Spoon S2000 hard top instead of one that is shaped like the standard roof.
Interesting about the air curtains. I am ordering an after market front wing for a mk1 MX5 that has those in the design. I thought they were to redirect some air towards the brakes to cool them down. But I guess it would do both.
I think It won't cool your brakes, if anything it will reduce the amount of air going to your brakes because the air curtain reduces the amount of air the wheel touches. I could be wrong, I'm adding another smaller hole to redirect some of the air from the aircurtain to straight on the brakes
Would rear fender flares work as well as whelk covers ? Or does fender flares even work at all?
Thank you.
What about pickup trucks that are higher off the ground. Anything there? My particular pickup has 15 inches of clearance to the floor pan (stock height).
Most have some big rims on those. Get wheel covers and under tray as well as a bed cover unless you wanna go the extra mile and add those bed covers that make a truck look like the cyber truck.
I am watching all your videos the last few weeks. They are great. Now I wool tuft tested my rear Window. Quite disturbed Flow in the middle. Then fitted 4 small Vortex Generators and after varying their angle 2 Times, I have attached Flow All the way down the rear Window. At the Moment I have no way to measure pressure. When I fit a spoiler lip I get more disturbed Flow again down in the middle of rear Window but still better than Stock. Is there a way to find out which Setup has lowest frag without measuring pressure on the Window?
Check my videos / books on measuring changes in drag.
Why is it that you want air separation at the rear of the car? Why wouldn't you want the air to smoothyl integrate at the rear? Might seem like a dumb question, but I really want to know
Because any 'wrap-around' of that airflow will cause a low pressure on that surface, helping pull the car backwards. All covered in my books in detail, including measuring this low pressure.
some people use DUCT TAPE on their radiator openings
What about using separation edges on the front bumper, on the sides where it begins to curve. Have you tried this?
Not normally wanted - instead you want attached flow arounds those corners.
My firebird seems to scoop it air up under the car with a plastic thing, creating a pressure to go up into the radiator.
so the small gap on the honda insight wheels is actually good!? i never thought about brake cooling holes! i was about to buy one of these completely flat discs for my wheels, would they make my brakes overheat?
it's going to depend a lot on ambient temps, the weight of your car and how aggressively you drive - but consider that most\parts on any given car are engineered for world wide markets so brake cooling in Afghanistan mountains isn't going to be the same as driving around the praries of Iceland.. common sense
How can I reduce the drag of my Dodge Promaster City van?
@JulianEdgar how close would lowering the ride height be in the list of things that improve aerodynamics? Would it be in the top 10 and if so where would you rate it? I ask because my Tesla Model X has adjustable air suspension and I've contemplated replacing the static rear camber arms with adjustable camber arms to reduce the negative camber that accelerates inner tire wear while riding on the "Very Low" setting.
Yes lowering is good for drag, especially on slippery cars where the easy stuff has already been done.
Hi Julian. Would the addition of mud guards on a Prius Prime negatively impact aerodynamics/MPG very much? Is it worth adding them on for the protection they provide?
Mud flaps typically increase drag considerably.
@@JulianEdgar Thank you for the reply.
I ran into over heating issues at Road Atlanta in July. I installed an oil cooler and since then someone told me to duct it even a one inch lip around it. It sets in front of radiator corner so maybe the air build up on it will push air away not through it? I also installed a wind tunnel tested center hood louver that is supposed to help air passing through radiator escape in low pressure zone two inches behind radiator. Louver has big lip in front to deflect high pressure air up so air comes out of hood. I still have the small rear spoiler on my hatchback going up not down. Only because I think it helps car stability at high speed 140 mph depending on track. I had a skid plate under engine to smooth air flow but I removed it because I was scared of over heating engine and transmission. Any feedback thank you?
Also, I have the best flat floor and rear diffuser I can come up with for now. I'll revisit that rear diffuser later.
For oil cooler / radiator flow, you need to test pressure each side of the heat exchangers.
@@JulianEdgar thank you
My veloce book covers all this...
Would love to see you do a reaction video to the aero modified tesla on the youtube channel 'boostedbois' - he literally made his own body shape to everything rear of the A-pillar and also taped up the gaps on everything infront of the A-pillar.
All the mods improved his 1/4 time, however the question is whether it was due to aero or weight reduction...
A bit confused as to why you want separation at the rear side of your car, can you please explain?
Reduce suction peaks.
Thank you sir...you have given me great amount of info for my seminar presentation on Aerodynamics of race cars
Great!
I was thinking of attaching some kind of plastic cover in front of the front wheels like many manufacturers nowadays do. What do you think Julian?
Wheel deflectors? Yes, will make a small reduction in drag.
@@JulianEdgar yep
@@JulianEdgar any suggestions about what material i may use? And how to attach it?
@@dukinse5198 Heat bent ABS and screws going into captive nuts. All covered in my books.
👌👌👌
Or increases exit flow of air from cooling systems
Sorry, what does?
I don’t get why smooth hubcaps aren’t a thing in auto parts stores.
Hello! What could be the benefits / fuel savings if I implement those 5 upgrades on a 4 door sedan?? Mine it's a 06 SAAB 9-3...
How affective are winglets attached to the sides of a rear bumper?
This advertisement attaches to the front bumper but I am going to attach them to the rear bumper near the rear back of the rear tires.
smile.amazon.com/gp/product/B07T7ZZRGD/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
I haven't done any testing and nor have I seen any research evidence. My feeling is that they would need to much taller (eg 3-4 times higher) than shown in the pic to do anything much.
can someone explain me why the new, closed tires are all 4 the same now days?
i mean, left and right side wheels turn in a different way, so why is one side pulling the air up while the other side is pulling the air down while driving?
i realy didnt understand this 😕
Furthermore, the front and rear wheels should be different in design...
@@JulianEdgar oh, realy? why?
Different airflow behaviour at the front and back of the car.
What about lowering the car? Would it help as less air goes under the car?
Yes, lowering a car typically reduces total drag.
@@JulianEdgar thank you👍
Hello, what is the effect of high or low pressure on the drag force of the car?
Depends where the pressure is high or low. Just the same as if you said "what's the effect of pushing or pulling on the car?" Depends where you are doing the pushing or pulling.
@@JulianEdgar The drag force depends on the relative velocity between the car and the wind. When the drag force is high, this means that the velocity is high and the pressure is low behind the car, while the pressure is high and the speed is low at the front
@@user-pw2qs6dx1x Sure. But that's not what you originally asked!
@@JulianEdgar I mean the wind pressure on a car.
@@user-pw2qs6dx1x The 'wind pressure' on the car can cause both drag and thrust. It depends where it is acting. eg the 'wind pressure' on the leading edge of the bonnet/hood usually causes thrust (and lift).
dangit, I took off the undertray of my car for a year lol!
What are the practical gains possible depending on driving conditions? I live a simple life in the deep rural parts of the US midwest, drive locally on old fashioned two lane roads, and often never get over 45 MPH during daily driving. Combined with the fact that a lot of my driving is up and down grades in the hills, it doesn't seem like high efficiency automobiles get much better fuel economy on my route and driving style over my giant, flat faced full sized 1980's Ford cars and trucks, which certainly aren't aerodynamic.
Aren't most aerodynamic gains realized in speeds over 45 MPH, in terms of fuel economy and acceleration? If I drive 25-30MPH in my small town, how much is the real loss of my wind kite bullnose 86 F250 or 79 Lincoln Mark V with their giant flat face grills? How much can I realize in terms of performance through modification? How much more efficient are newer designs really at lower speeds?
By modifying the car to reduce drag, there will be little if any mileage gain if doing speeds of less than 45 mph in 1980s Fords.
You would see better gains by retrofitting a more modern fuel injection system. Most 80's Fords used a batch fire injection and wasted spark ignition. A modern port injection system with coil on plug ignition would net you some gains. Lightening your vehicle would also help. A big gain could be likely had by adjusting your driving style. Minimize the amount of time you spend over 50% throttle. Don't accelerate hard than you have to. Don't accelerate on uphill grades.
Basically, electric cars are perfect at this
Very informative content but the presentation is verbose. Subbed
Gladly most of these "tips" are illegal in Germany... Imagine everyday people would actually add lift creating rear spoilers to their hatches or block the cooling air of their motor. That's dangerous 🤦
How could adding a spoiler to a hatch create lift? Ignorance = fear.
@@JulianEdgar the spoiler you have shown is downwashing. The downwards curvature creates an suction area on the top of the spoiler which even expands forwards to the roof of the car. This creates lift in an amount, significant enough to spin you off the highway.
I don't know where you studied aerodynamics but this is basics and you should be ashamed to promote these dangerous modifications.
Ah, you're talking about the roof extension spoiler. (More than one spoiler design is covered in the video.) Yes, it will create a small amount of lift - inconsequential, especially on a squareback that has such little lift to start with.
Diesel? Low EGT? Son, there's a reason they have an EGT sensor and gasoline cars don't.
I am not sure what point you are trying to make. EGTs on diesels are typically far lower than on gasoline cars.
@@JulianEdgar Tell that to every trucker and diesel mechanic out there. I have SAE certified master mechanics and mechanical engineers in the family. You don't know what you're talking about, yet again. You're making assumptions and purporting to be an expert.
@@VeritasEtAequitas Not pretending to be an expert - but I can read technical references and temperature gauges. Bosch Automotive Manual 8 edition page 455 - exhaust gas temps in diesel cars can reach 450 degrees C. That's very low compared with the EGTs seen in gas engine cars. My point remains, EGTs in diesel cars are typically much lower than in gas engine cars, DPF burn-off excepted.
@Julian Edgar I loved your books, thank you very much. I got an overall 200°F drop on EGT just by fitting an undertray and by optimizing the intake. At 62mcc of injection and stock SOI my peak EGT was 1400°F, now i get 1200 and i can push more fuel to get more power. Its a very nice upgrade if you compare with Water/Meth injection that lowered my egt by 250°F.
@Veritas et Aequitas soot formation its not a factor to be considered in because EGT its dependant on load, actually diesel engines work the most of the time on the range of 400F to 800F (less than 300F on downhill without injection), PS: lower egt (leaner combustion) creates less soot. and AERO DOES NOT AFFECT REGEN PROCESS ;)
The problem is you are producing aerodynamic advice content with only superficial knowledge rather than first principals thinking , most of what you are explaining is your interpretation out of other peoples work and sadly interpretations are weak evidence and doesn't provide how to guide.
Non-specific criticisms are quite worthless. If you can identify specific errors, with evidence (eg citations in the published academic lit) to back them up, then please do so.