Streamlined Citroen ZX
 

Good day, ecomodders!

Here is my latest project - Citroen ZX.

http://imageshack.us/a/img43/2609/d0dp.jpg

http://imageshack.us/a/img854/6787/9lqe.jpg

This was actually the experimental part of my master thesis. I needed to analyse how drag affects a moving vehicle and how it's aerodynamics could be improved. So here is what I did. Firstly I created a rough model using Autocad.

http://imageshack.us/a/img546/4031/gil3.jpg

Then tested it with Autodesk CFD Project Falcon

http://imageshack.us/a/img854/2346/woq7.jpg

Then did the modifications and here is the final model

http://imageshack.us/a/img545/5233/l6lo.jpg

Put it in the CFD and got a Cd of 0.23

http://imageshack.us/a/img594/7736/h72h.jpg

NOW here is the interesting experimental part. The build began from the underside. Policarbonate and sheet metal was used

http://imageshack.us/a/img837/9991/s0u3.jpg

Then the boat tail construction started
http://imageshack.us/a/img856/8240/qjs9.jpg

http://img198.imageshack.us/img198/1258/ut2f.jpg

Boat tail underside made from textolite
http://img844.imageshack.us/img844/3258/ysqq.png

First test run early in the morning
http://img811.imageshack.us/img811/4848/fm08.jpg

Tuft testing

https://scontent.xx.fbcdn.net/hphoto...92&oe=570568F7

Covered the rear wheel arches, partially blocked radiator ventilation and covered the fog lights + some final touches. And I give You the final result

https://scontent.xx.fbcdn.net/hphoto...d2&oe=570D6665

https://fbcdn-sphotos-e-a.akamaihd.n...57862439_n.jpg

https://fbcdn-sphotos-b-a.akamaihd.n...83768874_n.jpg

http://img441.imageshack.us/img441/1669/0e6x.jpg

https://scontent.xx.fbcdn.net/hphoto...53&oe=573C9B0C

https://scontent.xx.fbcdn.net/hphoto...33&oe=570FA119

The summary

The master thesis was graded as almost perfect. So first mission accomplished. Due to the lack of time and money the detail of this project could have been better.

Currently I've removed all of the mods to adjust the brakes fix the clogged exhaust system and to make the car mechanically sound so to pass the mandatory checkup.

The fuel consumption

Orginal car ABA testing did 31.36mpg @ 56mph (speed limit).

Modified car same road same speed but warmer weather did 49mpg. This mpg increase is very close to the one that was theoretically estimated. Yet currently Citroen without the mods is showing a significant increase in mpg compared with the old testing. This might be due to the exhaust system fix and the warmer weather we are having right now.

Future plans

Make the boat tail shorter and more practical. Connect to the ECU to take control of the fuel mixture.

If you took the time to read this
You are awesome.Feel free to like and share my FB page. http://www.facebook.com/flylowlt

Warmer weather definitely improves mileage. My sig line has some numbers.

I started to put the car back together today. Since I have a bit more time now I can test more modifications individually. But before putting the flat bottom back on I've decided to see what difference in mpg would a front splitter make which I had laying in my garage from a rs fiesta.
http://img22.imageshack.us/img22/1247/17qh.jpg

I forgot to add tuft testing of the final model in the first post. Unfortunately the camera focused on the windscreen when we were filming yet the tufts are still visible. The mods did a major difference in airflow.

Nice project! I like it! Do you think that you don;t have trouble because of a boat tail from the cops?

Hi,

wow you have done a lot of work on this car.

If you want to modify it, I suggest you to make it narrower at the back. It will be better with side wind.

It is allowed to have one meter+ of cargo to be sticking out of the car as long as it is secured, marked and not draging or anything :)

I will try to redesign it a bit. I'll see what kind of a compromise i can work out. And I want to make the whole thing neater, use less white wrap :thumbup:

You did a fantastic job not only with the car, but with your post here on EM.
All the information is nice and neat and you did all the testing that is usually done and showed your results.

The final results look very much like a factory show car from the 1980s back when good aerodynamics actually brought bragging rights.

http://www.powerful-cars.com/images/...obe-iii-14.jpg

Great work and welcome to ecomodder :)

Wow,I knew that ford sierra was aerodynamic at the time but this prototype is full of 80's goodness. That is some good inspiration for the project and it has the wheel fairings which I would like to install.

Thank's Mike :thumbup:

I want those hubcaps!!!

Forgot to raise this question. I read that taper beyond 200mm from both sides is the most you can go. And if you make too much taper the flow will start to separate sooner. The same goes if you round the rear corners.

finaly have the time to post about the front splitter results. The fuel consumption increased by 5mpg or 0.5l/100km. The upside is that the high speed stability also increased :)

work is in progress

http://img266.imageshack.us/img266/8068/85r6.jpg

The citroplane v2 is reaching it's final form. The new mods include improved and smoothened underside, aero sideskirts, removed front mudflaps and finally shortened the tail by one meter with matched taper angles.
Got 46mpg which is very close to the original, yet currently it's getting cold here in Lithuania. During the tests it was 14C or ~57F outside. So quite hard to compare the results and to make matters even more frustrating during the tests either traffic, roadworks or mechanical problems kept interfering. Hope to do some more successful tests in the near future. And for now here are some nice pics that my friend made

https://fbcdn-sphotos-h-a.akamaihd.n...40044358_n.jpg
https://fbcdn-sphotos-g-a.akamaihd.n...29673698_n.jpg

Sexy pics. Got any numbers yet?

Great job! Share some numbers though :) And I couldn't agree more - sexy pics :thumbup:

THis looks like a great project!

Is it an XUD engine in the car? if so,are you running it on veg oil?

Already read the thread but didn't post. Your work is awesome, the ZX looks great. I'm also interested in knowing what engine you have.

AX, say hello to your big sister ZX. :)

AX, I can see one difference. Or actually two, if you count the boattail;)

How did I miss this thread?

CitroX - congratulations on your thesis, and thanks a lot for sharing your project here!

Yeah, the difference doesn't look half bad either :D

Are you going to do a bellypan on the car itself? Or, did I miss it? Are you going to work on wheel strakes?

You missed it. :P Post #1.

Subscribed.

https://fbcdn-sphotos-g-a.akamaihd.n...29673698_n.jpg

OK, what about the car ?

Does the Aerocivic have competition ?

What car ? :)

Looks like it, but @ just over 50 mpg CitroX is not quite there yet as far as MPG are concerned.

Sorry for the delayed replies but I have other projects as well. I see most of the questions have been answered. Thanks!
The Citroen has a 1.4 fuel injected 55kw engine.
HypermilerAX, loving the comparison :D I believe you have one of the ultimate budget hypermilers out there. I guess my choice to try hypermiling would be very similar.

So I did some testing recently. Here is what I noticed - covering to much of the front decreased the millage by as much as 8mpg. So removing most of the covers solved the problem and got my best mpg so far which is 4.8ltr/100km or just over 49mpg. I am guessing the car doesn't like warm air intake effect.
In the future I'm hoping to get narrower and less roll resistant tires, will try to improve the mirrors, remove the antenna.

https://fbcdn-sphotos-d-a.akamaihd.n...98915572_n.jpg

wow, V2 looks awesome! very well finished and styled

a decent MPG boost too! well done!

Thanks:thumbup: Hoping to get some small mods done in the near future. Meanwhile I wrote an article about an another aerodynamic Citroen.

https://fbcdn-sphotos-h-a.akamaihd.n...66273419_n.jpg

The ZX upon a few other mods is getting a full slippery white vinyl wrap with some graphics. Will update with the final result. http://cdn.imghack.se/images/a143328...d5a8c6a706.jpg

Best results so far! And finaly managed to perform my most accurate test yet. A-B 50.05 MPG (4.7l/100km), B-A 54.7 MPG 4.3l/100km. So the average consumption on a 247mile (400km) journey traveling at 59 mph (95km/h) was 52.27 MPG (4.5l/100km).

Modifications include front tire spats, full vinyl wrap with Grabmedia graphics, flush front fenders and increased tire pressure by 0.1 bar.

Profile pic:
https://fbcdn-sphotos-c-a.akamaihd.n...28661273_n.jpg

https://scontent-a-fra.xx.fbcdn.net/...67913130_n.jpg

At the factory:
https://fbcdn-sphotos-c-a.akamaihd.n...6eeac28273e924

https://scontent-b-fra.xx.fbcdn.net/...49652626_n.jpg

https://fbcdn-sphotos-e-a.akamaihd.n...63858400_n.jpg

Close up of the spats:
http://cdn.imghack.se/images/ecbfae3...018ce4751c.jpg

An interesting landmark in Lithuania - Hill of crosses
http://cdn.imghack.se/images/b34ffc8...2f4dd4d598.jpg

The vinyl car wrap really cleaned up the appearance, covering seams and giving the whole car a consistent visual texture. Beautiful.

What are the crosses about? Here in the States a cross by itself is usually roadside, indicating someone died in a traffic accident at that location.

Thanks. It really was a lot of work. Would have been impossible without some help and looks very neat now. I guess it even draws less attention now since it looks more like a normal car.

It's common to put crosses or candles at an accident site here too. But this is not the case. You can read about it here :) Hill of Crosses. It was brought down a few times as I remember.

Car looks wonderful. Thanks for the update!

CitroX, your car looks really great! 4.5 L100 is definitely a nice figure! How is your driving style? Do you follow the traffic stream and speed? Do you plan your driving for DWB (driving without brakes)? What is your average cruising speed?

For a long time I was surprised by how much fuel could be saved by not using the brakes on my 40 year old Saab 96. I reduced fuel consumption from about 7 l/100km down to 6 L100 this way. My cruising speed at highway is about 80 km/h and the transmission is 4-speed. Many vintage Saab enthusiasts agree on a fuel consumption between 6 and 8 litres per 100 km on these cars.

When I started to practise PnG (pulse and glide) with engine shut down during the glide cycles and while standing still I have managed to reach down to only 4.5 l/100 km, and I have no aeromods at all! It would be verry interesting to see what could be done with Citroplanas if it is driven an a rather extreme way. I think it's mainly about hitting the sweetspot of the engine's BSFC-map, i.e. the area where the engine is running the most efficient, wich usualli is at about 70-90% of maximum throttle a little above maximum torque, any time the engine is running. If the engine can's be kept near the sweetspot, shut it down and coast until it's time for next "burn cycle".

Well written explanation of driving without brakes and pulse and glide
 

Driving Without Brakes
Pulse and Glide

Thank's benphyr! It has taken some time for me to understand how this works, and that it really does. When I first read about PnG and that it can save up to 30% fuel I tried the wrong way and got quite disappointed. I later found out the importance of NOT giving full throttle, because of the carburettor's (or fuel injection's) full throttle enrichment.

To save 30% it is also of great importance to stop the engine when acceleration is not needed. "Digital driving" may be another way to put it. I often think about where you find the world's most skilled eco-drivers - At NASA and others in aerospace industry!
Rocket engines usually work quite digital in on/off cycles, or burn cycles. All excess speed from a too long burn cycle will sooner or later have to be counter-acted and the only way to reduce excess speed in space is a reverse burn cycle, wasting precious fuel. The only way to save maximum fuel is to never burn more than just needed to reach the goal. If you must use the brakes, you have failed!

Great looking boat tail, the one on the aerocivic looked kinda funky, your's looks preety professional.

Thanks, impressed by your driving style results. When I began this project it was mostly about the gains of the aeromods. And I kind of stuck to that for now. So I'm driving with a distance from other vehicles and doing everything I can to keep the speed as consistent as possible. The previous and most accurate test I've done was at 95km/h (59mph), which is 5km/h (3mph) more than usual.
The mileage could definitely be improved quite easily:
Slimmer summer tires, using your mentioned driving methods, mirror delete, lower suspension, giving the engine a simple spark plug, filter, oil change etc.,
and I always drive with a passenger and full tank of fuel.