Aeromods to a three-box saloon / sedan
 

Hi fellow modders,

The time has come to replace my Golf, which got a respectable average of 50's mpg (UK) with skinny, rock hard rubber eco tyres (Mitch-y Energy Savers), occasional use of B100 biodeiesel and a few aeromods:

- Grille Block;
- tyre spats (now gone);
- under tray (now gone but saw 62mog with this on); and
- wiper cover (melted in the sun).

My new steed is a (very) old W202 C-Class running the "bullet / bomb proof" M111.942 2 litre gas engine. I've only covered 70miles so far but these cars are anecdotally good for 27(UK) mpg, so not good at all.

The CD stock is 0.32 and there's an estimated frontal area figure of 2m2-ish. There are a couple of good pics on wiki:

https://upload.wikimedia.org/wikiped...c_sedan_01.jpg

https://en.m.wikipedia.org/wiki/File...-11-13)_02.jpg


Given the saloon bodyshape and no hatch to stealth mount Kamm extensions to, what are my options here?

- Grille block is a possibility, the Grille is huge and the temp gauge seems to be the accurate type.

- air dam?

- spoilers / camm extensions are out of the question as I'd have to drill holes in it and it would immediately rust to nothing

- undertray? (could catch water and make rust).

Not sure how much a modest roof spoiler will help, but at least look into it without discarding it as an option.

http://www.volkswagen-accessories.ie/roof_spoiler1
http://www.volkswagen-accessories.ie...fspoiler_l.jpg

http://ecomodder.com/forum/showthrea...zer-18660.html
http://istargazer.ca/sti/cf_roof_van...f-spoiler6.jpg


1. Just a little lip for a clean edge for the air to release from, or maybe like above?

2. Take weight out if you can live with the extra road noise of no insulation.

3. Grille block which you spoke of, although I'm not a fan of personally.

4. Conveyor belt chin spoiler.

There might be an image of that sedan in the thread below, check it out - may help you decide.

http://ecomodder.com/forum/showthrea...-26678-36.html
http://us1.webpublications.com.au/st...108676_2lo.jpg

Cd = 0.32 isn't bad by US standards, even today.

thanks Kach22i,

Lip spoiler would probs need drilling to fit - holes = rust!

What makes you not a fan of grill blocks?

s

I'm sure it's irrational to compare an old experience with current automobiles , but old biases are still there.

In 1983 or so I had a shortbox Ford van, no electric fans back them. A friend asked for help moving, I agreed and asked how far. Her reply, oh not far at all.

Turns out it was over an hour away (close to two with traffic), clear across metro-Detroit, one end to the other.

I still had my cardboard radiator block on so I had heat on short trips, would have removed it for anything other than a 20 minute drive.

The temperature that day went from 45 to about 75, not unheard of on a spring day in Michigan.

Needless to say I was upset watching my temperature gauge.

Since that day I no longer trust people telling me, it's not far, will not take long etc....

I also do not trust grill blocks not to induce overheating.

Yes I know electric fans in traffic make a huge difference, I however have no interest in finding out exactly how much of a difference.

NOTE: This summer the electric fan regulator on my S-10 gave out on a 90 degree day in heavy traffic. I had to pull over several times to prevent overheating as I had only ram-air cooling going through the radiator.

A grille block would have exacerbated this and made a far worse situation.

FYI: I believe the spoilers above the rear window on a sedan are attached with 3M double sided automotive emblem tape typically.

saloon
 

If you wanted the Kamm bad enough I suppose that you could lose the lid on the boot and fabricate a Kamm extension which included a hatch for access
http://i1271.photobucket.com/albums/...titled26_5.jpg
Your car will have reattachment,but there's nothing like a proper fastback for low drag
http://i1271.photobucket.com/albums/...titled23_7.jpg
M-B is using the more relaxed roofline to day,plus added length for low drag
http://i1271.photobucket.com/albums/...titled3_18.jpg
With the wings plucked off,this C-111 IV would be Cd 0.178.
http://i1271.photobucket.com/albums/...ntitled284.jpg

Let us question the need/want for a Kamm-back when M-B has done such an excellent job of managing the flow of air at the rear of the car (based on wind tunnel image).

Whatever M-B did the air is getting a clean release off the rear roof edge, perhaps boxy was better than curved there.

Aerodynamics by George Kachadoorian | Photobucket
http://i184.photobucket.com/albums/x...psxlmxj0ij.jpg

Looks to me, that adding any sort of Kamm contraption is unnecessary.

I'm not claiming that unattached flow is as good as attached flow, just observing that the existing flow isn't bad at all.

If it's not broke, don't fix it, right?

What I had in mind originally when I set up the graphic was to see how this sedan/saloon design is different from a hatchback - just for kicks.

We more often see the hatchback Kamm's attempt rather than Sedan/Saloon fix, just looking at the similarities and differences is all.

Great, I'll start with the low hanging fruit - driving style, correct tyre pressures, perhaps an air dam (we have less sturdy lawn edging in the UK - may cut up an old bumper I have lying around)

Sorry I missed this, I've been un-well.

Tell us about the use case; i. e. roads, speeds, load, etc. And how much pain you're willing to undergo for the result. We already know "no holes".

My best suggestion at this point: stance it.

http://i299.photobucket.com/albums/m...26058pm6op.jpg
View topic - slammed/stanced/dumped thread! • MBjunkies.com | Mercedes Forum for Benz Enthusiasts •

...on Moon disks.

Stanced on moon discs would be awesome... sadly it's gonna have to stay stock ride height for now.

Usage will be a split between (1) local running about, cross country twisty stuff / town work and (2) long trips on motorways or motorway-like A-roads.

'Typical' usage, then; no towing trailers or anything.

We all do what we can. You could go light-weight with credit-card sized wheel spats (in exactly the right place).