BMW e36 318 tds - modding thread
 

Hi All,

I'm back again with my lates and for now biggest ecomodd - I've changed car from Toyota Previa (you may remember my old gas guzzler from here: Previa Thread), to BMW e36 318 tds "Compact".
Few words about my new wheels, it has 1.7 liter diesel engine 90HP @4400rpm 190Nm @2000rpm (140lbs/ft), around 1215kg (2678lbs) curb weight. I couldn't find EPA rating for that but European rating is 28/38/57mpgUS (city/mixed/highway)

Of course it will be a subject of many mods, but first I have to deal with some minor issues (car is 15 years old). After that I'm starting to modify it.

During the time I was looking for a car I was playing with Paintshop and here are the results (Excuse my crappy Paintshop skills):

1. Stock - my car - "Berta" ;-)
http://andrzejm.superhost.pl/Berta/Berta08.jpg
2. "Ideal profile"
http://andrzejm.superhost.pl/Berta/aero1.jpg
3. "Real, achieveable profile"
http://andrzejm.superhost.pl/Berta/aero2.jpg
4. As above but external mirror deleted
http://andrzejm.superhost.pl/Berta/aero3.jpg

Of course I have to deal with OBDguino first to have a feedback from the car. That's my first planned modd ;-)

Keep your fingers crossed for me and Berta ;-)

Cheers

TBC ;-)

Congrats on the new (to you) ride:) I bet it feels different to have frontal area smaller than a barn:D You could probably coast forever in Berta. What size tires? Do they need replacing?
http://ecomodder.com/forum/member-pi...2663-drool.gif Wouldn't it be nice to have an Insight-clone? I just drooled on my keyboard.

The main difference between the photoshopped images is the wheel skirt, correct? Smoothing out the bodywork might be overkill, but a black horizonal line could be glued/painted on, making it optically smooth.

Wow!

You're going all out on this!



I'm currently figuring out how to block the grilles and make an undertray for my e36 estate..

Good luck and keep us up to date with mods-so I can steal some ideas!

The difference in coasting is HUGE. I'm not used to that ;-)
Unfortunately my wheels are pretty wide 205mm so I need to replace them, but first I have to take care of other things. Maybe next year? Or maybe I'll switch wheels with some BMW owner for stock BMW wheels with 185 tyres... I think it can be done.

Anyway I'll start to modd my ride soon so I'll keep you posted. I have some ideas how to improve aerodynamics, reduce rolling resistance and get as much miles from galon as I'll be able... ;-)

Stock tyres are either

205/60/15

or

205/55/16

TBH, they're not that wide for the size of the car.

The compact you ahve has the older e30 rear axle- good fun, but a bit snappy in certain conditions.

185 wheels make it laughably slidy..and going sideways does not get you good mpg:D

You may be right but I've found on Internet that for my car stock tyre is 185/65 R 15 H

And I'm sure with my hyppermilling driving technique you won't see me going sideways ;-)

It may actually be different for the Compact, and possibly because yours is a "Slow" diesel:p

You'll be sideways, dont you worry!

the "Pulse" part of P&G can get the wheels spinning in damp conditions..

We'll see ;-)

I got a chance to see Berta yesterday and that car has potential! With frontal area that small that little beemer could drive circles around my Pug307 and still get better milage;)

One thing that I noticed is that it has no airdam/chin spoiler. Is that standard in BMWs? Or maybe only on the ones with lower suspension? Anyhow, Andrzej told me that a smooth belly is planned, so no airdam will be needed, maybe just wheel spats.

Another thing which got my attention were the side mirrors, they are kind of big. They also have small bumps on the inside (window side), probably VGs to reduce noise.

Good luck with the modding, you've got a good starting point:cool:

First fillup and I'm impressed with the FE of Berta. I just wanted to know the baseline so I wasn't hypermilling too much. But still 52MPG it's a good starting point. I think I know my new goal I want to go for 1000 miles/tank.
Berta has 62 litres tank so I need to go below 3.85 l/100km (61.9 MPG US), and I'm almost sure I can achieve that. Keep your fingers crossed for that :)

First fillup and I'm impressed with the FE of Berta. I just wanted to know the baseline so I wasn't hypermilling too much. But still 52MPG it's a good starting point. I think I know my new goal I want to go for 1000 miles/tank.
Berta has 62 litres tank so I need to go below 3.85 l/100km (61.9 MPG US), and I'm almost sure I can achieve that. Keep your fingers crossed for that :)

Great early results!

I always admired the 318t because it was the only hatchback BMW availablein this market. (Of course no diesel version here.) I still see one occasionally on the road.

I'm looking forward to seeing what you do with it.

Unfortunately here in Poland we have very strict rules and I can't go for a boat tail or to delete mirrors. But for sure I'll try kamback, wheel spats, smooth belly pan, grill block. So there's a lot of work ahead of me.

To be honest I'm still thinking how far I can go for FE. Should I stip everything, delete as much as possible to save weight. But on the other hand I'm rarely driving in the city, and on the highway weight is not such a big issue. Any suggestions?

I wouldn't do the rear batman thing... whatever that is on the back window. You already have a fairly steeply raked back window. With that thing added you're actually increasing the size of the wake behind the car.

tjts - Unfortunately, you can't make that assertion without knowing whether flow reattaches on the stubby "decklid" portion of the hatchback.

If flow separates at/near the top of the rear window, and does NOT reattach downstream, then a properly designed "batman thing" will definitely help.

I think the profile of the rear of the car falls well outside of the optimum. My money's on Batman to the rescue.

BMW put a lot work in the E36 aerodynamics. They got the angle right at the factory. Either way you are increasing the size of the low pressure zone behind the vehicle which is counter productive. The batman thing or whatever is only useful on cars that have a blunt rear starting at the top of the rear windshield.
http://ecomodder.com/forum/member-pi...ck-vehicle.jpg
http://1.bp.blogspot.com/_JWSHr2FzJy...-12-10+128.jpg

I wouldn't strip it. If you stripped it what would you gain? 1 or 2 mpg? You can have a nice car and get 51mpg instead of 52 - not at all worth it.

Not quite. The "right" rear roofline would look a lot like a Prius, or the latest Mercedes E Class coupe (if you prefer a trunk), or like the Chevy Volt (if you prefer a "notched" hatchback style like the 318t).

The effective angle of the rear of the 318t (end of roof to tip of decklid) is ~20 degrees. The glass alone is closer to ~23 degrees.

The ideal angle, per the diagram you posted, is ~13 degrees. Not coincidentally, that's much closer to what you'll find on the Prius, E Class coupe or Volt.

Tuft testing of the 318t would probably show that there turbulence & flow reversal on the rear deck lid. That means flow separation (low pressure wake) starts at a point on the rear glass, not at the trailing edge of the "deck lid". It may seen counterintuitive, but a properly designed batman thing will permit controlled pressure recovery further aft and lower down, and would result in a smaller overall wake.

Given the angle of its rear glass, the 318t needed either a taller rear deck lid, a longer one, or a big-ass spoiler for better aerodynamics from the factory.

http://www.popsci.com/files/imagecac...lt%20small.jpg

(Chevy Volt - GM image)

I think that Metro has a point, and as you can see below the "ideal" aerodynamic profile is way different from the back of my 318 Compact.

http://andrzejm.superhost.pl/Berta/profil.jpg

Hi again!

It was a long time since my last visit here, but haven't forgot about you guys. Unfortunately there's many things that I have to deal with right now so my modding plans for Berta are those of low priority :( Anyway I just got back from Prague and it was for now the longest trip with Berta. But before about FE I wanted to tell you that there's a problem with Berta's injection pump, cause it's sweating with fuel. I presume 0.5 litre per 100km or something about that. :( I have to deal with that asap. Just need to but a gasket set take out the pump and fix it once for all. Anyway I've managed to drive Berta for 1195km (~743 miles) till the yellow fuel light went on. After filling up I've counted FE and it showed up that consumption was ~4.33l/100km (54.32 mpg US) I thing that's amazing with the leaking fuel pump. In a month I'm planning next trip (over 3000km), hopefully I'll be able to fix Berta till then, and maybe I'll have time and $ for some eco-upgrades. So keep your fingers crossed.

1200km on a tank is great! I bet other drivers with your model don't go above 1000km.
Have you tried a grille block yet?
Get that pump done!

Tomorrow I'm starting fixing Berta. Hopefully I'll take some pictures ;-)

HAve you increased the psi?

that is a great little car.
I agree in NOT stripping the car down. THere are certain creature comforts that are built into an upper tier brand.

I have an Infiniti Q45 and would never gut it just for 1-2mpg.
I even run the a/c on automatic....and get my 30+ mpg.

But the ideal profile is much longer than your car. You can't just have it end abruptly and still expect any benefit just because you followed that profile half way to its conclusion. With that modification you create a much larger low pressure zone behind your car.

:confused: Following the profile to the end of the car will reduce the area of turbulance behind the car, so it's worth something. Not as much as a full boattail, but better than nothing. Extending a 'tail has diminishing returns: the first foot is worth more than each additional foot by itself. Plus in Europe, anything that protrudes beyond the rear bumper will almost definately attract the wrong kind of attention (blue uniforms, etc.).

How is it going with Bertha? Have you fixed the fuel pump?

BTW I believe that you have a double entry in your fuel log on 05-04-2012 which is bring your average down. Not sure how to delete entries, maybe contact MetroMPG?

I can't believe I'm saying this, but I'd like to advocate something of a middle ground :p

The compact is about 20° , measured to the rear of the small trunk lid.
AndrzejM's Kamm is at 10° , increasing the wake area.

10° is less than what you can get away with, so it misses out some of the potential.
I'd go for something in between, around 15° or very near the optimal angle, and at the same time try to tie in the sides as well, making a trapezoid Kamm as seen from behind (ideally with rounded edges, and the rear filled in.)

Right now I'm dealing with the engine. Maybe I'll finish that next week. Then I'll have a fully working car as a base for eco-mods. The plan for now is to delete AC, PS and belt driven fan as well. Kammback and other aero-mods are planned for the future.

I haven't been here for a long time, because of many things that had happened in my life... But I'm still with you guys!

Anyway right now I'm in Sofia (Bulgaria) and I drove my wife's car here. MB W168 automatic and I've managed to squeeze more than 26 km per one liter (3.84 l/100km, 61.25 mpg US). Not bad, not bad at all :)

See you soon with some pictures of my Berta finally on the road...

Hi Again Guys!!!
Long time no see! Many things was going on and I didn't had much time to visit our forum. First of all I have my Berta back, because it turned out that engine was dying  But now after complete rebuild it runs like it should. I don’t have any picture from the process, because I was doing everything on my own and I didn’t wanted to destroy my camera with those black greasy fingers of mine. Anyway engine have new piston rings, polished crankshaft, new main and connecting rods bearings, block was honed, valves reached, new seals etc. Lots of work but I succeeded to finish that. Now Berta is running just very gently because I want engine to run-in completely before I’ll take it to the spin. So now I can deal with the rest of the car. I’ve removed AC, PS and belt driven fan during the process. So that’s my starting point. Now I have to wait for some funds and I’m starting aero mods. 

Ok guys now I have to read lots of new threads just to catch up 

See you soon

Good to see you're back and that Bertha survived the engine rebuild:)

Can't wait for the aeromod to begin :rubbinghands:

Yeah the aero journey just begins :)

Welcome back, seems you have done quite a bit of work on her.

Berta's first aero mod - kammback draft
 

Hi guys!

Today I've started to prepare template for kammback for Berta.

Here are the results

http://andrzejm.superhost.pl/Berta/kammi008.jpg
First fittings

http://andrzejm.superhost.pl/Berta/kammi009.jpg
http://andrzejm.superhost.pl/Berta/kammi010.jpg
http://andrzejm.superhost.pl/Berta/kammi014.jpg
After cutting, taping,etc.
http://andrzejm.superhost.pl/Berta/kammi015.jpg
http://andrzejm.superhost.pl/Berta/kammi016.jpg
http://andrzejm.superhost.pl/Berta/kammi017.jpg
http://andrzejm.superhost.pl/Berta/kammi018.jpg
http://andrzejm.superhost.pl/Berta/kammi020.jpg
http://andrzejm.superhost.pl/Berta/kammi024.jpg

So now let me know your thoughts! Of course that's only a template for the future. Now I just need a big piece of coroplast and voila kammback will be almost ready. :)

It looks good so far, but you need to roll Bertha outside and take a side picture, then you can compare it to the aero template.

Maybe today, it was dark outside when I've finished my work yesterday.

Looks good. Do the sides taper towards the rear? I would guess that they don't, but maybe better photos will show otherwise :)

Have you done any estimations of the cost of the final coroplast Kammy?

Todays picture.
http://andrzejm.superhost.pl/Berta/IMAG0359s.jpg
And comparision to aero template
http://andrzejm.superhost.pl/Berta/template.jpg
I think that it looks pretty good comparing to template. Don't you think so?

Yes sides taper towards the rear, but just slightly. I just want to use as much hatch surface as I can.

A piece of coroplast that should be enough to cover my needs costs around 60 PLN (less than 20USD) I will need some additional parts though but that shouldn't be an issue.

AndrzejM, where do you plan to/did you buy the coroplast?

Google "polipropylen kanalikowy". I got mine from the company Tuplex.

You can buy that in Castorama, Leroy Merlin or any other shop like that. Just go for "roof department" :)