1987 e30 project

[Monark]

Hello,

I'm relatively new to try to improve mpgs. I've been dabbling in some hypermiling techniques and very light modifications in order to get better mpgs. I've managed to get 29 mpgs out of my 2006 pontiac gto which I was kind of proud of since it is a big, heavy, high horsepower automobile. Although, I'm sure many here can do much better in much worse cars.

My daily driver is a 1987 bmw 325. It has the 2.7L eta engine which is supposed to be better on mpgs than the regular 2.5L i engine. Its been decent to me averaging 25-30 mpgs without much a problem.

However, come September I'll be clocking +/- 600 miles a week for work. I want to make the most out of this. At the current situation we're talking 20-25 gallons a week. So 50-65 bucks a week. I'd like to set out on a goal of getting a fairly consistent 40+ mpgs out of it. But 35+ is already a good start. The good news is I'll be doing about 85% (maybe even more) of my driving on the highway. I was wondering what advice you guys in all your genius could throw my way. An unfortunate bit of news, my front spoiler/air dam/whatever that goes under my front bumper was the victim of a stray roofing tar bucket. It was absolutely destroyed.

Should I hit up home depot and engineer one the shoots the air off to the sides or should I make it so its curved and long going inwards. Or even try to glue together the old one (its in like 6-7 pieces) and put it back in place?

Thank you for reading.

[320touring]

heh an e30 fan!

your eta (2.7 lump) can easily be modded to make good bhp and torque-making it more drivable and less stressed.

do you have those 'diving board' bumpers? They are heavy and even less aerodymamic than the european ones.

I'd advise switching to a manual trans to maximise mpg as you should already have a very long diff at the back.

As for the undertray, assuming the mounting threads are still on the car you could probably fashion a more effective one easily.

Fairly common to see 40mpg uk from 2.7 manuals being driven 'enthusiastically' over here.

Best of luck:-)

[Monark]

Originally Posted by 320touring

heh an e30 fan!

your eta (2.7 lump) can easily be modded to make good bhp and torque-making it more drivable and less stressed.

do you have those 'diving board' bumpers? They are heavy and even less aerodymamic than the european ones.

I'd advise switching to a manual trans to maximise mpg as you should already have a very long diff at the back.

As for the undertray, assuming the mounting threads are still on the car you could probably fashion a more effective one easily.

Fairly common to see 40mpg uk from 2.7 manuals being driven 'enthusiastically' over here.

Best of luck:-)

Thanks for the response-

I do have the diving board bumpers. I've contemplating tucking them in, but I'm unsure if it'll help or not aerodynamically.

I've already got a manual transmission with a 2.93 rear end with a limited slip.

As far as the undertray all the mounting threads are still there. So I guess I'll fashion one up. What kind of design would be better, flat or pointed at the front them angled down the sides?

Also in terms of blocking the grill. Should I block in the middle where the two main grills are, or in the space between the headlights and those grills? You might recommend both, but which would have a better impact?

[320touring]

for the undertray it may be possible to make the bottom of the car as flat as possible so i'd look at something starting at the level of the bottom of the front valence and extending back.

Sounds like a nice manual setup you have there!

have you done any mods to the engine? Be careful blocking the grill as the ir intake is behind the lhs light, and the stock fan sucks air through the rad-block the grill and you'd reduce that.

Have a look at the alpina 'cow catcher' front lip for the basic idea of an air dam for an e30

[Monark]

Originally Posted by 320touring

for the undertray it may be possible to make the bottom of the car as flat as possible so i'd look at something starting at the level of the bottom of the front valence and extending back.

Sounds like a nice manual setup you have there!

have you done any mods to the engine? Be careful blocking the grill as the ir intake is behind the lhs light, and the stock fan sucks air through the rad-block the grill and you'd reduce that.

Have a look at the alpina 'cow catcher' front lip for the basic idea of an air dam for an e30

Not really. A long time ago I installed a K&N air filter and that's basically it, in terms of directing impacting the engine. OH, I also have a thermostat that runs warmer than stock.

I also took out the those plastic pieces behind headlights to let more cool/cold air into the engine bay/air intake to get more grunt out of the engine. I've heard warm air is better for mpgs so I've recently (yesterday reinstalled those pieces.

As far as the air damn, that's definitely an interesting idea on how to take it. As far as covering up the bottom of the car front to back, that might be tricky, but I'll definitely take a look at it.

[DamageX]

I don`t know much about aero mods, but 325s came with heavy slabs of stuff on the trunk floor, which are good candidates for weight reduction if you don't need it for traction. Also, there may be a slight gain from running without the power steering. I drove an e30 for several years without the PS and didn`t have a problem with it. Lastly, don`t forget the basic tune up stuff like plugs/cap/rotor/O2 sensor

[some_other_dave]

And don't forget to slow down. Running at 55 MPH will give significant MPG benefits over running 65 MPH.

-soD

[Monark]

Originally Posted by some_other_dave

And don't forget to slow down. Running at 55 MPH will give significant MPG benefits over running 65 MPH.

-soD

Definately, I try to stay to the speed limit wherever I go, usually 0-5 miles under.

But again about the diving board bumpers. Will tucking them in help or hurt aerodynamics?

[mbarrus]

I'm looking at starting to aeromod/ecomod my '87 325 (manual, 2.7 eta)... just wondering if anyone else out there has done some things in the past and what worked well, etc. Any help would be appreciated.

[tjts1]

Front air dam. The taller the better. I used an upside down air dam from a volvo. A bit bigger than the IS lip. Also lower the front suspension to reduce frontal area. Ditch the power steering.