BMW 318iS e36 Project- Aiming for 45MPG (imp)-Suggestions Wanted!

[320touring]

318iS Ecomodding project

So after 9000 miles in 6 months, Ive decided that I really should try this ecomodding malarky on the daily driver..

The car is a 1994 BMW 318iS. its a 1800cc 16v 4cyl engine with circa 140bhp.

5 speed manual box (1:1 5th gear) and a 3.45 rear diff

Weight is 1240kg (2750lbs)

Car is completely standard and has returned approx 40.4 MPG(imp) over my time of ownership.

Currently I'm using the following hypermiling tips/tricks:

Tyres at 40PSI

P&G (engine on) using indicated load of 20mpg on the onboard econometer

DFCO using gears to reduce car speed approaching junctions etc


Both myself and my girlfriend use the car regularly- she's pretty good at the hypermiling, and is usually within an mpg or two of myself.

Aims

1. Improve the Car's average MPG from 40.4mpg to 45mpg.
2. Maintain the current level of practicality.
3. Utilise only "Reversible" Mods, so that car can be returned to stock if required.
4. Costs of any modifications must be covered by the savings gained
5. Total Outlay for Modifications should be no more than £250
6. The car must appear almost unchanged visually-Kammbacks etc are a no no with the police/insurance companies.


Here are some pics of the car, along with my proposals

(i'd be grateful if someone could place the "ideal" aero template onto the side view, please)

Side View (rear wing is missing due to me needing to refit it properly)


I've now refitted the wing- but I can see that having no rear wing would be advantageous- fitting a no wing bootlid should resolve this

Front End


Immediate thoughts centre around the Large Lower Grill/upper grill

closely followed by potential for wheel spats/smaller door mirrors

Rear End


Initial investigation suggests not too much to do outwardly here.. however I see potential for improvement by reducing the "parachute " effect of the bumper by sealing the gap from the spare wheel pan to the bumper

Front Wheel Arch/ Alloy wheel shape


These "Bottletop" alloys are an odd design, esentially the curved outer spokes are higher than the centre- meaning the alloy looks like a shallow bowl.

I could see covers working for these- any suggestions as to how to mount them?

Rear Arch


Again I can see potential for spats infront of the rear wheels, and if possible a way to tidy up the rear edge, as it sticks out past the wheel.

additionally, wheel covers could be fitted. I'm not prepared to fit rear arch covers though, as this car is fairly rare in having very solid rear arches- I want to keep it that way

Bonnet(Hood) to Windscreen angle


Any suggestions welcome here-is it worth trying to modify the angle?

Engine Bay Overview


Immediate things that spring to mind are

Top cover to quicken coolant heating
Wing/Slam panel seals to minimise air into the bay


Engine Bay Gap behind grills and Below Radiator




This has lots of potential for improvement:

bellypan to close off the bottom of the bay
Sealing behind headlights
Slam Panel Cover
Internal Grill blocks


Current Air Intake setup


Again, scope for improvement here by fitting a Warm Air Intake ducting air from the exhaust manifold (right rear corner of the bay) to the Air meter.

There's plenty of space infront of the engine to run some tubing- I just hope the air meter can adapt to the lower density warmer air


Other Ideas

Engine bay Weight Saving
Electric Fan Install
Interior Weight Saving
Source Smaller Wing Mirrors
Fit Taller Ratio Diff (3.25/3.15?)
Full length Belly Pan


I'd be interested to hear your suggestions/ideas/observations- please dive right in!

Thanks

[redpoint5]

How much time is spent on the highway vs in town driving? This should dictate where you expend your efforts. If you do a lot of stop and go, then reduce the weight. If you spend a lot of time driving fast, then reduce aero drag.

You have a lot of room in that engine bay and I wonder if you could easily retrofit a turbo. There has been some interesting discussion of turbo charging a car for efficiency, but I still have my suspicions that you would be doing well to even maintain your current MPG.

All of your ideas sound easy and cheap enough to me, and I'd be curious to see your results.

[320touring]

Originally Posted by redpoint5

How much time is spent on the highway vs in town driving? This should dictate where you expend your efforts. If you do a lot of stop and go, then reduce the weight. If you spend a lot of time driving fast, then reduce aero drag.

You have a lot of room in that engine bay and I wonder if you could easily retrofit a turbo. There has been some interesting discussion of turbo charging a car for efficiency, but I still have my suspicions that you would be doing well to even maintain your current MPG.

All of your ideas sound easy and cheap enough to me, and I'd be curious to see your results.

Hi, Thanks for your response!

To answer your question- the car currently does approx 75% Motorway and 25% in town driving..However the Motorway driving is often Rush hour, so stop start. Hence me thinking that weight reduction would yield some gains.

Regarding a turbo- I'd shy away from that modification for the following reasons
1. Need for aftermarket management
2. Temptation-my previous car (saab 9-3) was a turbo, and I found myself tempted by boost!
3. Sourcing even a 2nd hand turbo and associated parts would possibly blow the £250 budget
4. Adding complexity can be counter productive- the engine size is adequate for the size of car. its just a pity that the peak HP/torque are so high in the rev range on this 16v engine

I am, however interested in the possibility of timing up the cams differently to give more low end torque-would that produce similar effects?

[lowglider]

It`s hard to add anything big because you`ve already mentioned most of the key improvements.

Me knowing a lot more about BMWs than a sane person should ever know, I would suggest looking at all the usual tune up things like the condition of the air filter and spark plugs. After that I would advise testing your oxygen sensor, even if those things still work enought to pass MOT, they tend to worsen fuel economy. Oxygen Sensor Information has a good procedure on doing it.

I thought of that because getting 40mpg on a 318is shouldn`t take much effort and with bumped up tyres and P&G you should get more.

Otherwise the first thing to do is get back the engine bellypan, doesn`t matter if you get the original one or make one yourself, it will not only improve aerodynamics and economy but also reduce road noise.

Other than that a grill block is the key to faster warm ups and more mpg and like you have found out yourself, the back bumpers do tend to parachute on these BMWs but some easy underbelly manufacturing can improve that. I doubt full underbody will be worthwhile if you do the front underpan and remove the back parachute.

As for electric fan conversion that is a great idea, just get a fan kit with electric thermostat that you stick into the radiator and throw out that old viscous coupling fan, those things are often the culprit for engine damage due to overheating and can be very parasitic on smaller engines. Going electric will not only get you better fuel economy, but also horsepower, easier revving and reliability.

You`ve also mentioned the diff. The 328i has a 2.93 diff and that would be the way to go, because the 318iS is very lowly geared for sporty driving thus economy suffers.

One thing that you may have not though of is replacing the engine DME chip. These improve low down torque and a 10% better fuel economy can be realistically expected. I`m not talking about the cheap resistors but about EPROM chips that can be found on eBay for a few tenners.

Please update on this topic with the results you will get, because I`m eager to find out how much can be squeezed out of a 318iS coupe. These cars are great if you keep rust away from them, lots of these engines go beyond 400k miles without major overhauls.

[320touring]

Thanks for your post-very informative and helpful!

i've slotted in my responsed below:

Originally Posted by lowglider

It`s hard to add anything big because you`ve already mentioned most of the key improvements.

Me knowing a lot more about BMWs than a sane person should ever know, I would suggest looking at all the usual tune up things like the condition of the air filter and spark plugs. After that I would advise testing your oxygen sensor, even if those things still work enought to pass MOT, they tend to worsen fuel economy. Oxygen Sensor Information has a good procedure on doing it.

I currently have 2xe30's an e34 and this e36..my bro runs an e36 328 and has an e30 too- we're in a similar position to you-too many E/M numbers are bad for you

The vehicle has just had a new centre to rear exhaust fitted, but I've not checked that new fangled Lamda sensor.. Do you reckon a de-catting swould be advantageous?

Car had a service approx 3k ago with all new plugs/filters/oils- currently running on 10w40 semi synth as its the older 1798cc m42 lump

I thought of that because getting 40mpg on a 318is shouldn`t take much effort and with bumped up tyres and P&G you should get more.

Really? I was quite chuffed with the 40mpg, given two drivers and a trackday done in the car

Its fairly consistently about 39+mpg, and tyres are at 40psi, so still have some ride comfort.

Looking on sprintmonitor.de (logging site that generates my signature MPG icons) I'm apparently 3rd best MPG of all the 318iS on there, the ones above me appear to be about 42mpg.

Certainly using it exclusively on A road/Motorway I see about 42-43 at the moment

Otherwise the first thing to do is get back the engine bellypan, doesn`t matter if you get the original one or make one yourself, it will not only improve aerodynamics and economy but also reduce road noise.

Yeah, I believe the car should have both a front belly pan, and also a cover over the gap between teh grill and the slam panel at the top

Other than that a grill block is the key to faster warm ups and more mpg and like you have found out yourself, the back bumpers do tend to parachute on these BMWs but some easy underbelly manufacturing can improve that. I doubt full underbody will be worthwhile if you do the front underpan and remove the back parachute.

Fair comment re the underbelly pan- i'll certainly try the front/rear approach first.

Do you think inner grill blocks (to avoid stuff externally) would be effective enough?I'm essentially thinking I should try to seal the engine bay off as much as possible- the cooling system is in good repair.

As for electric fan conversion that is a great idea, just get a fan kit with electric thermostat that you stick into the radiator and throw out that old viscous coupling fan, those things are often the culprit for engine damage due to overheating and can be very parasitic on smaller engines. Going electric will not only get you better fuel economy, but also horsepower, easier revving and reliability.

Interesting point re the fan- Essentially I was thinking on adjusting the Cams as the engine mainly does high load, medium RPM work (pulse phases are done in 5th with the MPG needle reading 20..pulling through to approx 3500rpm for 70 mph)

Moving the torque band down would make the engine worke more efficiently in this spread?

I'm not a fan of the viscous anyways-esp the left handed thread and 32mm spanners!

You`ve also mentioned the diff. The 328i has a 2.93 diff and that would be the way to go, because the 318iS is very lowly geared for sporty driving thus economy suffers.

a 2.93 may be pretty long for the car, no? again, peak torque at 4500rpm and peak power at 6000rpm mean that along diff may be hellish slow to pulse?

I could see the benefit on the Motorway if driving at a steady speed though.

Do you know where there is a list of available diff ratios for the e36?

One thing that you may have not though of is replacing the engine DME chip. These improve low down torque and a 10% better fuel economy can be realistically expected. I`m not talking about the cheap resistors but about EPROM chips that can be found on eBay for a few tenners.

I'm aware of ECU rechipping, but I have my doubts regarding it- for better torque etc I'd probably look at going down the Megasquirt route-but thats too expensive for this project!

I'll see what I can find out though

Please update on this topic with the results you will get, because I`m eager to find out how much can be squeezed out of a 318iS coupe. These cars are great if you keep rust away from them, lots of these engines go beyond 400k miles without major overhauls.

TBH, its only a daily beater to me, too many valves not enough cylinders!

But I'm happy to do some basic modding to see the improvements.

Hopefully the aero mods could be applied to others in my fleet

[Arragonis]

I wondered if this was you the other day after you mentioned your unit, but I can't remember why when I found it. Don't worry I'm having a somewhat confused day

You seem to have done well with technique. One thing I would try is a more aggresive pulse - I can get George to under 20 MPG sometimes on a pulse although the whole P&G thing is still experimental for me. A harder "pulse" may work better for you though in the heavier 318 which will keep some momentum - I think the Aygo loses too much in the glide to make it worthwhile but I'm trying to see if I can get it to work for longer journeys.

For mods I found had the most effect, I would go with :

1. Take your tyres to 45. And then check the ride and ease back if it's too crashy - mine was. Get the alignment done as well just in case.

2. An outside block, clear plastic perhaps, for the Kidney part of the front grill (the upper part). I can send you the bolts from my bought in block if you want to PM me an address. That way you can just fix the plastic to them. There are only two though, you may need more depending on the material used. The lower one maybe after you've monitored temps.

3. Flat-mate tyre inflator and an AA card to save weight. This made quite a difference to the weight.

4. Leave off the rear wing, its for show

And these ones I never did but seem to work for others

1. Belly pan seems like an idea as it is very open down there where the extra 2 cylinders should be .The rear end parachute is worth a look too whilst its up on the lift.

2. Something to hide the wipers from the airflow.

3. You could try the "Pizzapan" covers for the wheels, I'm not sure what benefit there is to be had there but some here use them.

4. Skinnier or taller wheels and tyres - maybe some steelies from a 5, or maybe borrow the wheels from your 535 to raise the gearing a little ?

5. MFree mirrors (or their cheaper Corsavan equivalents).

I'm sure there is plenty more to be had from this car though. Are there many options for chip-tuning a NA petrol ? The one guy I have checked with for Aygos says the whole idea is carp.

EDIT - PS I am joking about the engine, you can get George's into a shoe box

[320touring]

Originally Posted by Arragonis

I wondered if this was you the other day after you mentioned your unit, but I can't remember why when I found it. Don't worry I'm having a somewhat confused day

Its almost as untidy as my unit

To be fair, Mine has recently been tidied and will hold upt o 13 cars if you're good at parking...

the only problem is that its 130miles round trip to get there.

You seem to have done well with technique. One thing I would try is a more aggresive pulse - I can get George to under 20 MPG sometimes on a pulse although the whole P&G thing is still experimental for me. A harder "pulse" may work better for you though in the heavier 318 which will keep some momentum - I think the Aygo loses too much in the glide to make it worthwhile but I'm trying to see if I can get it to work for longer journeys.

Yeah this is an area I'd like to experiment with, however, the lil 4 banger doesnt seem to get much more "GO" for dropping it to 15mpg- more noise and thats about it..

at 20mpg, the engine "feels" like its pulling well, if you know what I mean..plus the 20 is in the middle of the dial so easy to aim for when you're tired

Maybe with some free time and a spare day I'll try a 15mpg pulse and do some a-b-a testing on the m74..

For mods I found had the most effect, I would go with :

1. Take your tyres to 45. And then check the ride and ease back if it's too crashy - mine was. Get the alignment done as well just in case.

2. An outside block, clear plastic perhaps, for the Kidney part of the front grill (the upper part). I can send you the bolts from my bought in block if you want to PM me an address. That way you can just fix the plastic to them. There are only two though, you may need more depending on the material used. The lower one maybe after you've monitored temps.

3. Flat-mate tyre inflator and an AA card to save weight. This made quite a difference to the weight.

4. Leave off the rear wing, its for show

And these ones I never did but seem to work for others

1. Belly pan seems like an idea as it is very open down there where the extra 2 cylinders should be .The rear end parachute is worth a look too whilst its up on the lift.

2. Something to hide the wipers from the airflow.

3. You could try the "Pizzapan" covers for the wheels, I'm not sure what benefit there is to be had there but some here use them.

4. Skinnier or taller wheels and tyres - maybe some steelies from a 5, or maybe borrow the wheels from your 535 to raise the gearing a little ?

5. MFree mirrors (or their cheaper Corsavan equivalents).

I'm sure there is plenty more to be had from this car though. Are there many options for chip-tuning a NA petrol ? The one guy I have checked with for Aygos says the whole idea is carp.

EDIT - PS I am joking about the engine, you can get George's into a shoe box

1. 45 PSI on the Scaaaab was horrific, the car has just had new front balljoints and track control bushes-and I dont want to kill them too soon..I may try it later though, or maybe on the suave european roads

Its not particularly comfortable at 40psi on the m8 (esp on the glasgow centre bits)

2. I'll take the kidney grill block under advisement-trying to think if there is a way I can just block between the vertical slots with clear plastic like you say-cheers for the offer of attachments. I'll pull a spare grill off at the scrappy to investigate.

3. I have an RAC card-the youngest car in the fleet is the 1994 iS, the burds golf is of 1982 vintage..

that said-full size spare tyre is a must for me-too much time on single track roads up north with no signal on the mobile for me to be confident..

Additional options

1. Believe me, the proliferation of valves and dearth of cylinders is a cause of annoyance to me, but it was 3 owner and 9 months MOT for a weeks wage..I'll try to source a BMW undertray from a scrappies, failing that some plexiglass from B&Q should suffice.

2. The wipers do annoy me-as they're a visible disturbance to the lines of the car-hell,the ariel is built into an A pillar-so why not hide the wipers?

problem is that it doesnt have a "proper" BMW bonnet, so the bonnet oppens towards the screen, not away from it. HTere are however, tray sections in the scuttle that something could be mounted to- I feel a ponder coming on.

3. I'm very keen on this idea- could possibly combine fitting narrower tyres on steels with fitting flush hubcaps- mounting to the bottle top alloys looks "challenging", but again, a time to look at the wheels and do some trial fits is not a bad plan..

The 535 wheels wont fit as the 225/65/15s are bulbous!

4. EMMMMFREEZ to quote barryboys, may be a plan-certainly lose the "prince charles" look from the front end.

Chip tuning I'm sceptivcal about(see my post above) but I believe more torque can be wrestled from the m42 lump.

As for the engine quips-worry not, I slag it constantly Your wee citroen (it really just is!) has a nice engine note-kind of like half a vauxhall v6 (like when the headgasket goes on mv6 omegas!

[Arragonis]

Originally Posted by 320touring

Yeah this is an area I'd like to experiment with, however, the lil 4 banger doesnt seem to get much more "GO" for dropping it to 15mpg- more noise and thats about it..

at 20mpg, the engine "feels" like its pulling well, if you know what I mean..plus the 20 is in the middle of the dial so easy to aim for when you're tired

Maybe with some free time and a spare day I'll try a 15mpg pulse and do some a-b-a testing on the m74..

The problem I find with P&G in Scotland is the 2-lane motorways, A-roads and bypasses. Nowhere is quiet enough to try it without someone wanting to punt you along or off so its hard to test and probably even harder to use here practically at any time of day. Instead I usually find a truck going roughly the speed I want and follow it.

Today has been tricky though as its a bank holiday - ok not here but a lot of people take the same day as England so the roads are quiet - so no trucks. So instead I just drove both to and from work with no HM.

Result is a daily average to work of 54 and back of 57 (back is downhill). This included me joining a row of 2 other Aygos on the bypass to make a red/white/blue threesome () at 70.

I have new music on my USB key as well, which is never good for FE...

[320touring]

Originally Posted by Arragonis

The problem I find with P&G in Scotland is the 2-lane motorways, A-roads and bypasses. Nowhere is quiet enough to try it without someone wanting to punt you along or off so its hard to test and probably even harder to use here practically at any time of day. Instead I usually find a truck going roughly the speed I want and follow it.

I just do it anyway.. The idiots that sit in the outside lane doing 65mph and holding everyone up are responsible for the fact that faster cars/trucks behind me cant pull out to pass. I'm not speeding or going too slow, so they can swivel

Funnily enough, had a trucker behind me yesterday in heavy traffic- when the car infront slowed suddenly he had to take to the hard shoulder to avoid hitting anyone- he spent the rest of the journey 100 yards backk from any car..They really are ignorant of the effort required to heft 44tonnes to a halt

Today has been tricky though as its a bank holiday - ok not here but a lot of people take the same day as England so the roads are quiet - so no trucks. So instead I just drove both to and from work with no HM.

Result is a daily average to work of 54 and back of 57 (back is downhill). This included me joining a row of 2 other Aygos on the bypass to make a red/white/blue threesome () at 70.

I have new music on my USB key as well, which is never good for FE...

Yeah Monday was a dream run in..even this morning wasnt too bad once I'd got onto the m8..

looks like 230 miles from £35 at 1.329 in the old e30 320.. not too far off 40 UK MPG

As of tomorrow then its a return to the diseasal destroyer as driven by my carshare colleague- she got a mazda6 2.2 tdi to replace the frankly brick sh*tehouse nissan Cashcow.. here's to cheaper commutes

[Arragonis]

Sometimes when I potter along in the slow lane on an empty M8 I sometimes get near missed with people trying to pull undertakes of the people they are behind - its like I'm invisible. They are racing and not concentrating.

So then I started only pottering along behind something big and hard not to see like a giant truck or bus, and it makes no difference.

Now if they are having trouble spotting something 30 feet tall and 20 wide and usually painted bright orange what chance do the rest of us have ?