DIY upper & lower partial grill blocks - 2005 330Ci convertible
 

Hi all,

New to the site but thought I'd share my progress on my 330i soft top - I've just made partial upper and lower grill blocks today and fitted them. It seems to me that the size of the grills and amount of air going through the grills is much more than needed for the climate here and heat generated by the engine.

I live in the North of England and have owned the 330i for about a year, I do sometimes get the roof down despite the British weather! It's a sweet car to drive, and having owned Diesels before it I love the 3 litre 6 cylinder straight 6 engine, hardly too eco friendly but it is fairly economical for the type of engine - 30+ mpg US on a highway trip.

It's a sound car, I have done lots of preventative maintenance to keep it running well, replacing the MAF sensor, eliminating air leaks (famous E46 BMW problem), new vanos seals, using premium tyres (Continental), premium fuel, it's been remapped to gain a few bhp and advance the timing slightly for mpg.

Being a facelift 330 it has a 6 speed gearbox and turns 2500rpm at 70mph, not too bad.

I recently tweaked the wheel alignment and changed the front and rear toe to close to zero, I have not done enough miles before doing the grill block to know how much difference changing the toe made, maybe 1mpg at highway (motorway) speeds - it was about 0.5 degrees toe in on the front and 0.7 on the rear, now close to zero at both ends but slightly toe in at the rear for stability.

Sadly I can't see much more low hanging fruit to mod the aero on the car - the underside seems well optimised, I don't want to change the looks or driving experience, and I don't want to block the brake ducts for insurance reasons/safety.

Anyhow, here are some pictures of the car and grill blocks:

Pose shot of the car, freshly waxed:

http://ecomodder.com/forum/member-ti...8-161814-2.jpg

Upper grill block (about 65% block, with air duct added for intake)

http://ecomodder.com/forum/member-ti...7-201358-2.jpg

Lower (about 70% block)

http://ecomodder.com/forum/member-ti...7-201456-2.jpg

I made the upper block and duct from hardboard covered in Gorilla tape (fancy duck tape), and the lower block from cardboard covered in agricultural black film. Oh and some cable ties to hold them in place and more Gorilla tape to fix the blocks and round off the air vent for the intake.

For the upper block I made an air channel to feed the air intake at the top of the kidney grills. I had noticed when the engine had only been driven a few miles, the throttle response was better than if driven a bit longer. I also noticed inlet air temps a bit high after driving for a while - 110F when cruising at 65mph on a 70F day, along with some pinging from the engine. Since pinging will cause the car to pull timing I figure cooler air is best for my engine to optimise econony.

I wanted to keep some airflow to the radiator and aircon condensor, which sits right in front of the radiator, and into the engine bay to avoid plastic and rubber parts deteriorating too much, the exhaust manifolds sit to the side of the engine and give out quite some heat.

If I drive in a relaxed manner on the highway at 65-70mph using cruise control (in gear/ no coasting), with the occasional blast to overtake, I can NEVER hit 33mpg US, typically it is 30-31mpg US. The OBC is very accurate it seems for mpg. If I can achieve 33mpg US with these mods with my typical highway driving style then I will be happy - this is a milestone for me as it is 40mpg in UK measurements, so to achieve this from a 3 litre gasoline will make me very happy.

I have an Andoid head unit with a bluetooth OBD dongle, running torque, so can keep an eye on coolant temps and intake temps. I have also set an alarm on Torque, so if the coolant ever goes over 212F it will shout at me through the stereo - normal max. temperature is 205F and the car won't let it rise more than a couple of degrees before the fans coming on slowly.

A quick drive after fitting the grill blocks at highway speeds gave a couple more mpg more than I would normally expect to get, driving at 65-70mph, in two directions. I will know more about how well the grill blocks help with mpg in the next week as I drive some more on the highway.

I did some steady speed mpg testing at 40-55mph before the grill block, so I will repeat this to see if I can measure an improvement - at higher highway speeds of 60-75mph the benefit should be more of course.

Hope you find this interesting, be good to know what you think of this.

Tim

tim,
Welcome!!
I didn't notice if you had increased the psi in the tires. Typically 40-44psi will get you a couple of mpgs.

Thanks! Crikey you read quickly.

I tried 45psi in the rear tyres but got excessive centre wear on the tyres, so I'm back down to 40psi - factory unladen pressure. The 45psi was in between the unladen and fully laden pressures which are somewhere about 50psi. I think the Continental Sport Contact 5s I am running don't respond too well to higher pressures due to this experience.

The fronts are at 36psi, the factory figure. I am worried about adverse wear if I go above the unladen factory numbers as happened on the rear. The car has a near 50:50 weight distribution (something like 48F, 52R) so I don't think the front tyres are being punished too much and would benefit a great deal from higher pressures.

I am going to go for the Michelin Pilot Sport 4 tyres next, which have a slightly better EU fuel economy rating than the Continentals, and have won some performance tyre tests for their grip, and should have better wear too. These tyres might gain 1mpg or so on the highway.

Nice to see you enjoy a large gasoline engine too!

👍👍👍👍👍👍👍👍:thumbup::thumbup::thumbup::thumbup::thumb up:

The trick for me was the underbelly pan, grill block and taller tires!

And driving below 65.....����

http://ecomodder.com/forum/attachmen...chmentid=20301

http://ecomodder.com/forum/attachmen...chmentid=20302

http://ecomodder.com/forum/attachmen...chmentid=20303

http://ecomodder.com/forum/showthrea...der-18279.html

Thanks, I've made an album and linked to the pictures in it now, so they appear larger.

I did some testing last week, on my local 2 way test road, I did testing at 40-55mph. Same tyre pressures as last time, and same brand of fuel.

The results show a calculated gain of 0.5mpg in the testing, however, it was gusty today so that may have showed less gains then there would be in better weather conditions.

However, I did a 30 mile run on a familiar road cruising at 65mph, and with the occasional moment at 70-ish mph to overtake quickly. The result was 40mpg UK, 33mpg US, which means I reached my goal on that day. There was wind around though so I'll reserve judgement, however the wind direction was across me, so not a tail or headwind.

So the initial results at high speeds look good, I would expect to get 31-32mpg US normally in those conditions, so it's possible I've gained 1.5-2mpg at highway speeds with the partial grill blocks and achieved my goal of 40mpg UK.

There is less wind noise at the front so I think drag is reduced to some degree.

I will see what happens next time I go on a run to see if the mpg contiues to be a couple higher than normal.

Sweet Ride!!

Cheers Mobilone. I just spent the afternoon applying a rust proofing wax to the inside of the front arches (Waxoyl), hope to keep it sweet for a long time.

Electrohydraulic power steering conversion should get you a few mpg. On ebay.co.uk there's lots of pumps from older cars that will work properly if you just plug it in.

Sounds interesting. Would that require the belt drive being modified or the steering rack or pipework?

330Ci is an M54 engine right?

http://www.propel-auto.com/admin/par..._image_290.JPG

Looks to me like a shorter belt is all you need, that engine doesn't have the PS bolted on.

An electric PS pump I think is not very hard to hook up, not that I have done it before.

Very interesting. I think for now it's beyond the scope of what I have planned for my car. I think I would need an alternator upgrade as it looks like these pumps can draw 15A-50A current, I have worries over the load on the alternator, mine is already the lower powered one for the E46 BMW, and it takes a minute or two for the voltage to come up nicely after a cold start, and also the insurance implications. I would also be worried about steering feel as the Bimmer is a slightly sporty car.

Very good idea though!

Still getting decent economy from the 330 on longer journeys, with a small contribution from the grill blocks hopefully.

I logged the fuel economy on a 25 mile stretch yesterday, cruising at 60mph. The road in question has a series of gentle uphill and downhill sections, and is never particularly flat. I had about 10 jaunts up to 65-70 while overtaking (I hate stretching out overtakes), and spent roughly 5-10% of the time coasting in neutral downhill. For comparison, at 60mph on a flat road, the economy "BMW swingometer" will show roughly early 40s mpg (UK), late 30s mpg (US) (and it is quite accurate I believe).

The result on this 25 mile trip = 44mpg (UK), ~37mpg (US), perhaps 3mpg better than a journey using cruise control all the time. I used cruise on the flat and uphills, and knocked it off on downhills to avoid a light loaded portion of the BSFC map.

The car was nicely waxed which might have given me a tiny amount of economy :thumbup:

Next time on that journey, I am going to try coasting in gear downhill at that speed of 60mph, as the car is only turning about 2000rpm at that speed. I was mulling over how to increase economy after the trip, and the car uses ~0.35 gallons/hr (US) at idle, so this is the equivalent of about 170mpg (US) when coasting in neutral, and while I have power on (using cruise mainly), it will vary from about 20-50mpg.

So I have my mind the span of fuel usage is 20mpg-170mpg(US), with that data above, using neutral gear coasting.

Next time when I try using in gear coasting, the span of fuel economy will be 20mpg to infinite mpg, with the coasting in gear, and the longer coasting time in gear, the better for economy, obviously.

If I am losing too much speed downhill I will give the throttle a quick stab at about 2/3 throttle to efficiently speed up about 5mph using a good BSFC condition for the car.

I guess the deciding factor is whether the use of drivetrain friction to lose speed (with infinite mpg) and then a high burst of power (a bit like a pulse of P&G), to add a bit of speed, when travelling down slight downhill sections, is more efficient overall than coasting downhill in neutral using a bit of fuel, and having a longer coast phase.

The 330 does feel like a low drag engine, it does not decelerate very much on the overrun, has low tension piston rings which help, 5W-30 oil, and a relatively low compression ratio (think it's 10.2:1). I have a suspicion the idle control valve is held open during DFCO to reduce drag, certainly it feels too free spinning to me for a conventional engine with closed air intakes, I will see if I can get my Delphi diagnostic on it to keep an eye on what the idle control valve is doing on overrun, and check if Torque can display the ICV value (don't think so but I'll check again). The ICV does get used at up to 1500rpm when driving under load, I believe, so it would be good to see if BMW utilise it on the overrun too at higher revs.

I have no idea what the outcome will be, but I hope it might surprise me. If I could get late 40s mpg (UK), early 40s mpg (US), while maintaining an average of 60mph, I would be over the the moon.