Aerodynamics.............

[Deelerock]

How aerodynamic aren't these things. Driving from canberra to sydney today. Sat on 115-120 kmh. Worse fuel efficiency than poking around town. Wind resistance? Anyone else have the same issue? Wife was in the car too but she is skinny.

[n plus one]

IME every 10km/h over 100km/h costs around a litre per hundred.

When I travel with a mate with a dual cab Hilux he gets better open road economy than me, but a soon as we hit the dirt I get better - the Deefer's push a lot of air...

[Deelerock]

Yep. You are about right. 120 kmh say for 300 km. that's six litres. I drove 570km till the lights came on. Usually comes on at 620km in the 130. That's 50km shy of usual

After the bas remap in the old 110 puma the efficiency in that thing was good. 650 to the tank before the lights came on. Highways were similar too. The torque gain must negate or overcome the aerodynamics to a certain degree. Also the useable rev range widens giving reducing need to change gears.

I might book a remap in next week.

[vnx205]

I'm not surprised.

Let's suppose that your around town running includes mostly freeways and you can sit on 65km/h most of the time.

How much more power do you think it takes to push something through the air at 120km/h compared with 65?

Twice as much? Two and a half times as much?

I think the answer is about three and a half times as much. Even if we allow for the stop start driving in town, the power needed to push through the air at 120 is a heck of a lot more, so naturally you will use quite a bit more fuel.

I haven't tried driving at 120 to see how bad my fuel consumption would be, but I have observed the opposite effect. Whenever I go to Tasmania, I get better fuel consumption even with the camper on than I do on long trips around here. The roads, the distances and the scenery mean that I drive slightly slower and the fuel consumption improves.

[PAT303]

Driving south from the Alice and east from Kalgoorlie I always seemed to hit headwinds,it's not unusual for me to get less than 500 from a tank,600+ in town. Pat

[vnx205]

The mention of headwinds has reminded me of the worst fuel consumption I have had on the open road.

Driving west from Dubbo with the camper on, I encountered hundreds of kilometres of headwinds that I suspect were over 50km/h. Even when I slowed down about 15km/h slower than I would normally drive, I used 2 or 3 litres/100km more than usual.

With that headwind, I calculate that I was trying to push the Defender through the air at about 130km/h.

[Deelerock]

All said and done. Would not trade it for anything else. If we wanted aerodynamic we would have bought something else I guess. These buggers are made to plot along... Smell the roses (or dust).

That said. She is good for building work. Site to site. Pick ups and drop offs. Way better fuel consumption than my mates 78 cruiser.

[Blknight.aus]

Remember the important stuff.

Aerodynamics don't count in low range.

[JDNSW]

There are two major aerodynamic problems with the Defender - the first is the large cross section area compared to most light vehicles, but the second is the high ground clearance (and rough underbody including wide wheel arches to accommodate long travel suspension) mean that a large part of the aerodynamic drag is from turbulence under the vehicle. There is little that can be done about either of these and retain the offroad ability and interior space.

A future Defender replacement is likely to get some improvement by reducing the 'waste' cross section area represented by the chassis, but at the expense of flat floors.

The square rear of the wagon/hardtop is almost certainly a lot more aerodynamic than you think, as the sharp corners allow the airflow to break cleanly from the sides and roof. The front is more problematic, and drag would almost certainly be improved by a row of vortex generators across the front edge of the bonnet and mudguards - this would also help reduce the number of insects on the windscreen.

Aerodynamic drag is proportional to the square of the speed, which, when you think about it, represents an increase in energy consumption per kilometre to overcome aerodynamic drag in direct proportion to the speed. Other energy losses, primarily rolling resistance of tyres and frictional losses within the engine and drive train are generally independent of speed or may actually decrease with speed, for example, centrifugal force will decrease rolling resistance of tyres as speed increases, but these effects are usually small. For most practical vehicles, aerodynamic drag reaches 50% of total drag at around 60kph, so that speed reductions below this give little advantage in fuel economy.

Variations in engine efficiency with rpm and throttle opening also come into it, and as a general rule you can say an engine is most efficient at the maximum torque rpm. The variation in efficiency is quite small for diesels, but can be very large for petrol engines, especially carburettor engines - this means, for example, that my Citroen, with exceptional aerodynamics, has its most economical speed at 110kph.

All these losses discussed above are in addition to the energy actually needed to move the vehicle over the road, and this depends mainly on the road surface and how it is driven - every time you apply brakes you waste energy, so the most economical driving technique is to drive as if you knew the brakes did not work - anticipate the need to slow and take your foot off so you rarely have to touch the brake pedal. Similarly, slow on crests of hills so you don't have to use brakes on the down slope to stay within the speed limit etc.

And if you drive too slowly, remember there are parasitic loads on the engine, such as the airconditioning and alternator, that depend mainly on how long the engine is running, so that on a per kilometre basis these increase as you travel slower.

As a last comment - some Series Landrovers were fitted optionally with an economy device consisting of a strong spring that came into effect on the accelerator pedal at about half throttle, so that unless a determined effort was made, you never got more than half throttle. I have never owned one of these, but they were said to be quite effective!

John

[Dougal]

The drag coefficient of a disco 3 is apparently 0.41 (source: New Car Review: 2005 Land Rover LR3 (http://www.theautochannel.com/news/2004/09/23/233791.html) ) which is very good for a 4wd.

Yes it's still punching a big hole through the air, but it's going to have only 2/3 of the wind resistance of a defender (Cd ~0.6) which has similar projected area.

Power to beat wind resistance cubes. But fuel consumption only squares as the higher speed gets you there faster.

[Drover]

To coin an old expression "Slippery as a brick" :eek:

[Beery]

And yet despite all this and the fact that they running a constant 4wd system they are still no worse, if not marginally better than most jap 4wds for fuel economy.
Says something for European diesel technology

[landy]

I've got an app on my phone that I use to track fuel/servicing trends and costs. I have noticed that I get the best economy if I stay around 90kmh. I'll averidge 11.3 L/100 km. Bear in mind I have a bit of a weight problem as the cars 2.4 tonne. So all up pretty happy.
If I tow the camper though, I'm at the mercy of the gods! It shoots up to 13.9 L/100km

Cheers

[Deelerock]

I've got an app on my phone that I use to track fuel/servicing trends and costs. I have noticed that I get the best economy if I stay around 90kmh. I'll averidge 11.3 L/100 km. Bear in mind I have a bit of a weight problem as the cars 2.4 tonne. So all up pretty happy.
If I tow the camper though, I'm at the mercy of the gods! It shoots up to 13.9 L/100km

Cheers


What engine is it?

the towing kills me too. fuel consumption is much better than the jap varieties, but its not apples for apples when you compare it to the larger capacity toyota engines (i much rather prefer LR choice in diesel motors). That said, no where near as good as my mates amarok around town and on the tow.

That said, I noticed towing with the 110 post remap was better.

The aerodynamics is not great, but I think even worse with a 130 and canopy.......

[PhilipA]

The square rear of the wagon/hardtop is almost certainly a lot more aerodynamic
than you think, as the sharp corners allow the airflow to break cleanly from the
sides and roof. The front is more problematic, and drag would almost certainly
be improved by a row of vortex generators across the front edge of the bonnet
and mudguards - this would also help reduce the number of insects on the
windscreen.

These blokes are on the wrong track then.
Airtab: Aerodynamic fuel savers for truck, tractor, trailer, bus, RV (http://www.airtab.com/how.html)
I have tried them on an RRC but didn't seem to make any difference + or-, but I was towing my camper trailer.

Regards Philip A

[Dougal]

These blokes are on the wrong track then.
Airtab: Aerodynamic fuel savers for truck, tractor, trailer, bus, RV (http://www.airtab.com/how.html)
I have tried them on an RRC but didn't seem to make any difference + or-, but I was towing my camper trailer.

Regards Philip A

Yeah sharp corners only work on boats that plane on water. On vehicles they make for big suction behind the vehicle that makes the Cd worse.

If blunt rear ends were awesome then planes would have blunt rear ends. But they don't, they taper to minimum.

[goingbush]

Yeah sharp corners only work on boats that plane on water. On vehicles they make for big suction behind the vehicle that makes the Cd worse.

If blunt rear ends were awesome then planes would have blunt rear ends. But they don't, they taper to minimum.

When I used to make R/C 3D Funfly aircraft I used to leave the trailing edges of control surfaces squared off , this in effect , aerodynamically speaking made the surfaces appear to have about 1/3 more chord , and made the model much more manoeuvrable , but at the expense of drag, and flutter at high speed, But 3D models are generally only flown at low speed.

Strangely my Iveco , which admittedly is more aerodynamic than a Defender but a lot higher, returns the same fuel consumption no matter if I going 85kmh or 110kmh ??

[Ancient Mariner]

I don't know what this does for drag but it does seem to keep the rear window cleaner:D

[JDNSW]

These blokes are on the wrong track then.
Airtab: Aerodynamic fuel savers for truck, tractor, trailer, bus, RV (http://www.airtab.com/how.html)
I have tried them on an RRC but didn't seem to make any difference + or-, but I was towing my camper trailer.

Regards Philip A

No, they are on the right track - but the square corners are better than rounded corners typically seen on most cars. To give an example, the Citrroen DS, which has an exceptionally low drag coefficient, looks rounded at the back - but this is deceptive. The back ends aerodynamically in a sharp step that breaks airflow away, extending round the sides and top of the rear window, and a similar step across below the bumper, terminating underbody, which smooths airflow by having the underbody gap smallest between the front wheels and increasing smoothly back from there. Adding these vortex generators would improve airflow, but don't expect a big difference, as much of the drag is from turbulent airflow under the vehicle and from the sheer size of the frontal area.

John

[PAT303]

John,I fitted a webber ''economy'' carby to one of my 2.25's,it got economy by cutting the power by half. Pat

[dromader driver]

My 110 trayback is most fuel efficient sitting around 95 km/hour. over 110 is a definite no no.

[JDNSW]

John,I fitted a webber ''economy'' carby to one of my 2.25's,it got economy by cutting the power by half. Pat

Yes, that is one way of improving economy. But let's face it, Series Landrovers, or the petrol ones anyway, were not designed with economy in mind. The engine is low compression and designed for durability and driveability with fuel economy way down the list of design factors, not only for the Series vehicles but also for the Defenders, although diesels are markedly better.

John

[Don 130]

Anyone remember this tip?
http://www.aulro.com/afvb/technical-chatter/155266-wheel-bonnet-aerodynamic-improvement.html
Don.

[JDNSW]

My 110 trayback is most fuel efficient sitting around 95 km/hour. over 110 is a definite no no.

Traybacks are less aerodynamic than wagons or hardtops due to the shorter cab. Also, you will probably find that leaving the tailgate off or open and lying flat will make a marked difference. The foot high tailgate on my tandem trailer feels like the brakes are on once you get over about 80!

John

[Dougal]

Traybacks are less aerodynamic than wagons or hardtops due to the shorter cab. Also, you will probably find that leaving the tailgate off or open and lying flat will make a marked difference. The foot high tailgate on my tandem trailer feels like the brakes are on once you get over about 80!

John

The best result for a tray back is a cover or canopy. It's been proven on wellside decks that removing the tail-gate doesn't help. Instead it creates more recirculation behind the cab which increases drag. On shallower and longer decks however the results would need checked.

[AndyG]

Anyone remember this tip?
http://www.aulro.com/afvb/technical-chatter/155266-wheel-bonnet-aerodynamic-improvement.html
Don.

Thanks, reinforces my objective to have a 110 tourer with no roof rack or trailer, however an awning would be very nice, maybe standalone.

[vnx205]

It's been proven on wellside decks that removing the tail-gate doesn't help.
If you are thinking of the Mythbusters' test, they certainly concluded that the aerodynamics were better with the tailgate in place. They concluded that the utes were designed so that there was some sort of vortex created behind the cab that needed the tailgate to work properly.

I'm not sure that you would get the same result with a cab shaped like the Defender.

I do remember that towing a very light empty box trailer behind my Series III slowed it down a lot more than having that same trailer full of bricks. There was also a lot of drag behind my car when the trailer was empty.

[AndyG]

Has anyone tried a bonnet mounted wind deflector ?

[Pickles2]

The Defender is the first vehicle that we have owned where on occasions we get better economy in the city than we do on a trip.
Cruising at 100kph, I thought I'd be well in front of my "city" figures, but I wasn't.
Couldn't work it out until someone mentioned the "effort" that it takes to push a Defender through the air at that speed?
Pickles.

[Graeme]

Not just Defenders - my 3.0 D4 gets significantly better economy around town than getting to and from town at 100 kph, not that Wagga is anything like Sydney or Melbourne.

[JDNSW]

The Defender is the first vehicle that we have owned where on occasions we get better economy in the city than we do on a trip.
Cruising at 100kph, I thought I'd be well in front of my "city" figures, but I wasn't.
Couldn't work it out until someone mentioned the "effort" that it takes to push a Defender through the air at that speed?
Pickles.

Your first diesel? Petrol engines vary more in efficiency than do diesels, and are less efficient in stop/start driving than in continuous operation, where diesels are pretty much the same efficiency.

John

[DiscoMick]

I was looking at the LR bulbar on the front of a Defender at the weekend. It has sloping fronts on the two uprights either side of the grille. I was thinking a mesh screen might keep a lot of bugs out of the grille. I wonder if such a screen, sloping backwards at the top, might also deflect a lot of air over the front edge of the bonnet and improve the aerodynamics? Just a thought...

[JDNSW]

I was looking at the LR bulbar on the front of a Defender at the weekend. It has sloping fronts on the two uprights either side of the grille. I was thinking a mesh screen might keep a lot of bugs out of the grille. I wonder if such a screen, sloping backwards at the top, might also deflect a lot of air over the front edge of the bonnet and improve the aerodynamics? Just a thought...

Might do (the aerodynamics - certainly catch the bugs), but I suspect it will not go high enough. The problem is the smoothly rounded front edge of the bonnet and guards tends to keep the airflow following the top surface due to the Coanda effect - and then the airflow hits the near vertical windscreen and is deflected straight up. What is needed is either a row of turbulence generators along the top edge to break the airflow away, or a deflector fixed to the top of the bullbar that extends above the bonnet - often seen on trucks, but of doubtful legality.

One possibility occurs to me - the Citroen DS wagon I used to own had a fixed roof rack as standard. This had the front bar of the roof rack sleeved with a plastic tub that had spiral ridges on it, so that it acted as a turbulence generator. I wonder what the effect of wrapping the top bar of the bullbar with something similar would be? Perhaps a length of 10mm laid rope wound with spiral about 25mm between turns and maybe back to other way to give a diamond pattern. It could be temporarily taped in place, and if successful, held with a hose clamp at each end.

John

[Pickles2]

Your first diesel? Petrol engines vary more in efficiency than do diesels, and are less efficient in stop/start driving than in continuous operation, where diesels are pretty much the same efficiency.

John
Yes, our first diesel.
Thanks for that, Pickles.

[Tombie]

I was looking at the LR bulbar on the front of a Defender at the weekend. It has sloping fronts on the two uprights either side of the grille. I was thinking a mesh screen might keep a lot of bugs out of the grille. I wonder if such a screen, sloping backwards at the top, might also deflect a lot of air over the front edge of the bonnet and improve the aerodynamics? Just a thought...

And what else do you think it would do? ;)

Like raise the load on your cooling system :angel:

[DiscoMick]

And what else do you think it would do? ;)

Like raise the load on your cooling system :angel:



I did wonder about that, but would an angled bug screen really make much difference? The electric fans on my Disco come on whenever the air con is on anyway.

[pibby]

Variations in engine efficiency with rpm and throttle opening also come into it, and as a general rule you can say an engine is most efficient at the maximum torque rpm. The variation in efficiency is quite small for diesels,


hi john - i've seen you make this comment a few times before so thought i'd ask. i've got a skoda yeti with the 2.0 vw diesel & dsg. i've been driving around with the instantaneous fuel consumption showing on the dash. the 'simple' rule seems to be the lower the revs for a set speed the lower the fuel consumption.

the specs have the peak torque from approx 1700 rpm upto whatever. the car always drops into the lowest gear it can and will often be on 1100 to 1200 rpm. if i use cruise control to drive at various speed points there is never a reduction of the instantaneous fuel usage when in its peak torque range.

as a further test, if i use cruise control and drive at a set speed at 1800rpm in a gear then manually change up a gear the rpm drops well outside of the peak torque range yet the instantaneous fuel usage always drops.

it seems like there is a host a variables which are working here but the primary factor is the engine rpm?

[Dougal]

hi john - i've seen you make this comment a few times before so thought i'd ask. i've got a skoda yeti with the 2.0 vw diesel & dsg. i've been driving around with the instantaneous fuel consumption showing on the dash. the 'simple' rule seems to be the lower the revs for a set speed the lower the fuel consumption.

the specs have the peak torque from approx 1700 rpm upto whatever. the car always drops into the lowest gear it can and will often be on 1100 to 1200 rpm. if i use cruise control to drive at various speed points there is never a reduction of the instantaneous fuel usage when in its peak torque range.

as a further test, if i use cruise control and drive at a set speed at 1800rpm in a gear then manually change up a gear the rpm drops well outside of the peak torque range yet the instantaneous fuel usage always drops.

it seems like there is a host a variables which are working here but the primary factor is the engine rpm?

There are two concepts at work here. One is efficiency and the other economy.
They are often misused/interchanged, but they are quite different things.

Efficiency is how good the engine is at turning fuel into power. Economy is how good the vehicle is at turning litres of fuel (or $ spent) into distance travelled.

John is correct that the best overall efficiency point for a diesel engine is at rpm around max torque and high load (about 90%).
But this is only the most economical operating point if you require the maximum power the engine can produce at that point.

If you require less power then the best efficiency points (for the lower power) are found at lower rpm. Hence your gearbox changing up to lower rpm. The Engineers who programmed the box knew where to find the best economy.

I have a 6sp manual tdi scout and have the same thing. ~1200rpm is the lowest usable rpm resulting in the best economy if you can run smoothly at that speed.

[JDNSW]

hi john - i've seen you make this comment a few times before so thought i'd ask. i've got a skoda yeti with the 2.0 vw diesel & dsg. i've been driving around with the instantaneous fuel consumption showing on the dash. the 'simple' rule seems to be the lower the revs for a set speed the lower the fuel consumption.

the specs have the peak torque from approx 1700 rpm upto whatever. the car always drops into the lowest gear it can and will often be on 1100 to 1200 rpm. if i use cruise control to drive at various speed points there is never a reduction of the instantaneous fuel usage when in its peak torque range.

as a further test, if i use cruise control and drive at a set speed at 1800rpm in a gear then manually change up a gear the rpm drops well outside of the peak torque range yet the instantaneous fuel usage always drops.

it seems like there is a host a variables which are working here but the primary factor is the engine rpm?

My remark primarily referred to petrol engines and is simply a rule of thumb anyway - as is peak torque; usually the shape of the torque curve is more important than the actual peak torque rpm.

The variation in efficiency for diesels (and in fact for some of the latest petrol engines) is quite small, although it should be noted that the equivalence of maximum efficiency and maximum torque really only applies at full throttle. But you are right, there are a host of variables. Just a few - combustion efficiency, which is the one that varies little for diesels, thermal efficiency, that is, what proportion of combustion heat goes into the cooling system and exhaust (turbocharger recovers some of this), pumping losses - this is where petrol engines lose when throttled compared to diesels, aerodynamic losses within the engine - proportional to rpm or more likely the square of the rpm, fortunately pretty small for most engines, frictional losses, usually pretty small, parasitic losses (alternator, aircon, fan, oil pump, power steering, water pump, all pretty much proportional to rpm, but can represent a large proportion of power use at cruising speeds).

There are two confusing factors affecting your observation that peak efficiency is dependent on engine rpm - the first is that for most cars normal driving is at very small throttle openings, using perhaps 10% of available power, so that actual engine efficiency variations are swamped by other losses, particularly parasitic losses. The second is that your observations include variations in gearbox efficiency - which will usually be less as you change up.

John

[Tombie]

I did wonder about that, but would an angled bug screen really make much difference? The electric fans on my Disco come on whenever the air con is on anyway.

Yes it does.

Stick a good gauge behind there and watch how much harder the cooling system is working to shed the thermal load.

Dougal or similar will no doubt have the engineering data, but a perforated mesh in front of an air flow is incredibly restrictive.

Hence why I smile when seeing 4wds with shade cloth over the front on boiling hot days to keep the bugs out the radiator.
Those poor vehicles are running much warmer - just the normalised gauges dont indicate the extra stress.

[Ancient Mariner]

Just to be different The top 150mm to top of intercooler shrouded as am after some more heat:D

[JDNSW]

Yes it does.

Stick a good gauge behind there and watch how much harder the cooling system is working to shed the thermal load.

Dougal or similar will no doubt have the engineering data, but a perforated mesh in front of an air flow is incredibly restrictive.

Hence why I smile when seeing 4wds with shade cloth over the front on boiling hot days to keep the bugs out the radiator.
Those poor vehicles are running much warmer - just the normalised gauges dont indicate the extra stress.

Yes, they run hotter, but not as hot as the ones without any radiator protection do with the radiator core stuffed with insects and grass seeds. A chaff guard is absolutely necessary for any vehicle used actually off road (i.e. in paddocks) in this country. And also essential during swarms of the Australian plague locust.

But that said, shade cloth is not suitable, as it stops too much air. Insect mesh is OK, but probably needs backing - the Series 1-2a grille makes a good support for it, and my 110 has insect mesh backed by chicken wire behind the grille.

John

[Tombie]

Agree John..
However you aren't doing 100km/h tugging a caravan through spinifex!
Lugging along the fans are pulling the air from behind the mesh enough.

[lebanon]

A good info on the subject

Improving Aerodynamics to Boost Fuel Economy (http://www.edmunds.com/fuel-economy/improving-aerodynamics-to-boost-fuel-economy.html)

[Rurover]

I don't know what this does for drag but it does seem to keep the rear window cleaner:D

Mariner,

Well, you've got me...I presume it's a vent for encouraging "flow through" cabin ventilation. But does it also suck in dust on dirt roads (and maybe exhaust fumes??)

If it doesn't do the sucking bit but DOES keep the rear window clean, I'm keen to learn more.

Alan

[JDNSW]

Mariner,

Well, you've got me...I presume it's a vent for encouraging "flow through" cabin ventilation. But does it also suck in dust on dirt roads (and maybe exhaust fumes??)

If it doesn't do the sucking bit but DOES keep the rear window clean, I'm keen to learn more.

Alan

I would be pretty certain it is to improve flow through of air. It should not let dust in provided vents or heater are open at all times. I doubt it woould do much for aerodynamics, although it may act as a vortex generator for the airflow over the roof.

To keep the rear window clear, twenty or thirty years ago deflectors to direct a portion of the airflow from the roof down the back of wagons used to be common as after market add-ons, and were actually designed into a few wagons. They seem to have disappeared in recent years, possibly because they do not help aerodynamics, but also because wagons no longer seem to have flat rear glass. Another reason may be that rear wiper/washers are now common, and fewer buyers regularly use dirt roads where dust rather than road grime is the problem.

I can't remember seeing one on a Landrover, but I can't imagine it improving aerodynamics (or making them much worse either).

John

[Ancient Mariner]

Mariner,

Well, you've got me...I presume it's a vent for encouraging "flow through" cabin ventilation. But does it also suck in dust on dirt roads (and maybe exhaust fumes??)

If it doesn't do the sucking bit but DOES keep the rear window clean, I'm keen to learn more.

Alan
Sorry no connection inside to out of cabin .If you type in (aircon abit different ) in the bottom search box some info and pics if interested

AM

[JDNSW]

Agree John..
However you aren't doing 100km/h tugging a caravan through spinifex!
Lugging along the fans are pulling the air from behind the mesh enough.

No, but you may well be doing so afterwards - and spinifex is not the major problem. Most native grasses have seeds that are effective in blocking radiators, as do some exotics. Ideally, of course, you would remove the screen for on-road driving - but that is only slightly more likely to happen than cleaning the radiator after driving offroad.

And would help with the other major problem, fortunately sporadic, the Australian plague locust. Swarms of these can block the radiator in less than a kilometre, and once dried are very difficult to remove. The screen some distance in front of the radiator blocks just as rapidly, but at least it is visible, and some air gets to the radiator, without locusts, around the edges, especially if it is on the bullbar.

John

[Tombie]

Locusts.. Great aren't they!
Driven in a few plagues now...
Air intake was a larger issue interestingly.
Just hosed the buggers out of grill but the airbox was almost full...

[ezyrama]

The Tardis is as aerodynamic as a core filled besser block, has a turning circle that encompasses 3 post codes, A driving position that makes you lean on the centre cubby box and bugger all legroom in the back seat, BUT, it's the only car I have ever owned that puts a smile on my face every time I jump into it!!
Wouldn't swap it for anything.
Cheers Ian

[Dougal]

Locusts.. Great aren't they!
Driven in a few plagues now...
Air intake was a larger issue interestingly.
Just hosed the buggers out of grill but the airbox was almost full...
I'm told they taste quite good fried. But I have no desire to try.

[zak]

The 115km - 120km is where you went wrong. sit back at 100km and chill. Your deefer was probably revving at 2.3k haha bye bye fuel economy. not to mention im guessing your not running highway tyres.