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As it happens, I have been closely monitoring the fuel consumption of my new (to me) Ford Focus MkII 2 litre petrol.
I started off with 38.4 mpg.
After I pumped the tyres up I got 41.5.
Then I fitted a K & L air filter and had a full service and got 42.2.
These are all brim-to-brim calculations and the driving included quite a lot of motorway at 65 - 70, but some short town journeys. Mostly two people. Total mileage: 1566, enough to give a general idea, anyway.
P.S. The dashboard read-out, which has proved to be pretty accurate, gets to near 44 mpg on a motorway run.
Edited by FocalPoint on 27/06/2011 at 20:01
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I'd love to see a controlled test on the K & N. Actually, there have been a few
Put the stock one back on. It'll make no difference to economy or performance and, unlike the K & N, it'll actually work as a filter.
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I'd love to see a controlled test on the K & N. Actually, there have been a few
Put the stock one back on. It'll make no difference to economy or performance and, unlike the K & N, it'll actually work as a filter.
+1
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You're saying the K & N doesn't do its job?
I might actually be tempted to try your test, but the old filter was filthy and it's been binned. It wouldn't have been a fair test and I'm not buying another just to find out.
I'm happy to accept that the K & N will at least filter the air. It may or may not affect economy. I can't be bothered to find out.
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I have used a K&N once but never again - the state of the MAF due to oil contamination just wasn't acceptable.
I can understand the use of a K&N for a track-day car with huge bhp where rebuilds are frequent - but not on a road car, not for sensible people anyway.
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Well common sense should indicate that the OEMs would exploit any easy gains before going to the considerable trouble of designing 4 valve heads, variable valve timing, reworking the inlet ports etc. Exactly the same rule applies to catback exhaust systems-there's simply no reason for the manufacturer to plug up the exhaust.
Intake systems (upstream of the throttle) are sometimes slightly restrictive but it is geometry of the air box and entry/exit piping that causes the restriction, not the filter. The shape of the airbox is governed by the available space in the engine bay and a bolt on kit will face the same problem.
The other snag about cones on sticks is that they have a nasty habit of acting as hot air intakes, whereas factory plastic snorkles are very good at taking in air from outside the engine bay and insulating it from the hot air in the bay. Factory intakes may look as sexy as syphilis-but they work very well.
In winter, hot air intakes can be quite useful at improving mileage, but in summer the ECU will be unhappy with intake temperatures over ~30-40C and will often pull spark timing.
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Agreed, I can't see there being any appreciable gain to be had in this area - losing the airbox itself may increase turbulence around the filter killing torque. Most Citroëns, for instance, use the same filter across the range. In other worlds the smaller engined cars have a performance filter standard being that the standardised filter "breathes" well enough to keep the larger engined model happy! I suspect most manufacturers rationalise in a similar way these days.
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"I can understand the use of a K&N for a track-day car with huge bhp where rebuilds are frequent..."
"Put the stock one back on. It'll make no difference to ecnomy or performance and, unlike the K & N, it'll actually work as a filter."
RT, for someone who likes to give the impression you know what you're talking about, you seem muddled. You either think it works or it doesn't. Make your mind up.
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I'm afraid they don't. RT's remark about race engines was to highlight that their criteria are different to that of a road car. Crystal clear.
[grammatical howler amended]
Edited by unthrottled on 27/06/2011 at 22:30
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"I can understand the use of a K&N for a track-day car with huge bhp where rebuilds are frequent..."
"Put the stock one back on. It'll make no difference to ecnomy or performance and, unlike the K & N, it'll actually work as a filter."
RT, for someone who likes to give the impression you know what you're talking about, you seem muddled. You either think it works or it doesn't. Make your mind up.
I didn't make both statements but I will answer:-
At very high flow rates, a K&N will flow better than a standard paper filter at the expense of filtration - useful therefore for a highly modified track-day or race engines where the frequent rebuild interval makes the increased wear rate unimportant.
Standard road cars have flow rates constrained by many factors including filter inlet, manifold design, valve timing - in other words the filter itself isn't the limiting factor in flow - so there's no measurable flow increase - power/economy are controlled by the ECU settings these days (unlike the old carburettor days) so there's no improvement in power or economy but engine life will be decreased.
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As it happens, I have been closely monitoring the fuel consumption of my new (to me) Ford Focus MkII 2 litre petrol.
I started off with 38.4 mpg.
After I pumped the tyres up I got 41.5.
Then I fitted a K & L air filter and had a full service and got 42.2.
These are all brim-to-brim calculations and the driving included quite a lot of motorway at 65 - 70, but some short town journeys. Mostly two people. Total mileage: 1566, enough to give a general idea, anyway.
P.S. The dashboard read-out, which has proved to be pretty accurate, gets to near 44 mpg on a motorway run.
That's not bad. What If I told you Iwas getting 39mpg from a 4 speed auto, mazda 6? It would seem as though your's should be a little more based on that
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Nearly 40mpg from a biggish petrol auto is pretty good, I'd be very surprised if you could get much better economy than that from that particular car.
My old Mark 1 1.8 Mondeo used to give around 35mpg cruising at 80-odd on longer motorway trips. Cars were lighter and with fewer encumberances back then.
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Setting aside the potential DPF problems.................... does it still hold true that a diesel excels at slow speed stop start "urban" driving (as against a petrol on the same duty cycle) wheras a pertol excels at constant high speed Motorway work (as opposed to a diesel)
Though again I suspect the super high gearing on modernday diesels probably makes them Motorway efficient
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If diesels were inefficient at stop start driving, taxis wouldn't use them.
Diesels, unlike petrols, retain their efficiency down to low load s so they tend to get much much better mileage in urban driving.
On motorways, you generally run the engine at higher load so the efficiency of the petrol improves more markedly than the diesel, narrowing the efficiency gap. Diesel still comfortably ahead though.
Unless you've got a 5.7 V8 or something, the gearing isn't as critical as people like to think. At motorway speeds, the power required to overcome air resistance dominates-and this rises with the CUBE of speed. Tall tales of diesels getting 50+mpg at a genuine 90mph are implausible.
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I have a similar commute... 115 miles each way, only do it once or twice a week at most. Rest of the time the car is used by my wife to go to work - all city driving.
I am running a 2003 318Ci manual - this has the 2000cc valvetronic engine. 110k miles on the clock.
I drive sensibly and keep a close eye on the analog mpg meter. Downhill I go a lot faster than going uphill. Sometimes, I have a bit of 'fun'.
During the ast 8k miles, I have averaged 36.8mpg - this is brim-to-brim calculations.
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My old Passat PD130 used to give 50-55mpg at a steady, indicated 85 cruise (on the computer, which was about 3% optimistic). This was a real 'sweet spot' for that particular car.
However, at 90 and above, consumption increased quite sharply to low 40s / high 30s
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My old Passat PD130 used to give 50-55mpg at a steady, indicated 85 cruise (on the computer, which was about 3% optimistic). This was a real 'sweet spot' for that particular car.
However, at 90 and above, consumption increased quite sharply to low 40s / high 30s
That's pretty damn impressive! what reg was your PD130?
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HI. on my year 2000 volvo estate 2.litre manual i get 35mpg average over my 51mile round trip to work (the longest distance between roadabouts is 3.5miles!!!)
.just dropped my car off for its 100,000 service and mot, and got a car from the volvo/saab indie to use for the day...a saab 9000csi 2.0 turbo auto....and according to the trip mpg computer i was averaging 31.9 mpg not bad for a 175bhp auto with 192,000 miles....and yes i did play with the kick down wooosh hahahahaha
Paul.
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It was a 2003 / 03 reg, the so-called 'Sport' model with the AVF high-torque engine and 6-speed manual box.
The VAG PD engine is gruff and grumbly (even its most ardent fans would call it a bit uncouth at times), but it certainly delivers the grunt and economy. Also the Passat B5.5 saloon is a very slippery shape.
On one late-evening 360 mile round trip from Cheshire to Heathrow, when the motorways were quiet, the trip computer gave the average speed for the journey as 69mph, and the fuel consumption as 55mpg (around real 51mpg, corrected for the trip computer error).
I can't claim that ALL Passats are that economical, maybe I just had a good 'un. It was an excellent family barge.
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2.0 petrol auto - average over 2.75 years and 35,000 miles =38 mpg (brim-to-brim calcs.)
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2.0 petrol auto - average over 2.75 years and 35,000 miles =38 mpg (brim-to-brim calcs.)
Similar to mine - what car's that with mate?
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I didnt want to start a new thread,
I've heard internet stories about the autobox in mazda 6 being problematic after around 100k miles. All of these were based on the jatco autobox though.
My question - how reliable is the autobox on my model/year of car? is it mazda in-house or jatco?
Any help much appreciated, Thanks
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