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Hi,

 
I have recently found out that manufacturers purposely reduce the efficiency of our cars with inefficient air filters and exhaust systems. Does anyone know if this is true? This will apparently reduce BHP and MPG. How do you go about correcting these 'mistakes' by the manufacturers?

Thank you

Jack
 

Where have you 'found this out' from? Not a seller of aftermarket air filters and exhausts, by any chance? Given the pressure on manufacturers to improve fuel consumption/reduce emissions, don't you think that if they could simply change an air filter here and an exhaust there to gain a few mpg it would have been done long ago?

I know that my 100bhp car uses the same air filter as the 170bhp version, so anyone who thinks they're going to gain anything from changing it is kidding themselves. You might gain a little power from fitting a tuned (4-1/4-2-1) exhaust manifold if the standard item is sub-standard and you can get the ECU re-mapped to suit.

I read an article online the other day, which I cannot seem to find anymore. I drive a 1.9Tdi Golf V and apparently I can make it more efficient by making it 'breath' better. It did not really say how exactly, just mentioned the air filter and exhaust. I am not really into tuning cars usually but if it means I can get more MPG then I would be willing to try it.

Thank you

Jack 

jack the lad:

I read an article online the other day, which I cannot seem to find anymore. I drive a 1.9Tdi Golf V and apparently I can make it more efficient by making it 'breath' better. It did not really say how exactly, just mentioned the air filter and exhaust. I am not really into tuning cars usually but if it means I can get more MPG then I would be willing to try it.

Thank you

Jack 

There is a little bit of truth. If the air filter has better flow (as some oil-impregnated cotton gauze or rubberfoam ones) it can have (marginally) better output and efficiency in naturally aspirated engines by allowing more air in. I doubt that is the case with turbo engines like yours and mine, though, because the turbo will blow as much air into the cylinders as you need, until the pressure limiter kicks in.

This sort of goes hand in hand with the whole Fifth Gear artical on Monday night (11th August).  In it they did some sensible modifications, reduced weight, lower friction tyres and revised ECU in a petrol VW Polo, in which they proved that despite the modifications, the car was no more efficient.

Certainly from personal experience, the only real improvements in fuel economy come from electronically tweeking the engine with a "tuning" chip and that was only really effective in a turbo diesel.

The main risk from a manufacturer's point of view with better breathing filters is that they let too much particulate matter into the engine if not properly maintained. For the manufacturer it is not worth the risk of shortening engine life or damaging the air mass sensor, hence best left to the aftermarket where it is hoped the buyer will follow the revised servicing requirements.

 Likewise for remapped ECU chips they might improve MPG but at the risk of engine damage if fuel is sub-standard.

 Exhaust systems could easily be improved but that would add significantly to the manufacturing costs.

I once owned an early model VW Passat VR6, which clearly had a compromised induction system and upon investigation it transpired that the variable geometry inlet manifold the engineers specified was dropped by the bean counters to hit a target selling price. The manifold was available from the component supplier on the after market for €1,000 in Germany but this increased to £1,000 if imported through a UK agent, so I never got around to buying one.

I inserted a container of Vicks Sinex Nasal Spray in the engine compartment of my Land Rover and got no discernable increase in either power or mpg. I was bloody furious. Took it straight back and got my money back.

giulivo72:

There is a little bit of truth. If the air filter has better flow (as some oil-impregnated cotton gauze or rubberfoam ones) it can have (marginally) better output and efficiency in naturally aspirated engines by allowing more air in. I doubt that is the case with turbo engines like yours and mine, though, because the turbo will blow as much air into the cylinders as you need, until the pressure limiter kicks in.

Turbo cars operate far more efficiently when colder dense air is about, hence water spray systems used in high performance turbo charged engines.

A good quality replacement filter from a reputable company such as K&N will increase the air flow as they do not restrict the flow in the same way an OE filter does. The first thing I did with my 159 was to get the dealer to fit a K&N panel filter. This does not invalidate the warranty and gets cleaned and re-oiled at the service intervals stipulated by Alfa. I have noticed an increase in fuel economy of approx. 1-2 mpg.

I have just fitted a generic chip that has transformed the fuel economy. On a run upto Glasgow and back yesterday I returned an indicated 48.6 mpg with an average speed of 63 mph. This is obviously taken from both Motorway and town driving. Without the chip I could not get the car to do better than 43.4 mpg.

Money well spent I would say.

Which chip did you buy? Does anyone know what the difference between a panel filter and a induction kit is and how this will effect performance.

Thank you. 

James Read:

I inserted a container of Vicks Sinex Nasal Spray in the engine compartment of my Land Rover and got no discernable increase in either power or mpg. I was bloody furious. Took it straight back and got my money back.

Your problem is that over the counter medication just isn't strong enough - a couple of hits of my Seretide Accuhaler in the induction and our Fabia runs like it's got NOS tanks.

Ventolin is good for short term boosts.

There are some advantages to being asthmatic it seems.
 

jack the lad:

Does anyone know what the difference between a panel filter and a induction kit is and how this will effect performance.

Physically...... 

Panel Filter  -  The type usually fitted to a production car.  For descriptions sake, a rectangular element, made from paper that filters the air of particulate matter (although oil impregnated foam elements which are more efficient are available).  Fits into the air inlet box on the vehicle engine.  The air inlet box will potentially have a valve for warm air recirculation for cold starting and running conditions.  Designed to let the engine run in most environments, e.g. opening to the air box will usually be sited high in the engine bay to prevent water induction in wet conditions.  Will have also been designed to be acoustically sympathetic.

Induction Kit  -  Replaces the air in let system and various pieces of ducting with a free-er flowing larger bore air inlet and filter.  The filter may take several forms but for descriptions sake is a cone element with a oil impregnated foam insert which will be sited in an area of free flowing cold air (away from the engine, and where possible, placed in the front bumper of the car).  More sophisticated tuning induction systems will have some sort of cold start valving.  Designed primarily to make the engine run more efficiently, but in an optimal environment.  Will also be an increase in induction noise.

Practically....

For descriptions sake again, if a standard panel filter runs at 50% efficiency then a free flowing after market panel filter may run at 60% efficiency and an after market induction kit 70%.  Of course there are many after market induction kits that make the vehicle run worse, the only real benefit (?!?!) being an increase in induction noise.  

How it will affect performance is dependent on the vehicle.  In general in most conditions it should improve the performance, but by what percentage will depend on the car. 

This is a very simplified description, but I hope it explains your question.

jack the lad:

Which chip did you buy? Does anyone know what the difference between a panel filter and a induction kit is and how this will effect performance.

The chip I have bought is from DTUK, speak to Andrew and quote Autocar. I paid approx. £220 delivered. Fitted it myself in approx. 10 minutes. It has 16 positions on it and it comes preset at 7, after a bit of playing about I have increased it a couple of turns.

Pick up in all gears is dramatically improved, runs a little smoother and returns a better mpg.

 There are plenty of companies around offering similar products, however I picked this one as it comes with a 3 year warranty and is TUV approved at the right price. Generic chips like this one do not give you the sort of gains that a remapped ecu chip would give you as they are written to a set of parameters, these will be carefully monitored as they can be bought by any Tom, *** or Harry to work on any car with differing engine tolerances thereby giving different results in performance gains, hence the various settings available.

Panel filters and induction kits, read Tegs post.