Benefit of a Free-Flow Air Filter + Supercharger?
Discussion
IIRC, fitting better flowing air filers to normally aspirated engines allow more air to be sucked into an engine, therefore increasing performance.
However, if the engine is Supercharged then the compressor is working even at idle speeds, so air is constantly pressurised before being stuffed into the cylinders.
Seeing as the supercharger compressor is already shoving more air than is ambiently available, changing the resistance of it's INTAKE side is not an issue, as it will always OUTPUT 'boosted' air.
However, how come air filter manufacturers and tuners claim bhp increases for free-flow air filters with Supercharged engines?
All I can think is that it enables the Supercharger to run more efficiently, therefore reducing the bhp required to spin itself.
Someone care to explain the real reason?
However, if the engine is Supercharged then the compressor is working even at idle speeds, so air is constantly pressurised before being stuffed into the cylinders.
Seeing as the supercharger compressor is already shoving more air than is ambiently available, changing the resistance of it's INTAKE side is not an issue, as it will always OUTPUT 'boosted' air.
However, how come air filter manufacturers and tuners claim bhp increases for free-flow air filters with Supercharged engines?
All I can think is that it enables the Supercharger to run more efficiently, therefore reducing the bhp required to spin itself.
Someone care to explain the real reason?
Get a drinking straw and try sucking/blowing through that - then try the same through a one inch pipe.
It takes work to get air through a narrow pipe - which can be more gainfully employed elsewhere.
So a free-er filter and head work are always worthwhile 'cos you get 'free' energy from them
It takes work to get air through a narrow pipe - which can be more gainfully employed elsewhere.
So a free-er filter and head work are always worthwhile 'cos you get 'free' energy from them
planetdave said:
Get a drinking straw and try sucking/blowing through that - then try the same through a one inch pipe.
It takes work to get air through a narrow pipe - which can be more gainfully employed elsewhere.
So a free-er filter and head work are always worthwhile 'cos you get 'free' energy from them
Dave, Whenever you post i can't get out of my head the image of
'Dave Angel, Eco Warrior' from the fast show!!!
'Shirely, don'd do that love!'
planetdave said:So are you saying that the energy required by the supercharger to operate is reduced (as the 'straw' is wider).
Get a drinking straw and try sucking/blowing through that - then try the same through a one inch pipe.
It takes work to get air through a narrow pipe - which can be more gainfully employed elsewhere.
So the engine doesn't produce more power, it's just the Superchrger draws less energy, and thus this 'saved' energy (by way of a more efficient Supercharger) is delivered to the flywheel?
The supercharger will actually use slightly less power with a restricted inlet (if you block the suction hose of a hoover with your hand, the motor speeds up as it's having to work less hard)... but the fact that you are restricting the flow means that less charge is getting into the engine, so the engine produces less power, and the drop in output of the engine is generally more than the drop in consumption of the supercharger.
Think of this one: when you supercharge a carburetted engine it's generally best for a variety of reasons to put the carb before the supercharger, so the supercharger is sucking through the carb. You control the engine's power output by means of the throttle butterfly, which is part of the carb, restricting the intake side of the supercharger, just like a restrictive air filter would.
Think of this one: when you supercharge a carburetted engine it's generally best for a variety of reasons to put the carb before the supercharger, so the supercharger is sucking through the carb. You control the engine's power output by means of the throttle butterfly, which is part of the carb, restricting the intake side of the supercharger, just like a restrictive air filter would.
The part load behaviour is not really relevant if you're looking for gains in peak power. Whatever turbo/supercharger system you use, increasing the pressure (and hence density) at the supercharger intake enables it to produce a denser charge at the outlet. This means that you want to avoid having any significant restriction upstream of the supercharger at full throttle. For a normally aspirated engine, any restriction here comes straight off the bottom line as you can never recover the lost pressure. For supercharged engines there are other ways of increasing the charge density, but you still can't beat having a system which inherently breaths well.
Some form of heatshield/CAI would be better.
See this for some airflow/filtration testing
www.bobistheoilguy.com/airfilter/airtest1.htm
>> Edited by edc on Wednesday 9th June 17:26
See this for some airflow/filtration testing
www.bobistheoilguy.com/airfilter/airtest1.htm
>> Edited by edc on Wednesday 9th June 17:26
Thanks Chaps. Just ordered the full induction kit with cone online.
Retail price in UK is circa £225.
Retail price in US is $335
jaguarxp.com doing a special offer at $149 which includes shipping to the UK.
That's well under half price of the UK equivilent - at around £83 - for (apparently) 12 more bhp at the rear wheels. That's just £7 per bhp
I do love the exchange rate at the moment
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