Td5 air intake

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shotgun0589

shotgun0589

New Member
Posts
151
I've got one of these air scoops fitted to my Td5....

BcbJbjwmkKGrHqQH-EYEquVLEsYUBK0fSHQh_12_zpse3504e62.jpg


Since fitting the engine noise seems to have increased and mpg is slightly lower than before.
Is forced/cold air better for the engine?
At the moment it's pretty bloody cold, so is that a factor? I've been told that cold air is better for an engine as it is denser and adds oxygen, but is it?
I've had a mild tune up to about 160bhp (done before fitting the scoop) so will that need to be re-done?
I was going to fit a snorkel as I think some of these have scoops at the top too?
Any ideas?
 
shotgun0589 said:
I've got one of these air scoops fitted to my Td5....

BcbJbjwmkKGrHqQH-EYEquVLEsYUBK0fSHQh_12_zpse3504e62.jpg


Since fitting the engine noise seems to have increased and mpg is slightly lower than before.
Is forced/cold air better for the engine?
At the moment it's pretty bloody cold, so is that a factor? I've been told that cold air is better for an engine as it is denser and adds oxygen, but is it?
I've had a mild tune up to about 160bhp (done before fitting the scoop) so will that need to be re-done?
I was going to fit a snorkel as I think some of these have scoops at the top too?
Any ideas?
Click to expand...

It does look a bit daft. Also isn't cold air thinner :s I'm pretty sure it is.
 
Thanks for the advice, I've changed it back to the standard one now, I'll see if it makes any difference ... other than not looking ****!
Cheers for the advice folks.
 
Cold air = more power (more oxygen per unit mass of air allowing more fuel to be burnt per revolution possibly explaining your economy decrease in the cold weather with ducted cold air)
Warm air = better economy (for the inverse reason of above)

Lots of older vehicles used to have jackets around the exhaust manifold to duct warm air into the inlet (I know this also helped carb icing on carb cars but some single point injection
Stuff had it to)
 
jpfour said:
Cold air = more power (more oxygen per unit mass of air allowing more fuel to be burnt per revolution possibly explaining your economy decrease in the cold weather with ducted cold air)
Warm air = better economy (for the inverse reason of above)
Click to expand...

Wrong way round I'm afraid.

The ratio of O2 to the other components of air is unaffected by the air temperature. Cold air is more dense so by default a given volume of cold air will contain more O2 than warm air.

The fuel injected into the cylinder is metered by the injection pump or the ECU and therefore no more fuel is burnt when cold dense air is inducted. However the burn will be more efficient leading to more power per given volume of fuel with cold air which also has the effect of increasing mpg as lower throttle settings are needed to maintain engine output. Its why we fit intercoolers to cool the inducted air which has been heated by the turbocharger. Otherwise we would have to heat the air to get any gains according to your formula.

Warm air leads to reduced combustion efficiency because there is less O2 per given volume and therefore less mpg as bigger throttle settings are required to maintain engine output. Any sort of combustion engine working in hot countries never performs as well as when working in colder climes. Have you never noticed that your engine runs much better and is more responsive when the weather is cold? The effect is even more pronounced in petrol engines.
 
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