A n00b question about Diesel engines.

[C64]

Is it true that diesel engines already have maximum airflow, so fitting something like a K&N air filter or desrestricting the air box will have no effect on the performance?

[Pupo]

No, not true. But you can not expect something from just putting a filter. Should be set and other engine parameters to the new volume of air...

[C64]

Why do K&N etc say all you need to do is replace the air filter for a boost in BHP?

[oldford]

They want to sell lots of filters.
The effect of these filters is grossly overrated.
Besides on a diesel more air does not generate more horsepower. More diesel does generate more horsepower.
The amount of diesel is calculated from how far the throttle pedal is pressed and something called the smoke limit, not how much air is going into the engine.

[stonedagain]

The oil used on aftermarket filters can cause problems with the airflow meter, a film of oil becomes deposited on the heated plates in it & can cause a loss of performance.

[MilesNorton]

i've got 2 years a diesel engine in my car and i hadn't to replace such a air filter or give it some liqiud...it's fine as it's

[C64]

They want to sell lots of filters.
The effect of these filters is grossly overrated.
Besides on a diesel more air does not generate more horsepower. More diesel does generate more horsepower.
The amount of diesel is calculated from how far the throttle pedal is pressed and something called the smoke limit, not how much air is going into the engine.

So it's true then.

Diesels do have 'Wide Open Throttle', so these specialist air filters are nonsense, as they can't possibly offer any more oxygen anyway?

[z786]

plus not to mention, one of the reasons ppl put these filters on their car is 2 make it sound more beefed up, doubt you'l hear any of that from a diesel engine

[bampotman]

The oil used on aftermarket filters can cause problems with the airflow meter, a film of oil becomes deposited on the heated plates in it & can cause a loss of performance.

This is a common problem with the K&N filters but other brands don't have so much oil.

I had a non k&n on my diesel and never had any problems. I had remapped my ecu from 130 bhp to 170 bhp so the filter did help but if you haven't done that then you won't really see a difference