"Warm Air Intake" Apparently increases fuel efficiency?

**RobST162** · 02-02-2010, 12:43 PM

guess I should ditch my intercooler

**river** · 02-02-2010, 12:48 PM

Hi,

Originally Posted by RobST162

guess I should ditch my intercooler

No. Just mount it against the radiator.

seeyuzz
river

**oldcorollas** · 02-02-2010, 03:03 PM

Originally Posted by RobST162

guess I should ditch my intercooler

depends if you are after power or economy

for power there is no question that colder/more dense is better..

**AdrianS** · 02-02-2010, 03:22 PM

Originally Posted by river

No. Just mount it against the radiator.

Yep. Should give a 0.0000001% fuel economy gain, and you get a nice "tinkle tinkle tinkle" sound on boost as well.

**Billzilla** · 02-02-2010, 05:21 PM

Originally Posted by AdrianS

Yep. Should give a 0.0000001% fuel economy gain, and you get a nice "tinkle tinkle tinkle" sound on boost as well.

.... and that tinkling noise causes you to get off the throttle and so save fuel dummeh!!!

**Squid** · 02-02-2010, 05:46 PM

I remember doing all this at uni with our crazy polish physics professor (vaguely).

Mathematically speaking how an increase in intake temp (T1) result in an increase in efficiency? Because according to my calcs it can only make it go down. Admittedly I haven't used my maths brain much recently but I just don't see it happening. As suggested any economy observed may be purely incidental.

Also note that the website in question has a vested interest in selling you stuff. Going by that, hyclone has also proven an increase in efficiency hasn't it?

**Moppitt** · 02-02-2010, 07:08 PM

Speaking of pumping losses and as alluded to a page ago there is the BMW valvetronic system.

Unfortunately the best explanation I can get is (urgh) wiki and autospeed but heres the links:

Autospeed

and Wiki

Wiki.

These are, more or less, technically correct, just I dont have access to the BMW technical documents any more.

It is interesting to sit in one of these and stab the throttle from idle as you can hear the valves go from almost silent to audibly closing as the lift increases up to ~9.8mm.

The thing I'm not sure about though is how does this reduce pumping losses when it has really just moved the restriction from the throttle butterfly to the inlet valve? What other factors have become an issue here - high air velocity causing better swirl and tumble etc?

**AdrianS** · 02-02-2010, 10:48 PM

Reducing lift will automatically reduce duration, so the inlet is open for a much shorter time. This means that rather than dragging air past a throttle butterfly, the engine is basically pulling a vacuum in the cylinder at the end of the inlet stroke; you get most of this energy back because the air acts like a spring, and pulls the piston up at the beginning of the compression stroke.
You still have bad efficiency because of partial cylinder filling, which you can partially solve with direct injection. This lets you run effectively very lean, by having a pocket of stoich. mixture at the top of the cylinder, and the rest filled with a mixture of air and exhaust gas. It's a type of stratified charge system.
According to wiki, the latest BMW engines have direct injection, variable lift (valvetronic), and timing (VANOS). Let's see the mechanic in outer nowhere diagnose that !

**Moppitt** · 02-02-2010, 11:21 PM

Ohh, energy recovery, hadn't thought of that.

Yeah, they've had VANOS for well over 10 years now, valvetronic was added to the mix in 2001 but only started showing up a lot around here around 2003-4 and was added to the straight 6's about 2005. Direct injection appeared late 2006 iirc and you're absolutely correct - if it breaks down its a tow-to-dealer job.