Why You Should NOT Remove Swirl Flaps on BMW N47 / N57

In this video I talk about how swirl flaps work and exactly whether or not you should consider removing the swirl flaps on your BMW N47 or N57 engine intake manifold.

The N47 is the 2L diesel and the N57 is the 3L diesel from BMW and both engines share the same design, just with one being a 4 cylinder and the other being a 6 cylinder engine.

[FoxHotelLima]

From an engineering point and thousand of miles done in an N57 data-logging, I can tell you that Swirfflaps do not increase fuel consumption and are there only for emission purposes and that is to increase EGR gas flow at lower rpm'/load and in the cruise. Remove them in conjunction with EGR removal only and you will see massive gains in MPG. Swirl flaps should not be removed while EGR is still functioning

[Assimilator]

Swirl flaps don't increase the amount of air into a cylinder when closed, what the swirling air does is improve fuel and air mixing partly as a result of the angle it enters the combustion chamber (like you said) but also because of the increased air speed, which helps light throttle emissions, power and economy.

[jameschaffe]

Worth mentioning my 2011 n47 d20c has separate swirl flaps between manifold and head, bmw call it a “gasket” but it contains the flaps and shaft. Easily replaced for £25-50

[JaseWilks]

Thought I recognised the name, thanks for the comment on my upload George. I appreciate what you're saying with this one, but it really doesn't apply to my 330D as you recommended. And with the correct coding out and remapping, the car runs 100% better than it did. The restriction of air flow over the flaps was quite unbelievable in my opinion, removing a combination of parts (EGR/Swirl Flaps/DPF(if you choose) can prevent you from having to fork out on HUGE diagnostic & repair bills.... ever again.
It all depends on what you are comfortable doing at the end of the day, and I have no regrets. The car feels amazing.


Keep up the good work mate.

[beppelombardo]

M47 / M57 = immediately remove Swirl valves
N47 / N57 = check condition

[MilanPatel]

My BMW independent mechanic mentioned a manifold leak (not sure from where but there is lot of carbon soot built up around manifold & cover). My 2008 X3 E83 N47 2.0d is showing 3 glow plugs faults, so while we are replacing Glow plug might get manifold replaced. Was going to order cheap Manifold without flaps from eBay but he advised to buy one from reputable parts supplied with flaps and actuator motor given Genuine costs $2.5k in Aus. So after having seen your video it explains why he asked me to stick to original setup. Very nice animation by the way. You X3 N47 videos have really helped me understand how my car drives. Hopefully with your helpful advice and Timing chain hanging in there, I can get from 200k km to 250k before I dump this car. Not sure if I want to touch any of injectors just yet, one of them is starting to leak very slight diesel though)

[davidknowles]

Preparing to delete the swirl flaps on my 2004 X3 M47. Would much rather have a drop in torque than a grenaded engine.

[lehelzelenka]

From what I heard, it's not only a hardware mod. You need to do a swirl flap software delete too.

[grahamrowland]

Good info. The flaps also cause the air speed to increase which aides mixing

[ApcaaLypS]

Let's also mention that these swirl flap round gates falls down from the tube and enters the engine combustion chamber, unless you're lucky enough where they get stuck right before the engine valves.
When tuning my bmw at some point I had to remove the EGR and also remove these swirl flaps, So when I checked I found two swirl flap gates were already stuck and could destroy my engine at any time, luckily I removed them In the correct time.

[birdpersonchickpea]

Great video I learned a lot from your stuff George keep it up. My personal opinion delete them swirl flaps. Yes there is a good reason for them being there but the potential damage they can do if they fail out weights the benefits. 100% delete them! I’m saying this cause The bar wore out and broke on my n47 and destroyed anything and everything to do with the cylinder that ate it. Could have saved a lot of money and still had a fully functioning car if I had deleted them earlier

[aurimaslab]

I've got N47 130kw swirls removed and dpf regeneration occurs frequently
. Almost every 200km in city on short journeys... 149K km on the clock

[gangstar]

I was about to remove swarl flaps over the lock down situation. Thanks for that Grorge.

[DCAKAJ]

thank you, this video changed my mind, l got an EGR delete from darkside developments, and i think im gonna get a new engine cover with new air intake, so hopefully l'll increase engine life

[jamesward]

2 well worthwhile N47 deletes - swirl flaps & EGR. Do both or neither. Ideally do both. They suck.

[bilbobagins]

finally! Most of people told me to remove them but i knew bmw engineers put them for a reason and uve explained it. Thank u for the explanation George!
greetings from abroad

[marco]

They are there for low emissions same as the egr
They re just done so they pass euro 4

[sjdava]

I've got an N47 with the brass bar going through the intake for the swirl flaps. The end flap was badly worn: where the bar goes through, as if the flap was stuck and the bar wasn't, causing friction/wear on the plastic flap. It was so worn that it was about to fall off. Luckily we spotted this beforehand and removed the offending flap. 135k on the clock.

[seanelderton]

Hi George could you show a video of how to replace the swirl flaps please

[ilyasfulat]

6:41 isn’t it possible just to replace the rod and swirl flaps? Why the need to replace the inlet manifold if it’s just the rod and swirl flaps in question.