Possible intake restriction?

[Dave1027]

What is the purpose of the deflectors I have outlined in red? Maybe they keep water and debree from entering? Seems to me they would create a low pressure area at the intake inlet? Has anybody tried cutting those out?

http://home.comcast.net/~dl1027/files/ZHP/PICT0002.jpg

[Hornung418]

Any and all restriction occurs in the head. You will not gain any noticible increase in torque and power by removing those portions of hard plastic.

From a GS3, this was sent.

[Dave1027]

Then how is it that supercharging gets these motors to 350+ hp?

[Hornung418]

Compressing air and increasing fuel mixture is not quite the same as snipping some bits of plastic near the intake.

From a GS3, this was sent.

[Dave1027]

Sure but people install CAIs that boost intake flow and add a little hp. I just thought that adding a little air pressure at the inlet could add a little response at cruising speeds.

Also, it just seemed to me that BMW designed a pretty cool setup that positions the intake inlet in the grill for efficient air flow but then they have those deflectors in the way which seem to negate the whole thing. Didn't make much sense to me.

[mimalmo]

Probably has more to do with the direction of airflow. Remove those and it may create a pocket of air behind the grill. Somehow I doubt BMW engineers would design something like that to restrict airflow.

[Avetiso]

Cold air intakes add power because of cold air, if I'm not mistaken. I believe: intake temps drop because of position and heat shielding. Colder air is denser air, meaning it becomes a little harder to suck in; so you get a bigger filter that breathes easier to help it suck in more air. = moar powah.

+1 on cutting out the vent being useless. Don't do it.

[Hornung418]

Cold air intakes are pretty worthless in their own right. They are really just noise makers.

The only proven way to add power over stock is to increase the distance the air has to travel before reaching the MAF. Then the air is smoother and freer flowing that the MAF can read more air and the DME will adapt the fuel to the appropriate mixture to retain 14.7 AFR. Open up your stock intake and look at the little horn in there. That trumpet is what smooths the air before it is read by the MAF. Now take that out and slap a ridiculous open filter on the end of it and take a guess how that affects the readings. No amount of heat shielding will make up for the poor readings.

This is my setup:

9714

And while I may sound like a yuppy know it all, it's been proven across all the forums with different makes and models.

If you have any more questions about making a little bit of power here and there, feel free to ask :)

[Avetiso]

Justin, the pic of your car is sexy. Seriously. Make that your siggy.

[Newjack]

Justin, the pic of your car is sexy. Seriously. Make that your siggy.

+1


The bottom line OP, is that these cars have really great airflow stock. Cold air intakes on these cars don't really do anything towards more power or torque, they just sound better. I'm running an AFE CAI with a dry filter, and it sounds great. But any actual gains from having it on can't be felt on the butt dyno.

Like Justin pointed out, the long tube intake he has probably helps gain more power than my CAI for the reasons he explained. Smoothing out the air to get a more accurate reading from your MAF. But the gains hes getting from his CAI vs mine are extremely tiny. I'd bet I gained anywhere from 1-3 HP / ftlbs of torque from my CAI.


As for your original question, I have not cut out those deflectors, but I trust BMW in their engineering that they added those deflectors for a reason.

I think as far as making small amount of power goes, weight saving is the best option. What is the ratio? Every 10lbs taken out is 1HP felt?

[Hornung418]

Yeah 10lbs : 1hp.

From a GS3, this was sent.

[derbo]

Yeah 10lbs : 1hp.

From a GS3, this was sent.


I better lose like 30lbs.