Factory airbox "veocity stack" (for lack of a bett

[hella 325]

You know the velocity stack type thing in the air box, I know its fot straghtening out the airflow but the gap between that and the box is very small would it benifit more to leave it in or take it out? I have heard both.

[JesseDuncan]

Take it out and see what you think. I had a loss of torque at low engine speeds, but a little better throttle response on the highway. I opted to leave it in. The afm is calibrated to have that horn in there, and it may be off without it. The gap there is small, but BMW put that in there for a reason, and I seriously doubt they would have installed it in such a way that it was hurting power.

*edit* there was a thread about this at http://www.r3vlimited.com/phpBB2/vie...ht=airbox+horn

[Digitalwave]

Leave it in, the mid-range is much smoother and idle is much smoother with the horn installed. There are no gains to taking it out.

[hella 325]

ok thanks

[nando]

take it out! you'll get mad tite gains y0, like .1hp!

[rwh11385]

http://www.r3vlimited.com/phpBB2/viewtopic.php?t=1310&highlight=stock+dyno

I decided today to take it to work and dyno it to get a good solid baseline for the upcoming motor swap. The best I could get out of it was 135.5rwhp/139.9rwhp, which I didn't think was too bad for mileage on the motor.

Next, I yanked the powersteering belt off to see how much hp/tq the pump was taking. This resulted in 137.7rwhp/143.2rwtq.

Dyno graph - removed powersteering

After this, I decided to see how much the silencer inside the airbox was hurting power. It didn't hurt power as much as I expected it would. Power did go up to 138.3rwhp, but peak torque did go down slightly to 143.0rwtq.

138.3-137.7= .6hp

I don't have a silencer......I was not able to retain it with the M30 AFM. Oh well.

[Skafrog]

Nando, it doesnt matter if it gains you .1 HP, you gained power. Little things add up. Some of you guys really need to go hang out at a track once in a while.

[rwh11385]

Nando, it doesnt matter if it gains you .1 HP, you gained power. Little things add up. Some of you guys really need to go hang out at a track once in a while.

I'll have to go the other way on that. like my friend with a caged track 325i told me..... just go to the track, you'll stop worrying about MAFs and shit once you get there. your new concern will be handling and keeping it ready for events.

what is .1hp going to matter? as charlie says or those other illuminati....focus on the most important part to having a faster car - the driver.

chip it, rip it. (maybe put M30 afm/19# in it) but worrying about silencers is a waste of time.

[nando]

Nando, it doesnt matter if it gains you .1 HP, you gained power. Little things add up. Some of you guys really need to go hang out at a track once in a while.

and that's going to make what, .0001 seconds difference in your lap times? :roll:

[hella 325]

not worried about it, just curious. lol w/o it will it be louder?

[Digitalwave]

not worried about it, just curious. lol w/o it will it be louder?

No.

[hella 325]

k...seems usless to mess with it....it stays

[Skafrog]

Nando, it doesnt matter if it gains you .1 HP, you gained power. Little things add up. Some of you guys really need to go hang out at a track once in a while.

and that's going to make what, .0001 seconds difference in your lap times? :roll:

Yes. Dont roll your eyes, thats faster laps, period.

[DanGillan]

Nando, it doesnt matter if it gains you .1 HP, you gained power. Little things add up. Some of you guys really need to go hang out at a track once in a while.

and that's going to make what, .0001 seconds difference in your lap times? :roll:

Yes. Dont roll your eyes, thats faster laps, period.

haha, its true, you dont realize how much each .1 of a second counts at the track

[rwh11385]

I really doubt it is worth the time it takes to fuss over the airbox silence or will really do you any good, unless you are so experienced you don't have any seconds to shave off besides more HP.