BMW M5 Forum and M6 Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
1,073 Posts
Discussion Starter · #1 ·
After cleaning the air filter the other day I decided (having read the s38 b38 training guide off of bmwe34m5.com) not to put the intake horn from the airbox back on, I reckon it gives a bit more intake noise :cool: (as suggested in the guide).
Has anyone else tried this ?, If not give it a go and see if you agree. Hopefully it doesn't have any bad implication's for the filter - I dont see how it would.

Phil.
 

·
Premium Member
Joined
·
2,941 Posts
Phil,

Please reread the article. It only says that a Helmholz resonator was added to reduce the air-intake noise.

The intake horn from the S38B38 has three openings.

1: The air-intake
2: Connection to the air-box
3: Connection to a helmholz resonator.

The Helmholz resonator is the black-box underneath the air-intake and consists of two openings. One larger to which the air-intake is connected and a small hole. The diameter of this hole is tuned to attenuate standing waves with a fixed frequency band. This reduces the intake noise, but does NOT affect performance.

This is not the case for the air-intake horn for the S38B36's for the Swiss and Austrian markets (maybe some more, in the ETK referred to as Common wealth). The E34 ///M5's 3.6 for these markets have a bended intake horn with the air-intake pointed downwards. This reduced the intake noise, but from an aerodynamic point of view, this isn't perfect, especially not at full-throttle, high revs and high speeds.

The capacaity of the air-filter is best used when the pressure on the entire surface is evenly divided. This is exactly what the air-intake horn does!! Leave it on!
 

·
Registered
Joined
·
1,073 Posts
Discussion Starter · #3 ·
Raymond, thanks for the reply. I'll probablyput the horn back on soon. I never thought that it gave any benefit in performance, I think cleaning my K&N helped that one. The air box minus the horn does make the engine note sound better. I thought some of the board members who look to improve their ///M's acoustics would like to try running without the horn, and see what they thought. Has anyone ever tried disconnecting the the cooling duct for the alternator and extending it to the airbox intake to try and create a ram air effect ?.
Cheers,
Phil.
 

·
Registered
Joined
·
1,073 Posts
Discussion Starter · #6 ·
ECM, interesting article. I have only removed the the little inlet horn between the box and the rear of the n/s headlight, but I think from the article I will 1. try a paper filter and 2. re-fit the horn. I don't think my engine has been running lean and hopefully not been incurring excessive amounts of particulate with the K&N. At least it is a standard panel replacement and not the full induction kit I have.

cheers.



ECM4 said:
......you guys need to read this article: http://www.bmwe34.net/E34main/Upgrade/Air_filter.htm

........messing about with the airbox can definetely effect performance.
 

·
Registered
Joined
·
310 Posts
when I had my 97 540i/6 speed, I had dyno'd the car. I did a run with a K&N cone filter attached to the maf, and a run with the stock air box and oem filter. Other than this all I had was exhaust on the car.


This was the result with the K&N, and might I add the air/fuel was excellent. I do not have the graph of the other dyno (they just sent me the better of the two), but I assure you the K&N gave me both more hp and torque. It was only a few of each but it was an improvement. I cant even begin to describe how good the car sounded with the K&N also.

The point is, this is the data I got from a dyno.
Yes the car may have sucked in air differently if it were going, say 70 mph.
But I highly doubt it would lost more than say 1 or 2 hp, certainly not 15!
And yes, the engine may have sucked in a few more microscopic particles of dust each year.
But will this shorten the engines life by 50,000 miles, or maybe just 5?

Either way I guess we may not be able to truly find the answers to some of these questions, but Id say if you really enjoy the sound, and it makes you that much happier about driving with it (I know mine did), then go for it!:M5launch:
 

·
Registered
Joined
·
310 Posts
If you have loud exhaust, however, I dont think the filters make a noticeable improvement from what I remember.
I think everyone with stock or reasonably quiet exhaust owes it to themselves to just try one of these filters and see the incredible sound. From the menacing growl they make in low and mid range revs on the throttle, and all the way to the high rpms, the sound is really nice.
I remember taking the cone off the 540 once I had exhaust because I didnt notice the differnce anymore, all I really heard was the exhaust.
So, personally I wouldnt use the filter with exhaust, but swear by it on a car with stock exhaust.
 
1 - 9 of 9 Posts
Top