BMW E46 Fanatics Forum banner

1 - 16 of 16 Posts

·
Slow in, slower out
Joined
·
4,754 Posts
Alpha-N is just a speed-density method of engine management. Instead of an air flow meter or mass air meter, speed-density uses manifold pressure to sense engine load. Manifold air temperature is used to make small corrections for air density. Using the load factor, the injector pulse width is calculated based on engine speed. A motor with LOTS of cam may not develop enough vacuum at low loads and speeds so throttle position is sometimes substituted for manifold pressure to sense engine load.


Ed
 

·
Banned
Joined
·
639 Posts
teamdfl said:
Alpha-N is just a speed-density method of engine management. Instead of an air flow meter or mass air meter, speed-density uses manifold pressure to sense engine load. Manifold air temperature is used to make small corrections for air density. Using the load factor, the injector pulse width is calculated based on engine speed. A motor with LOTS of cam may not develop enough vacuum at low loads and speeds so throttle position is sometimes substituted for manifold pressure to sense engine load.


Ed

all i got form this post

BLAH BLAH BLAH ENGINE BlAH BLAH BLAH SENSOR BLAH BLAH BLAH LOAD


must be an informative post
 

·
Mod Squad
Joined
·
12,633 Posts
teamdfl said:
Alpha-N is just a speed-density method of engine management. Instead of an air flow meter or mass air meter, speed-density uses manifold pressure to sense engine load. Manifold air temperature is used to make small corrections for air density. Using the load factor, the injector pulse width is calculated based on engine speed. A motor with LOTS of cam may not develop enough vacuum at low loads and speeds so throttle position is sometimes substituted for manifold pressure to sense engine load.


Ed
Waaaay over my head. Sounded smart though :D So why would this be better, or would it?
 

·
Slow in, slower out
Joined
·
4,754 Posts
russ330 said:


Waaaay over my head. Sounded smart though :D So why would this be better, or would it?

A mass air system is more accurate over a wider range of airflow rates and results in better emissions. For a track only car with huge cams, ultimate power is the only concern so alternate engine management sytems are often used for ease of tuning and reduced intake tract restriction. The mass air meter (MAF, HFM, etc) or air flow meter can be a restriction at higher engine speeds, especially when headwork and cams are involved. A speed-density system allows you to remove the mass air meter from the intake tract because is uses a MAP (Manifold Absolute Pressure) sensor to sense engine load.



Ed
 

·
Banned
Joined
·
639 Posts
so it makes yr car faster ???


is that what you are trying to tell us ed
 

·
Slow in, slower out
Joined
·
4,754 Posts
andy 323i said:
so it makes yr car faster ???


is that what you are trying to tell us ed

It makes money fly out of your wallet faster.


It makes your car faster only if the mass air meter is a significant restriction. Unless you port the cylinder head and run huge cams, don't bother.




Ed
 

·
Banned
Joined
·
639 Posts
okay upi lost me again at IT
 

·
Registered
Joined
·
2,013 Posts
Ok, let me try to use an analogy. :D

Suppose you're trying to measure how many people are coming into a stadium. The typical method would be to have them enter the building thru those rotating gates. This method, while effective, obviously limits the speed at which people can enter the building.

If you don't need to know *exactly* how many people are coming in, you have another method. Assuming that there is only one large corridor thru which people can enter, you just observe how fast people are walking thru this corridor and how many people wide this corridor is.

Method A is like the HFM used in our cars. It's accurate but it poses a restriction.

Method B is like the Alpha-N. It's not as accurate, but there's no "bottle neck". You can also imagine that if the amount of people walking thru the corridor is low (say, only 5 people entering the stadium every minute), this method of counting is very inaccurate.

Hope this helps...
 

·
Registered
Joined
·
2,493 Posts
Yeah but I dont want anybody walking in to my air intake :)

If they do how many people has to walk in to my air intake to to make my car go faster?
 

·
Registered
Joined
·
3,055 Posts
For stuff like this I would contact Samir at rennsport he knows our cars like the back of his hand..... I doubt many others from the board would be able to help you out here.... Try Samir or maybe someone over at AA
 

·
Bimmerfest Co-Founder
Joined
·
12,823 Posts
I am not sure it is really worth the coversion costs...the CSL comes with it and only has around 10HP gain. Additionally because you are estimating the amount of air any engine changes (cams, etc) effect the air flow and mean that the estimates need to be reworked (more dyno tuning).

As //M PWR 00 suggested talk to Samir.

Tim
 

·
Registered
Joined
·
405 Posts
Alpha-N is for race use only. you cant even drive your car on the street if you have the Alpha-N. you would need to like carry a computer with you all the time so that you can put in the temperature, and all that good stuff. so if your planning to use your car JUST for race then Alpha-N is the way to go.
 
1 - 16 of 16 Posts
Top