Short Ram

[DaNO]

Just curious to see if anyone has a short ram intake, if so, do you like it?

[prd318ownr]

well i have a cold air intake which has giving me what i think is a bit more power, its routed just under my radiator so it gets cooled air away from that hot a$$ air. So yeah, i like it..

[GDB]

A short ram will only make your car louder, it will not have any performance gains.

[m44ic]

a short ram intake will suck more air but it is true that the air will be warmer giving less power than colder air. but if you have a cold air system that is five feet long you wont gain any power, up top the car will be starved for air because of the intake length even if the air is cold, so I try to have something in between, with the 318's its easy cause you dont have to travel very far to get cold air. so the key to a good intake is that it is short but brings in cold air, my intake that I fabricated has a custom heat shield and the filter sits right behind the headlight so when I go to the track I take out the headlight and bring in gobbs of cold air

[Boxbrownie]

Thats why I am keeping the stock set up and just letting as much cold air into the airbox as possible, the engine gets cold still air, a short ram effect, and the best filtration. Probably why BMW engineered it that way in the first place! :biggrin:

Best regards David

[aceyx]

actually, BMW designed this car with both a short, and long air tube.

it's what they call DISA, and takes advantage of the fact that a short tract benefits high rpm operation, while a long tract benefits low to medium torque. there's a flap that switches between the two, i believe it's controlled by the ECU.


how many of the people that have installed CAIs know this? c'mon, raise your hands. (this was new to me as of this year as well).

[Boxbrownie]

actually, BMW designed this car with both a short, and long air tube.

it's what they call DISA, and takes advantage of the fact that a short tract benefits high rpm operation, while a long tract benefits low to medium torque. there's a flap that switches between the two, i believe it's controlled by the ECU.


how many of the people that have installed CAIs know this? c'mon, raise your hands. (this was new to me as of this year as well).

Indeed they did but this is just within the inlet manifold system, once upstream of the MAF sensor its every air molecule for itself!

Best regards David

[aceyx]

Indeed they did but this is just within the inlet manifold system, once upstream of the MAF sensor its every air molecule for itself!

i don't quite follow (remember, i just learned this within the past year); what does this mean?

[Boxbrownie]

i don't quite follow (remember, i just learned this within the past year); what does this mean?

Sorry...it means that the variable length inlet manifold system is built within the inlet manifold itself, a valve changes the airflow to create more ram effect for better torque at lower engine rpm, the inlet tract before the MAF (mass air flow) sensor is not changed by this system, therefore anything you do upstream of the MAF sensor will not be affected by BMW's variable system.
What you will be doing is lengthening the whole inlet tract substantially over OEM thus creating different airflow characteristics, whether this this be better or not.....hmmm.....you could actually bugger up the carefully tuned pulse air effect that has been designed into the system by BMW (hence the use of resonator cavities these tune for pulse as well as sound).
I personally prefer just to get as much cold "still" air into the airbox first, then let BMW's carefully designed variable system sort out when I should be getting better torque or better flow for power.....each to his own though!

best regards David

[Fender]

Not sure what a Short RAM is - Must be an open filter under the hood, based on responses.

I have dual port RAM air and it made a big difference, though I haven't dino'd the car. I cut an extra opening in the black box, and vented air thru both flood light openings. IE: I don't have flood lights.

This was the first of two engine Mods I've made so far:
1st - Dual Port Ram Air. Big difference. Quite noticable, even at low RPMs.
2nd - Dinan software upgrade. There was a difference, but not as noticable (I was dissapointed actually).

[aceyx]

box, thanks for the explanation. unfortunately, i can't read anything lately unless it has at least a few citations to cases. (i've also lost my ability to do simple maths).

the stock system has two lengths of tube, before the actual "box" itself, and before the MAF, right?

or does the DISA refer to the intake manifold, post MAF?

i thought it was the former, but i've never taken the air box apart except to change the filter. my opinion is that the inlet seems in a fine place as is, without the need to drop coin on a "special" tube, filter and heat shield.

[pdxmotorhead]

DISA is the intake manifold.
Works like the old Corvette ZR1 two plane manifolds.
Had a flaper valve and a long and short runner system.

Dave.

[Boxbrownie]

box, thanks for the explanation. unfortunately, i can't read anything lately unless it has at least a few citations to cases. (i've also lost my ability to do simple maths).

the stock system has two lengths of tube, before the actual "box" itself, and before the MAF, right?

or does the DISA refer to the intake manifold, post MAF?

i thought it was the former, but i've never taken the air box apart except to change the filter. my opinion is that the inlet seems in a fine place as is, without the need to drop coin on a "special" tube, filter and heat shield.

It is the latter......the DISA is contained within the inlet manifold system itself.....all you are doing if you lengthen the inlet tract forward of the MAF/Airbox is increasing the length of both systems, and I firmly beleive that BMW probably spent more time and money tuning the system than any after market indipendant ever could....but then I work in R&E in the auto industry, and I would say that wouldnt I? LOL

Best regards David