induction

[armanib]

Hello i have seen a few cars that have removed a headlight and fitted some sort of induction kit like this one

Howcomes there is no filter? Wont the loss of filter cause decrease in engine life span?
Anyone got a picture of a car setup like this engine bay?
I thought about running ducting from my air intake to behind my kidney grill so the air is forced in but someone mentioned the heat from engine will heat up air in ducting causing power loss

[Elecblondie]

Normally an air filter would be retained. Having no filter may reduce life span, if you're unlucky the engine might suck something in the day you remove the filter and go bang. Having said that there are many people trying their luck with no filter, though usually not with an air intake that sits flush with the front of the car.

There are plenty of pics around on the site.

The air spends the best part of not very long sitting in the ducting when you're sucking it in quickly so I can't imagine heating it up is ever a problem, the only thing to make sure is to take it from somewhere cold in the first place.

[GrindCulture]

the only thing to make sure is to take it from somewhere cold in the first place.

Like behind the headlight, as per BMWs design. Whether or not removing the headlight gives any noticeable gains seems to be somewhat undecided, but I'd imagine for actually road usable performance the gains would be negligible.

[armanib]

oh i was thinking by air being forced in it would help the car to go faster

[Bewdley320T]

This is generally done by guys with serious engines/mods and on cars used for track days. The benefit on a normal road car would be minimal and when you balance it against losing a headlight and spoiling the look of the car your better off leaving this to the serious boys.

[armanib]

oh

[Elecblondie]

Given that the front of the e30 is so flat you may even find that, at speed, the air traveling over the bonnet leads to there being lower pressure just below it at the head lamps. Obviously the air that goes smoothly from in front of the car over the bonnet is going to go faster than the air that hits the front and pushes out, so the smooth airflow will be at a lower pressure, this would suck the air at the headlights up; either completely nullifying or reducing the ram air effect. In the worst case the low pressure area could reduce the pressure at the intake below atmospheric. ;)


I thought it might be interesting to do some maths on it, I hope it's right:

Say you have an m40b18 so 0.45l per cylinder swept volume. in one revolution 2 cylinders will intake making 0.9l per revolution. Say you are looking at the top end @ 5000 rpm, that's 4500 litres per minute (0.075 m^3/s). Now say your headlight aperture is 15cm, thus cross sectional area of ~0.018 m^2. Assume it is 10 cm long (0.1m) so for the sake of argument the relevant inlet volume is 0.0018 M^3 thus for 0.075 m^3 to pass every s that volume must be passed 0.075/0.0018 = 42 times per second. It is 0.1m long therefore the intake air must be traveling at 42x0.1m^s or around about 10 mph. With air approaching at, say, 70 mph you would obviously get an increase in inlet pressure. Unfortunately even if the air isn't being actively sucked out of the way by aero effects it has much easier lower pressure paths to go to than the inlet tract so it would raise the inlet pressure a negligible amount. That is assuming that you get the full pressure of the air going towards the car at the inlet, which I assume would need a coefficient of drag = 1, which I have on good authority is a bad thing .

[punk_sy]

Given that the front of the e30 is so flat you may even find that, at speed, the air traveling over the bonnet leads to there being lower pressure just below it at the head lamps. Obviously the air that goes smoothly from in front of the car over the bonnet is going to go faster than the air that hits the front and pushes out, so the smooth airflow will be at a lower pressure, this would suck the air at the headlights up; either completely nullifying or reducing the ram air effect. In the worst case the low pressure area could reduce the pressure at the intake below atmospheric. ;)


I thought it might be interesting to do some maths on it, I hope it's right:

Say you have an m40b18 so 0.45l per cylinder swept volume. in one revolution 2 cylinders will intake making 0.9l per revolution. Say you are looking at the top end @ 5000 rpm, that's 4500 litres per minute (0.075 m^3/s). Now say your headlight aperture is 15cm, thus cross sectional area of ~0.018 m^2. Assume it is 10 cm long (0.1m) so for the sake of argument the relevant inlet volume is 0.0018 M^3 thus for 0.075 m^3 to pass every s that volume must be passed 0.075/0.0018 = 42 times per second. It is 0.1m long therefore the intake air must be traveling at 42x0.1m^s or around about 10 mph. With air approaching at, say, 70 mph you would obviously get an increase in inlet pressure. Unfortunately even if the air isn't being actively sucked out of the way by aero effects it has much easier lower pressure paths to go to than the inlet tract so it would raise the inlet pressure a negligible amount. That is assuming that you get the full pressure of the air going towards the car at the inlet, which I assume would need a coefficient of drag = 1, which I have on good authority is a bad thing .

erm yea what he said

[m_jermyn]

Show off

[m_jermyn]

lol is that a NO? Now im confused

[daimlerman]

One issue here is the legal aspect of removing a headlight. You may,just,make a tiny power gain by ducting air into a filter this way,but you will certainly attract the wrong kind of attention to your car that may well reveal more issues that cost more in fines and penaltys.

[appletree]

I read somewere that a general rule of thumb is a ram air system wouldnt start to give any gains from forcing air in to the engine untill you got to 140mph.

You would probly get the best gains from the cold air side of the system. Normly you can run a enclosed filter between the headlight grill and the AFM with some ducting to get the cold air but retain filtration.

Dont know how you'd get on at mot time with three lights either.

[stonesie]

You would 100% FAIL the MOT with 3 lights, they have to be symmetrical so if you are going to the bother of removing a main beam unit you have to go the way appletree has with retrofitting all-in-one light units in place of the dip beam's.

[armanib]

Given that the front of the e30 is so flat you may even find that, at speed, the air traveling over the bonnet leads to there being lower pressure just below it at the head lamps. Obviously the air that goes smoothly from in front of the car over the bonnet is going to go faster than the air that hits the front and pushes out, so the smooth airflow will be at a lower pressure, this would suck the air at the headlights up; either completely nullifying or reducing the ram air effect. In the worst case the low pressure area could reduce the pressure at the intake below atmospheric. ;)


I thought it might be interesting to do some maths on it, I hope it's right:

Say you have an m40b18 so 0.45l per cylinder swept volume. in one revolution 2 cylinders will intake making 0.9l per revolution. Say you are looking at the top end @ 5000 rpm, that's 4500 litres per minute (0.075 m^3/s). Now say your headlight aperture is 15cm, thus cross sectional area of ~0.018 m^2. Assume it is 10 cm long (0.1m) so for the sake of argument the relevant inlet volume is 0.0018 M^3 thus for 0.075 m^3 to pass every s that volume must be passed 0.075/0.0018 = 42 times per second. It is 0.1m long therefore the intake air must be traveling at 42x0.1m^s or around about 10 mph. With air approaching at, say, 70 mph you would obviously get an increase in inlet pressure. Unfortunately even if the air isn't being actively sucked out of the way by aero effects it has much easier lower pressure paths to go to than the inlet tract so it would raise the inlet pressure a negligible amount. That is assuming that you get the full pressure of the air going towards the car at the inlet, which I assume would need a coefficient of drag = 1, which I have on good authority is a bad thing .

Yer im now confused

[Brianmoooore]

Dont know how you'd get on at mot time with three lights either.

You would definitely fail, assuming your car hasn't been ordered from the road before MOT time for being unroadworthy.
Lights have to be symmetrical, and both dip and main beams are compulsory.