3.0 airbox - aux intake tube

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PJH
Joined: Thu 26 May, 2011 20:33
Posts: 18

  Z3 roadster 3.0i
Location: enfield

3.0 airbox - aux intake tube

Post by PJH »

Hi - first post in a really helpful forum and hope to get some advice

Am considering the air flow mod suggested by Mike Fishwick - seemed cost effective, sensible and subtle.

http://www.zroadster.net/forum/viewtopi ... =18&t=8918

and was about to pop to the local B&Q to grab the bits required but thought I check my z for suitability first- all seems fine in terms of layout at the front lower end (near radiator beneath bumper to first capture air) of the system with the other lower intake hole (below visible so all seemed ok to go ..

But then I removed the airbox to check for the aux intake tube on the bottom of the airbox which is noted in the article and to which the newly installed intake tube is secured to.. cant see it there at all and very little space to cut out. Aside from which securing the piping without the tube seemed like a messy

I suspect that my car - 06/2000 manufactured has a revised airbox without the aux intake ..?

Is there an alternative option for this box as the principles of the airflow mods seem sound

any advice most welcome

PJH

Mod Edit: Link changed to the same article on this forum, where it was originally posted. R.
beerbelly
Joined: Fri 07 Feb, 2014 20:12
Posts: 177

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Re: 3.0 airbox - aux intake tube

Post by beerbelly »

I read a post on a forum once that made a lot of sense that said these airbox mods that try to funnel air into an airbox actually make it harder for your engine to get the required amount of air at high speed. the thing that made me think was (I picked up on this as I ride motorbikes) wear an open faced helmet at 10 mph and you can breath fine take it up to 70 mph and you start struggling to get a breath even though your mouth is open in the airflow . its something to do with turbulence and negative pressure just inside your mouth. the same affect happens inside these tubes you stick through your front grille .the engine runs at its best drawing from a reservoir of static air and your engine has a max flow capacity and the manufacturers will have made the airbox big enough to supply that.if not the performance mod would be a bigger airbox. I have looked but cant find the post but the guy seamed to know his stuff
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Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: 3.0 airbox - aux intake tube

Post by Southernboy »

The most sensible route to go if you're simply looking to provide less resistance to the airflow would be an alternate filter such as Simota or similar genre.
If you're thinking "forced" induction as in turbo charger or supercharger, then perhaps something a little more involved will be required. If you read up on fitting a forced induction system, you will find that there are other mods to be made other than air delivery under pressure. The "extra" air induced requires more fuel, which requires a higher pressure fuel pump which requires a set of injectors to deliver the extra fuel, which requires the engine management to be re-calibrated, which requires a new exhaust system to vent the extra gasses etc etc etc....
A Simota filter is going to be a heap cheaper at a couple of hundred £'s.... or an alternative cheaper filter which will do the job of de-restricting airflow... :wink: One "pleasurable aspect of the Simota filter is the "growl" from the intake when the foot goes down hard on the gas.... 8-) ....I have only had a Simota fitted, so can't comment on the "note" provided by any other filter brands.
Another consideration... there is always speculation regarding "cool" air vs hot air going into the motor. The myth suggests that cold air provides improved power since it is theoretically denser than warm air. I have seen tests done where the belief was carefully checked using accurate measuring equipment, and it seems there is not any substantial improvement - certainly not measurable in multiple horsepower gains. The UK is largely at sea level, so the volume of oxygen in the atmosphere is pretty high in most areas and one should get about as many HP as one can from the motor. Increasing the oxygen content by % into the air mix requires a nitrous set up, which will provide neck snapping power surges when activated. The system can be tempered to simply "tweak" the performance somewhat vs providing Saturn rocket boost...
Mechanically you could have the cams replaced with performance cams and the cylinder head can be "gas flowed"... the point of performance cams is that they keep the intake and exhaust valves open for a fraction longer than OEM allowing more air / fuel mix to be injested. Again this will require the engine management to be re-calibrated accordingly.
Fitting a Simota or similar filter may (or not) improve acceleration response, but not overall horsepower. You need to determine what you want to achieve for your motor and make the required changes to that end.
"Normal is overrated"
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PJH
Joined: Thu 26 May, 2011 20:33
Posts: 18

  Z3 roadster 3.0i
Location: enfield

Re: 3.0 airbox - aux intake tube

Post by PJH »

Thanks Folks

Not planning down a forced route just to increase airflow to the existing oem set up - did consider a Simota or similar but more than happy with the lovely burbling noise of the straight six, am mindful of attracting insurance hike ups and the cost to impact seems poor value for money particularly on the expensive carbon units ..

not sure if you can answer my core question - on the airbox aux intake... and the revisions to these on later models ?

regards

PJ
Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
Posts: 2093

  Z3 roadster 2.8
Location: Daglan, France

Re: 3.0 airbox - aux intake tube

Post by Mike Fishwick »

I did not mention an auxiliary intake into the air box! The B&Q air inlet feeds via the inlet stub below the LH headlamp, as used on the M Roadster, to feed into the usual space behind the LH headlamp, where the airbox normally breathes from. It is therefore no more than an approximation of the M Roadster inlet path, and simply provides an efficient route for the incoming air, rather than the original tortured route which requires the air to make two reverses of direction, and negotiate some narrow passages.

The regard to the auxilary intake tube, perhaps you are getting confused by the M Roadster's auxiliary intake pipe from the air box to the idle control valve, (?) which when a K&N or Simota-type filter is fited requires an additional mini-K&N filter of its own' As my article was written around my 2.8 this was not mentioned.

Engines prefer a turbulence-free - air supply, which is the purpose of the air box. All this mod is doing is to improve the supply of air TO the airbox - the original route is anything but efficient - like trying to run a sprint while wearing a gas mask.

As for a Simota or similar 'ram air' inlet, their inlet is inevitably from the space vacated by the original airbox. Their impressive intake may well operate to capture a larger amount of air, and ram it into the filter - but to do so it would have to be presented directly to the airflow, such as at the front of the car. To fit one under the bonnet, and then claim additional power, is to fool yourself. So many people confuse noise with power. In fact, a Simota breathing warm air from under the bonnet will reduce engine output in comparison with the standard air box.

Anyway, there is plenty to information available regarding the poor filtration properties of an oil-damped fabric air filter.
A Z3 is not just for Christmas - it's for life!
PJH
Joined: Thu 26 May, 2011 20:33
Posts: 18

  Z3 roadster 3.0i
Location: enfield

Re: 3.0 airbox - aux intake tube

Post by PJH »

Many thanks Mike - I had (incorrectly) assumed that this was a secondary system to augment the original - now (think) I understand that this replaces the original set up and utilises the standard intake to the front of the airbox where is breathes from the standard routed intake behind the LH headlight ?

regards

PJ
PJH
Joined: Thu 26 May, 2011 20:33
Posts: 18

  Z3 roadster 3.0i
Location: enfield

Re: 3.0 airbox - aux intake tube

Post by PJH »

http://www.bimmerforums.com/forum/showt ... air-intake

now I understand....

thanks to all again

regards for Easter

PJ
Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
Posts: 2093

  Z3 roadster 2.8
Location: Daglan, France

Re: 3.0 airbox - aux intake tube

Post by Mike Fishwick »

I blocked off my original intake path with foam rubber, to prevent loss of air in the reverse direction. The clever French use 90 mm drain pipe, so perhaps this winter I will make a larger-bore replacement, which will match the inlet aperture of the air box.
A Z3 is not just for Christmas - it's for life!
PJH
Joined: Thu 26 May, 2011 20:33
Posts: 18

  Z3 roadster 3.0i
Location: enfield

Re: 3.0 airbox - aux intake tube

Post by PJH »

Would be very interested to find out how that project goes if you take it on Mike

regards

PJ
Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
Posts: 2093

  Z3 roadster 2.8
Location: Daglan, France

Re: 3.0 airbox - aux intake tube

Post by Mike Fishwick »

I'll put it in this site, with pictures - this winter
A Z3 is not just for Christmas - it's for life!
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