Sharing CAI data

[Sajk]

Hi,

I had a heavily shielded "cold air intake" with 1 inch thick heat shielding on the hot side and bottom of the vendor supplied heat shield along with sealing shielding stuck to the bottom of the bonnet to close off the "box" that the filter was in.

Last weekend I did some logging of intake temps against the stock intake and found the following.

Under traffic idle circumstances - Really no difference once heat soak sets in fully. About 25-30 degrees C hotter than ambient.

Once underway the stock intake dropped to 15 degrees above ambient and the CAI about 19 degrees.

The real difference is in recovery time from heat soak. The stock intake quickly drops down to 15 degrees (sometimes lower) above ambient but the CAI takes much longer.

Stock intake is on to stay. I will miss the intake noise but its not worth it.

I know this has been done *to death* but I thought I would share some actual measured data not opinion. Same day, same road, same ambient.

cheers

 

[NZ00Z3]

Thank you for sharing your experiences with the data to support it. Most people don't take the time to do the before and after measurements. It's greatly appreciated.

 

[Sajk]

Pleasure. Unfortunately on this subject in particular the facts are often overlooked.

 

[the Nefyn cat]

I guess that's why I've stuck to the oem set-up. Best get myself some
https://www.ebay.co.uk/itm/194248088970?hash=item2d3a169d8a:g:1tcAAOSw8QJg9f1Y
and whack it round the airbox.

 

[miller1098]

Were all different in the way we look at and treat our cars and for me the intake noise is part of the driving pleasure,I can afford to lose a few horses.plus I’m lucky to have 2 ,one standard and one to feel like your ripping the road up

 

[t-tony]

I have to agree with that Hugh, the Ramair I had on my E85 was an awesome soundtrack and sounded like it was faster regardless if it was or not.

Tony.

 

[Sajk]

I am actually thinking stock box for summer and intake for winter. On a side issue I can thourougly recommend a cone made by Injen or Amsoil which is made from spun nanofibre material made by filtration specialists Donaldson (they make industrial filters and power core filters). The Injen cones cost a bit more than the usual suspects but they actually filter the air and flow well.

In my climate it is not so dusty. The k&n filter never really got dirty. The Injen one did. Nuff said I think.

These filters are actually a paper based cone covered by spun nanofibre. No oil. Vacuum or compressed air clean.

 

[the Nefyn cat]

spun nanofibre

Wasn't he in Lord of the rings?

 

[Sajk]

Wasn't he in Lord of the rings?

Yes but he left his filters at home

 

[Mike Fishwick]

Apart from the juvenile attraction of intake noise, I do not see and point in fitting a cone-type filter inside the engine compartment - that is anything but a Cold Air Intake, and is still restricted by the original around-the-headlamp intake path. ! As seen from these temperatures, it is really no better than the stock intake, and there are plenty of compelling reasons for avoiding any K&N type of filter.

I built a REAL cold air intake, using 70 mm rain water pipe and fittings, for about £2, which breathes from the high-pressure area in front of the radiator, rather than the convoluted path which BMW imagine to be an adequate intake route. Maybe it is not the ultimate intake, but it has to be better than the over-priced and noisy products on the market - it depends on whether you want fact or fantasy!

 

[miller1098]

Fact or fantasy...now that’s a question. Most of what I’ve ever done was once a fantasy for me ,so I think on that basis I’ll keep fantasising lol

 

[Sajk]

Mike have you logged intake temps? Would be interesting.

 

[Mike Fishwick]

No - do not have a suitable thermometer. All I can say is that a straight-ish 70 mm pipe has to be better than the original BMW idea, which calls for the incoming air flow to stop and reverse its direction twice, while finding its way through a narrow gap. I hesitate to claim that the engine is more powerful etc etc as we are often told an under-bonnet K&N filter will!

I do claim however, that the volume of the air going into the air filter will be increased, and that its temperature is going to be very close to that of the ambient airflow striking the front of the car. During summer we can often have 40+C temperatures, so every bit of waste heat which is not drawn into the engine has to be a good thing.

The advantage it is not just a lower air temperature, but also the larger quantity of induction air which my intake provides. A cone filter under the bonnet - even if surrounded by an enclosure - can do neither, and suffers from the usual ills of such a filter element.

I have posted an article with photos, but have just discovered that it has already been posted! Sorry about that.

 

[Pingu]

Page 5 shows CAI data (https://www.zroadster.org/threads/testo-datalogger-what-do-you-think.18350/page-5)

Standard airbox modifications (https://www.zroadster.org/threads/air-filter-box-modification.26207/#post-442497)

Keeping cool (https://www.zroadster.org/threads/trying-to-stay-cool-image-heavy.18828/#post-316224)

 

[Sajk]

No - do not have a suitable thermometer.

Mike a cheap blue tooth odb2 adapt from eBay, a few dollars, and the free torque app for your phone will do the job that is If you have an odbii port under the steering wheel.

 

[Mike Fishwick]

I have only just bought a smartphone, but find anything more than making a phone call is really beyond me! I must buy a portable thermometer with a long cable . . .

 

[andyglym]

I took my K&N57i Induction off and the performance was night and day difference on the positive side. It's a shame really as I used to chuckle like a 10 year old school boy with the great noise.

 

[Woodsta888]

I must buy a portable thermometer with a long cable . . .

Whaffor?

 

[Mike Fishwick]

I see what you mean - a smartphone off the OBD2 port - perhaps I am still in the age of steam, but I do not have a temp sensor in the air box. The manifold temp will be higher.

 

[Pingu]

I took my K&N57i Induction off and the performance was night and day difference on the positive side. It's a shame really as I used to chuckle like a 10 year old school boy with the great noise.

The noise that you hear is caused by what I call the syringe effect.

It is when you pull on a syringe too fast and you get a slurping noise.

You will also notice that when you do it, the syringes piston is more difficult to pull on and it even "backslides" down the tube when you let go.

All of this is happening in your engine if you have a restricted air filter.

In a single cylinder engine, the piston only moves down because the inertia of the previous power stroke is moving it, but a multi-cylinder engine also has the assistance of the other cylinders' power strokes. If the draw into the cylinder is restricted, the power/inertia is trying to pull the piston down while the syringe effect is trying to pull the piston up.

It makes a nice noise though

Personally, I'd rather have an engine that screams like a banshee