I have an Opel Corsa D 1.4 turbo. I have bought a Conic Air Filter, but I need to know what I can do to make a better installation. I don't think that I have a good one, because is too close to the warm air from the engine. To install it, I remove the air filter access front part, and replace the air filter for the conic filter, and put it over the top of the open original box of the air filter. I have attached a photo.

My Question

Is there a better configuration for this air filter installation that will draw cooler air for the intake rather than heated air from the engine compartment?

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  • There is no space, and it is located behind a light already :) I would suggest to remove that remain of an old air box, and see what you can fit in there, basically you need a bigger air box, with a bigger intake tube coming from a front of a car. But yea, technically, after every single modification your ECU should be "remapped", because to rely on fuel correction as a bit wrong... Commented Jul 11, 2016 at 22:15
  • 1
    Ram air intake! Commented Jul 11, 2016 at 22:29

3 Answers 3


Judging by the relative absence of space in the engine bay, any attempts at relocating the intake will involve a fair amount of engineering and gnashing of teeth.

I would recommend keeping it in its present location but restoring the air box cover. It won't help much with heat soak through radiation but should reduce convective heat loads felt by the intake filter.

That said, I am skeptical about how much difference in performance this modification will make. There is a Q&A about the impact and effectiveness of CAI's here:

Unless you're planning to go drag racing, the vehicle's best off retaining its OEM setup.


This is a very difficult question to answer. Altering the airflow path before the airflow sensor can lean out an engine, which might improve performance, but cause unnecessary heat and stress. Without dynamometer testing with careful monitoring of Air/Fuel ratios, any changes are speculation.

Your current installation is probably particularly sensitive, since the filter shape has changed, and the distance to the airflow sensor is very short. Vortexes and boundary flows will not have much time to settle out, and may not be laminar flow across the actual sensor wire or film - which may cause significant discrepancy between measured and actual airflow.

Obviously you want the largest and coolest amount of air you can get, but figuring out this configuration will be difficult without a lot of repeated trial and measurement. "Bigger" is not always better.

The only other possibility is to closely copy a proven "aftermarket" system, but even this strategy has risks, as not every single aftermarket vendor is perfectly honest. [cough] Some of the performance gains printed on the box are at the cost of tricking the airflow sensor into running lean.

The truth is that the OEM airbox is typically of excellent design, and the Mass Air Flow sensor scaled to the particular characteristics of that design. Changing a filter element in the stock airbox to a different brand or style (e.g. K&N) will not likely be a problem if properly maintained.

However, redesigning a complete Cold AIr Intake system, without years of engineering experience, access to a dyno and other measuring/logging equipment, and a lot more time and money than the result would be worth, is simply not a good idea in my opinion. Also remember that you are ultimately limited by Engine Control Module programming and fuel trims, and you are "using up" the ability of the ECM to compensate for other variables. To truly take advantage of a modification that affects (and improves) Volumetric Efficiency, the ECM must be made aware of the modification and reprogrammed to reflect the changes in its air/fuel ratio and timing tables.

So... in order to make certain this really IS an answer, I would remove the conical filter, restore the stock airbox configuration, and purchase a bespoke K&N type oiled gauze filter to replace the stock pleated paper type. I honestly don't think that cone filter arrangement is going to help you. I do like the way it looks, but ultimately I doubt it will help, or perhaps even harm your overall performance.

  • 3
    I know that on some vehicles MAFs don't take kindly to oiled filters.
    – Zaid
    Commented Jul 11, 2016 at 20:27
  • In most cases, between the MAF, MAP, and IAT sensors, the small amount of air flow which will incur from having an aftermarket air filter will be made up for without tuning efforts. There is enough adjustability in the engine control module to make adjustments as to not cause any issues with fueling or going lean. @Zaid - It's over oiling which causes the issues (user error) I'd bet. If the oil stays on the filter, there shouldn't be an issue. Commented Jul 11, 2016 at 20:38
  • @SteveRacer thanks for the information, for your recommendations I think I'm going to sell it. It's not a bad brand, is a Ram Air (Made in the UK, handmade). But for what you are saying about the ECM who must be made aware of the modification and reprogrammed to reflect the changes. I think is too much for me, I don't know how to do it, and I don't want to touch the original car that much. Are you sure that I need to remapp o reprogram the ECM? Commented Jul 12, 2016 at 22:59
  • @Pablo Entrala - I'm not saying it will cause a huge problem; my point is that really signifigant gains will require ECU reprogramming. And my point about going lean is not about the ECU ability to compensate, it has to do with changing the flow path from the stock airbox. The OP's setup has the cone very close to the MAF, which may not be able to resolve vortexes and variations in the laminar flow at different CFM rates. Since the actual airflow sensor measures a very small portion of the flow and then scales it (guesses) at overall flow based on MAF internal diameter.
    – SteveRacer
    Commented Jul 13, 2016 at 4:03
  • If the airflow is now biased around the actual sensor, total airflow is under-reported and huge lean issues can result. A further problem is this increases performance, leading the customer to beleive it's working great - but without the realization that it's lean, hot, making NOx, and slowly eating up engine reliability if left unchecked.
    – SteveRacer
    Commented Jul 13, 2016 at 4:03

What you have done is the simplest and easiest install for these filters. Anything better involves some work and some custom parts.

You need to find space. What people often do is place the filter in the corners behind or under the headlights. To do this, you will need a longer tube, so find a generic tube of flexible material of the same diameter and attach it. Be careful about placing the filter too close to the ground, it can aspirate water when you are driving in the rain, and that's bad.

I would leave it there, since the original filter was there. If you are worried about hot air, you can install a piece of cardboard between the filter and the engine, it may help keep the hot air away a little bit.

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