When should I change my air filter? 13500 miles on the car. Have most of you went with the oem are aftermarket.

 

Service schedule says to check the percentage of the air filter life every 12,000 miles/1yr. They spec no hard mileage or time which kind of makes sense. Someone who drives in a very low-dust area is not going to need to replace it as soon as someone who is in a very dusty/pollen-filled environment. Based on the vast majority of other cars on the road, 3 years/36K is probably a good ballpark for how long a factory air filter will last.

 

I changed my stock air filter out for the Lavenza 'Blue' air filter that was all the rage a few years ago while I was waiting for my C8 to be delivered..Since then a few more companies have released filters,or even complete air box replacement kits..The one I have read about, and has impressed me is the Haltech Hornet..if the gained horsepower numbers are to be believed.

 

Every 4 years or 45K miles if your car doesn't have a monitoring system.

 

I've always pulled the air filters out every 10K miles. I put Vararam CAI's in my C5, C6 and later my C7. I also bought a air filter cleaner kit and used it to clean the filters. It works great. But with my C8 I put in an Attack Blue filter, which I can use the same cleaner kit. The Halltech is impressive but it's also more money that I wanted to spend at the time. Just my 2 cents.

 

I put in an Attack Blue filter at 7000 miles when I caught a sale on it.

 

I have been holding out for more dyno results. With what I have seen from so many vendors, their dyno graphs look very suspect to me. Especially when the graph is just moved up +10HP across the board.

 

This is what I now have

 

I have seen a couple independant dyno tests and they resulted with about 5 hp above 5200rpm with the AFE dry or oil and Attack Blue filters. Don't expect to feel any difference in power, I did not. I would wait until the oem filter needs replacing, then opt for an AFE dry or Attack Blue filter. I am not convinced the aftermarket air intake systems are worth the money.

 

Read Your Owners Manual !!

 

Not sure if I get any additional HP but I do notice a little improvement in sound to my NPP exhaust with the Attack Blue. At first I thought it was just me but my wife asked what I did to my exhaust so then I knew it wasn’t just me. Wasn’t necessary to change at the time I did it so can’t respond directly as to when you should decide to make a change other than what’s in the owners manual

 

I intend to replace mine with an OEM filter. From the owner’s manual:

 

Dont use a cleaner kit for the Attack blue filter. Its a dry nanofiber filter but you can still wash it and reuse it! The great thing about it is you only need soap and water.
Don't use oils, chemicals or cleaning kits. Otherwise you will absolutely ruin the filter.

 

Dyno results used to market products is a dark hole. If you have any experience with the "commercial" dynos out there, then you know you can make them output just about anything you want it to show.

Aftermarket CA Intakes are interesting. Funny with all of the real engineering that goes into a high performance car's intake (so it is NOT the gate to airflow), that immediately after introduction along comes a whole group of aftermarket companies claiming to have beaten the factory engineering team. This is the same with EVERY high performance car manufacturer out there - Porsche, AMG, BMW, Mustang, Corvette, Camaro, Lamborghini, Ferrari, Aston Martin, Dodge, Plymouth, etc.

Ask yourself - why are ALL these engine designers so lame they cannot get an intake system done? And yes, agree with @dohabandit, funny how the performance numbers are always just enough to be "under the radar" so to speak. Not enough gain to really feel it, not enough gain to challenge it if you feel you didn't get the 10hp. It's low hanging fruit in the aftermarket, right next to exhausts.

In a way, I don't begrudge these companies for selling their wares. It's entrepreneurial, it's the American way, and as long as the buyer feels it in the butt dyno (where there is a direct correlation to the butt wallet - the more spent, the more power can be felt), I'm glad they're making money and employing people.

 

Use the OEM air filter.
"High performance Air Filter" Is a misnomer.

You are likely to believe that it has something to do with increasing power, but actually a high performance filter will maintain or reduce power, because it filters more effectively and improves PCV action at WOT by providing a pressure drop.

If removing the filter or installing a less restrictive filter increases power above OEM due to mitigating pressure drop, it would reduce PCV WOT function for non-dry sump engines and reduce the life expectancy of the engine.

 

I don't think quality aftermarket air filters reduce any power, but they have shown on independant dynos of 3-5 rwhp above 5200rpm. How much do you think PCV WOT pressure will be affected with such miminal gains? How about air restriction between new vs dirty air filter?

 

I think you misunderstand the way I'm using performance. If you purchase a high performance air filter for your home, what does the word 'performance' implies for your health? It has nothing to do with power, yet the filter may still be a 'performance' filter because it is cleaning much better than other filters. That is why the 'high performance air filter' is a misnomer; The aftermarket uses the terminology to sell filters, it is confusing and misleading and not necessarily to help clean your engine.


I think 3 to 5 hp is negligible. You can run the car back to back on a dynometer and see a similar or larger loss.
For example here is a C8 with a procharger run twice in a row.


When we are + and minus hp from environmental conditions, temperature, viscosity, etc... basically 3 or 4% of wheel horsepower (5% bhp~)
(remember higher temp = lower viscosity = more power delivered)
These factors interplay in a way that cannot be accounted for on the basis of just 5 or 10hp.

In other words, I wouldn't sacrifice or even risk the quality or longevity of an engine over 5 or 10hp. There is hp coming and going due to temperature related variables. Not to mention friction and situational basis as tire compound (different tires react to heating differently) and road conditions (not all surfaces are equivalent even on a track on the same day) which further plus or minus final tire force and energy transfer, these are normally negligible considerations but on the basis of 5hp or 10hp they are worthwhile in magnitude since we are discussing 5hp and 10hp differences, those variables as viscosity and friction are in that range of gain and loss.

What I am confident for
1. All engine crankcase needs to see a vacuum at wide open throttle, however slight, 0.5" Hg is typical
2. The OEM develops their air cleaners with a specified, intentional pressure drop over some mileage which can promote crankcase evacuation
All OEM does this, from Toyota Corolla to Nissan Altima to Honda whatever, there is an intentional design plan for promoting high mileage and crankcase cleaning action on behalf of the PCV system and it's units are on the magnitude of 0.5" Hg or fractions of a PSI, easy to disrupt from leaking and modifications.



The pcv system is easy to disrupt. Air filters are notoriously easy to sell and install and the engineers of the original intake system went through great lengths to develop a system which they are confident will protect the engine.

I am reminded of a post I read once

https://www.corvetteforum.com/forums...post1604771349

 

When aftermarket air filters advertise themselves for " performance" increase they are almost always referring to a flow improvement or restriction reduction. They don't tend to care about increasing filtration over oem nor do most any claim do (because they don't)

The downside to this flow improvement is almost always reduced filtration (in which 4 layer oiled cotton gauze as well as dry synthetics will most certainly do). But how much filtration you need to keep the engine free of damaging silicates for 50k or 100k or 400k miles is debatable and also variable considering environmental factors.

Nonetheless there should be zero need for pcv modification. As you pointed out the difference in flow and power between a stock paper filter and even a gigantic and extremely low restriction single layer synthetic is probably 5hp or a minimal amount of kg/h air volume that would be exceeded in multiples by just driving the same car with the same hardware in 40f sea level density altitude to taking it to 100f 6000 foot altitude. The vehicles SAI and PCV system is already designed to operate within that very significant variance in pressure and much more.

 

Let's look more closely at this claim, and I agree, this is the reason for selling these aftermarket intake systems.

With an NA engine the laws of physics play a clear part. An NA engine can only ingest a maximum volume of air based on these laws. Air intake need on the LT2 is not infinite.

A formula that I think is simple enough to convey the message is - Airflow (in CFM) = (HP x 0.625) x 1.1104.

If I apply it to the LT2 at 495 hp I get (495 x 0.625) x 1.1104 = 343.53 CFM to satisfy this engine's air volume intake needs.

I'm making an assumption here, I cannot imagine the engine design team created an intake that would fall short of the need to flow 344 CFM of air to feed this engine of all the CFM it can use. That includes the filter element and the charge tubes, intake manifold, etc. If I am wrong, then there MIGHT be merit to an aftermarket "filter" that flowed better or was less restricted.

On an engine which I have a lot more practical "hands on" experience, the 4.0L Hot V engine (an FI engine) used in the MB AMG GT, GTS, GTR, GTR Pro, GTR BS, and beyond, The stock air intake system (and filters) is the same used on all these models:

GT - 456hp
GTS - 505hp
GTR- 550hp
GTR Pro - 575hp
GTR BS 720hp
And at least one aftermarket build of 1100hp 4.0L Hot V using the factory air intake system. So, assuming the AMG factory engineers designed an intake system to flow enough volume to satisfy all of these HP ranges and beyond, some "naive" owners of GTs and GTSs fall for the aftermarket intakes that cost well into the $thousands, and cut off the factory one BC slick marketing leads them to believe the aftermarket really caught the AMG engineering team sleeping and their aftermarket intakes offered more air flow, or less restriction.

 

Maybe, maybe not. ... Probably

The important thing to note is we cannot make any extrapolations from another platform.

The only way to determine our air intake systems efficiency and efficacy is through complex modeling and ultimately rigorous controlled condition testing.

Sometimes a filter element helps improve powe a bit. Sometimes it doesn't.

Sometimes the airbox itself had a volumetric limitation. Sometimes it doesn't

Sometimes the flow path is not optimized. Sometimes it is.
Sometimes the intake temps get influenced negatively by intake routing or design, sometimes they dont, or sometimes an oem mitigation technique is used and works.... sometimes it partially works, sometimes it doesn't work much.

But yes in a perfect engineering world merely changing the filter "shouldn't" free up much power but of course we don't live in a perfect engineering world.