Derestricting Intake Air Flow

[mikeross]

Seems like a lot of work, re-work to the stock air intake. I am sure Hyundai would classify such modifications as warranty VOID. I am from the school, if Hyundai wanted unrestricted air flow that bests performance & economy they would have. No matter how much air you let in, the computer controls what the engine receives.

If this is the case, would they need to reprogram or alter the mass air flow sensor in order to do that?

 

[Rey]

Mikeross,
All modern cars computers are constantly adjusting fuel ratios to achieve a constant 14.7 air fuel ratio in closed loop mode. This adjustment is done through the mass airflow sensor (MAF) and oxygen sensors. When the exhaust/intake are derestricted more air is allowed to flow, and the ECU adjusts adding more fuel to maintain the 14.7 ratio. The range of adjustment is not infinite, but I have never seen its limits reached in any vehicle with just intake and exhaust mods. If the limit is reached your check engine light will illuminate indicating an overlean condition.
At wide open throttle the motor goes into an open loop mode wherein fuel is liberally dumped into the motor without regard to maintaining a certain air fuel ratio. This is a stock overly-rich mixture as low as 10:1. Derestricting has the effect of leaning the open loop mixture to a ratio to a better mixture for power.
I have a fair amount of experience derestricing GM motors in the LS series which power contemporary Corvettes. I have always, always seen more power. Intake derestrictions of about 8-10 hp, cat back exhaust about 10-12 hp and headers 10-20 hp, depending on collector length. Bear in mind that a stock Corvette intake/exhaust louder than a stock Hyundai, which would appear to indicate less restriction in a stock mode.

 

[radicaltimes]

Unless you have a turbo or supercharger there wouldn't be any gain to hacking up the fresh air intake system. It should flow more than enought CFM for the motor. Take a look at a C5 Corvette. Where the air tube goes over the radiator. You would think it wouldn't be large enough for 405hp and up.

 

[Rey]

No doubt motors can run and survive with very restrictive intakes, and have done so for generations. This is not to say they "run" just as well restricted. Motors are air pumps and any intake restriction causes power loss, which is commonly referred to as "pumping loss".
To cruise at a steady state on flat ground requires very little power, and pumping loss is just a small fraction in that power requirement. My personal experience is that reducing intake and/or exhaust restrictions does increase highway gas mileage. It is not a lot, more or less in the vicinity of 1-2 mpg. In town driving with short trips and stop and go is almost impossible to compare.
I am sure that manufacturers have the ability to measure power at cruise speeds while under load, but tuners using modern dynos run at wide open throttle. Tuners always see power increases with exhaust/intake derestrictions, particularly if the motor is as restricted as the Hyundai is in stock condition.
Where derestrictions are most felt and most practical is in high-speed passing. Most people these days use interstates exclusively for inter-city driving, for which passing power is unnecessary.

 

[TexasGenesis4.6]

I know I'm new to this site, but I see a lot of non-empirical evidence behind some of the claims, especially on this forum. I don't want to sound like a know-it-all, but I've done some extensive modifications on vehicles (2003 Dodge Ram HEMI and 2005 BMW 545i) and although that doesn't make me an expert, some of this airflow talk is repeated over and over on the forums of the previously mentioned vehicles.

Question/Answer #1
You must change your ECU to get more power (at least from the airflow side of things). Empirical evidence: track-side install of a cold air intake (CAI) (I wish they had one for the 4.6) on a 2003 HEMI. Before changing airflow I ran consistent 10.18s in the 1/8th mile. Installed CAI same night so no change in temp or wind factor, consistently ran 9.8. So changing the airflow DOES have an effect without having to change ECU. You can also look at a dynometer when switching to a CAI and notice the power torque curve. I agree with MotorSportsAuthority, it's a ratio.

Question/Answer #2
What is that filter thingy on top of the airbox for? It's to filter out exhaust fumes coming back thru (I can't remember the exact definition) the airbox either when the car shuts off or starts up (like I said, I can't remember). I did the same thing Rey did on my BMW, I removed this on my BMW also. Some of the hesitation from the throttle-by-wire was eliminated from the Bimmer. It is a know alteration on the BMW forums, but I'm not sure there is too much difference.

I can say that I haven't even begun to look at the engine compartment of the Genny yet, but I've only had the car 3 weeks. I traded the HEMI for this vehicle and I can say that I don't miss the truck at all.

 

[bradyb]

Exhaust generally in a normally aspirated car does not get you a gain in horsepower. If exhaust restricts flow it may reduce heat sink which will not increase hp but prevent the loss of hp.

Ask any Vette owner who has gone through the exhaust game - much money, no more power but a better look and sound.

I respect your experiences with your 'vette friends. One of my favorite cars and a previous owner too.. I feel you are correct, if exhaust is too large it reduces savaging properties, in which the exhaust pulses and heat combine to extract the exhaust from the system, there are several wraps and ceramic coatings to help with this process. when this process is reduced you loose torque big time.

However this forum is about the Genesis. Although the 375-385 HP Tau V8 is a fine world-class motor there have been some manufacturing "compromises" two of which are intake and exhaust. For some reason Hyundai seems notorious for adding pich-points and hard bends to their exhaust systems.

I have done some simple modds k and n, wierd flap elimination, and a borla cat-back system. After Borla had the car on the dyno they realized an increase or 17HP and 22FTTQ, at the wheels. There is a huge difference in drive ability with the car. After the intake modds power was slightly more intense. I've reduced my 0-60 from 5.5 to 4.8 secs. not too bad... oh mileage went up too.

anyway my point is simple. Not all manufacturers extract all the power from their power plants. There are compromises to be made. For an example spending 1000 on an exhaust for an evo mr may not yield much if anything, an expensive cat back on a factory v-6 sport sedan?.... header and stinger combo for a cal-bug?

perhaps there is some power to be found

 

[BigBadGenesis]

^^^Is there any drone with the Borla or any compliants with this exhaust?

 

[jeder9999]

Has anyone tried to eliminate the air chamber aft of the air filter and before the throttle body? Doing so would create a straighter, more direct path for the air into the engine. I am a former G35 owner, and a very common mod was to do this by purchasing the "Z tube" -- the intake tube off a 350Z that did not have this extra chamber. Matter of fact, Stillen sold them, it was such a common mod. It appears that our chamber is held on by a screw, and that the inlet to where it connects to the main air intake tube could simply be capped off.

 

[darrell]

It's a foam filter housed in a plastic mesh housing located directly above the removable paper filter. It's a back up and isn't meant to be changed. You forgot fuel filter (which is in the fuel pump inside your gas tank. The Fuel tank air filter, filters fumes when you are filling up your gas tank, you never need to change that unless...and this is gross....spiders (and sometimes rodents) crawl down in there and like to build nests. They block the vent that lets the gas vapors escape when you are filling up your tank. Often you will be unable to fill the tank in one shot and will have to continuously hold the gas filler tube neck and manually fill the tank instead of just setting the nozzle on autofill.

This is a intermittent problem I have had since first owning my Genesis.
Where do I find this filter?

 

[Big Ben]

Has anyone tried to eliminate the air chamber aft of the air filter and before the throttle body? Doing so would create a straighter, more direct path for the air into the engine. I am a former G35 owner, and a very common mod was to do this by purchasing the "Z tube" -- the intake tube off a 350Z that did not have this extra chamber. Matter of fact, Stillen sold them, it was such a common mod. It appears that our chamber is held on by a screw, and that the inlet to where it connects to the main air intake tube could simply be capped off.

I got my K&N filter in last night and removed the sponge and flapper in the air box - it was a perfect fit. I expected the exhaust to sound different but it did not. I have added a K&N cold air intake to my vehicles for the last decade and it has made a difference - better gas mileage and more power on both of my honda accords (I4s) and both of my dodge durangos (V8s). I heard the diffference through the stock exhaust as soon as I fired them up. This was just the filter though but the engine runs much smoother. I drive over 100 miles round trip to my office and back each day so will let you know if I get better gas milege.

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[bradyb]

^^^Is there any drone with the Borla or any compliants with this exhaust?

drone with the Genesis+Borla cat back is noticeable at low rpm and slight incline with the driver pressing into the gas pedal.

when in the appropriate gear the is NO drone or cabin resonance. Borla actually tuned this exhaust to the car and cabin to maximize power and minimize internal noise....

~B

 

[Driv200]

Don't want to take away from this good info, but I have just done a CAI on my Rspec and thought it might offer some suggestions. I attached dyno gains. Vids further down in the posts.

http://www.genesisowners.com/hyundai-genesis-forum/showthread.php?t=8919

 

[jeder9999]

Does anyone have any ideas how I could cap-off the inlet tube where the secondary airbox/silencer is, just in front of the throttle body? Today I removed it and measured the inlet. 1 13/16" ID and 2 3/16" OD. There is a thin rubber gasket on the plastic flange, so a cap around 2 1/4" would probably work. If anyone can suggest where I can buy a cap in that size, and what material, I will be the guinea pig and try it out. The sleeve length on the cap would need to be roughly an inch, so that the existing clamp (or a different pipe clamp) could fit around it.

The secondary airbox/silencer is attached in 2 places, both with a 10mm fastener. It came off and went back on very easily, so NP to put everything back to normal for dealer trips. Took me about 30 seconds.