air intake???????????????????
07-08-2002, 04:04 AM
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air intake???????????????????
hi everyone! i 'm thinking of getting some performance upgrade to the 350z when it arrives. but since i dont have much $$$ to get a turbo upgrade so i think i will just get an air intake system. but i got confused when i saw an "air intake system" and a "cold air intake system". can anybody help me to explain the difference between them? thanks!
07-08-2002, 08:03 AM
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With a cold air intake (or CAI, for short) the intake is enclosed and often shielded from the engine bay. The opening for this intake usually has somewhat of a direct path to "fresh" air from the front of the car. Describing an intake as Cold Air is somewhat misleading in some cases. They don't always get colder air, nor do they always have a benenfit over a standard aftermarket intake system. But this is a topic of much debate. The intake system on the 350Z is very close in concept to a CAI. The intake air is taken from the front of the car. But the stock system will most likely lean toward the restrictive side.
Another thing to keep in mind when upgrading the intake is the ECU. ODB II systems, like the one in the 350Z, will detect the increase in air flow. Then it will retard the timing, to handle the condition. Thus negating any benefit from the increased air flow. ECU tweaks will be very important in the performance gains from I/H/E (intake/headers/exhaust) over the long haul.
I'm sure others will have their thoughts on the subject.
JD
Another thing to keep in mind when upgrading the intake is the ECU. ODB II systems, like the one in the 350Z, will detect the increase in air flow. Then it will retard the timing, to handle the condition. Thus negating any benefit from the increased air flow. ECU tweaks will be very important in the performance gains from I/H/E (intake/headers/exhaust) over the long haul.
I'm sure others will have their thoughts on the subject.
JD
07-08-2002, 09:44 PM
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thanks alot for all that information! i used to think that the computer will add more fuel if more air flow in.... but then it seems not. thanks again! 
07-09-2002, 06:47 PM
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I don't think you will have to hack the ECU to see changes from I/H/E. The Spec V guys are getting 21 hp gains from a header/intake combo and Altima guys are seeing big increases from bolt ons also. Nissans seem to take well to tuning and respond very well to mods. You could probably get even more power with a tuned ECU, but it is in no way a prerequisite to making power.
07-09-2002, 09:43 PM
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Without ECU adjustments to get more fuel for the increased potential airflow, you're wasting your money.
You aren't going to notice 10-15 HP on a car with 287.
Save your money and avoid the go-fast crack pipe until you can afford real performance upgrades that are more than just fart noise.
You aren't going to notice 10-15 HP on a car with 287.
Save your money and avoid the go-fast crack pipe until you can afford real performance upgrades that are more than just fart noise.
07-10-2002, 12:08 AM
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And look at their "dyno" numbers. Not much difference to even care about. 3-5 hp is more likely "my dyno is calibrated, no mine is, no mine's corrected, no mine is" nonsense.
It's the same on every car forum in the world. Intakes and exhaust are almost unmeasurable without and ECU tune.
You'll hear a 100 stories, but in the end, it's always butt-dyno error.
It's the same on every car forum in the world. Intakes and exhaust are almost unmeasurable without and ECU tune.
You'll hear a 100 stories, but in the end, it's always butt-dyno error.
07-10-2002, 12:39 AM
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Originally posted by ITZBITZ
Without ECU adjustments to get more fuel for the increased potential airflow, you're wasting your money.
Without ECU adjustments to get more fuel for the increased potential airflow, you're wasting your money.
There are also ways to get around ECU changes for forced induction. You can add a boost sensitive fuel pressure regulator to up fuel pressure under boost.
Aftermarket ECU's that offer performance enhancements aren't there to dump more fuel for I/H/E. They have more aggressive fuel and ignition curves so that the AF mixture is run a little leaner at higher rpm's and timing is advanced a little more. It makes for a slightly less reliable engine and may not meet emissions standards.
If an intake offers no performance gain it is because it offers no extra air flow over the stock intake. Some are just well designed from the factory. If it ain't broke don't fix it.
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07-10-2002, 06:42 AM
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My current car has a header and intake with the stock ECU (due to the old ITS rules). I got a nice increase in mid range torque and peak HP. So while an ECU upgrade (and exhaust upgrade) helps maximize the performance of these parts, it certainly isn't a prerequisite.
BTW: I had my butt calibrated recently so I know what I’m talking about.
BTW: I had my butt calibrated recently so I know what I’m talking about.
07-10-2002, 07:04 AM
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JDZ,
Maybe Nissan is different, but I know that other NA cars that run ODB II ecu's see very little if any performance after a period of time. It appears that the ECU "learns" and after some period, it begins to retard timing, thus negating the benefits. Unfortunately, I don't know all the specifics so I can't tell you more. The IS300 guys buy the Area 51 or SRT intakes because they come w/ reprogrammed ECU's or piggybacks. I wish I had the full technical explanation for you. Also, I don't know if it is for sure a problem with ALL ODB II cars.
JD
Flying-
Does your car have an ODB II?
Maybe Nissan is different, but I know that other NA cars that run ODB II ecu's see very little if any performance after a period of time. It appears that the ECU "learns" and after some period, it begins to retard timing, thus negating the benefits. Unfortunately, I don't know all the specifics so I can't tell you more. The IS300 guys buy the Area 51 or SRT intakes because they come w/ reprogrammed ECU's or piggybacks. I wish I had the full technical explanation for you. Also, I don't know if it is for sure a problem with ALL ODB II cars.
JD
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Does your car have an ODB II?
07-10-2002, 05:00 PM
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Hmm. I've heard people speak of this problem with OBD-II but I haven't modded an OBD-II vehicle before so I don't have any experience. I'm kind of skeptical because I've never heard a logical explanation of how the relearning occurs. Also, people are usually speaking of SOTP (butt dyno) loss in performance in the discussions I've seen. I always figured that they were just getting used to the added power.
07-13-2002, 04:01 AM
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I don't see how OBD-II has anything to do with negating the effects of a air intake modification. If the intake truely allows more air to the engine than a stock unit, the ECU will figure out on its own that more air is capable of being moved into the system. Now if the amount of air is more than what the air/fuel maps of the ECU contain, like forced induction, then yeah, some retardation of timing or pinging may occur at high RPM just because the ECU doesn't know what to do. For most cars, a simple intake is not going to exceed the ECU's air/fuel maps, and will not be a problem. A increase in performance will be realized if indeed more air is flowing through the engine.
07-13-2002, 12:08 PM
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so a bigger air intake will help right? (not counting how much hp increase) so how about the filters? does an oil filter create less air flow than the paper once? and does anyone know what kind of air filter that will come with the 350z ? ( i guess it's the paper one but i just want to make sure. i sometimes like surprises but sometimes i dont... just wish it's K&N's oil filter!) 
07-13-2002, 05:29 PM
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CAI or just Cone filter will help..
The ecu can change it's fuel map automatically within a certain range, when it detect more air flows. It has some kind of map sensor, that can detect atmosphere pressure.
Another bonus is that you don't have to buy filter every 6 months - 1 year or so, since you can just wash them and reoil them. Save you $$$ in the long run.
ONe last bonus is that you get the thoraty sound when you put the pedal to the metal!
Another bonus is that you don't have to buy filter every 6 months - 1 year or so, since you can just wash them and reoil them. Save you $$$ in the long run.
ONe last bonus is that you get the thoraty sound when you put the pedal to the metal!
07-15-2002, 03:09 AM
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There are gains to be had.... My expirience is from my VQ powered Maxima, which should be similar to the 350Z's.
I would say a intake alone added 2-3 hp, no big deal. The catback exhaust added a few more, but a y pipe (header/downpipe) with the 2 added 20+hp. I hace never dynoed my car, but it pulls so much harder it is unbelievable.
I think the ECU will adjust, and try to add more fuel. On occasion (spirited driving) my CEL will come on indicating a rich fuel mixture. I am no expert, but I would guess that ECU is increasing fuel, and does so to a point that it adds more than the amount that it takes to trip the sensor. The ECU only thinks it is running rich because it has added so much fuel to compensate for all the extra breathing. There are no other signs of the car running rich, ie build up on plugs....
I would say a intake alone added 2-3 hp, no big deal. The catback exhaust added a few more, but a y pipe (header/downpipe) with the 2 added 20+hp. I hace never dynoed my car, but it pulls so much harder it is unbelievable.
I think the ECU will adjust, and try to add more fuel. On occasion (spirited driving) my CEL will come on indicating a rich fuel mixture. I am no expert, but I would guess that ECU is increasing fuel, and does so to a point that it adds more than the amount that it takes to trip the sensor. The ECU only thinks it is running rich because it has added so much fuel to compensate for all the extra breathing. There are no other signs of the car running rich, ie build up on plugs....
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