A&Q about 350Z
Q:
Joe is correct. Given a car is cruising at 60mph on a flat surface it takes X amount of hp and torque to keep it at that speed. Now when you install the k&n filter which flows more which means it produces more hp and torque what happens is now the car doesn't have to work as hard to maintain 60mph. Not working as hard means you save on gas. Mods that in general improve gas mileage and have been proven is intake, exhuast, high flow cat, headers, pulleys, light weight wheels, light weight flywheel, light weight drive shaft, reduce curb weight, anything to reduce friction inside the engine such as balance and blueprinting, port and polish (which also helps fuel atomization). Things that hurt gas mileage in general are cams, adj. FPR or rising rate FPR, larger injectors, higher output fuel pumps. Of course most of this stuff has to be in sequence. As for computer chips or reburned ECU's some help gas mileage, some don't affect it, and some hurt gas mileage. Back to the topic at hand, a cold air intake or k&n drop in style filter will not hurt gas mileage but rather should help. Any restrictions in the breathing system of the car will help gas mileage if the restrticion is lessened which is why intake and exhuast can generate up to 2 mpg savings.
1977 280z: Intake, exhaust, high flow cat, header, euro damper, cam, MSD, adj. FPR, 3.7 lsd, F+R sway+strut bars, 2580lbs
1984 300zx: intake, exhuast, high flow cat, headers, JWT ECU, F+R sway bars, F strut bar
06 WRX TR
A:
I think 1z is correct. Your explaination is fine, but as 1z pointed out you're not taking into consideration the electronics or "ecm".
Once the paramaters are programed into the ecm , such as air temp., air velocity and or mass, math takes over. Once you change a parameter, like unrestrict the airflow, the ecm compensates by adding more fuel. The ecm is not "smart" it doesn't know that you have added a cai. It knows that you're moving more air past the maf sensor and it had better add fuel or your car will go lean. I think the problem here is that you believe this to be a simple air / fuel mixture equals horsepower ratio. If we were talking about a carburated engine and you added a cai, your mixture would be lean, you would have to add fuel. Thats exactly what the ecm is doing on a fuel injected modern car. Adding fuel and lowering miles per gallon.
A:
If you want to increase mpg you should buy a "tornado". this restriction in the airflow causes the ecm to lean your mixture givin you more mpg. (because the computer senses less air is flowing) It's the opposite concept as the cold air induction.
NNA runs this site!!!
A:
hmmmmmmmm...I was heading into joe's corner, but now I am not sure. My initial belief was just as Joe states about increased air induction, etc. In my case I actually drove the Z harder in my first 400mi trip W/O pop charger ( better gas mileage) , than I did on same trip the second time w/pop charger installed. 2nd trip, I set cruise to 80mph, and pretty much kept with the setting. I am still wondering about the cold air/hot air question ? By the way...what does CAI stand for?
'06 Silver Alloy 350Z Touring
A:
cold air induction.
also the colder air is the denser it is, the denser it is the more you can pack into any given space, hence more cold air now means you (the computer)can add more gas which in turn now means more hp.
the maf senses air temp, air velocity and or mass flow. all of theses factors help the computer decide how much gas to add to the mixture...........
a cai that allows hot air in prolly counteracts the hp gain you would have gotten if the flow was colder.
hence some of you (jwt popcharger people) prolly get better gas mileage with a cai, simply because of the hotter (less dense) air
NNA runs this site!!!
A:
CAI= cold air induction. Do a search on the net for how stuff works related to intake and you'll see that a better breathing filter will increase flow, hp, and gas mileage. As for your test Zoom a lot of things could have been different between your trip. There could have been a slight gradient change going home or the wind going against you or it got hotter outside, etc. When I commute to school I can't compare the trip to school vs the return trip. On my commute there is a gradient change, there is a wind change, I leave at different times of the day, I tend to drive harder going home to get there faster, etc. Like I mentioned in my post I've done the intake upgrade on several cars of all different years and engines and have only ever seen an increase in mileage. I've done it on my 77 280z EFI, 84 300zx n/a, 73 Ford Maverick carb. 302, 91 T-bird 302 HO, 94 B2300 mazda truck, 2001 Mitsu galant 2.4 cyl, 99 dodge dakota V6, 99 toyota Tundra V8, 96 Rodeo V6. Every single one of these cars gained at least 1mpg. A few of these cars had exhuast systems added later which only increased gas mileage more.
As for running leaner, sure you will burn less fuel but you also lose power. By losing power it then takes more work to keep the car at a constant speed. Increase the power and it takes less work to keep the car at a constant speed. Yes fuel mixture is increased but as mentioned the computer compensates to keep a balanced air/fuel ratio. You only start losing gas mileage when you have a really high air to fuel ratio. First off a CAI won't affect the air fuel ratio by anything significant on a stock or close to stock car. Second with the modern ECU's these days the computer compensates for it. It's like how people report thier car gets better gas mileage and more power when it's colder outside. Lastly the only way I can see a loss in gas mileage is if you put on a CAI system that was proven to lose hp over stock. If you remember correctly when the CAI systems started popping up for the 350z many of them actually lost hp over stock. People fail to research mods before doing them. Having a loss in hp would mean it requires more work to keep the car moving which means a decrease in gas mileage.
1977 280z: Intake, exhaust, high flow cat, header, euro damper, cam, MSD, adj. FPR, 3.7 lsd, F+R sway+strut bars, 2580lbs
1984 300zx: intake, exhuast, high flow cat, headers, JWT ECU, F+R sway bars, F strut bar
06 WRX TR
A:
i'm still sticking with Joe C...
because this is what i believed for the longest time...
but i get what you mean 1Z... guys try this... i've already done it just messing around...
take off your filters... and don't cover the intake but restrict it... because covering it would suffocate the engine and it would die anyway... but as you feel the suction on your hand... (preferably... i'd hate to see someone suck a sock or a rag in their plenum)... you'll notice the engine dies down... now aside from the obvious... engine suffocation... is the MAF sensing that there is less air coming through and cutting the fuel... or is it just making it too hard for the engine to breath???
ok now here's another senario...
especially for you popcharger guys... if you simply change the filter element... you ARE NOT CHANGING the tube DIAMETER... therefore you ARE NOT allowing more air to reach the intake manifold... you are simply making it easier for the engine to obtain the air...
now... if you were to swap for CAI... and assuming it did have a larger diameter... aside from the amount of air running across the MAF... how is it going to know if the pipe that the air is flowing through is larger?
my answer is: it's not... it's simply going to think that there is (X) amount of air running across the sensor and (X) amount of fuel is needed... becuase unless you tune the ECU to the new air fuel ratio dependant on the CFM that the intake is capable of... the MAF is going to assume that it is the stock diameter... because like you said... the ECU is not smart... it just does the math... now that in my belief is what would get the engine to run lean...
so what i'm saying is... changing the filter is going to make the engine suck in air easier... not allow more air... with the stock intake the engine will still use the amount of air it is designed for it's just going to not have to "work" as hard to get it... making it less restrictive...
now what do you guys think?
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I don't think, I know...
Well, I don't think you know either
Post Edited (Sep 14, 8:40pm)
A:
Wow, guess everyone has forgot a few things here at cruising speeds what A/F ratio are you generally at? Thats right 14.7:1 doesnt matter how much air you take in if you're cruising at 55mph with a stock intake the car works to keep the A/F ratio right at that mark. If you have a CAI the car works to keep its A/F ratio right there as well. Now which one has to do less work to keep that A/F ratio? Exactly point proven.
Currently parting out 1990 300zx TT.
A:
Damn...now I don't know what to believe. All the above comments make some sense to me, but obviously someone is right and someone is wrong....or are they? I'll just keep driving and enjoying the ride !!
'06 Silver Alloy 350Z Touring
A:
actually guys, on some sites, especially the acetone websites, they state that colder air actually decreases mpg, due to less fuel being burned efficiently due to drop in temperatures, but an increase in hp due to denser air going into the engine. When its warm outside, the fuel burns better, and you use the gasoline more efficiently, and it makes sense actually, in my TT, in the winter I get less mpg, but in the summer it shoots up quite a bit, though on hot days I can feel more lag on the turbos, but on chilly mornings, I get an extra 2-3psi on the turbos, and its damn fun!
'93 Red TT 5 speed; Bone stock for now, but still kicks ass!