I don't get it. I read an older thread about how these mods will increase MPG. If supposedly RPM's don't change with a Y pipe mod (I didn't notice any drop with mine), how does the car save gas? If the Maxima is traveling at 40 mph, and the RPMs are the same as before, wouldn't this mean the car is working just as hard as before? So where does the increase MPG come in if the car is working as hard as before?

 

Maybe because the extra airflow helps burns the gas better or something? I dunno..

I never noticed a difference.. I burn more gas with the Y-Pipe because I tend to excelerate faster now to hear the sound..

 

I'm starting to think that maybe this is some kind of a marketing scam so that people like me say, "Wow! I can get more power and better gas mileage! This means my pipe will pay itself off from the extra gas saved over time!"

 

Yeah. Works great in theory, but not reality.

 

probably not???????????
cause if u got more air u gonna need more gas. i think dont know cause dont have a y pipe.

 

I didn't notice a significant increase in fuel efficiency. But the theory would be that the engine wouldn't work as hard to get to a specific RPM. You won't notice a dramatic increase in fuel efficiency because the ECU control the fuel delivery. Just be happy with the power damn it. If you're gonna worry about fuel efficiency.. Buy a metro.

ZuM

 

I am happy with it sucka. I just don't understand how it would work for the MPG side.

 

It just gets rid of a restriction. If you have an intake. Its air.. easy in, easy out. It makes the motor a more efficient pump.

ZuM

 

The Y pipe makes your engine work more efficently. Thus more power is avail for propelling the car. If you can keep your foot out of it, your mpg should go up. But in reality, the go pedal gets the better of you.

 

I noticed quite an increase in highway mileage after I got my JWT intake. I use cruise control all the way on my trips from SF to LA, and when I arrived I had over a quarter tank of gas left. Usually I'm below the quarter tank mark. I didn't notice any increase with my y-pipe though.

 

Actually with intake, Y-pipe, and exhaust and such will DECREASE your MPG, even though your motor is more “efficient” making more power. This is likely because ECU programming may be required to make these mods increase mileage.

I've had all these mods and tested.

 

I think you just contradicted yourself. If the engine is more efficent, it quite obivously should better gas mileage. Let's look at it this way. If a given engine is 55% efficent bone stock. Ie.. it takes xxx hp at xxx rpm to make the car go a steady 60mph. Now if you add the intake, Y and exhaust system that is PROPERLY matched for the car, let's ASSUME it makes the engine 65% efficent. Now it only takes xxx-10% at xxx rpm to keep the car going at a steady 60mph. I would assume that the more efficent car would require less gas to keep the car running at that 60mph right? This is a very loose example but I hope it illustrates my reasoning.

 

anyone NOT read what Jeff is saying? By adding a less restrictive intake (w/ a velocity stack), a less restrictive exhaust that is better able to utilize the exhaust pulses, yada yada yada, you WILL increase your gas mileage because you are increasing the engine's volumetric efficiency. You are able to stuff in more air into a given space (the combustion chamber). So when the car is in close loop mode, the car will run more efficiently and not decrease gas mileage. Only when you go into open loop mode will the car demand more fuel due to the increase in air flow along with the increase in cam/spark timing. I've got fuel records on the Z dating 3 years back and I can show you the gas mileage increase after the intake install, then again after the exhaust install. I can do the same for the Maxima.

 

I'm just curious as to the "sound" these mods make. I currently don't have either on my Maxima, but would like to know. Is it noisy at idle speeds, or only over 3000 RPM, or what? I kind of like the quiet sound of my Maxima, but I know that means more restriction. Any input?

 

If you keep your stock exhaust. You shouldn't hear the Y-Pipe much at all during normal driving. The same pretty much goes for the intake. But when you go WOT. The two will sing in harmony. =) My car makes a roar with a background of a hiss. Pretty freaky sounding.. =) But during normal driving. You don't hear much with the radio on. You will notice a slight change in engine tone with the intake. But its a change in tone. Not really a change in volume. You have a 3rd gen. So what I say may not completely apply to you. But it should be about the same. If you really like your car very quiet. Stick with stock.

ZuM

 

Jeff92se, I did not contradict myself. Did you see the quotes aground efficient? Now, if your drive at WOT most of the time, or a good deal, like many people on the board, your gas mileage will DECREASE.

Believe what you want, but I have the figures. It would be nice if these logical equations worked, and again, I’m sure with some ESU tweaking it would, but depending on drivinng contitions. There are so many other variables you left out, its not that simple. It takes more gas to make more for example, not just more air, and million other conditions.

Anyhow, now any added MPG I got while in cruse speed/normal driving was more then lost when stepping on it.

For example, if you tend to race a lot, likely you do if your adding these perfromance mods, you can race the exact same amount of times and duration after these mods, and your gas will be gone faster. Try it your self, and you'll see.

 

Tex, sorry man. Didn't mean it to turn into an argument. Yean I agree w/ you 100%. If after mods, you give in to the urge to got WOT, yes by all means the mph will go down. But the thing is I already mentioned that(in a previous post) so I thought that must have not been your reasoning. Actually even w/ ecu tweaks, if you go wot, the mileage will go down. Can't really change that fact. At WOT the fuel/air ratios are pretty rich so = more gas!

 

Yes, and I was saying it will go down even more at WOT with the mods. And we all know most of us drive more at WOT then not