CAI: Affect on MPG

jt14894 · Jul 16, 2005

Hi all,

I'm a recent new owner and I've been searching and researching the various posts on which CAI is best. So far I've narrowed it down to JLT, C&L and Steeda. They all have their advantages and disadvantages, but they all seem to show some definite gains in HP, RWHP, and torque. The one thing I am curious about is MPG, since I definitely want to make this pony a little more fuel efficient, in addition to increasing performance. For those of you who have the JLT, C&L, Steeda or any other CAI, how much has it affected your MPG?
I prefer to use 87 octane, since gas prices are sky high, so by tuning it to 87 will I get similar performance and MPG gains to 91 and higher octanes?
I appreciate your input.

BlueJoker · Jul 17, 2005

subscribing...

jt14894 · Jul 17, 2005

BlueJoker said:
subscribing...

Sorry! I'm not following ya!

chrisfowler99 · Jul 18, 2005

jt14894 said:
Sorry! I'm not following ya!

He subscribed to the thread to monitor replies.

IE: He's interested in the response too. (as am I)

jt14894 · Jul 18, 2005

chrisfowler99 said:
He subscribed to the thread to monitor replies.

IE: He's interested in the response too. (as am I)

AAH! I see. I'm still relatively new to the forum so I'm still learning a few things like these.
Thanks for the info.

Alec · Jul 19, 2005

With more air you need more fuel but you're not supercharging, so I doubt you will see a decrease in MPG. Raise your tire pressure, less rolling resistance better MPG.

Btw does your 03 350z have any tire scuffing/ alignment problems?

xierxior · Jul 19, 2005

anything you do to allow more air to get into the motor will decrease gas mileage. anything you do to increase the amount of air that can leave the motor will increase gas mileage (higher ratio rocker arms, headers, full mandrel bent exhaust)

mustangman70 · Jul 19, 2005

If you want better gas milege sell the car and buy a honda civic.......OR DONT modify the car.......More horsepower requires more air AND fuel crammed into the cylinder.....

jt14894 · Jul 19, 2005

Alec said:
With more air you need more fuel but you're not supercharging, so I doubt you will see a decrease in MPG. Raise your tire pressure, less rolling resistance better MPG.

Btw does your 03 350z have any tire scuffing/ alignment problems?

I try to keep my tires at the proper psi according to the factory, but I may try adjusting it to see what happens.

As for my Z, it had the tire feathering and alignment issue, but it was fixed and the tires were replaced all under warranty at 19,000 miles.
So far I haven't had any other issues, but I'm going to have it checked again just to be sure since the 30,000 mile service is coming up.

DukeOfValencia · Jul 19, 2005

xierxior said:
anything you do to allow more air to get into the motor will decrease gas mileage. anything you do to increase the amount of air that can leave the motor will increase gas mileage (higher ratio rocker arms, headers, full mandrel bent exhaust)

I'm not sure this is entirely true. My understanding is that by reducing the effort the engine has to get air/fuel in, burnt, and expelled, the better the mileage would be (to a point). So technically, opening up the intake side should reduce the effort to "suck" the air into the cylinder. This is true unless your exhaust is so restrictive that it negates the gain on the intake side. Think of it this way, stuff your mouth full of cotton, then run around the block. Then remove the cotton and try again... the second run was easier because your body was more efficient without the cotton because you could get the air in (and out) easier. Not the best analogy, but you get the picture.
However, I wouldn't expect a huge gain... maybe less than 1 mpg on average.

I don't know, maybe I'm way off base...

Maybe the proper question is, if you have a CAI and a tune, what MPG are you getting on average... anyone got good hard results so we can put the issue to bed?

mustangman70 · Jul 19, 2005

Yes but all we need is oxygen to run......In a computerised system in order to get the "best" combustion doesnt the computer add or take away fuel to get it right??? IF the perfect A/F ratio should be achieved, and the computer senses more air, wont the computer add a bit more fuel???

Correct me if im wrong im not too much of en EFI guy that just my uneducated guess...........

xierxior · Jul 19, 2005

mustangman70 said:
Yes but all we need is oxygen to run......In a computerised system in order to get the "best" combustion doesnt the computer add or take away fuel to get it right??? IF the perfect A/F ratio should be achieved, and the computer senses more air, wont the computer add a bit more fuel???

Correct me if im wrong im not too much of en EFI guy that just my uneducated guess...........

<- EFI guy I'll admit I've never tuned anything other then a 1987 transam with a 383 AFR 210 heads 236/236 cam etc etc believe me that was a huge headache I'll never touch anything under ODBII again ODB1 SUCKS the mass air sensor maxed out at like 254.9 grams per second that was like 3400rpm on that motor lol.. anyways lesson learned ALWAYS go aftermarket if you're messing with older fuel inejected cars.

and you are correct even tho you are reducing the amount of (work) the motor has to do to take the same amount of air in.. it still does take more air in and will need to add a little bit of fuel to correct the air/fuel I believe this is why cold air kits are coming with tunes.

jpiatchek · Jul 19, 2005

Gas mileage.

jt14894 said:
Hi all,

I'm a recent new owner and I've been searching and researching the various posts on which CAI is best. So far I've narrowed it down to JLT, C&L and Steeda. They all have their advantages and disadvantages, but they all seem to show some definite gains in HP, RWHP, and torque. The one thing I am curious about is MPG, since I definitely want to make this pony a little more fuel efficient, in addition to increasing performance. For those of you who have the JLT, C&L, Steeda or any other CAI, how much has it affected your MPG?
I prefer to use 87 octane, since gas prices are sky high, so by tuning it to 87 will I get similar performance and MPG gains to 91 and higher octanes?
I appreciate your input.

With Predator 91 tune and C & L CAI, i got about 23 mpg on the interstate at 80 mph. Not sure if this was better than stock or not since I did't take a road trip before the tune. It certainly didn't hurt mileage, and seemed to increase it a bit around town.

jt14894 · Jul 20, 2005

jpiatchek said:
With Predator 91 tune and C & L CAI, i got about 23 mpg on the interstate at 80 mph. Not sure if this was better than stock or not since I did't take a road trip before the tune. It certainly didn't hurt mileage, and seemed to increase it a bit around town.

From what I've been reading in the posts, it seems like most GT owners are modding their cars almost as soon as they roll off the dealer's lot and so there's no real stock numbers to go by.
I don't plan on adding mods for a while, so I'll be keeping track of my stock MPG until I start adding mods.
Right now, I'm still going through the break-in and the car has been averaging about 18 MPG combined city/hwy (18.449 MPG at my last fillup) so I'm sure that once the break-in is done the MPG should increase, thats if I'm not street racing or anything, to around 20 MPG city/hwy.
Thanks for the info.

428CJ · Jul 20, 2005

My GT is stock and I recently got 25.4 mpg on the freeway cruising at 65 with a passenger. I usually get 17-18 mpg around town but stop lights and freeway onramps seem to have a major impact on my mileage.

jt14894 · Jul 20, 2005

428CJ said:
My GT is stock and I recently got 25.4 mpg on the freeway cruising at 65 with a passenger. I usually get 17-18 mpg around town but stop lights and freeway onramps seem to have a major impact on my mileage.

Cool! I was hoping to hear from some stockers.
Thanks!

DukeOfValencia · Jul 21, 2005

ok, well, mine's stock and I went to Vegas with 2 passengers (yes, someone was in the back seat!). I got between 23-24 mpg going 70-80 mph. Around town is 18-19 mpg.

Mike Wyatt · Jul 21, 2005

My understanding is that Ford uses a tune that allows 87 octane fuel- they wanted to advertise "uses regular gas", and made the compromise. This is supposed to be less efficient (less MPG) than a tune that uses higher octane.

By increasing the air flow through adding a CAI, you are able to retune which has several effects:

1. More HP. maybe 20 extra HP.
2. More air and therefore more fuel through the system, but requires the higher octane.
3. Should get better mileage (MPG)- but whether the added cost of 91 octane offsets is up in the air.

Do I have this essentially right?

Also- I have averaged (all-around driving) 20 MPG over the last 1000+ miles. On the highway, I get about 24, around town about 17-18. Manual trans.

jt14894 · Jul 21, 2005

Hey! Thanks for the stock info.
So once I finish with the break-in, I should expect anywhere between 17-18 MPG city and 23-25 MPG on the highways before adding a CAI or other mods.
Now if we could have someone with them to post their numbers, that would be great.
Anyone? Anyone? Bueller?

jpiatchek · Jul 21, 2005

gas mileage

jt14894 said:
Hey! Thanks for the stock info.
So once I finish with the break-in, I should expect anywhere between 17-18 MPG city and 23-25 MPG on the highways before adding a CAI or other mods.
Now if we could have someone with them to post their numbers, that would be great.
Anyone? Anyone? Bueller?

I get 22-23 mpg on the interstate at 80mph. This is with Predator 91 tune & C & L CAI.

CAI: Affect on MPG

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