Intake idea....

Danbob · Tue Feb 14, 2012 4:09 am

I was browsing around my auto parts store for tuneup parts today and came across Spectre Intake parts....Anyone make an intake for their car out of these yet? I am thinking of doing it...Some guys on the SX4 board did it and were satisfied with the results. I really just want a couple more miles per gallon, and a bit of growl so I am thinking 100 bucks or so for this vs. 2something for essentially the same thing from rrm might be a better investment. Please weigh in with thoughts/opinions

~tc~ · Tue Feb 14, 2012 5:56 am

In a fuel injected car with O2 sensors, more air = more fuel = worse mileage

Danbob · Tue Feb 14, 2012 6:49 pm

So I would totally agree with you, except that when I installed the RRM intake on my sx4, gas milage went up consistantly by 2-3 mpg. I know it's wierd, but others have reported the same.

~tc~ · Wed Feb 15, 2012 1:14 am

I have offered a number of times on a number of forums to statistically analyze the data and PROVE whether it works or not, and nobody has ever taken me up on it.

My guess is you remember all the bad tanks before and all the good tanks after. Tank-to-tank, with no changes, you could easily see 2-3 MPG difference, I doubt the intake shifts the data enough to be clearly different than the "noise" of all the inherent variation.

Danbob · Wed Feb 15, 2012 4:15 pm

~tc~ wrote:I have offered a number of times on a number of forums to statistically analyze the data and PROVE whether it works or not, and nobody has ever taken me up on it.

My guess is you remember all the bad tanks before and all the good tanks after. Tank-to-tank, with no changes, you could easily see 2-3 MPG difference, I doubt the intake shifts the data enough to be clearly different than the "noise" of all the inherent variation.

~tc~ wrote:I have offered a number of times on a number of forums to statistically analyze the data and PROVE whether it works or not, and nobody has ever taken me up on it.

I would love to see this only because I have been wondering the same as you for years...I wonder if it really is just made up in our minds that intakes give more power and better mpg because they are loud and have a straighter path to the motor...It'd be interesting to see if any data changes.

jute2003 · Wed Feb 15, 2012 6:37 pm

I've always thought that the power gain from something like an intake was rather minimal but the mpg increase was real. A lot of the percieved effect is likely placebo but still, there have been many guys I trust who have used SRI's or CAI's and been pleased with the mpg bump. It'd be interesting to see some real data about the difference.

gaww · Fri Mar 16, 2012 3:59 pm

~tc~ wrote:In a fuel injected car with O2 sensors, more air = more fuel = worse mileage

Not really the case - unless the installation screws up the operation of the sensors. Millage will be only impacted by changing the fuel/air ratio. More total air (at same density) going through the system at max throttle will increase power, but not impact mileage.

~tc~ · Sat Mar 17, 2012 12:59 am

Uh, no.

Mileage is determined by amount of fuel injected. Heavy foot = open throttle = more air = more fuel = worse mileage. Yes, you make mor power and get there faster, but burn more fuel per mile doing it. Throw in the aerodynamic drag raising as the square of the speed, and it gets even worse.

The only way this changes is through fundamental changes in the thermodynamic operation of the engine - changing compression ratio, pumping losses, etc. In the end, compression ratio "cures all" - it is the only way to increase both power AND efficiency simultaneously, and, in the end, this is why everyone is going to direct injection, purely to be able to safely run higher compression without having to deal with pre detonation.