CAI has no impact on highway mileage

[K4RL]

Hi all,

A few weeks ago, I made a 400+ mile road trip and figured it'd be a great chance to compare the CTS intake to the stock air box. I simply installed the stock intake on the way out, then installed for the CTS intake for the return trip, recording mileage via the onboard calculator. I expected to see slightly better mileage out of the "less restrictive" CTS intake, but to my surprise the calculated efficiency was identical. Both got 40.4 MPG, with little regard for driving efficiently on my part. My average speed was mid/high 60s and the temperature was about the same for both trips. Note that the rest of the car is totally stock, too.

I guess there's no reason to get an intake without a tune, unless you're just in it for show/sound. Maybe I can convince my wife that we need a stage 2, family race car... But hey, good news is that 40 MPG is pretty good for a gas car!

Karl

 

[Johnny Blaze]

not bad at all

 

[PLF8593]

This is unsurprising. The stock airboxes on these cars are designed for everyday driveability AKA low-end breathing room. On a highway in your top gears the stock airboxes are going to have just about the same flow as an aftermarket intake. The MK6 was a lil different. That car's stock airbox was pitiful.

 

[K4RL]

Hm, my thought was that, if there was any difference in ease of flow, one would see it most prominently in low RPM (such as cruising on the highway). At high load, the turbo should suck up all the air it needs regardless of what intake you have, right? At least until you raise boost high enough to approach max flow rate through the intake.

 

[zmaster]

Were you using hypermiling techniques like going up to 65 then coasting back down to 60?
I've been trying to get better gas mileage on my longer trips and I'm wondering how others have been getting good efficiency with their 1.8 Golfs

 

[K4RL]

Were you using hypermiling techniques like going up to 65 then coasting back down to 60?
I've been trying to get better gas mileage on my longer trips and I'm wondering how others have been getting good efficiency with their 1.8 Golfs

Like I said, I wasn't paying much attention to getting good mileage. I'm not even that good at the technique you mentioned. Still, I'm pretty impressed with the efficiency of this car - maybe VW is cheating on the gas emissions tests too

 

[brettg]

It's not that hard to get decent numbers. I have a 35 mile commute and I get about 42 mpg (according to the computer at least) when I just take it easy. I don't do anything special other than be super light on the accelerator, watch top speed and minimize braking. I'm sure a true hypermiler could greatly increase that.

 

[PLF8593]

Yeah, I have a 50 mile commute and I average 37 going 75 in cruise control in my (manual) GTI. 70, 38-40. 65, 39-43. These cars get extremely good gas mileage. It's the future.

 

[toledospeed]

Interesting tests, thanks for sharing OP.

I found the same in my testing as well on my TSI with an "open" intake. I also found that my 0-60 times were slower than stock after repeated tests using two different "open" intakes (fastest times achieved were using the stock intake, no snow catcher, and drop in filter by 0.2 sec). And, as GolfWang said, the car also drove better as a DD, since the stock intake provided smoother, less choppy airflow at the low end. I wasn't willing to trade any driveablity for a bit more intake sound. Sure, these tests are not scientific, but if something doesn't perform as well on the street as it did before the mod, I remove it immediately from my car after doing the comparison tests (the real test is to go back to stock like you have).

I'm not even convinced a custom intake, particularly an "open" intake, after a tune will yield much of anything on most cars. It will greatly depend on the intake used, and the car will have to put down a lot of power before the stock intake becomes a limiting factor.

For example, this Golf R dyno on the JB1 (same stock intake a GTI and the 1.8 TSI). Car achieved 323 whp/347 ft-lb wtq on 100% stock intake and filter.

http://www.golfmk7.com/forums/showthread.php?p=156333#post156333
(Startiing at post 100, see the dyno George posted and then read on to see my and other comments)

I am starting to hear good things about the Forge intake (yeah, the $1000 one). However, unless you are making serious power, that is a lot of jack to spend on something that isn't a limiting factor for most cars.

 

[zmaster]

Thanks for the responses! I do a weekly 75 drive and I've only managed to get ~42mpg at best and that's 55-65mph. I'm thinking it has to do with all the hills