I have a 2008 w/ the 4sp auto. I am at 58000 and I have a few tips for better mileage. I commute 100 miles a day and get a combined 30 mpg. On trips, it is closer to 34 mpg.

1. Use the cruise control whenever possible. You lose fuel constantly moving your foot up and down.

2. Purchase Vortex generators and place them as prescribed, even with the back of the antenna. They start to really work at 65+ mph. These little shark fins stir up the air flow at the back of the car and reduces your drag.

3. The top grill serves no cooling purpose above 15 mph. Cover up the front or back side of the grill. If you can find some flexible cutting boards, that some use for splash guards, and mount them behind the grill. It is a nice mod. For long trips, use the sticky plastic wrap and cover the upper grill to make the nose aerodynamic.

4. Let your engine breathe! Remove the useless intake hose. The plastic nozzle remaining points straight at the opening in the fender. Add a rubber coupling from the cold air parts isle at the local parts store and press it over the end. This will extend it into the fender. Now knock out the faux front brake cooling ducts. You have now turned the hole into a ram air inlet. Of course ram air needs a breatheable filter; get a high flow replacement air filter.

5. Finally, ditch the steel rims for aluminium rims. This reduces rolling weight which allows you to put more power to the ground.

Hopes this helps

 

vortex?? and im debating blocking out my upper gril with painters tape or something

 

Actually, the steelies are typically lighter than most of the aftermarket Aluminum rims set ups. You have to pay attention to the total weight. But also the further the weight is to the outside (away from the Hub), the worse the performance.

 

This is true if you go from 16" steelies to 19" aluminum bling, but a direct size for size the common aluminum rim weighs less.

 

I am not referring that you always keep the grill taped, it's not for show. When you normally show off your ride nobody wants tape covering the grill. Othe other hand, if you are traveling 500 miles or more to an event, painter's tape will keep the bugs and debris off the nose until you get there.

 

what are XXR wheels?

 

They are a low priced after-market brand of wheels... google is your friend.

BTW, they've been very popular with those owners looking for budget-priced wheels over the last several years.

 

To "stir up the air flow" sounds like a good definition for creating drag via turbulence. Is there any testing that verifies they improve air flow and by themselves result in improved gas mileage?

How is it known the upper grill provides cooling only for the first 15 mph?

 

I located a paper by some Mitsubishi engineers studying the use of vortex generators on a Lancer.

http://www.mitsubishi-motors.com/cor...004/16E_03.pdf

Their test results showed a modest but appreciable improvement in laminar flow at 50m/s with the modest rake of the lancer hatchback rear window, which they appear to consider representative. However, I can't help but wonder to what degree that modest laminar flow extension would apply to a much more vertical rear window such as ours. Also, 50m/s is equivalent to 112mph by my calculator, so I wonder what if any practical advantage materializes for our cars even on the highways. Looks to me like you'd probably save much more gas by reducing your speed below 65mph.

PS. I wouldn't be surprised if the factory spoiler is a better solution for the xB2. It's designed to deflect air downward over our hatch, thereby improving laminar flow.

 

I actually performed a study on these on my own car and found that the air flow is forced downward which brought my aero drag closer to my vehicle. Drag reduction vortex generators are used on the high-end Subaru WRX and the Nissan 350Z to bring airflow down the rear of the vehicle to provide more air downforce to the rear soiler. Drag reduction was used by the Ford GT40 when they designed the rearend to reduce drag behind the car.http://en.wikipedia.org/wiki/Vortex_generator http://www.bing.com/videos/watch/vid...ors&FORM=VIRE3


I placed a computer case fan behind the grill and hooked it up to a volt meter to measure wind flow. The fan was producing the most voltage at about 7 mph then decrease to 0 @ about 15 mph. I did some research on line about the Scion xB gen.2 grill and they reported tha the air flow created a barrier over the holes and the air flowed around the grill. This observation was recognized by the Scion division and you will now notice the hood of the xB now almost completely covers the upper grill. I covered my grill on a trip from Washington to California during the summer and it did not effect cooling one bit, even when I was waiting at the drive through.

 

Here are my grill block and aero-hubcaps





My best tank was 35.5 mpg but I usually get 33-34 mpg. My next project is rear wheel skirts like this

 

How did you determine how far down the back of your xB2 (that car specifically) the laminar flow extended at normal highway speeds and how did you determine whatever fuel economy it resulted in? I note the video specifically says at 60 MPH the vortex generators had no appreciable impact on the Corolla's MPG, is that the basis of your 65 MPH number?

The space behind the upper grill is mostly a compression zone with air spilling downward to the radiator, the top of which only extends two to three inches above the base of the grill. The specific location and orientation of your test fan will have a huge impact on your test result.

PS. The percentage open area of the grill will also effect the result.

 

The placement was decided based on dusting the roof and rear of car with flour. The car is then brought up to highway speed for a couple of miles. A definite line of flour is formed on the roof where the drag lifts the air off the roof. After taping off the line, I washed the car, installed the fins as directed by the manufacturer, about 3" before the line. I carefully removed the tape and removed any residue. I performed the test again and was suprised to find that the flour remained on the car half way down the rear window where the flour swirled on the glass. Now the down side, I need to use the rear wiper more on wet roads as the tire spray gets sucked upward and swirls against the glass. This proves the drag behind the car has reduced in length. The longer the drag is behind the vehicle, the greater the drag. Boeing invented the wingtip verticle fins to reduce drag that pulls on the end of the wing. As for how I came up with the magic 65 mph, that was the hardest part. In order to convince my wife that it was worth putting the fins on the roof, I kept track of my mph and placed a pinstripe of tape over the fuel gauge at the 5/8th mark. We regularly drive from Seattle to Portland, so the round trips were averaged and found that at approximately 65 mph, I started to increase my mpg slightly. I found the "sweet spot" around 75 mph which is where the engine is at the lower end of its power band (around 3,200 rpm.) Where you can really find the lack of excessive drag is when you put your foot down to pass. I used to dread passing because I had to put my foot to the floor to get passed a vehicle, now I push half way down and I forget it's a box and zip past someone.

As for the grill, you can't convince everyone. They just have to see it for themselves before they are convinced. Test it yourself on your Gen2 xB and be your own judge. I'm not a scientist, but by your replies, you must make a 6 figure income because I can tell you must have a masters degree in fluid dynamics. That is all I have to say about that.

 

Don't feel the need to get defensive or aggressive, Trevor over-analyzes and challenges everything, even his own mods.

 

^^^^ x2 dont take personal!!!

 

Thanks for the description, very interesting. You didn't mention how much mpg improvement you can clearly attribute to driving at the "sweet spot" with the vortex generators (no other mods or other factors perhaps coming to play).

Guess I don't know anything about Boeing's specific rational, but everything else I've learned about vortex generators is they are intended to increase the effectiveness of airplane control surfaces at low speed. They accomplish this by bringing higher speed air into contact with them (flaps, elevators, rudder). There is apparently a downside in that it reduces maximum air speed due to the additional drag, but that is considered less important than lowering the stall speed. I'm guessing this is not something they would use on a fighter jet since max speed is probably more important than stall. I suspect the Mitsubishi paper I linked above is the pioneering investigation into their use on cars.

 

so im going to find some wood and tuck it behind my grill and see how that works! hopefully butterknifes are involved

 

Go Cap'n butter knife !

 

possibly any pics with the vortex generators on your xb to see what it may look like and where they would be installed? and also, with the OEM spoiler is there a difference if the vortex generators are needed or not?

 

It got personal when he mocked me and tried to call me a liar. That's personal.