wushen

I recently put in a K&N air filter in my stock manual 08 XB2 which allegedly improves mileage by 13% or 3.6 MPG. At 40 bucks this pays for itself in fuel costs in 4-5 tanks and adds 3 horsepower. I'm trying to research the potential MPG/HP gains of performance exhausts and potentially headers...If I can pay for some ponies through fuel savings, I'd be happy to do so. I'm having a hard time finding these statistics, I'm hoping someone can refer me somewhere where I can get this data to determine the cost effectiveness of upgrading my exhaust. (first hand experiences are helpful too) I typically keep a car until it costs more to repair than the car's worth, so if it pays for itself in 50,000 miles it'd be well worth it, and possibly worthwhile if paid for in 100,000. I appreciate any cost effective fuel saving ideas, especially if it makes the car more fun to drive.

Thanks,

Brian

pyroman131

An air filter in your stock airbox that adds 3 horsepower? This I've gotta see!

I don't think there's much research on this as I've never heard of a filter adding so much fuel savings and horsepower.

The best way for you to find out is to do some hand calculations and post your results. They won't be official, but at least you'll provide some insight.

TheQuietThings

biggest bunch of noise i have ever heard. if its so much better than OEM, why didnt toyota use it from the factory? Dont believe everything you read...

frankiietc

CARB regulations ^

wushen

Those stats were printed in an O'reiley's Auto Parts in-store catalogue specific to the Camry (same filter/engine) I found this link www.knfilters.com/filtercharger.htm with simular claims, but neglects to specify the mileage claims, in the link they say 1-4 HP increase. As for mileage, I haven't had it in long enough to notice a difference (3.6 miles is tangible but maybe not noticeable) As for the HP, it definately has a lil bit more accelleration and has a bit more of a rumble to the engine, it seems to rev a bit hotter. As for why Toyota doesn't include them at purchase, my theory is they want to make money off of the 10$ disposable filters you're supposed to buy every 2 oil changes, or buy their TRD aftermarket filter for 80 bucks...the same reason GM recalled their electric car, they didn't make money on mantainence. I should say too about the mileage, according to that same store catalogue, the replacement filter actually had a better mileage increase than K&N's cold air inductor, if they were trying to fleece buyers, you'd think they'd make their 220$ kit more appealing than their 40 dollar one in mileage as well as hp....I've no idea why mechanically the inductor wouldn't be better for MPGs...

I'm still curious about researching efficiency benefits of Performance exhausts, please try to limit conversation here to cost effective MPG gains.

Thanks,

Brian

wushen

Frank,

Are you guessing it's carb regulations, or do you know it's regulations? I'm not doubting you, I'm just wondering if I need to swap the old one in for emissions testing, or if I need to tweak something.

I appreciate your further input

Thanks

ScionFred

iTrader: (1)

First, the claims of increased fuel economy through the use of an oiled cotton gauze air filter vs pleated paper is 100% false unless the paper filter is dirty, clogged and in dire need of replacement. Second, there are no "performance" mods that will pay for themselves through fuel savings. Those days are long gone. Modern OBDII engines are already so efficient that it's far beyond the reach of garage mechanics or even the aftermarket to improve them.

The best things you can do to increase your fuel economy are to shed vehicle weight, improve the aerodynamic drag coefficient and drive for best economy. You can remove the 35lb spare tire and replace it with a bottle of slime and small air compressor (3lbs). Filling your tank only half way sheds 42lbs of extra fuel weight. Good luck improving the drag coefficient beyond what Toyota engineers could manage using a wind tunnel and advanced computer modeling. The best thing you can do is to leave the trip computer set to 'current mpg' and govern your right foot accordingly.

If you're looking to save every ounce of gas, tinting your windows will help keep the car cooler in summer and reduce the amount of time you need to run the a/c. Windshield sun screens also help. Keep your tires inflated to oem spec or higher. Shift early, brake early, coast often and use the cruise control on level ground but not when going up hill.

Good luck.

CIONIDE

iTrader: (1)

^^ x2

Also, from personal experience I can tell you that after putting in the K&N drop-in air filter at 30k miles (I now have 87k), there has been absolutely no measurable increase in mpg. I have the calculated mpg for every single tank of gas since new on a spreadsheet...

and yes, ****-retentive has a hyphen in it.

ScionFred

iTrader: (1)

Every tank? Shouldn't "****-retentive" be bold, underlined, capitalized with an exclamation point?

A good example of just how much more efficient today's engines are is the Ford Mustang GT. I had a 1987 with a 225 bhp 5.0L V8 rated for 15mpg city, 22mpg hwy. The 2011 Mustang GT has a 412 bhp 5.0L V8 rated for 17mpg city, 26mpg hwy. **

** Note that between 1987 and 2011 the EPA has changed the way they test fuel economy and the newer method typically yields lower mpg estimates. Usually in the range of 2mpg less than the older method.

TrevorS

iTrader: (1)

The key to this is the word "allegedly". You can add all the performance mods you wish, but unless it's for the purpose of improving performance, you're just wasting your money -- you're definitely not going to be saving gas.

09BCMxB

There was a test done recently comparing fuel mileage and "driveability" on newer cars and an old carbureted Buick using extremely plugged stock paper air filters and new paper air filters. The tests showed that the new fuel injected, computer controlled cars got the same fuel economy with either filter but lost some acceleration with the clogged filter. The old Buick on the other hand would barely accelerate and got extremely poor gas mileage. If I can find the link I will post it.

fwiw - If you look at my sig, I've added a CAI and an exhaust among other things. When each was first installed there was a small measurable difference but within days at most the computer returns everything back to "stock" specifications. Without reprogramming or a "piggyback" you won't see any real mileage or performance gain.

TrevorS

iTrader: (1)

I think you're being a little too hard on the ECU. It will do it's damndest to maintain an optimal AFR, but it won't object to greater ease in pulling in air and greater ease in ejecting exhaust. Genuine performance upgrdes will indeed result in improved performance, the difference the ECU makes is just that if the improvement throws off the AFR, it will most definitely work to correct it. That in itself will not negate the advantage of a genuine performance upgrade. It's merely the ECU learning how to properly work with it -- that's the advantage of having a learning ECU, it "reprograms" itself !

ScionFred

iTrader: (1)

Well said Trevor. The fact that our ECU can adjust to 20% larger fuel injectors, 6 psi of boost and 100hp/tq over stock without a CEL speaks volumes about it's capabilities. As soon as I finish my return fuel system I'll be probing even further to find the limits of our learning ECU.

09BCMxB

Hey guys, you got me wrong. Trevor, what I'm saying is the computer is very well programmed. With as you put it genuine performance upgrades such as what ScionFred has, more power can be made. 14.33 is very impressive.
The OP however is looking for better fuel efficiency from simple bolt-on mods. And I stand by my assertion that for that to happen the ECU will need to be reprogrammed. The mapping from the factory is always a bit of a compromise since the cars have to perform the same wherever they are, and for whomever is driving it.
I have experience using Hypertech programmers on American vehicles and remapping Harleys and sport bikes. In every case we were able to increase efficiency and depending on the mods, power. For example, many sport bikes can gain 3/10ths in the 1/4 mile just from a remap with no other mods.
Just to qualify my statements, I had a motorcycle shop and still ride and race a carbureted 10.6 second street legal Harley with a programmable digital ignition. I don't claim to be an expert but like you both, this is not my first hot-rod.

ScionFred

iTrader: (1)

"fwiw - If you look at my sig, I've added a CAI and an exhaust among other things. When each was first installed there was a small measurable difference but within days at most the computer returns everything back to "stock" specifications. Without reprogramming or a "piggyback" you won't see any real mileage or performance gain."

The above paragraph was the source of my confusion and I presume Trevor's as well. Thanks for clarifying what you meant. I agree that factory tunes tend to leave some performance potential untapped but unfortunately with Toyota ECUs locked tight, there's little that can be done. You can do some things with piggybacks but it's not nearly as good as remapping the ECU programming.

I've never tuned a sport bike but I imagine that there's quite a bit of performance to be had since many of them are intentionally de-tuned by the factories.

frankiietc

I was replying to the post above , Toyota does have to make their cars pass the carb regulations, I'm pretty sure they have to sacrifice some mpg's doing so.

TrevorS

iTrader: (1)

Can't say I know any engine associated xB2 mods that unquestionably improve fuel efficiency. But I'm satisfied valid N/A mods can increase performance (not including a resistor "chip" enriching the AFR). When you say "but within days at most the computer returns everything back to "stock" specifications", I interpret that as being return to factory HP and torque characteristics as well. I flatly disagree with that and there are dynos around that demonstrate it. Regarding mpg, it's mostly a question of how one drives, but if remapping can improve it without hurting optimal operation of the emissions controls, sounds good to me ! However, my suspicion is remapping in this case means tossing emissions controls in the trash (which is no doubt normal for a track situation). To each their own, but I personally don't really consider that a viable option for a road vehicle.

09BCMxB

I apologize for the overly simplistic generalization in my statement. I was too focused on the OP's question of fuel savings rather than power.
I believe ScionFred made the best point as to the easiest ways to increase fuel efficiency.

For anyone that is not familiar with what the ECU does and why, here is my not too simplistic but still general description of what it does and it's predesigned limitation. This applies to most current vehicles on the road.
The ECU while quite powerful, uses preprogrammed maps that work on the standard "if, and, or" axiom. There is typically more than one map - switching depending on load, style of driving, quality of fuel, among other things. The computer makes decisions and adjustments in an attempt to keep the A/F ratio stoichiometrically correct - meaning the perfect air/fuel ratio. This is rarely 100% possible because of many variables - air quality, fuel quality, random misfires etc. Because of this the ECU will err on the side of slightly rich in a given map with the catalytic converter burning off the unburned fuel.
The ECU also controls ignition timing, on some vehicles the cam timing and/or how many valves open at a given time, shift timing on automatics and often the gauges in the car among other things.
Reprogramming or "remapping" the ECU would allow you to optimize the map parameters in the computer to deliver better fuel efficiency and power. High end cars like the Corvette can be quite fine tuned and with an aftermarket computer every parameter can be adjusted. Typically a plug in programmer for a typical car will have preset maps than can be slightly tweeked. Unfortunately it seems our Scions at this time are not able to be reprogrammed although I think a company sells a "piggyback" computer that works with all the standard emission controls on the car.

A vehicle cannot be all things to all people. The engineers cannot assume every variable. Case in point - when Harley released the then new twin-cam engine, they claimed to have over 100,000 miles in testing. Within months of release it was recalled. I think Ford claimed even more miles of testing with the original Focus "The World Car". Again, within months it was recalled. These are just 2 cases that I'm aware of. Interestingly, Ford and Harley later collaborated on the Harley V-Rod.

There is a lot more but that's the gist of it.
Again, I don't claim to be an expert but this is the information that I know.

ScionFred

iTrader: (1)

09BCMxB, that was a good overview of modern OBDII engine management systems. They are indeed compromised by having to satisfy government emissions and fuel economy regulations, operate in all climates, altitudes, etc. There are probably ways to tweak them for better fuel economy but since most of the economy compromises are for the sake of safety and engine longevity, it's not easy to gain meaningful increases in mpg. Greater performance at the expense of mpg is a lot easier, IMO.

To expand a little on the "learning" capabilties of the Toyota ECU, as I know it. The ECU does indeed use preprogrammed 'if' and 'or' maps as a starting point but also includes the ability to adjust those map values using long term fuel trims (LTFT) by +/- 20% and short term fuel trims (STFT) by +/- 25% based on very fast and accurate wideband O2 sensor AFR feedback when in closed loop operation (O2 sensor overrides maps). Essentially this allows the ECU to adjust the preprgrammed map values by +/-20% without much fuss or up to +/- 45% in the extreme. Any more than +/- 20% long term variance will likely cause various CELs to appear incessantly.

So when your CAI, header and full exhaust result in the ECU seeing 300g/s MAF at 50% TPS opening instead of the preprogrammed 250g/s at 50% TPS, it can adjust the STFT immediately and after a few occurances it will adjust the LTFT to match the new condition. It then continues to refine the LTFT based on STFT based on o2 feedback. LTFT changes are essentially the same as re-programming the initial fuel mapping by up to +/- 20%.

There are several piggyback EMS's that can work with Toyota ECUs and one in-line ECU (Allan Phillips Racing X1). Piggys merely modify sensor data to the ECU to produce a desired result (and often undesired results as a consequence). The X1 actually interfaces directly with the ECU and can alter the preprogrammed maps. Unfortunately the X1 was designed for the V6 Toyota Tacoma and although successfully modified to work with the TC and M/T XB2, it did not work satisfactorily with my A/T XB2.

That's all for now.

09BCMxB

Learn something new everyday (well, almost every day). Didn't know Scion allowed for that much adjustment.
We did a reprogram on an '06 Ford F250. My friend had put a K&N filter and taller tires thinking it would help - which it didn't. After I convinced him to get a Hypertech, without custom tuning we were able to gain 5mpg and made enough torque gain to cure a constant shifting issue on hills. I still believe quite a bit of gains can be made on stock to lightly modified motors - both in fuel economy and power.
I would love to get the X1 and since I have a stick I maybe wouldn't have some of the issues you had but $2K is a little more than I want to spend now. I do like how many data points it provides for more accurate tuning.