Double your gas mileage almost or close to it.

[bountyhunter]

The title of this thread is really incorrect: if any adjustment to the engine results in doubling of fuel mileage (or even 20% increase) it means there was something very seriously wrong with it before. That is assuming apples-to-apples comparison in driving test. You can "double" mileage comparing steady speed driving at 35 mph to stop and go with hard acceleration.

Auto makers are under SEVERE cost penalties to meet CAFE fuel mileage standards and they are not leaving much on the table in terms of mileage. You can get some power increases with tuned intake/exhaust systems as well as "remapping" the spark advance and FI patterns but it's not a whole lot to be gained. I put the Weapon-R cold air packaqe on my Cavalier. The dyno tests published for it show maybe 6 HP increase.

Most people who start screwing around with sensors or emissions systems end up doing a lot more harm than good.

 

[bountyhunter]

Another common sense point not mentioned:

There is only a specific amount of energy available to be derived from the fuel. In the combustion process, some goes unburned because it does not get oxygenated into a form that burns. The unburned fuel get burned in the catalytic converter.

A cat converter is a little smaller than a football. Look at some round figures:

A horsepower is about 750W. Lets assume a VERY POOR engine design where 20% of the fuel went unburned and could somehow be "recovered" and converted into 20% more power or fuel economy.

Suppose you have a 200HP engine. If 20% went unburned, that would mean at full power about 40HP (about 30,000W) were being burned in the CAT. Some of use who do heatsinks have a rough idea what 20kW would do to something that size... let's just say it would rapidly melt. So, the reality is, only a very small (probably less than 5%) of energy from the fuel goes unused.

The point is: if there is a significant amount of "extra power" or "extra mileage" to be had... where could that energy come from?

 

[audioguru]

The point is: if there is a significant amount of "extra power" or "extra mileage" to be had... where could that energy come from?

It comes from the electric motor and battery in a hybrid car.
There are a couple of PURE ELECTRIC ONLY cars that do not have an engine. But they cannot go far without an overnight charge.

 

[bountyhunter]

I was referring to the idea that a modern gas powered car can magically have a bunch more power or gas mileage by "tweaking" something. I'm really old, I remember the 60's..... engines were so poorly designed that doing almost anything to "improve breathing" to it did increase power and mileage. That is almost reversed today: like motorcycles, new car engines are pretty well tweaked for power and there is very little fruit left unpicked in the "optimizing" area. Screwing with the engine mapping is best left to the experts.

 

[tcmtech]

Actually that fuel efficiency and power gains come from solid physics. Taking a 15 - 20% efficient engine in a vehicle that gets 15 MPG up to 30 - 35% efficient would nearly double the equivalent MPG without breaking any rules of physics.

As far as real world engine efficiency nearly 100% of the fuel gets burned but only 35% at best of it gets turned into mechanical energy. The rest goes to the production of waste heat that either goes out the tail pipe or out in the radiator.

Suppose you have a 200HP engine. If 20% went unburned, that would mean at full power about 40HP (about 30,000W) were being burned in the CAT. Some of use who do heatsinks have a rough idea what 20kW would do to something that size... let's just say it would rapidly melt.

Relating to that 30 KW heat energy thats not really an unimaginable or unrealistic number to get from an exhaust system. Given that your exhaust gas volume is obviously going to be considerably higher than the volume of the intake air and that it can easily reach red hot temps at the exhaust manifolds it can easily be calculated.

In simpler terms for a rough equivalent that most of us can relate to a typical home furnace can easily be rated at 100,000 BTU which in kilowatt terms is about 32 KW. Given a furnace of that size would have an air flow of around 2000 CFM at 140 degrees F its not unreasonable to consider that by reducing the air flow rate to say 400 CFM and raising the temp by an equal factor of 5 it would thusly give you an air temp of around 700 degrees F with a flow rate that is well within that of a normal exhaust system temperature ranges and flow rates and way below the melting point to the ceramic material and stainless steel that a catalytic converter are made from.

In fact most converters don't start doing their job efficiently until they get to over 700 F and higher! (that means that you are in fact dumping usable fuel into your exhaust system, IE lowering engine fuel efficiency, in order into to keep the catalytic converters hot enough to work.)

The actual safe working temp of a catalytic converter is around 1350 - 1650 F which is what most of us would understand and recognize as glowing bright red in open sunlight hot!
https://en.wikipedia.org/wiki/Catalytic_converter

Thats how you can nearly double your MPG numbers in many vehicles just by modifying the emissions systems and related tuning and still be well within the confines of respectable internal combustion engine physics!

Just because your vehicles engine may be capable of 30 - 35% efficiency in converting fuel energy to mechanical motion does not mean that it is actually tuned to be that efficient. Emissions tuned is not efficient tuned rather it just tuned to meet the specifications of some politicians who are more concerned about what is in your tail pipe than whats in your wallet.

 

[bountyhunter]

Thats how you can nearly double your MPG numbers in many vehicles just by modifying the emissions systems

No, you can't and I genuinely hope nobody starts screwing with their engines based on that statement. I know a tiny bit about engines (about 50 years experience) and I will absolutely GUARANTEE that if there was even a 5% gain to be had by "tuning" the engine, car and bike makers would be using it. car makers are pressed to meet CAFE as it is and the FED is raising the numbers. They will pay big fines if they don't meet the MPG limits.

If you have a magic tweak that does that, please post some dyno data showing the improvement.

 

[Sceadwian]

You can lean an engine out that far... But it'll fall apart from thermal stress 100 times faster.

 

[tcmtech]

If you have a magic tweak that does that, please post some dyno data showing the improvement.

They are still all over the place online if you know where to look.

How many stories and write ups have their been over the years about how some well known and published auto magazine teamed up with a good reputable engine builder and turned a low powered fuel pig of a stock engine out of some generic vehicle into a powerful fuel efficient and highly reliable ,now 'off road use only' rated, street rod engine with before and after dyno and fuel consumption tests to prove it?

Back in the 1990's when I was getting out of high school these where nearly the story of the week in every major auto enthusiasts magazine and had been since the earliest days when the government started stepping in and dictating that what comes out the tail pipe is more important than how much fuel it takes to get some place!

 

[Sceadwian]

What does it matter if you can do it with half the fuel if you produce twice the waste? Long term efficiency.

 

[bountyhunter]

https://repairpal.com/blog/fuel-economy-busting-the-myths

Computer Chips and Programmers
Automobile manufacturers employ some of the best and brightest engineers and have billions of dollars dedicated to research and development. One fuel-saving device the industry has developed is the computer chip or programmer. To save on fuel, a programmer can be downloaded into a vehicle’s electronic engine control system. It will “lean” the fuel system during cruise in order to increase fuel economy. But like Newton’s Law of Physics, anytime an action occurs, an equal, but opposite reaction takes place. Though this programmer may help your fuel economy, it can also cause potential long-term damage to the engine’s valves or pistons. Many of these chips and programmers work well at increasing fuel economy, but have little regard for durability or emission requirements.


Installing High Flow Intake and Exhaust Systems
High flow intake and exhaust systems increase an engine’s volumetric efficiency (the breathing of the engine). These product manufacturers claim incredible fuel economy results, but independent testing frequently shows only nominal increases in power and fuel economy. Sometimes, the cost of these products outweighs the actual realized fuel economy increase.

I have a lot of experience with "performance" intake and exhaust systems on bikes. The best exhaust give a small increase in HP at the middle/upper power band with the cost being loss of low end power and torque. NO FREE LUNCH. The "low restriction" air filters do more harm than good because they change the airflow so much they have to be rejetted and require new carb needles with different taper. Bottom line: you can get a little more power in a narrow RPM range and screw things up elsewhere.

 

[bountyhunter]

They are still all over the place online if you know where to look.

Then I guess I don't know where to look. Please post any modifications done where a reputable lab test showed an increase in either power or mileage based on that mod.

 

[bountyhunter]

They are still all over the place online if you know where to look.

How many stories and write ups have their been over the years about how some well known and published auto magazine teamed up with a good reputable engine builder and turned a low powered fuel pig of a stock engine out of some generic vehicle into a powerful fuel efficient and highly reliable ,now 'off road use only' rated, street rod engine with before and after dyno and fuel consumption tests to prove it?

Please post a link to any case where simple or inexpensive mods were made to a properly running engine that resulted in significant increases in power or mileage.

 

[bountyhunter]

Back in the 1990's when I was getting out of high school these where nearly the story of the week in every major auto enthusiasts magazine and had been since the earliest days when the government started stepping in and dictating that what comes out the tail pipe is more important than how much fuel it takes to get some place!

Back in the 60's I remember the story of the magic 100 mpg carburetor the Oil Companies bought so they could bury the design. Do a search, that myth persists to this day as well.

I just want to see any properly running cars where somebody did a simple tweak and got a big increase in mileage or power.

 

[Sceadwian]

Such tweaks exist Bountyhunter... As I said previously, they rely on running the engine lean. Higher temperature, lower lifespan.
The overall usefulness of the engine drops like a lead weight if it's brought out of design spec. Modern vehicles have to keep all viewpoints in mind.

 

[tcmtech]

As I said previously, they rely on running the engine lean. Higher temperature, lower lifespan.

Actually it is just the opposite. In the days before fuel injection it was common to re jet an emissions compliant carburetor slightly richer to around a 12.9:1 A/F ratio opposed to the stoichiometric ,cleanest burning ratio, of roughly 14.7:1 A/F ratio and adjust the ignition timing to a more advanced point a few to several degrees more advanced than the factory emissions setting was. After that the EGR system was completely useless so it got blocked off along with the other emissions related components which where also removed such as the air injection systems, the catalytic converters, and the rats nest of related vacuum controls that where just useless parasitic loose devices at that point.

In most vehicles those two changes alone would not double a vehicles fuel millage but in most cases a 10 - 40% gain would be seen. For further engine efficiency it does take intake modifications, camshaft profile changes, cam timing changes, compression ratio changes and other internal engine modifications.

What it comes down to is that the A/F ratio and mechanical design that is most effective at producing complete combustion of the fuel is not the same one that produces the greatest conversion of fuel to usable mechanical power. Changing a 15% mechanically efficient engine into a 30% mechanically efficient engine is in fact all it takes to double its MPG numbers.

In the more modern vehicles there are no air injection pumps because the camshaft designs have been changed to allow the engine to pump more air through the combustion chamber similar to how an efficient off road camshaft design did years ago however the valve opening and closing timing is at different points in the stroke cycles.

None of it is mystery science just good engine building knowledge and understandings and yes I believe scead is right some engine life expectancy is lost but if the money saved on fuel more than justifies an engine wearing out when the vehicle wears out opposed to what we have now where the vehicle is worn out before the engine is even 1/2 used up in many cases who really cares?

As fas as my proof goes, well I have been modifying my vehicle engines and emissions systems for nearly 20 years now and I can say I have found these changes to be well worth it and have proven themselves many times even though I am well known for being anything but a conservative driver!

Regarding motorcycle engine I have no clue as to their changes or modifications let alone what improvement can be made. What I do know is I know far too many people with motorcycles that at most 1/5 the wight of a average sedan and have 1/3 the horsepower but yet get nearly the same MPG numbers. WTF is that about?

 

[bountyhunter]

Not trying to be difficult, but the starting post of this thread said:

"Double your gas mileage almost or close to it.

I have been experimenting with this for about a year. There are several things that can be done to increase gas mileage but the thing that works best is to replace the air intake temperature sensor with a fixed resistor. "



My point is, it sounds like somebody is saying there are simple and easy mods to be done to an engine that can nearly double the gas mileage.

I don't believe it, I don't believe anything close to it. I would like to see some actual data reflecting this.

And I know for a fact you could not run an engine lean enough to cause that much mileage change without burning a piston.

 

[bountyhunter]

Regarding motorcycle engine I have no clue as to their changes or modifications let alone what improvement can be made. What I do know is I know far too many people with motorcycles that at most 1/5 the wight of a average sedan and have 1/3 the horsepower but yet get nearly the same MPG numbers. WTF is that about?

???????????? A "typical" 750 bullet bike weighs about 450 to 500 pounds, and puts out maybe 100 - 125 HP. With rider, the weight/power ratio is around 6 pounds/HP. Name a me a typical sedan in that ballpark. And the gas mileage would be in the 35 - 40mpg city range and about 50 - 60 highway depending on speed (air drag is dominant). The "liter" bikes (1000 cc) can have power up to maybe 160 HP. Gas mileage drops slightly, but is still far better than any car with comparable performance.

If you know somebody with a bike that gets comparable mpg numbers to a typical sedan, that bike either needs work or got worked on by a moron.

 

[bountyhunter]

Actually it is just the opposite. In the days before fuel injection it was common to re jet an emissions compliant carburetor slightly richer to around a 12.9:1 A/F ratio opposed to the stoichiometric

That's my point. carburetor engines were really bad for getting power out, nothing like new engines. The engine in my 2002 Chevy Cavalier is 144 cu/in and gets about 160 HP out with no turbo (FI, tuned intake and exhaust). New cars get WAY more mileage/power than cars did even as recently as the 80's, and they have to in order to meet fuel standards. If somebody is saying they can "tweak" 40% more mileage or power out of a newer FI engine, I am calling BS on that. Is not possible. They don't leave that much power untuned in the basic engines anymore. And I would like to see any actual test data showing somebody took a newer FI engine and did some "magic" and suddenly reduced fuel consumption even 20%.

 

[tcmtech]

Actually my point is that even with todays EFI engines the same tuning tricks still apply but are unfortunately harder to do due to the fewer mechanical parts that can be changed directly themselves.

Many vehicles today do not even have distributors so in order to bump up the ignition timing the signals from sensors need to be changed or tweaked in some way to fool the computer into changing the timing.

Same with the EGR block off method from years ago. Back then the EGR valves could just be blocked without any computer knowing or caring. Now the computer knows when its been blocked so the simplest solution with that is to re rout the EGR to feed fresh air instead of exhaust back into the engine.

As far as richening or leaning out the the A/F ratio yes the old carburetors just needed their jets and related parts changed. With EFI you have O2 sensors that monitor the A/F ratio, intake air temp and mass, and engine temps so their signals have to be cheated to get the computer to richen or lean out the mix.

The point is the old tricks can still work and in some cases work surprisingly well but to do them you need to know what the computer wants to see and how it sees it in order to fool it into doing what you want it to do not what the factory programmer wanted it to do!

If I could get access to a reprogramming system that let me go in and completely rework my vehicles fuel maps and change what I want changed I would not have to modify sensors and systems. Unfortunately I have yet to to find a programmer software system that lets me get full control of my vehicles computer controls. The only other option is to separate the EFI system from the vehicle and install a completely independent aftermarket commercial control system that can be programmed to my wants. Not cheap though.

Relating to the OP's claim of doubling fuel mileage I would be skeptical but I would believe that with some vehicles it could be possible. I have gotten 10 - 50% MPG gains on vehicles by doing sensor tweaking and emissions system mods myself so I know it can be done and gains can still be had.

What anyone chooses to believe or not believe and who's advice to follow or not follow is entirely up to them. I know what worked for me in the past and present and I will continue to experiment and modify my vehicles in the future in what ever way I choose to just to see what changes can be done. Its my vehicle and my money so I can do as I please with it and expect no less freedoms for anyone else to do the same!

 

[Dragon Tamer]

Do you have any photos? This is something I would have to try but my car is increadably hard to work in. The engine is cramed in really tight so it is hard to fix or modify anything. I am lead to belive that if you are going down to a 1k resistor an the engine is thinking that it's driving through hell, then you would get considerably less power out of the engine. You could add a multi throw switch to modify the resistor value without having to pull over and replace the resistor.

Throw a temperature sensor of your own in there so it starts out on the 1k resistor in the summer at a certain temperature, and on the 10k in the winter below another temp.