18 May 2010
Can I tune my car with the Unichip myself?
Short answer - Yes you can if you want to.
Long answer - If you purchase a PnP kit, it will arrive already tuned and shouldn't need any additional tuning. If you either want to tune, or you have an application that isn't supported by our PnP options, you can certainly tune the Unichip with the Uni-Tune software.
The Unichip can be tuned as many times as desired and can be tuned to work with any desired vehicle or any set of parts on those vehciles. With the Uni-Tune software, you can "tweak" the custom maps that come on a Unichip included in a Plug-n-Play kit or build maps from scratch. The Unichip is capable of controlling a lot of functionality, and with the Uni-Tune SW, you control every aspect of the Unichip.
Technical answer - The Uni-Tune software allows the user to access via a Windows based PC so that you can adjust and modify any values the Unichip is using.
Settings data
Because the UniQ works on essentially any application, there are a series of settings that can be adjusted so that the UniQ can talk with the desired OEM computer. You can have Map 1 set up to talk with a 2010 Z06 and map 2 set up for a 2001 Toyota Tacoma (there are five map sets in the UniQ and all can be set up as desired) that each require different settings for communication.
In the screen shot above, you can see that you can choose what the UniQ uses for it's various inputs and then specify minimum and maximum values. On this screen you can also see the current values, set when the UniQ begins changing signals during engine start, set input sensitivity, set up full throttle and closed throttle maps, set a rpm limiter, and choose the crank style. Each of the various functions have their own set up pages with the appropriate variables listed.
You can set the settings files accordingly and put the Unichip in the Corvette in the morning and then switch it to the Tacoma in the afternoon... obviously that's not a likely scenario but it's a way of pointing out the UniQ is pretty flexible.
Tuning data
When it comes to actually tuning, you can close out of the setup screens and have a high density map to make your changes in.
The UniQ has five map sets each of which contains multiple tables you can see on the option tabs at the top of the lower section of the tuning display in the fuel map above. You can access timing, fuel, TPS, Boost, and six "optional" tables that you can set up to manipulate essentially any signal that you can tap into from the OEM sensors or tap into something that you add as an additional sensor. In each of the "option" tabs, you have multiple options to choose from that appear when you click the "Off" button under the Option button as shown in the screen capture below.
Extras
If you click on the Extras tab on the left column, you get access to additional capabilities like launch control, Lambda signal manipulation, map temperature compensations, cat signal manipulations, and CAN bus access.
Capabilities
The Uni-tune SW gives you complete access to the most advanced piggyback tuning system in existence. Whether you want to simply tweak an existing map for a higher octane fuel, or add a progressive nitrous system and tune a turbocharged stroker motor, the UniQ can handle the job and with the Uni-Tune SW so can you.
For a more complete list of capabilities, take a look at the Tuner Section of our website.
11 May 2010
Why is the UNICHIP better than the 75-100 dollar "chips" mounted inline in the Air Intake Sensor?
Short answer - Inexpensive "chips" use a resistor to make a linear change on one input to the computer (OEM ECU) controlling your engine. A linear change is, by definition, correct under a few conditions and incorrect at thousands of others where it accomplishes little to nothing. The Unichip is a computer that makes tens of thousands or changes on multiple inputs to the OEM ECU... the correct change at all points, like only a computer can.
Long answer - Your engine's ECU responds to an innumerable combination of values when making its control decisions. Inexpensive tuning options use very simple tricks to effect a linear change to just one of those values but, unfortunately, the required changes on that channel are not linear and - therefore - can't be properly modified with a linear change. Additionally, that channel is not the only one that should be changed to make power. That means while the inexpensive tuning solution may potentially provide a "correct correction" in one small area, that same correction is "incorrect" everywhere else. The Unichip makes thousands of discrete corrections... each "correct" for the specific values being changed and the Unichip makes changes on multiple channels.
Technical answer
Computer control - The functionality of your car's engine is essentially identical to the engine sitting in your grandfather's car from the 1950's. There may be more valves per cylinder, higher compression, and there's fuel injection in place of the earlier engine's carburetor but the big picture is identical. Fuel is mixed with air to produce a combustible mixture, that mixture enters the combustion chamber, gets compressed, is ignited, and exits the combustion chamber... basic Otto-cycle operation which is unchanged since the mid-1800's when Nicolas produce the first car with one in it.
What has changed dramatically is how that process is controlled. Forty years ago, everything was done mechanically, hydraulically, and pneumatically; it worked pretty well but required constant attention and tweaking. Engines couldn't be set to the limit without fear of frequent failure and everything needed to be frequently retuned. Today a computer runs the show. Depending upon the application, the ECU controls everything from basic engine operation to literally everything the engine does. To control the engine, the ECU receives feedback signals about what's happening in the engine and send out control signals to achieve the desired operation.
To generate the feedback signals, the engine is covered in sensors that report what's currently happening to the ECU and with sensors to tell the ECU what the driver wants to happen next. A typical engine may have a dozen or more sensors each dedicated to reporting something very specific to the ECU. One sensor reports on the water temperature in the cooling system, another reports on the position of the throttle plate, another reports the composition of the exhaust gases.
Its all about the signals
At any given instant, by looking at the values of each feedback signal, the ECU has a unique snap of the current condition or state within the engine. The ECU compares that current state with the commanded state being asked for by the driver and sends out the appropriate command signals. If the current state matches the commanded state, the command signals will be the same as the last set of signals since the engine is performing as desired. If the current state is different than the commanded state, the ECU makes preprogrammed changes to correct the deviation. At any given instant, there is a command state and a current state which means there is only one set of appropriate command signals the ECU will send to the engine... it's a computer and like any computer it always responds the same way to the same set of incoming data.
Changing performance. To "tune" a computer controlled engine, you have two choices... reprogramming or piggybacking.
• Reprogramming leaves the sensor feedback signals unchanged but changes the ECU's response to those signals so that something other than what the OEM intended happens. Reprogramming can be accomplished either by rewriting the code in the OEM computer or removing the OEM computer and replacing it with something else.
• Piggybacking leaves the programming in the ECU unchanged but changes the sensor feedback signals so that the ECU's perception of the engine's current state is inaccurate. Piggybacking can be accomplished by either adding a piggyback computer or by somehow altering the values on one or more of the feedback signal channels.
The relative advantages and disadvantages of the various options are addressed in another Blog entry and are beyond the scope of this discussion, so the only things we'll be looking at for the rest of the entry are using inexpensive "tuning" options vs. using a true piggyback computer.
Volts, Hertz, and Ohms
The ECU controls the engine and the ECU's perception of the engine's current state is entirely based upon the signals it receives from the engine and exhaust mounted sensors. In response to a specific value of whatever that sensor is monitoring, a discrete value is sent to the ECU. Depending upon what the sensor is monitoring, that value may be a discrete voltage or a discrete Hertz, but in all cases there is a unique value sent to the ECU for each state being detected by the sensor.
FDX
Like any computer, the ECU operates at a particular speed known as a fetch-decode-execute (FDX) cycle during which it performs its operations. ECU FDX cycles are around 8 MHZ - 16 MHz which means the ECU completes between 8 and 16 million cycles per second. Whether the engine is idling or screaming at redline doesn't matter, and a better FDX speed won't make the engine run better, it's just how often the ECU completes a cycle. For discussion purposes, let's assume 8 MHz FDX cycle.
During each FDX cycle...
• Fetch
o The ECU "fetches" the current value from every sensor it's connected to. As already discussed, the discrete value the ECU fetches from each sensor corresponds to a very specific condition that exists in that part of the engine at that instant.
- If your engine is spinning at 6,000 rpm, the ECU fetches data 1333 times per revolution or 3.7 times every degree of crankshaft rotation.
- The sensors are divided into two different sets and the ECU looks at both.
• Feedback group - provides the ECU data on the current engine state.
• Command group - provides the ECU data on the desired engine state.
• Decode
o The values for all of the feedback sensors are "decoded" and converted from electrical signals into digital numeric values and entered into the appropriate locations in the ECU's algorithms and tables and the numbers are all crunched to determine the engine's current state and the commanded state.
o The ECU compares the current state and the commanded state for deviation.
o ECU algorithms determine the appropriate control signals to correct calculated deviations between the current and commanded engine states.
• Execute
o The digital numeric values for each control signal are converted to the appropriate electrical signal.
o The control electrical signals are transmitted to the engine for execution.
So, your vehicle's ECU is fetching, decoding, and executing data about 8 million times per second and at every one of those cycles, there is a unique set of feedback signals reporting what's happening in the engine and a unique set of control signals sent out to the engine. Note that for a large number of cycles, the signals may not change... for example at 6,000 rpm the injectors are only firing 50 times per second but the ECU will send out 4 million signals during that second most of which will obviously be "don't fire now" commands. None the less, the ECU is still generating commands all the time.
Signal scaling
Obviously, an important part of this computer control is what a particular value from a particular signal "means" to the ECU. As noted above, during the decode phase the electrical signals from the sensors are converted to digital numeric values in a process call scaling. Very literally, the signal comes is entered into an algorithm which converts it to a number. Every signal value has a corresponding unique number value for every sensor's every value.
Obviously, the relationship between the signal and numeric values must be precise... otherwise the ECU doesn't know what's happening and can not make accurate adjustments. Unfortunately, a critical aspect of signal scaling is that the relationship between the signal value and the numeric value are generally not linear. Air pressure is given by the equation...
q = ½ ρv*2
Where ρ is air density and v is the velocity of the air flow
You can see from the equation that when velocity doubles, pressure increases by four fold so when the engineers building the ECU's scaling algorithms, they include this non-linear relationship. As an example, let's look at a typical vehicle with a 0-5v MAF provides the airflow input to the ECU. Here are some values from that vehicle for both the feedback sensor signal and the corresponding numeric value after the ECU crunches that signal into an airflow number.
Sensor Output |
Numeric Equivalent |
Voltage change |
Numeric Change |
|
0.74 v |
3.43 g/s |
N/A |
N/A |
|
1.43 v |
11.41 g/s |
193% |
332% |
|
3.43 v |
83.43 g/s |
239% |
731% |
You can see when the electrical circuit values roughly double, the corresponding calculated airflow changes are not only significantly higher but the while the second voltage "double" causes more than twice the numeric change than the first "double." Makes sense since that what the formula says.
Micrometers and Axes
As mentioned above, there are two common ways of manipulating the feedback sensor signal values to achieve a performance change. The first is using an "in-line" chip typically mounted on the MAF or MAP sensor line and the second is using a piggyback computer. While the in-line sensor is a much less expensive option, the non-linear relationship discussed above is the key to why in-line chips are limited in capability.
From basic circuit analysis, the voltage in a circuit equals the potential time the resistance or...
V=IR
... and given that our vehicle's electrical system the potential is fixed, if the resistance increases current must decrease. In our tuning quest, if we can reduce the sensor output, we can make the sensor "tell" the ECU the airflow is lower than it actually is which will cause the ECU to command less fuel. The ECU believes it's commanding the appropriate "factory" fueling, but it doesn't have an accurate indication of the actual airflow. Since the actual airflow is unchanged, the actual mixture will become leaner which is exactly what we want because virtually all engines run overly rich in stock trim. The science is sound and the application of that science is simple... add a resistor to the MAF or MAP sensor line. This is exactly what you're getting when you install an inline MAF recalibrator.
To create an inline recalibrator, the manufacturer looks at where they want to create the "perfect" correction and determines how much they need to decrease the numeric value the ECU has calculated. Let's assume that our test vehicle is running a 10.0 - to - 1.0 AFR which is far richer than needed to make good power. If we want to change that AFR to 13.0 - to - 1.0, we have to make a -23.1% change to the amount of fuel being used. If we can decrease the ECU's airflow perception without changing the actual airflow, the ECU will command 23.1% less fuel and the AFR will be changed exactly the way we want. To do that, we need to look at the MAF circuit and calculate the resistance change needed to reduce the 0-5v sensor output by -23.1% at that point.
Too simple
If you're clever, you should see the fly in the ointment. You have a resistor with which you can modify the voltage to trick the ECU, but you have a single fixed value you can use. Because of the nonlinear relationship between voltage and numeric equivalent values, there is no single value by which you can change the sensor output that will produce the desired change across the entire range. You really need thousands of different corrections to do it right but you only have a single value to use. That being the case, your best is to choose that point at which you want your correction to be perfect and accept that at all other points the correction is wrong.
Beyond the nonlinear scaling requirement, there are some other issues which I've talked about in other Blog entries. The ECU commands a different AFR in Closed Loop than it does in Open Loop and when you make an inline resistor change to affect the Open Loop values, you are also inadvertently changing the Closed Loop values. The ECU sees all of those changes as errors and it builds fuel trims to correct those errors. Those fuel trims are applied, in turn, into the Open Loop fueling commands which obviously change the AFR. Additionally, when the engine is below normal operating temperature, the ECU uses very different routines; as soon as the engine warms up, those routines change but with a fixed resistance change, you're making the same change all the time. Finally, the ECU responds to ambient changes in air temperature and pressure by changing its commands but, once again, you're only able to make a constant change regardless of what the ECU is trying to do.
Bottom line, under a relatively small set of conditions, an inline MAF recalibrator can make the correct change to make good power, but under all other conditions it's making the same change which is simply wrong.
Doing it right
Changing the sensor outputs isn't fundamentally flawed and is based on a great concept. The problem is trying to use too simple of a device to effect the change. At Unichip, we use a powerful digital computer to analyze multiple sensor signals and make very precise changes to those signals at very specific points.
While the MAF recalibrator makes a single change to the MAF sensor signal at all engine speeds and airflow values, the Unichip makes over 92,000 discrete changes to that same signal. At the point where the perfect change is -23.1%, that's the change we make, but if the required change is -42.8% at another point, we make a -42.8% change at that point. And at the point where a +10.2% change is required, we can do that as well.
As a computer, the Unichip also has the capability to monitor multiple sensor signals and correctly respond as the ambient environmental conditions change as well as when the engine is under temperature. Not only can we detect when different changes are appropriate, we can also make those different changes.
MAF recalibrators only address one of the two variables in the combustion chamber which is AFR. Besides changing AFR with far more precision, the Unichip additionally addresses the other combustion chamber variable... ignition timing. We have the capability to make the same sort of changes with ignition timing that we do with AFR.
You get what you pay for. In the end, the old adage is true. Modern engine management systems are far to sophisticated to be tricked by a simple, fixed changed. Can you use a resistor to make a change, yes but at best you'll achieve very limited results. While a MAF recalibrator is based on sound science, it's simply inadequate to make the nonlineral changes that are needed to do that job. While a computer costs more than a resistor, you have to have an adequate tool to do the job and a resistor is not an adequate tool.
14 April 2010
I heard my vehicle's ECU learns out performance modifications. Will my OEM computer learn out the changes being made by the Unichip?
Short answer - No.
Long answer - The technical term for learning is "adaptation." All OBD2 compliant ECU's adapt, they all adapt roughly the same way, they all adapt roughly the same amount, and they all adapt in roughly the same time frame. Adaptation is a critical part of OBD2 compliance, drivability, reliability, and maintenance. The OEM wants the ECU to adapt, Unichip wants the ECU to adapt, and you want the ECU to adapt... assuming you have an aftermarket computer to handle it for you.
No OBD2 compliant ECU will learn out a correctly programmed Unichip and in fact vehicles modified with bolt-on intakes and exhausts will always be "less" adapted with the Unichip than without it.
Technical answer - Vehicle manufactures want to cost effectively mass produce vehicles and must comply with strict emission requirements. Faced with manufacturing stacking tolerances, variable ambient conditions, changing driving styles, and parts that begin wearing out the moment the vehicle leaves the factory, they nonetheless must produce vehicles that consistently and precisely comply with governmental regulations and deliver good performance. To do so, they use a "learning" computer to control the engine's operation. "Learning" computers, called adaptive computers, benefit the OEM in two ways...
o First, if the computers didn't adapt, the parts would have to which means every individual vehicle would have to be tuned because of stacking tolerances. That would make everything cost significantly more and might make production prohibitively expensive.
o Second, using the adaptive computer to enable each vehicle to age gracefully and not have to come in for service every six months. Without these computers, even after being individually tuned after production, each vehicle would need to be tuned frequently as its components wear out. With these computers, wear and tear is automatically compensated for and when you finally do have to get a tune up at 100,000 miles or so, you're really replacing worn out parts not tuning.
Stacking Tolerances
The first challenge the OEM faces is known as stacking tolerance which means that every single vehicle is a unique "stack" of thousands of parts, each of which has individual manufacturing "tolerance." If you've ever made anything, you know from experience creating two identical widgets is very difficult, which means time consuming, which - for manufacturing companies - means expensive.
Creating "close" widgets is much easier, quicker, and less expensive than producing identical widgets. If you can somehow adjust differences between your close widgets, they effectively become identical which means you can reduce widget cost while getting the same performance out of them. The engineering term for that adjustment "normalization." All OBDII and later ECU's normalize so that every vehicle performs correctly despite each one's different widgets.
Emissions requirements
All around the world, pollution and emissions are a priority and many governments mandate specific emissions compliance for vehicles. Regardless of the circumstances, the vehicle's exhaust gasses must either be within a narrow chemical range or the vehicle must indicate that it is not compliant.
Last month in the How much will my gas mileage improve with the Unichip blog I went into some depth about OBD2 compliant ECU's normalization for emissions and rather than rehashing all that here, take a look at that blog entry. In this entry, suffice it to say here that without ECU adaptation your vehicle wouldn't be legal and that it's engine is operating in places where the OEM ECU monitors and corrects performance (Closed Loop) and areas where it doesn't (Open Loop).
ECU learning
So, the OEM computer learns to eliminate variances caused by parts so those parts all work as required. The OEM computer corrects variances arising from stacking tolerances and wear and tear but there's yet another variance... aftermarket performance components. Even though these aren't planned for by the OEM, to the OEM computer a variance is a variance and regardless of what causes it and the computer uses exactly the same adaptation schemes to correct it.
Modified engine operation without the Unichip
Assuming a vehicle is a nominal production article with fairly light miles on it, the stacking tolerances and wear and tear typically yield LTFT's (read adaptation) of + 2 or less. In the case of a +2 value, that means the engine is operating slightly lean and the OEM computer is compensating (adapting/learning) by increasing fueling 2%. As the operator, you would never know anything is happening because the vehicle operates exactly as it is and no lights come on... exactly as designed. The OEM computer will continue quietly adapting until it reaches (depending upon programming and varying by manufacturer) between + 20-25% at which point it will pop a Check Engine Light (CEL) to tell you something is wrong.
Take that same vehicle and install a typical aftermarket Cold Air Intake (CAI) and exhaust and the LTFT's will quickly jump significantly... generally somewhere around +15. That's because the CAI is designed to trick the OEM computer into believing the engine is processing less air than it really is... because there's less perceived air, the OEM computer injects less fuel. Because the actual airflow is unchanged, the reduced fueling makes the engine a little leaner which makes a bit more power. The problem is that with "fixed" mechanical parts, the CAI engineer's Open Loop changes made for power (where the OEM computer isn't watching) also cause changes in Closed Loop (where it is). To the OEM computer, those "power" changes are variances and it's going to adapt to correct them. Sometimes that adaptation is complete and sometimes it's partial but in any case there are impacts when you put on those bolt-on parts.
o On vehicles with very low LTFT's, the vehicle is immediately much closer to the CEL trigger point as soon as the CAI goes on and it will probably get a CEL much quicker as wear and tear sets in. If your vehicle has a few more miles, or if it's not a nominal production article from a stacking tolerance perspective, you might get a CEL as soon as the intake is installed.
o On any vehicle, because the fueling changes required at high engine airflow (called load) and at low engine airflow aren't the same, and are generally very different, bolt-on parts that create fixed changes will always be seem as a problem by the OEM computer and create LTFT's. Depending upon the vehicle and the bolt-ons, you may lose all of the performance benefit from the bolt-ons as the OEM computer adapts.
Modified engine operation with the Unichip
Because each Unichip calibration is built for specific kinds of parts, each is designed to eliminate the problems those parts create as the OEM computer tries to adapt to them. The OEM computer doesn't see anything to adapt to because we literally build the adaptation normally associated with those parts into the Unichip maps which does two things.
o First, if a set of parts creates a +15 LTFT without the Unichip, the adaptation values in the Unichip map mean the OEM computer's LTFT's will settle out back down at the same + 2 that it had (in our example) because of stacking tolerances and wear and tear. That means your vehicle with the Unichip will enjoy years of OEM designed adaptation - none of which will reduce power - to correct for wear and tear before triggering a CEL.
o Second, each Unichip calibration optimizes the bolt on parts by optimizing values at over 90,000 points not relying on a single mechanical change. Not only does the Unichip clear up the adaptation, it optimizes values so that the bolt-ons make more power even where their making the desired correction.
Bottom line
All OBD2 compliant ECU's adapt. Unichip maps are designed to work with that adaptation so that your vehicle makes optimum power the day you install our kit and continues to make optimum power for years. Whether stock or with bolt-on parts, the only adaptation the OEM computer performs is because of wear and tear just like the OEM intended, and just like you want. It will never "learn out" a properly programmed Unichip regardless of what kind of vehicle it is.
9 April 2010
Will the Unichip increase my low end torque and my high end horsepower?
Short answer - Yes
Long answer - Although they're commonly synonymous with high and low rpm performance, horsepower and torque do not represent the same thing and they are not produced at different parts of the engine power curve. Unlike bolt-on modifications, with the Unichip your engine can create more torque at all rpm's which, in turn, means your engine makes more horsepower at all rpm's.
Technical answer - Although the terms horsepower and torque are often incorrectly used interchangeably, they actually describe different phenomena. Torque is power. Horsepower is work.
o Power is the rotational twist about an axis caused by a force acting at a distance (called a moment arm) from that axis...
T = r x F
Where r equals the length of the distance between the where the force is applied and the center of rotation and F is the amount of force.
If you place a wrench on a bolt, the amount of force you apply to the wrench and the length of the wrench determine the amount of torque - or twist - applied to the bolt. If the wrench is two feet long, and you pull with 100 pounds of force, you're twisting the bolt with 200 lb-ft of power... or torque.
o Work is the amount of power made at a given rate... a far more nebulous but very important concept. There are many types of horsepower, but for an internal combustion engine discussion, the one you're interested in is mechanical or brake horsepower, abbreviated bhp. Bhp isn't directly measured but is calculated from Torque using the equation...
bhp = T x rpm/5252
Where T is torque, rpm is engine speed, and 5252 is a constant.
What this equation tells us is...
- Engines create bhp at all rpm's and for any value of T there is a corresponding bhp value
- Engines create T at all rpm's and for any value of bhp there is a corresponding T value
- Anytime rpm is less than 5252, bhp < T
- Anytime rpm is greater than 5252, bhp > T
- Anytime rpm equals 5252, bhp = T
So why to diesel truck guys rarely mutter the letters bhp? Most TDi engines redline well below 4000 rpm which - putting the numbers into the equation above, means bhp is at least 25% less than T and since bigger is always better...
A 6.0 turbo diesel truck engine making 600 lb-ft is certainly something to brag about... but the 285 bhp its making isn't much more than a typical family sedan. How can something making only 286 bhp pull a 6000 lb trailer at 70 mph down the highway? It's not because it "uses torque."
For exactly the opposite reason, while the F1 crowd justifiably brags about 2.4L normally aspirated engines making 800 bhp, you won't hear them mentioning that while the engine is cranking out that bhp at 18,000 rpm, it's only making 232 lb-ft. How can an engine only making 232 lb-ft torque accelerate a car from 0-60 in less than 3 seconds and push a car in excess of 200 mph? It's not because it "uses horsepower."
In reality, both the diesel truck and F1 engines perform well when put into vehicles designed to take advantage of their strengths... diesel trucks need to pull strongly at low rpm so they last for years while F1 cars must be very light and produce very high power for short race periods.
Engineers design drive trains to allow those engines to work efficiently while the vehicle does what it's designed to do. To understand that efficiency, you have to look at the transmission/final drive gear ratios and where the engine is at its peak torque.
As you look at the following examples, consider two pretty common experiences...
o First, I talked about using a 2 foot long wrench to torque a bolt to 200 lb-ft which is a good pull but still something most guys could easily do. That's no more Torque than most small car engines produce so why don't we have human powered cars? It's not the power, it's the work. While the car engine makes the same 200 lb-ft of power, it can do it while spinning the bolt at 5000 rpm. You can make the power, but at about 2 rpm... for about 2 minutes, while the car's engine can do it until it runs out of fuel.
o Next, think about riding a multi-speed bicycle and what happens to speed and your legs as you work your way up through the gears. If you put out a constant amount of power, in lower gears you accelerate quickly but don't go very fast while in higher gears you accelerate slower but go faster. Just like your legs, the engines in the truck and the car always do the same amount of work at a given rpm... what changes is what gear the transmission is in. Even though power doesn't change, work does...
With that in mind, consider a "typical" diesel truck and a "typical" F1 car in three different situations... first at 30 mph, then at 60 mph, and finally at 120 mph... and let's see what they're doing.
Engine rpm |
Drive wheel rpm |
Flywheel T |
Drive wheel T |
Flywheel bhp |
Drive Wheel bhp |
|
1568 |
294 |
600 lb-ft |
3120 lb-ft |
179 bhp |
955 bhp |
|
8000 |
727 |
200 lb-ft |
2200 lb-ft |
304 bhp |
3351 bhp |
At 30 mph, the truck engine is spinning at just 1568 rpm, is in the heart of it's power band, and with the drive train's 5.33-1 total mechanical advantage the truck is putting some impressive numbers to the drive wheels and it's ready to uproot some trees. This is what the truck is built to do and this is the spot it's built to do it in.
The F1 engine is also at a moderate 8000 rpm (for an F1 engine that is, they idle at ~ 6000 rpm) and is still well below it's power band but because the engine is spinning so much faster than the drive wheels, the engine enjoys an 11-1 total mechanical advantage through the drive train allowing it to also put some impressive numbers to the drive wheels. You can see why these cars that weigh under 1400 lbs including the drivers accelerate like they do.
Engine rpm |
Drive wheel rpm |
Flywheel T |
Drive wheel T |
Flywheel bhp |
Drive Wheel bhp |
|---|---|---|---|---|---|
|
1951 |
786 |
500 lb-ft |
1241 lb-ft |
186 bhp |
461 bhp |
|
14000 |
1454 |
225 lb-ft |
2166 lb-ft |
600 bhp |
5777 bhp |
At 60 mph, things are changing. The truck has shifted into fifth gear because of the engine's low redline and the engine is already moving out the top of it's peak power band as the engine's volumetric efficiency begins to exceed the turbo's capability. The engine is still making 83% of the power it made above, but the work being done through the gears at the tire contact patches have decreased by almost 70% because the mechanical advantage is down to 2.48 as the transmission is running out of gears.
The F1 car is still in first gear and approaching it's power band and - because of the engine's very high redline - still enjoys the 11-1 mechanical advantage... while the truck's road wheel power is way down, the F1 car's power at the contact patch has almost doubled.
Engine rpm |
Drive wheel rpm |
Flywheel T |
Drive wheel T |
Flywheel bhp |
Drive Wheel bhp |
|
2925 |
1179 |
400 lb-ft |
992 lb-ft |
223 bhp |
552 bhp |
|
18000 |
2903 |
233 lb-ft |
1445 lb-ft |
798 bhp |
4951 bhp |
At 120, the story is complete. The truck is still in fifth gear, the engine is running out of available rpm, and power is starting to noticeably fall off... flywheel power is down by 50% compared to 30 mph and second gear while drive wheel power is down by 75%. As power is falling off, aerodynamic drag is increasing exponentially and the truck has literally hit a wall. This isn't what a full size truck is meant to do and it shows.
The F1 car, on the other hand, is like a dog that just got off it's leash and doing exactly what it was designed for. The engine is screaming at redline making its peak power and the car is in third gear pulling hard against the increasing resistance of the air. Although drive wheel power is down because of the decreased mechanical advantage as the driver up shift, it's still 45% higher than the truck and the car still has four more gears to go. It can't uproot a tree, but with 1445 lb-ft and 4951 bhp at the drive wheels and several gears to go, it's going to pull hard well past 200 mph.
o Unichip tuning. So with the understanding that an engine has "torque" at every rpm and "horsepower" at every rpm, what do you get when you install a Unichip?
When we build calibrations, we optimize the Air-Fuel Ratio and ignition timing (or injection timing for TDi applications) so that all engine rpm at high load the combustion chamber produces maximum power... maximum Torque.
With the Unichip, at 1000 rpm, the engine makes maximum torque and it does so at every rpm value all the way to redline. That means - by definition - maximum bhp at every rpm as well. So, whether you want to talk about power or work, Torque or bhp, the Unichip produces the most your engine will make.
24 March 2010
Will the Unichip void my vehicle's warranty?
Short answer - No
Long answer - There are two parts to this question. First, will your vehicle's OEM void your warranty if they find the Unichip on your vehicle? Second, will you vehicle's OEM find the Unichip on your vehicle/ Legally, no manufacturer can void a warranty because of the use of aftermarket parts or service so "legally" even if the OEM finds the Unichip, they can't void the warranty; you may find yourself suing the OEM to make the point however.
That makes the second question the more important in the real world. The Unichip makes no physical or electronic change to any of your vehicle's systems so there are no "footprints" remaining for the OEM to use to raise any questions.
Technical answer - Under US Federal Law, specifically the Moss-Magnusson Act of 1975, no manufacturer of any consumer product including automobiles may void their warranty because a customer uses non-OEM parts or service unless they can prove to the US FTC that those parts or that service caused the warranty problem. Legally, just because your vehicle's OEM might find the Unichip on your vehicle they may not void your warranty. Obviously, that doesn't mean OEM's can't and don't tell customers that their warranty is voided when they find modifications. They practical issue, then, is will the OEM know you have installed the Unichip.
Most aftermarket engine management system change engine performance by changing the data in the OEM ECU so that it responds differently. Every time the OEM ECU is reprogrammed, it records the event which means every time you use a reflash downloader, the OEM ECU records a footprint that you have been playing around. Whenever you take your vehicle in for service, the first thing the dealer does is download the ECU's data and when they do, they see all of the footprints. Most downloaders give you the ability to reprogram the ECU back to stock, but the footprint isn't the data so reprogramming the ECU doesn't help... in fact, now the ECU reports two reprogrammings not one.
The Unichip, on the other hand, leaves no electronic, electrical, or physical trace, or footprint it has been installed once removed. In fact, there is no electrical or electronic footprint even when the Unichip is installed and operating although obviously it's there to be seen if you leave it installed when your go to the dealer.
There are two schools of thought among car dealers... those who encourage - and even help - their customers to play with their vehicles and those who don't. Which school your dealer subscribes to is obviously something only you can determine.
We actually sell a lot of kits to dealers who install the parts for their customers. If you have a dealer that supports and encourages modifications, you can leave the Unichip installed when you take your car in for service and it won't interfere with or change anything while they do their work. They can reprogram the OEM ECU, scan and download the OEM ECU, and do anything else they want and will never see any changes because of the Unichip. They also can't inadvertently erase or change the data within the Unichip because unique hardware and software is required to program the Unichip.
If your dealer doesn't support modifications, or if you're unsure and unwilling to take a chance, you can remove the Unichip in just a few minutes before you take your vehicle in. Once the system has been removed, there are no footprints of any kind remaining to raise any questions. Regardless of what tools the dealers may be using, it's impossible for them to see the Unichip was ever installed.
22 March 2010
Does my engine revert to stock when the Unichip is removed?
Short answer - Yes
Long answer - All changes actually happen inside the Unichip and your vehicle is stock even with the Unichip installed. When the Unichip is removed, the changes happening within it are no longer being made so everything about your vehicle continues exactly as intended by the OEM
Technical answer - Your engine is computer controlled by its Engine Control Unit (ECU). Everything happening within the engine is based upon the control "maps" loaded into the OEM ECU and the signals from the engine and exhaust mounted sensors telling the OEM ECU what's happening in and around the engine. With the Unichip installed, then engine, the OEM ECU, and all of the sensors are completely unaltered... that is to say they are completely stock. The signals themselves are what changes
Sensors are each designed to detect and report to the OEM ECU specific conditions and do so by generating a unique electrical signal for each unique engine condition. With the Unichip installed, the sensors accurately detect the actual condition it's designed to observe and sends the appropriate signal to the ECU. After the signals are sent out of the sensors, they enter the Unichip which is installed electrically between the sensors and the OEM ECU. The Unichip very specifically makes changes to the signals and then passes them on to the OEM ECU. Even with the Unichip installed, all of the sensors are completely stock and perform as designed.
The OEM ECU, also bone stock, receives not the signal sent by the sensors but the ones modified by the Unichip so it's perception of what's happening in the engine is slightly "erroneous" The OEM ECU goes to the site in its control map based upon the Unichip changes signal rather than the site determined by the original sensor signal. Although the changes are typically small, this "erroneous" map site is the correct site for the data received by the OEM ECU and, as such, the OEM ECU is both stock and responding correctly. Even with the Unichip installed, the OEM ECU is completely stock and performs as designed.
The changes made by the Unichip are very specific (individual correction points at less than 0.3% load change at about every 15 rpm increment). The Unichip determined site changes are carefully selected to fine tune the engine for better performance.
15 March 2010
How much will my gas mileage improve with the Unichip?
• Short answer - Your normally aspirated, gasoline vehicle will produce more power and consume less fuel with the Unichip than without it, but how that changes average mileage depends on a number of variables including your right foot.
• Long answer - Average fuel mileage depends on engine design, emission requirements, fuel grade, and how you drive your vehicle. As with most automotive question, whether you'll see a mileage increase is "it depends." Although possibly counter intuitive, your vehicle's engine always uses the same amount of fuel to make a given amount of power unless it is somehow modified. What actually changes is how much power it makes and how long it makes that power. How much power it makes depends upon multiple variables like the engine's condition, ambient environmental conditions, fuel grade, and accelerator position. How long it makes that power is determined solely by how long you keep the accelerator pushed down and what you ask it to do. If you're not just driving to and from the corner market and do exactly the same thing, with the exact same vehicle, under exactly the same conditions with a correctly tuned Unichip, your vehicle will use less fuel that it does without the Unichip.
• Technical Answer - A vehicle's average mileage depends upon what governmental emission requirements that vehicle was designed to meet and how you use the vehicle. The engine is a surprisingly complex and sophisticated computer controlled machine and to understand why that machine does or does not deliver improved mileage, you have to understand how the system works. Basic engine design, governmental requirements, the OEM's engineering solutions to meet those requirements, and how you drive the vehicle all impact mileage.
Basic engine design
o Instantaneous fuel economy. The fuel mileage you observe is really the time averaged instantaneous mileage for everything the engine does. Starting, idling, accelerating, decelerating, steady state cruising all require different amounts of fuel to produce the different amount of power need to accomplish that task. The amount of fuel the engine uses to make a level of power is called Brake Specific Fuel Consumption.
Brake Specific Fuel Consumption
• The amount of fuel a particular reciprocating engine uses to make a given amount of power is determined by engine design and for a given design it is a fixed value. Engineers evaluate requirements for the engine, and then choose the shape of the combustion chamber, the compression ratio, etc... all of which combine to produce an amount of power for a given amount of fuel. Stated differently, the amount of fuel a reciprocating engine uses to produce a given amount of power is called Brake Specific Fuel Consumption and is expressed by the equation
Brake Specific Fuel Consumption = Pounds fuel used divided by horsepower-hours
or
BSFC = lb / hp-h
• What this equation means is:
o A given engine always consumes exactly the same amount of fuel to make a specific amount of power for a specific amount of time.
o A given engine may have different a BSFC at a different power levels.
o A given engine has only one "peak" BSFC which corresponds to the lowest mathematical ratio... that is the lowest fuel used to produce the most power. Every other BSFC is worse than that peak value for that engine.
• What this equation does not mean is:
o A given engine consumes the same amount of fuel under all conditions. If you ask the engine to make more power - or make the same amount of power for a longer time - without modifying it, it uses more fuel. If you ask it to make less power - or make the same amount of power for a shorter time - without modifying it, it uses less fuel.
o One BSFC is "ideal." Every road engine is a compromise intended to provide a good average across a number of requirements. A particular engine's BSFC for idea power is different from that same engine's minimum fuel consumption BSFC, which is probably different from its minimum emissions BSFC.
• Virtually all production road vehicle engines are set richer than optimum under Open Loop conditions and can be leaned out to yield a smaller - that is changed to as to use less fuel to make the same amount of power - BSFC value.
• The only way to change an engine's BSFC at a specific power level is to physically modify the engine (raise the compression, add a supercharger, modify the ECU, etc...).
Average fuel economy
Everyone who logs their fuel mileage knows that their vehicle's mileage changes from one tank to another. Since BSFC doesn't change unless the engine is modified, something else must be causing the mileage change. That something isn't the engine compartment, or in the ECU, it's in the mirror. What you do with your vehicle changes how much power you ask from the engine and how long it makes that power.
• Were you driving with the air conditioning on one trip and off on another?
• Was the vehicle weighed down with a heavy load on the first trip and empty on the second?
• Were you well above the speed limit on one but at the limit at the other?
• Were you slugging through two feet of snow on the first test and on a sunny spring day on the second?
The time average of instantaneous BSFC for a particular engine is what you see as for average fuel economy. If an engine of fixed design and control maps has to work at high power levels it operates at a higher BSFC and will deliver lower economy. If it has to work at low power levels it operates at lower BSFC and will deliver higher economy.
Every time you drive, you command a different power level for a different amount of time which means that every trip is an average of a "unique" set of instantaneous BSFC's.
Governmental Requirements
Emissions reduction - The second factor affecting fuel mileage has nothing to do with basic engine operation, but is an artificial requirement imposed by society on all gasoline Otto-cycle engines that are road legal to minimize exhaust emissions.
As a society, we decided reducing pollution is a major consideration and have implemented requirements for street vehicles such that they spend most of their operating time at in an environmentally friendly mode.
In the 1996 the Federal Government mandated all vehicles intended for street use meet OBD2 standards which include emissions requirements that all OEM's must meet including mandatory stoichiometric emissions for most driving conditions.
Air-to-Fuel Ratio
While BSFC is viable engineering concept, a closely related measurement is much more easily measurable that is more commonly talked about is Air-to-Fuel Ratio, or AFR. While BSFC expresses fuel consumption relative to power, it's difficult to measure without a dynamometer but AFR can be measured directly from the engine exhaust. Rather than expressing fuel consumption relative to power, AFR expresses fuel consumption as a byproduct of the chemical reaction within the combustion chamber... a less precise measurement but much easier to obtain.
