Johnnu

Apologies for a very basic question.... been around for 66+ yrs and not up on the latest car tech talk. Owned a '62 FI Vette all my life (till 2007) and am lost in today's world of performance talk. Q2: What's a "tune"? How does one "purchase a tune"? Sounds like something I could get into a lot of trouble with if I finally pop for a new car (my 2000 Subaru outback doesn't require anything but oil changes, plugs and filters) :-) Thanks again, John N.

daredevil95

Chip tuning 101:

Chip tuning
Modern engines are equipped with an engine management system which can be modified to different settings, producing different performance levels. Manufacturers often produce a few engines which are used in a wider range of models and platforms, and this allows the manufacturers to sell cars in various markets with different regulations without having to spend money developing and designing different engines to fit these regulations. This also allows for a single engine to be used by different brands, tuned to suit their particular market.



Performance tuning 101:

Performance tuning focuses on tuning an engine for motorsport, although many such cars never compete but rather are built for show or leisure driving. In this context, the power output, torque, and responsiveness of the engine are of premium importance, but reliability and fuel economy are also relevant. In races, the engine must be strong enough to withstand the additional stress placed upon it, and so is often far stronger than any mass-produced design on which it may be based, and also that the vehicle must carry sufficient fuel. In particular, the transmission, driveshaft and any other load-bearing powertrain components may need to be modified in order to withstand the load from the increased power.
In most cases, people are interested in increasing the power output of an engine. Many well tried and tested techniques have been devised to achieve this, but all essentially operate to increase the rate (and to a lesser extent efficiency) of combustion in a given engine. This is achieved by putting more air/fuel mixture into the engine, using a fuel with higher energy content, burning it more rapidly, and getting rid of the waste products more rapidly - this increases volumetric efficiency. In order to check the amount of the air/fuel mixture, air fuel ratio meters are often used. The weight of this fuel will affect the overall performance of the car, so fuel economy is a competitive advantage. This also means that the performance tuning of an engine should take place in the context of the development of the overall vehicle.
The specific ways to increase power include:
Increasing the engine displacement by one or both of two methods: "boring" - increasing the diameter of the cylinders and pistons, or by "stroking" - using a crankshaft with a greater throw.
Using larger or multiple carburetors, to create a more controllable air/fuel mixture to burn, and to get it into the engine more smoothly. In modern engines, fuel injection is more often used, and may be modified in a similar manner.
Increasing the size of the valves in the engine, thus decreasing the restriction in the path of the fuel–air mixture entering, and the exhaust gases leaving the cylinder. Using multiple valves per cylinder results in the same effect – it is often more difficult to fit several small valves than to have larger single valves due to the valve gear required. However it is difficult to find space for one large valve in the inlet and a large valve on the outlet side. Sometimes a large exhaust valve and two smaller inlet valves are fitted for improved flow. As the pressure generated during combustion provides more force to exhaust the waste gasses than the force available to inlet clean charged gas, a larger inlet valve area is needed to provide easier flow. The two smaller inlet valves' total area is larger than that of the single exhaust valve and thus provides that easier inlet flow. This is why exhaust valves are typically smaller in area than the inlet valves.
Using larger bored, smoother, less contorted intake and exhaust manifolds. This helps maintain the velocity of gases. Similarly, the ports in the cylinder can be enlarged and smoothed to match. This is termed cylinder head porting, usually with the aid of an air flow bench for testing and verifying the efficiency of the modifications. Manifolds with sharp turns force the air–fuel mix to separate at high velocities as fuel is heavier than air.
The larger bore may extend right through the complete exhaust system, using larger diameter piping and low back pressure mufflers, and through the intake system, with larger diameter airboxes and high-flow, high-efficiency air filters. Muffler modifications will change the sound of the car's engine, usually making it louder; for some tuners this is in itself a desirable effect.
Increasing the valve opening height (lift), by changing the profiles of the cams on the camshaft, or the lift (lever) ratio of the valve rockers (OHV engines), or cam followers (OHC engines).
Optimizing the valve timing to improve burning efficiency - usually this increases power at one range of operating RPM at the expense of reducing it at others. For many applications this compromise is acceptable. This can usually be achieved by fitting a differently profiled camshaft. See also valve timing, variable valve timing.
Raising the compression ratio by reducing the size of the combustion chamber, which makes more efficient use of the cylinder pressure developed and leading to more rapid burning of fuel, by using larger compression height pistons or thinner head gaskets, or by milling or "shaving" the cylinder head. High compression ratios can cause engine knock unless high octane fuels are used.
Forced Induction; adding a turbocharger or supercharger. The air/fuel mix entering the cylinders is increased by compressing the air. Further gains may be realized by cooling compressed (and thus heated) intake air with an air-to-air or air-to-water intercooler.
Using a fuel with higher energy content and by adding an oxidizer such as nitrous oxide.
Reducing losses to friction by machining moving parts to lower tolerances than would be acceptable for production, or by replacing parts. A common example of this is, in OHV engines, replacing the production rocker arms with replacements incorporating roller bearings in the roller contacting the valve stem.
Reducing the "rotating mass", which comprises the crankshaft, connecting rods, pistons, and flywheel. Doing so can improve throttle response due to lower inertia, as well as reduce overall vehicle weight. This may be achieved by using alloy parts instead of steel. However a heavy crankshaft can void the need for a flywheel (common on V6 engines).
Changing the tuning characteristics electronically, by changing the firmware of the engine management system (EMS). This chip tuning often works because modern engines are designed to produce more power than required, which is then reduced by the engine management system to make the engine operate smoothly over a wider RPM range, with low emissions. This is called de-tuning and produces long-lasting engines and the ability to increase power output later for facelift models. Recently emissions have played a large part in de-tuning, and engines will often be de-tuned to produce a particular carbon output for tax reasons.
Lowering the underbonnet temperature, which has the effect of lowering the engine intake temperature, therefore increasing the power. This is often done by installing a type of thermal insulation (normally a heatshield, thermal barrier coating or other type of Exhaust Heat Management) on or around the exhaust manifold. This ensures that more heat is diverted out and away from the underbonnet area.
The choice of modification depends greatly on the degree of performance enhancement desired, budget, and the characteristics of the engine to be modified. Intake, exhaust, and chip upgrades are usually amongst the first modifications made as they are the cheapest, make reasonably general improvements, whereas a different camshaft, for instance, requires trading off smoothness at low engine speeds for improvements at high engine speeds.
Furthermore, tuners may also use analytical tools to help evaluate and predict the effect of modifications on the performance of the vehicle.

JIM5.0

daredevil95 described it very detailed above. I hope you get all this.

Basically, back in the classic cars, like your '62 Vette, the car "tunes" itself mechanically. What I mean is the weights and springs in the distributor cap mechanically advance and retard your spark firing as you increase and decrease in RPMs.

A tune is what we call the computer program that does this advancing and retarding today.
Modern cars now use computers to electronically advance and retard the spark firing. The computer and tune program also adjust many other things as daredevil95 described. These things include, but are not limited to:
*How much fuel to shoot into the engine,
*How far to open the butterfly intake valves for the RPM your are running vs how far you have the gas pedal depressed,
*Engine fan speed (for hotter days, your cooling fan will turn faster to help keep the engine cool)
*When to shift gears in an automatic transmission,
*For cam phasing (if so equipped), how far forward or how far backwards to advance/retard the cams and valve lifts,
*Cylinder deactivation (if so equipped),
And literally dozens more parameters.

Cars today have so much stuff in them that the only way to adjust and operate them properly and reliably is by computer and the tune program. Controlling all of these things mechanically would make the engine much too big to even fit in the engine bay.

daredevil95

That was a cut & paste....I don't want to be known for plagiarism. I forgot to place the source at the bottom.

JIM5.0

Oh, no problem! Knowledge is knowledge, no matter how you obtained it, whether you learned it from something else or if you discovered it yourself.

One historical sense of plagiarism that we wrongfully give credit to is Issac Newton and Gottfried Leibnitz. Both men are wrongfully credited to being fathers of Calculus, when in fact, calculus was already around before them. They only put the concepts into mass use in their works and put the procedures of calculus in writing in very inclusive writings. Sure, they expanded calculus and created new techniques for it, but they by far did not invent calculus.


Anyway, I digress.
Other things that the computer tune does is control emissions equipment on your car. They do this by taking input from the mass air flow sensors and O2 sensors and adjusts spark and all accordingly to make a cleaner combustion.

And the computer also takes readings form the engine block knock sensors and retards timing to prevent detonation. Heck, if our cars can variably change compression ratio on the fly, the computer would even reduce compression ratio to stop engine knocking (detonation).

ski

Taking it a step further, a modded tune increases performance with 3 primary components:
- Torque management table(determines engine output torque as a function of throttle position and rpm).
- Fuel delivery table(determines A/F ratio as a function of manifold air pressure and rpm).
- Spark table(determines timing as a function of manifold air pressure and rpm).

It also improves throttle response crispness, and gives an auto tranny crisper and more aggressive shifts.
Plus, it can be designed for different fuel octane ratings, and for modifications that change the engine's airflow, like a CAI(cold air intake), headers, and FI(supercharger, turbocharger).

You can purchase a tune either pre-installed in a handheld tuner, or at a dyno shop. The handheld tuner is a handy device that can not only hold multiple tunes, but can also be used to change values, like timing, A/F, max rpm and speed, differential ratio, and tire size.

SpartaPerformance

Plain and simple a "tune" is a new computer program uploaded into the car to enhance performance when you add parts. It's uploaded via a handheld device. The most popular hand held tuners are from SCT, and the most common performance upgrade for Mustang owners is a new cold air intake tube and a tune.

Johnnu

Many, many thanks everyone. Finally, it makes sense this word "tuner". You're, of course, correct, in the old days we used to work rather hard to make the changes that a computer can now do for us almost "on the fly"... And, I love the idea of being able to unplug that "shift solenoid".. THANKS, John N.

JIM5.0

I remember that you had to manually tune-up the old carb cars by hand because the car wears in, the needle settings come out of position, the distributor cap rotor, weights, and springs wear down and the spark goes off, etc.

Today, cars are capable of going 100,000 miles in between tunes because the computer tune never comes out of position or wears down like distributor rotors, etc. And from what I understand, the 100,000 mi tune-up is only a recalibration to match the engine wear.

StuckInNYForever

Also keep in mind that most, if not all, performance upgrade parts will require a new tune to either optimize or even allow the car to function. The tune can also optimize the car specifically for a certain octane fuel, allowing you to maximize power that way.