Tuning and Forced Induction Glossary

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In preparation for the 1.5 and 2.0, it's time to start collecting some common acronyms associated with forced induction and tuning. The idea is to edit this list as we become more educated on the new platforms. But for now we can use this as a starting point.

If you'd like to suggest edits or additions, feel free to post in the comments and I'll add accordingly.

Credit where credit is due; the initial list was taken from member "Abilor" and other very knowledgeable guys on Mazdaspeedforums.org.




AFR – Air Fuel Ratio. The mixture of fuel and air entering the engine cylinders and being combusted. Calculated by a sensor which examines exhaust gas for oxygen content, AFR is measured in lambda, which is the same for all fuels. 1 Lambda = 14.7:1 AFR with petrol/gasoline. 1 Lambda represents different air to fuel ratios with different fuels, and is more consistent regardless of your gasoline/ethanol mixture.

ALT - Absolute Load Targets. Many ECUs use load based targeting to calculate other variables such as boost PSI. Whether or not this applies to Honda remains to be seen.

APP – Absolute Pedal Position for Drive by Wire.

BAT - Boost Air Temperature. The temperature of the air entering the engine at the intake manifold; an upgraded intercooler can bring these temperatures down, which is a VERY good thing.

BCS - Boost Control Solenoid. In addition to EBCS aka boost control solenoid (see WGDC)

BOV – Blow Off Valve. Vents excess boost pressure to the atmosphere (VTA).

BPV – Bypass Valve. Also known as CBV (compressor bypass valve). Recirculates excess boost pressure through the system.

BT – Boost Targets. Your map’s boost targets across the RPM range. Also can mean Big Turbo, and upgraded turbo.

BTDC - Before Top Dead Center. A relative position of an engine's crankshaft used for calibrations.

CAI - Cold Air Intake. In naturally aspirated motors, CAIs can reduce intake temps for better performance. In forced induction motors, improvements over SRIs (Short Ram Intakes) are limited, due to the presence of the vehicle's intercooler.

CAN - Controller Area Network. Communication protocol used by automotive manufacturers to communicate data between computer modules within a vehicle. Includes ABS computer, ECU/PCM, radio/climate controls, instrument cluster, etc.

CAT – Catalytic Converter. Transforms hydrocarbons into more inert states that are better for the environment. Typically referenced using lowercase letters, ex. "I deleted my cat."

CBE – Cat-Back Exhaust. A system that, when combined with other exhaust modifications, is designed to reduce backpressure and ultimately enable the turbo to spool faster. CBE efficiency improvements may include high flow resonators and/or mufflers which can contribute to pronounced exhaust noise.

CC - Combustion Chamber. This is where the magic happens: fuel and air are compressed by the piston in the cylinder, ignited by the spark plug, and combustion pushes the piston back down the cylinder imparting force to the crankshaft.

CEL - Check Engine Light. The yellow light on the instrument cluster that alerts you to an ECU self-diagnosis of an issue; the "code" for the issue can be pulled by a OBD2 reader, and researched on the forums for resolution.

DBW - Drive By Wire. Substitution of traditional human interface elements with electromechanical actuators; in our case, usually refers to the electronic manipulation of the throttle plate given the input of the accelerator pedal.

DISI – Direct Injection Spark Ignition. It injects fuel directly into the cylinders, which has a cooling effect, aiding combustion. More here:
http://auto.howstuffworks.com/direct-injection-engine.htm

DP – Downpipe. The pipe coming straight off the turbo and leading to the exhaust piping. Upgraded DP’s are generally less restrictive due to more efficient routing; such as placing a high flowing CAT in the exhaust stream (if one is present), reducing back pressure and allowing the turbo to spool faster. They are less restrictive because they use one which allows exhaust gases to pass through with less resistance. Resistance causes back pressure and may slow the spool of the turbo, which increases low end torque but ultimately may decrease peak output. Many factory turbos are engineered in conjunction with the intake system to spool quickly to maximize low end torque and throttle response, hence the restriction.

EBCS - Electronic Boost Control Solenoid. The device which, when subjected to the WGDC, physically closes the wastegate to build boost.

ECU – Engine Control Unit. The computer that makes realtime adjustments to your engine’s performance as dictated by the turning parameters you are running (factory or otherwise).

EGR - Exhaust Gas Recirculation. Mainly there for emission control at the expense of buildup of unwanted contaminants.

EGT - Exhaust Gas Temp.

EWG - External Waste Gate. A wastegate that is located independent of the turbo. Honda runs an internal wastegate on their factory turbos.

FMIC – Front Mount Intercooler. A radiator type unit, but in reverse, that cools air driven by exhaust pressure from the turbo, which heats the air up; cooler air combusts better, so it’s necessary to cool it before entering the turbo intake. FMIC’s are usually located in front of the car’s radiator, or adjacent to it, and significantly reduce “heat soak” under all conditions except at idle. An FMIC bleeds off some of the heat caused by pressurization of air by the turbo (the air entering the cylinders), not exhaust pressure (the air exiting the cylinders). "Heat Soak" refers to the tendency of the Intercooler to become hot itself, and therefore loose effectiveness as a heat dissipation device. This effect is exacerbated slightly by engine bay temperature where air induction occurs.

g/s - Grams per Second. see MAF

HPFP – High Pressure Fuel Pump in direct injection motors.

IAT - Intake Air Temperature. The temperature of the air passing through the MAF; not nearly as critical as BAT. Comparing Intake Air Temperature to Boosted Air Temperature can be used to determine the cooling efficiency of the Intercooler. Also, a lower IAT will result in lower BATs under normal operation, but variances in IAT seem to have less of an effect than similar variances in BAT.

IM - Intake Manifold. The network of piping that allows air from a single intake to enter four separate cylinders. The smoother the airflow, the better.

IWG - Internal Wastegate. A wastegate physically located within the turbo.

KR – Knock Retard. The degree to which the ECU is reducing engine timing to prevent detonation. It is important to know the causes of Knock (detonation), which you can discern via KR in an engine that is mechanically sound. Lean AFRs, hot BATs, advanced timing, all cause KR. Ideally, at WOT (wide open throttle), there will be little to no KR.

LTFT - Long Term Fuel Trim. The average value the ECU is using to adjust fuel injection to reach target AFR's. Will fluctuate while ECU is being "trained" after first 50 - 100 miles of being reset.

MAF – Mass Air Flow sensor. The reader that senses the air flowing into the engine; the ECU uses it’s realtime values to make critical calculations regarding how much fuel to inject into the engine. The ECU's calculations change depending on learned long term fuel trims (LTFT) in closed loop operation. These fuel trims are expressed as a percentage error between requested AFR/Lambda and observed AFR/Lamba. +2% means 2% more air is coming in than expected (and requires 2% more fuel to achieve requested AFR/Lambda), and -2% is just the opposite.

MAP - Manifold Absolute Pressure. Measured at the intake manifold post intercooler (same sensor as BAT).

MBC - Manual Boost Controller. A device which the driver can operate to control boost levels.

MBT - Minimum Timing for Best Torque.

NVH - Noise, Vibration, and Harshness.

OBD-II - On-Board Diagnostics protocol II. Definied by the Society of Automotive Engineers (SAE) document J1979. The required standard PID protocol for all cars sold in the US after 1996.

OCC - Oil Catch Can. An additional reservoir in the circulation of the crankcase vapors (PCV). OCCs are added to help capture contaminants that, as part of smog control, may be redirected to the combustion chamber and subsequently burned off. Over time, this can reduce the accumulation of deposits in various areas such as the intake manifold (depending on PCV design).
http://oilcatchcan.com/
Things to look for in a catch can (done by a competitor but the info is solid):
http://www.ecoboostperformanceforum.com/index.php?topic=2142.0

OEM – Original Equipment Manufacturer. An OEM part is a stock part.

OTS - Off The Shelf. After used when referring to standard tuning maps vs. custom maps.

PCV - Positive crankcase ventilation.
http://www.aa1car.com/library/pcv.htm

PID - Parameter Identification. Term used for a signal input to the PCM/ECU, a value calculated by the PCM/ECU, or a system staus flag. Many are defined by the OBD-II protocol, and some are manufacturer-specific.

PNP - Plug and Play. A device that can be used immediately and easily after installation.

PSI – Pounds per Square Inch. A pressure measurement when calculating boost.

RP - Race Pipe. A portion of an exhaust with the cat deleted.

RPM – Revolutions Per Minute. The rotating speed of the engine crankshaft.

SRI - Short Ram Intake. Often used with turbo inducted motors to improve throttle response with minimal negative impacts to intake temps (post-IC).

STFT - Short Term Fuel Trim. The real-time value of adjustments made by ECU to reach targeted AFR.

TB - Throttle Body. The part of the air intake system that controls the amount of air flowing into the engine.

TBE - Turbo Back Exhaust. A full replacement of the exhaust from the turbo back, including downpipe, catalytic converter (if located behind the turbo), resonator(s), and muffler. The goal of the system is to reduce backpressure and allow the turbo to spool faster.

TDC - Top Dead Center. A position of the engine's crankshaft used to calibrate timing.

TIH/TIP - Turbo Inlet Hose or Turbo Inlet Pipe. This pipe is the second half of an intake that leads directly to the turbo turbine. On cars which use a larger than stock turbo (BT or Big Turbo), the intake and the TIP are one piece.

TMIC – Top Mount Intercooler. A radiator type unit, but in reverse, that cools air driven by exhaust pressure from the turbo, which heats the air up; cooler air combusts better, so it’s necessary to cool it before entering the turbo intake. TMIC’s are located on top of the engine and are generally accompanied by a ram style induction system to channel airflow. Larger TMIC’s are more efficient and can be used to help optimize boost, but are still prone to “heat soak”. See FMIC.

TP – Throttle Position. The position of the throttle on the engine applied by the ECU through Drive by Wire system. The ECU controls TP based on fueling, boost, load, or other parameters identified by the manufacturer.

TP - Test Pipe. A portion of the exhaust with a cat deleted.

VE - Volumetric Efficiency. For turbo cars, this metric is usually between 60-85%.

VTA – Vents to Atmosphere.

VVT - Variable Valve Timing

WGA - Waste Gate Actuator. Deploys the Wastegate.

WGDC – Waste Gate Duty Cycle. The values that operate the wastegate’s closing percentage; the higher the percentage, the more the wastegate is closed, and the more boost is built and crammed into the intake manifold for more power.

WMI - Water Meth Injection. A method of spraying a coolant into the engine cylinders to improve compression and reduce KR.

WOT – Wide Open Throttle. Otherwise known as “Lead Foot”



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Viet_Racer

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Seeing things like this make the car even more real. Can't wait to see members take deliveries.
 
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Updated with 1.5 turbo configuration.

1.5T: Single-Scroll MHI TD03 with internal wastegate.
 

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There are a number of errors in here.

1. Every engine is different but the downpipe almost always comes off the turbo, not the exhaust manifold. And it doesn't lead to the "CBE," it leads to the CAT.

2. The "OCC" is not part of the "oil circulation of the engine." It is part of the engine ventilation system and it removes oil vapors from pressurized air coming out of the crankcase or even out of the head. This oil is not always put back into circulation in the engine.

3. The "BPV" should actually be called a "CBV" (compressor bypass valve). And it routes excess boost pressure back to the turbo intake specifically. I assume "through the system" meant through the intake system, but you never know.

4. CAI info is wrong. All engines run better when the initial intake charge is cooler. Even though the turbo will preheat the intake air, if it comes in at a lower temperature, it goes out of the turbo at a lower temperature. It's just physics. The turbo is not a regulated heater. It can only add so much heat and the colder the input, the colder the output.

5. A CBE does NOT place the CAT farther from the engine. It doesn't do anything to the CAT. You can't move the CAT without screwing up the emissions. It's called "CAT back" because it's in BACK of the CAT (i.e behind it or after it in the exhaust system).

6. MBC is not necesarily in the cockpit. In fact, many are under the hood. Many people who bother to place a boost controller in the cockpit use an EBC (electronic boost controller), not a MBC.
 
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Edited the OP. Few notes:

In a majority of modern FI cars, a CAI has been observed to offer limited performance benefits over an SRI. While initial intake temps may vary as much as 10-15%, we have seen less than a 0.5% delta in BATs in all driving environments; except during or immediately following an idle condition. We suspect the majority of oversight is due to the inability of some tuners to replicate real world driving environments on a dyno (i.e. HO shop fan to the grill & RAI). I've retained some language here so readers aren't "fooled" into thinking CAIs offer a significant performance benefit over SRIs (and the subsequent risks of placing the filter lower in the vehicle's engine bay). This will be worth revisiting when we have greater empirical data on 1.5T.

It's believed that both the Si and CTR will offer a twin cat setup - one on the DP and the other on the MP before the resonator. Aftermarket CBE manufacturers (for lack of a better term) may infuse the 2nd cat directly into the CBE to minimize multi-piece costs and improve routing of the exhaust flow. Some have been known to move the position of the cat(s) in order to accommodate a slight change in the exhaust routing (without impacting the primary/secondary 02 sensors). I've added a description for TBE to help distinguish some different approaches.
 
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Let me add that all feedback/edits are welcome. Each subject above could benefit by having a reference for additional reading. If you have one, or would like to suggest an edit, copy/paste the glossary item along with your suggestions. Should help make things easy to swap out. Thanks! :cool:
 
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A question I see come up a lot is "what mods can I do without a tune?" The answer is, whatever allows the system to operate within the factory parameters of the ECU. If you're unsure as to how a particular component impacts air and fueling, best to wait until a proper readout is available.

As a general guideline, until we know more about the platform, here are the things to avoid prior to proper tuning solution:
- BOV or 50/50 BPV
- TBE
- FMIC
- Intakes with a larger diameter MAF housing
- Test pipe or removal of cat(s)
- TD04 or bigger turbo

I expect this list will get edited. But for now, we should assume that all of these can significantly impact metered air or fueling outside the parameters of the fuel pump, injectors, or ECU. Prior to installing, best to ensure it's been properly tested not only as a stand-alone piece, but in conjunction with other mods you plan to utilize.
 
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Below is an analysis taken on a high mileage turbo direct injection motor with carbon buildup. As cheap insurance, it is HIGHLY recommended to install a basic catch can kit and monitor carbon/oil deposits both on the intake/exhaust valves and the cylinder heads. If left unchecked, the deposits can accumulate on the oil control rings and lead to aggressive oil consumption, despite strong compression results. Increased oil residue can make it way down the turbo, 02 sensors and cats, and can cause further damage over time.

It's unknown as to what degree this will impact Honda's direct injection motors. Temps, valve timing, and oil/fuel quality all play a part. But it's worth mentioning here for those who are considering a mod path.

This motor: 164K with 12K on the plugs. Oil being consumed at 1QT every 200 miles. The 02 sensor (replaced 200-300 miles prior to the plugs being pulled) is believed to have partially contributed to a lean condition as higher quantities of oil were burned/passed along the sensor. Oil changed with OEM filter and Penzoil Conventional 5W-30 for 90% of its life.

IMG_94191.jpg IMG_14631.jpg IMG_00921.jpg IMG_00911.jpg IMG_00901.jpg IMG_00891.jpg
 
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AhmedTitef

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not all car buyers know these information, however their cars still drivable in mint condition after 200k miles.
 

                           





















































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