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What a performance upgrade changes
An engine makes more torque when it can burn more fuel, at a combustion timing it can tolerate, and keep doing so without breaking or overheating. The fuel needs oxygen. For a given engine speed, the practical limit is the mass of air that reaches the cylinders, not the volume of the inlet tract and not the boost pressure on its own.
Garrett describes the turbocharged version of this directly: compressing the air raises its density, a charge-air cooler can raise that density further by cooling the air, and the higher air mass allows a higher fuel flow at a similar air-fuel ratio. The same mass-flow idea applies to a naturally aspirated engine. A larger throttle, a better port or a tuned runner only helps when it increases the air mass that is trapped, in the speed range the engine is actually used.
Most upgrades fall into one of four groups. They increase the air mass per cycle, they move the engine speed at which that air arrives, they let the combustion use the air that is already there, or they make the engine strong enough to keep the result. A part that changes the airflow also changes what the carburettor or the ECU thinks is happening. The calibration page and the hardware page have to be read together.
Air path
Throttle bodies and airflow. The throttle is a variable restriction. A larger body reduces full-throttle pressure loss, and it can also slow the air and make the pedal coarser.
Inlet manifolds and runner length. Plenum volume, runner length and runner area move the engine speed at which the inlet helps fill the cylinder.
Cylinder head, ports and valves. The port, the seat and the valve opening set how much air can enter once the manifold has delivered it.
Camshafts and valve timing. Duration, lift and overlap decide when that opening happens. Variable timing moves the same compromise around with engine speed.
Fuel and combustion
Carburettor tuning. On an engine without electronic injection, the carburettor is the mixture control. Jet, needle and choke changes have to follow the airflow.
Fuel system upgrades. Injectors, pumps and rail pressure have to supply the fuel mass the new air mass requires, including at the fuel the engine actually runs.
ECU remapping. A remap changes the stored requests and limits for torque, fuel, ignition, boost and protection. It does not add airflow by itself.
Ignition timing for performance. Spark advance is limited by knock as well as by the timing that would make the most torque.
Compression ratio. A higher geometric compression ratio can improve efficiency, and it raises the temperature at the end of the compression stroke.
Exhaust
Exhaust system tuning covers primary length, collectors, silencers and, on a turbocharged engine, the turbine housing. The exhaust can help scavenge the cylinder during overlap. It is also the energy source for a turbocharger, and a restriction that the piston has to push against.
Forced induction and charge temperature
Forced induction. Supercharger types, turbocharger types, parallel and sequential twins, twin-scroll housings, variable geometry, compound two-stage charging, and a supercharger used with a turbocharger.
Charge cooling, intercoolers and water injection. Why compression heats the air, what that does to density and knock, and how an intercooler or water injection changes the result.
Capacity and the parts that have to survive
Engine displacement raises the volume drawn in on every induction stroke. At the same volumetric efficiency and engine speed, a larger displacement takes in more air mass. Bore and stroke also change piston speed, flame travel and the loads on the rotating assembly.
Several real limits are not airflow devices. The cooling system has to reject the extra heat. The oil has to survive the bearing loads and, on a turbocharger, the heat in the shaft housing. Pistons, rods, the head gasket and the fasteners see higher cylinder pressure once more fuel is burned. The clutch and gearbox see the torque. These parts do not create the gain. They decide whether the gain can be kept.
Nitrous oxide is a separate method. Released into the inlet, it adds oxygen when it breaks down in the combustion chamber, and the evaporation cools the charge. It is not a supercharger and it is not a remap. The extra oxygen needs extra fuel, and the quantity has to be matched to that engine. Treat any kit figure as the manufacturer's claim for a stated setup, not as a result this engine will make.
Measurement
Data logging for engine preparation and design is the record of whether a change did what it was meant to. A serial log from the ECU, a stored oscilloscope trace, a Crypton engine analyser and a crank-angle combustion system such as the Plex PCA-2000plus keep different evidence. Shaft torque from a dynamometer is a further record, and it sits beside those rather than replacing them.
Using the pages together
A longer inlet runner, a shorter exhaust primary and a camshaft with more overlap are all speed-range choices. They can add to each other at one engine speed and work against each other at another. A compressor adds heat and, if it is a turbocharger, exhaust backpressure. An intercooler recovers density and also drops some of the pressure the compressor made. The carburettor or the ECU then has to meter fuel and ignition for the air that actually arrives.
Measure the change on the engine in question. A pressure gauge, an air-fuel measurement, ignition or injection timing, and knock or exhaust temperature where the installation can show them, are more useful than a catalogue power figure. How those measurements are taken, from a serial ECU log and an oscilloscope through a Crypton engine analyser to a Plex combustion-pressure system, is set out in data logging for engine preparation and design. The calibration guides already on this wiki, including ME7 torque, load and boost and EDC15 fuel control, are about particular control systems. They are not a specification for every engine in this section.
Sources
The linked pages carry the detailed citations. The air-mass statement above follows Garrett's turbocharger system description, and the temperature effect of compression follows the isentropic relation NASA sets out. Both are used again, with page references, on the forced-induction and charge-cooling pages.
Garrett Turbo Tech 101. Garrett Motion. Compressor, charge-air cooler, density and the turbine. Accessed 2026-11-11.
Isentropic compression or expansion. NASA Glenn Research Center. Pressure, temperature and the ratio of specific heats. Accessed 2026-11-11.
Open each version to inspect formatting, tables and photographs.
Revision 2: Engine performance upgrades
What a performance upgrade changes
An engine makes more torque when it can burn more fuel, at a combustion timing it can tolerate, and keep doing so without breaking or overheating. The fuel needs oxygen. For a given engine speed, the practical limit is the mass of air that reaches the cylinders, not the volume of the inlet tract and not the boost pressure on its own.
Garrett describes the turbocharged version of this directly: compressing the air raises its density, a charge-air cooler can raise that density further by cooling the air, and the higher air mass allows a higher fuel flow at a similar air-fuel ratio. The same mass-flow idea applies to a naturally aspirated engine. A larger throttle, a better port or a tuned runner only helps when it increases the air mass that is trapped, in the speed range the engine is actually used.
Most upgrades fall into one of four groups. They increase the air mass per cycle, they move the engine speed at which that air arrives, they let the combustion use the air that is already there, or they make the engine strong enough to keep the result. A part that changes the airflow also changes what the carburettor or the ECU thinks is happening. The calibration page and the hardware page have to be read together.
Air path
- Throttle bodies and airflow. The throttle is a variable restriction. A larger body reduces full-throttle pressure loss, and it can also slow the air and make the pedal coarser.
- Inlet manifolds and runner length. Plenum volume, runner length and runner area move the engine speed at which the inlet helps fill the cylinder.
- Cylinder head, ports and valves. The port, the seat and the valve opening set how much air can enter once the manifold has delivered it.
- Camshafts and valve timing. Duration, lift and overlap decide when that opening happens. Variable timing moves the same compromise around with engine speed.
Fuel and combustion
- Carburettor tuning. On an engine without electronic injection, the carburettor is the mixture control. Jet, needle and choke changes have to follow the airflow.
- Fuel system upgrades. Injectors, pumps and rail pressure have to supply the fuel mass the new air mass requires, including at the fuel the engine actually runs.
- ECU remapping. A remap changes the stored requests and limits for torque, fuel, ignition, boost and protection. It does not add airflow by itself.
- Ignition timing for performance. Spark advance is limited by knock as well as by the timing that would make the most torque.
- Compression ratio. A higher geometric compression ratio can improve efficiency, and it raises the temperature at the end of the compression stroke.
Exhaust
Exhaust system tuning covers primary length, collectors, silencers and, on a turbocharged engine, the turbine housing. The exhaust can help scavenge the cylinder during overlap. It is also the energy source for a turbocharger, and a restriction that the piston has to push against.
Forced induction and charge temperature
- Forced induction. Supercharger types, turbocharger types, parallel and sequential twins, twin-scroll housings, variable geometry, compound two-stage charging, and a supercharger used with a turbocharger.
- Charge cooling, intercoolers and water injection. Why compression heats the air, what that does to density and knock, and how an intercooler or water injection changes the result.
Capacity and the parts that have to survive
Engine displacement raises the volume drawn in on every induction stroke. At the same volumetric efficiency and engine speed, a larger displacement takes in more air mass. Bore and stroke also change piston speed, flame travel and the loads on the rotating assembly.
Several real limits are not airflow devices. The cooling system has to reject the extra heat. The oil has to survive the bearing loads and, on a turbocharger, the heat in the shaft housing. Pistons, rods, the head gasket and the fasteners see higher cylinder pressure once more fuel is burned. The clutch and gearbox see the torque. These parts do not create the gain. They decide whether the gain can be kept.
Nitrous oxide is a separate method. Released into the inlet, it adds oxygen when it breaks down in the combustion chamber, and the evaporation cools the charge. It is not a supercharger and it is not a remap. The extra oxygen needs extra fuel, and the quantity has to be matched to that engine. Treat any kit figure as the manufacturer's claim for a stated setup, not as a result this engine will make.
Measurement
Data logging for engine preparation and design is the record of whether a change did what it was meant to. A serial log from the ECU, a stored oscilloscope trace, a Crypton engine analyser and a crank-angle combustion system such as the Plex PCA-2000plus keep different evidence. Shaft torque from a dynamometer is a further record, and it sits beside those rather than replacing them.
Using the pages together
A longer inlet runner, a shorter exhaust primary and a camshaft with more overlap are all speed-range choices. They can add to each other at one engine speed and work against each other at another. A compressor adds heat and, if it is a turbocharger, exhaust backpressure. An intercooler recovers density and also drops some of the pressure the compressor made. The carburettor or the ECU then has to meter fuel and ignition for the air that actually arrives.
Measure the change on the engine in question. A pressure gauge, an air-fuel measurement, ignition or injection timing, and knock or exhaust temperature where the installation can show them, are more useful than a catalogue power figure. How those measurements are taken, from a serial ECU log and an oscilloscope through a Crypton engine analyser to a Plex combustion-pressure system, is set out in data logging for engine preparation and design. The calibration guides already on this wiki, including ME7 torque, load and boost and EDC15 fuel control, are about particular control systems. They are not a specification for every engine in this section.
Sources
The linked pages carry the detailed citations. The air-mass statement above follows Garrett's turbocharger system description, and the temperature effect of compression follows the isentropic relation NASA sets out. Both are used again, with page references, on the forced-induction and charge-cooling pages.
Revision 2: Engine performance upgrades
What a performance upgrade changes
An engine makes more torque when it can burn more fuel, at a combustion timing it can tolerate, and keep doing so without breaking or overheating. The fuel needs oxygen. For a given engine speed, the practical limit is the mass of air that reaches the cylinders, not the volume of the inlet tract and not the boost pressure on its own.
Garrett describes the turbocharged version of this directly: compressing the air raises its density, a charge-air cooler can raise that density further by cooling the air, and the higher air mass allows a higher fuel flow at a similar air-fuel ratio. The same mass-flow idea applies to a naturally aspirated engine. A larger throttle, a better port or a tuned runner only helps when it increases the air mass that is trapped, in the speed range the engine is actually used.
Most upgrades fall into one of four groups. They increase the air mass per cycle, they move the engine speed at which that air arrives, they let the combustion use the air that is already there, or they make the engine strong enough to keep the result. A part that changes the airflow also changes what the carburettor or the ECU thinks is happening. The calibration page and the hardware page have to be read together.
Air path
- Throttle bodies and airflow. The throttle is a variable restriction. A larger body reduces full-throttle pressure loss, and it can also slow the air and make the pedal coarser.
- Inlet manifolds and runner length. Plenum volume, runner length and runner area move the engine speed at which the inlet helps fill the cylinder.
- Cylinder head, ports and valves. The port, the seat and the valve opening set how much air can enter once the manifold has delivered it.
- Camshafts and valve timing. Duration, lift and overlap decide when that opening happens. Variable timing moves the same compromise around with engine speed.
Fuel and combustion
- Carburettor tuning. On an engine without electronic injection, the carburettor is the mixture control. Jet, needle and choke changes have to follow the airflow.
- Fuel system upgrades. Injectors, pumps and rail pressure have to supply the fuel mass the new air mass requires, including at the fuel the engine actually runs.
- ECU remapping. A remap changes the stored requests and limits for torque, fuel, ignition, boost and protection. It does not add airflow by itself.
- Ignition timing for performance. Spark advance is limited by knock as well as by the timing that would make the most torque.
- Compression ratio. A higher geometric compression ratio can improve efficiency, and it raises the temperature at the end of the compression stroke.
Exhaust
Exhaust system tuning covers primary length, collectors, silencers and, on a turbocharged engine, the turbine housing. The exhaust can help scavenge the cylinder during overlap. It is also the energy source for a turbocharger, and a restriction that the piston has to push against.
Forced induction and charge temperature
- Forced induction. Supercharger types, turbocharger types, parallel and sequential twins, twin-scroll housings, variable geometry, compound two-stage charging, and a supercharger used with a turbocharger.
- Charge cooling, intercoolers and water injection. Why compression heats the air, what that does to density and knock, and how an intercooler or water injection changes the result.
Capacity and the parts that have to survive
Engine displacement raises the volume drawn in on every induction stroke. At the same volumetric efficiency and engine speed, a larger displacement takes in more air mass. Bore and stroke also change piston speed, flame travel and the loads on the rotating assembly.
Several real limits are not airflow devices. The cooling system has to reject the extra heat. The oil has to survive the bearing loads and, on a turbocharger, the heat in the shaft housing. Pistons, rods, the head gasket and the fasteners see higher cylinder pressure once more fuel is burned. The clutch and gearbox see the torque. These parts do not create the gain. They decide whether the gain can be kept.
Nitrous oxide is a separate method. Released into the inlet, it adds oxygen when it breaks down in the combustion chamber, and the evaporation cools the charge. It is not a supercharger and it is not a remap. The extra oxygen needs extra fuel, and the quantity has to be matched to that engine. Treat any kit figure as the manufacturer's claim for a stated setup, not as a result this engine will make.
Measurement
Data logging for engine preparation and design is the record of whether a change did what it was meant to. A serial log from the ECU, a stored oscilloscope trace, a Crypton engine analyser and a crank-angle combustion system such as the Plex PCA-2000plus keep different evidence. Shaft torque from a dynamometer is a further record, and it sits beside those rather than replacing them.
Using the pages together
A longer inlet runner, a shorter exhaust primary and a camshaft with more overlap are all speed-range choices. They can add to each other at one engine speed and work against each other at another. A compressor adds heat and, if it is a turbocharger, exhaust backpressure. An intercooler recovers density and also drops some of the pressure the compressor made. The carburettor or the ECU then has to meter fuel and ignition for the air that actually arrives.
Measure the change on the engine in question. A pressure gauge, an air-fuel measurement, ignition or injection timing, and knock or exhaust temperature where the installation can show them, are more useful than a catalogue power figure. How those measurements are taken, from a serial ECU log and an oscilloscope through a Crypton engine analyser to a Plex combustion-pressure system, is set out in data logging for engine preparation and design. The calibration guides already on this wiki, including ME7 torque, load and boost and EDC15 fuel control, are about particular control systems. They are not a specification for every engine in this section.
Sources
The linked pages carry the detailed citations. The air-mass statement above follows Garrett's turbocharger system description, and the temperature effect of compression follows the isentropic relation NASA sets out. Both are used again, with page references, on the forced-induction and charge-cooling pages.