Top mounted intercooler
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A top mounted intercooler (TMIC) is an automotive intercooler mounted within the engine bay, above the engine. Because of restricted airflow to this location, a hood scoop is virtually a necessity for a TMIC.
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[edit] Advantages
- The TMIC may be placed close to the turbocharger and/or supercharger compressor and to the engine's intake. As a result, the intake tubing can be kept short. The longer the path from the intercooler to the engine, the more air must be pressurised within the hoses when a change in pressure is demanded - and the greater the lag imposed. When used in combination with quick-spooling turbochargers, such as ball bearing turbochargers, the result is a more responsive engine.
- Unlike front-mounted intercoolers, TMICs do not block any airflow to the radiator and/or oil cooler, allowing better engine cooling.
[edit] Disadvantages
- Heat from the engine may be conducted through to the intercooler, usually while trying to escape through an open hood vent. For this reason hot, cramped or poorly ducted engine bays (commonly the case with rotary engines) negatively affect the performance of TMICs.
- TMICs tend to be less efficient than similarly sized front mount intercoolers, due to the smaller amount of cold air flow through the hood scoop compared to the front grille area in most car designs.
[edit] Applications
TMICs are used in many street cars, such as all current intercooled Subarus, the MINI Cooper'S and also in older cars such as the Mazda RX-7 (86-91 model).
A properly designed top mount intercooler's advantage in responsiveness is preferred over more lagging front mount intercoolers in situations where responsiveness is more important than total power - notably in rallying, drifting, autocross and touge.
[edit] V-Mounted Intercoolers
The V-Mounted Intercooler is a hybrid system, developed to provide superior air cooling to a front mounted intercooler, yet still retain the short intake piping and radiator airflow of the TMIC. In this case, the intercooler is mounted horizontally, directly in front of the engine (although it can be at an angle). Most VMIC setups place the radiator below the intercooler, at a great angle, tilted back until it is almost touching the motor. Ducts are used in the front of the car to duct air through the intercooler, creating a ram-air effect, while the remainder of the air flows over the radiator, normally. The air is usually removed via a hood vent (a vent recessed into the car's hood near the front of the car; if it is mounted too far back, it will actually suck air into the engine bay), although in the case of a bottom-mounted intercooler, the air is allowed the exit underneath the car (although this is dangerous because is places the intercooler at extreme risk to damage from bumps and rocks). VMIC setups are typically utilised on Front Midship cars, as the location of the engine, far back in the engine bay, allows room for the system.
VMICs were pioneered on the Mazda RX-7, because rotary engines have a tendency to run hot. It was intended to be a compromise between a TMIC or a side-mounted intercooler (2nd Generation and 3rd Generation RX-7, respectively) and a FMIC. An intercooler in the stock position would not support high airflow (and thus limit top power, or create severe detonation in the engine, which damages rotary engines more easily than piston engines), while FMICs would block airflow to the radiator, leading to overheating. The RX-7 is the only car that currently has a VMIC kit available for it. VMICs on other cars are custom made, usually used on track cars and require significant investment and fabricating skills to properly set up and tune.
