When a gas is compressed its temperature also increases and vice-versa (this is why de-odorant's are cold!). Added to this are the pumping losses in a compressor (typically around 35% of the energy imparted is lost as heat to the charge in a centrifugal compressor) as well as any heat transferred to the compressed gas from, say, the engine or exhaust. Increasing boost therefore in-variably comes with an even greater increase in intake charge temps, especially when a compressor is reaching its working limit. If this is not addressed the best case you can hope for is lower power levels than you should be achieving, worst case is combustion chamber temps reaching pre-ignition levels and severe engine damage occurring as a result.
Charge cooling (or intercooling, they both mean the same thing, its the different mediums that count) is something that should not be underestimated, it has benefits beyond engine safety such as increased power and turbocharger efficiency. It is a common misconception that increases in intercooling results in more lag. Done properly it can actually reduce it. There are many ways to achieve it, all with benefits and downsides which are outlined below; to help you choose a type, or combination of types, that's best for you.
| Cooling type |
Benefits |
Downsides |
| Normal charge - to - air intercooler |
'Fit and forget' method of cooling, reliable, zero maintenance |
Creates lag due to increased intake tract volume, often difficult fitting (complex piping, bumper adjustments) can never cool below ambient air temp |
| Charge - to - water intercooler (charge cooler) |
Excellent cooling potential when ice is used in header tank, no increase in intake volume |
Requires fitting of extra radiator + tank + pump, often short effective cooling time without large rad' and tank |
| Water/methanol injection |
Excellent cooling potential, especially when 50/50 mix is used, power gains from methanol, zero resistance to intake flow + no increase in volume |
Tank will run out and could be dangerous when it does (although warnings/fail safes can be fitted by us), requires sizeable tank, not too effective as a sole source of cooling, methanol can be hard to get hold of |
| Nitrous injection |
again, excellent cooling, zero resistance to intake flow + no increase in volume |
Dangerous if used without extra fuel and needs re-tuning for (best controlled by a decent ECU), bottle runs out very quickly, puts extra strain on engine (though it creates more power) |
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