RS 265 - Inlet temperature

Discussion in 'Mechanical - Engine, Gearbox, Exhaust etc' started by George K, Sep 12, 2018.

  1. As I use the car for hill climbing the car goes to the line having queued up for several minutes with no forward motion. The result is lots of heat soak and high inlet temperatures - 70C plus which obviously knocks the power back. We are not sure whether a larger intercooler would make any difference in this scenario - someone has mentioned charge cooling, but I have no idea whether that is even feasible. Any advice welcome.
     
  2. Intercooling and charge cooling are one and the same thing. Some people confuse the terms to mean either air or water based intercooling but in reality intercooling is always charge cooling no matter what medium of heat transfer one is using. Larger intercooler will not help much if the problem is heat soak due to long periods of idling in hot ambient temperature. To actually solve this problem you have three basic options.

    1. Have a water spray bottle with you and keep the intercooler wet using it while you queue and wait. The water will vaporize and cool the surface of the intercooler while it's kept wet. Drag racing people do this and it's effective if your I/C itself is sufficient for actually running the car (if you have not increased boost and air flow too much for the present I/C to handle)

    2. Actual water injection. You can be safe and sure and just use the water spray system to keep the I/C surface wet, thus cooling it by means of evaporization, but have the system do this for you and add more spray for higher boost/revs when running the car. Or you could see if your engine management system will not take offence to running internal water injection, either alone or along with the external water spray. You will reduce inlet air temperature and knock tendency both to achieve a double benefit. WRC teams have been using both types of systems for years depending on whether rules allow it or not.

    3. Water-based intercooler with ice added to the reservoir. A water-to-air intercooler will not help your heat soak issues by itself, but it can give you a longer "buffer" before the heat soak will start affecting your inlet temps. The size of the buffer depends on how much water is in the system, i.e. how big a reservoir you have. If you have a reservoir has a large "lid" that allows you to add ice into the reservoir that increases the buffer effect to a large degree. If you can start your run when there is still ice in the reservoir you will notice a big improvement in performance compared to a traditional air-based intercooler. This method is used in hill climb cars and drag racers to name two typical usage scenarios.

    Some people might also use nitrous oxide to cool the I/C or spray it into the inlet tracts, but this is unnecesserily expensive and an internal NOS spray will almost certainly hurt the normal operation of your ECU. One other option would be a strong electric fan added to your current I/C that would run when you're queuing. This will work when the ambient temperatures are reasonable, but when the weather is hot water will do a better job.
     
  3. Very helpful, thank you. The way a charge cooler had been described to me was as though it was water-based hence my confusing description. Apparently the Megane ECU cuts the boost back when the inlet temperature exceeds 55C, so all the more important to resolve this.
     
  4. intercooler is air to air, chargecooler is air to water, that is the way it was explained to me years ago.

    I have run a chargecooler (air to water) in the past, very quick drop in air temperature and because you can keep the intake tract short there is very little boost lag, the only reason i removed mine was the unit i used was not efficient, it needed to be longer to give enough time to get rid of the heat.

    Going to have another look at this in the future.
     
  5. In fact the term "intercooler" is used wrong all over the world. In truth an intercooler is really just a charge cooler that is fitted between two turbocompressors in a compound charged engine. These systems were used in diesel truck engines for a long time before "intercooling" became a thing in passenger cars. Using the terms correctly such a diesel truck engine would have TWO charge coolers, one of which would be an intercooler (the one between the turbos, hence "inter"). The cooler in the middle is called an intercooler and the one fitted after the second turbo is called an aftercooler.

    Charge cooling means a method of cooling air that has been compressed by a charger which may be a turbo, a mechanical "supercharger" or even an electric "super"charger. Charge air is being cooled, hence "charge cooling". Almost no normal car actually has a real intercooler because normal cars very rarely run compound charging and if they do, they normally do it without intercooling, only using a single charge cooler (which should really be called an aftercooler).

    The marketing ploy here is that once Lotus started utilizing water-based "intercoolers" in the '80s on the Esprit SE and later on the Lotus Carlton, they called and labeled it "Charge Cooler". Afterwards people have been calling all water based charge coolers with that name, while the term "intercooler" was already widely understood wrong and used to describe aftercoolers. Car manufacturers are to blame, they just picked the names that sounded good and didn't mind that they weren't really referring to what the actual parts were doing.

    I use the term intercooler myself because after all these decades almost nobody will understand me if I use the correct term aftercooler... But charge cooling is charge cooling no matter if you use air, water, alcohol or nitrous oxide to cool the charge air. Since "intercooler" is now the widely accepted terms although used wrong, the normal usage scenario is to talk about air to air intercoolers and water to air intercoolers, but both are cooling the charge air and are charge coolers and not actually intercoolers :smirk:

    Sorry for nit picking, but I am what I am :smile:

    .......

    To OP: A better "intercooler" may help your racing performance but you also need to take care of the heat soak issue prior to starting the run. If your engine is standard, the OEM I/C should be more than sufficient, you just need a way to keep it colder before your run starts.
     
  6. I know this may be a silly thought, but in traffic my inlet temps rarely get above 40. This is mainly because the climate control is running the air con and hence the fan is running. Could you not some how manually override the fan to be running to draw air through your intercooler to keep the temps down? I used to do this sort of think with my race impreza as well as run the air blower on max heat to keep the water temp down before the start of the race and therefore once rolling could switch it off etc.
     
    • Have you heat wrapped your downpipe as that causes a shed load of heat?
    • Reflecta gold your intercooler piping especially that one above the rocket cover.
    • Run the cabin fans on max heat and max speed, thus the heater matrix pulling the heat from the cooling system and bay.
    • Some other suggestions would be to remove everything possible that doesn't need to be in the bay, aircon system, battery, any kind of covers etc etc, whatever isn't in the engine bay can't get hot and hold heat, think of it like layers of clothing.
    • PTFE gaskets can also help reduce heat transfer between the manifold and block, this may also be something to look into.
     
  7. Continuing on this theme, does anyone know what the recommended IAT is? I seem to have picked up that at 55C the boost may be cut back - is this right?
     
  8. cgrautomotive

    cgrautomotive RSM Trader

    The Megane's naturally have a tendency for high inlet temperatures from the factory, mapped cars are even worse!

    We have recently designed an intercooler which reduces inlet temperature from 35-40 degrees above ambient temps (similar to what you're experiencing) to between 7-10 degrees above ambient on a mapped car under load.

    We have the first development intercooler out and testing so we will be releasing more info in the coming week :sunglasses:

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  9. that looks interesting
     
  10. Wont that mask the water rad? As suggested by Darren, would it be helpful to manually over-ride the fan so as to keep things cool whilst queuing?
     
  11. It looks similar to the Airtech Stage 2 IC.

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    But iz looks (a bit) bigger than the Airtech.
     

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