I need to know the optimum/minimum air speed that needs to be going into the hood scoop/intercooler for cooling/preventing heat soak.

or another way to word it would be, what is the minimum speed you could be driving that your intercooler is still being cooled, or even cooled efficiently.

my buddy says 35mph is fine that it doesnt really matter any faster than that, but i am saying 55 mph is probably minimum for any sort of cooling to be taking place that helps the turbo.


does anyone know, or have any insight to where we could find this info because google doesnt help.

 

bump?

 

gang




















bang.....


im interested to find out as well

 

I teach engineering at a technical high school. There are too many variables to calculate a single min. speed. Variables like intercooler efficiency, ambient temperature, engine temperature, and humidity will change the air flow rate.

It is possible to calculate it but the answer would be a range in the form of a Psychrometric Chart. Just Google Psychrometric Chart to see what I am talking about.

 

To answer it simply, you both are probably right, it could be anywhere from 35 to 55 mph depending on the variables.

Also another variable I forgot about is pressure increase at different elevations because that will change the pressure drop of the intercooler.

 

i am saying generally, on a stock car

let me see if i can ask it another way

you are sitting at the race track, either drag or regular track, you are sitting there is grid getting ready to go. its lets say 80 degrees outside. if you had a fan what speed of air woudl it need to be blowing to keep your IC from heat soaking

 

heat-soak =when the intercooler heats up losing efficiency. If the intercooler gets hot enough it can reach 0% efficiency in which the intercooler becomes an inter-heater.

If you leave your car off their will be no heat-soak. Some people put bags of ice on their intercoolers between runs to cool down the intercooler, just make sure to remove the ice before you run the intercooler will not work unless air can pass thru it. Don’t use dry ice either it will destroy the intercooler.

If the car is running (idling) and the car is up to temperature the ambient temperature has to reach 150°F to become heat soaked(0% efficiency of the intercooler). This is assuming:

• Hood is closed / no air passing thru the intercooler
• the stock intercoolers efficiency 60% (this is an estimate)
• the density change of the intercooler is 8% @ 80°F (assuming my math is correct)
• stock engine / stock boost



to answer your question simply @ 80°F ambient temperature you will not reach heat soak(0% efficiency of the intercooler), but any thing you can do to lower the temperature of the intercooler will help. Because of the temperature (at 80°F) you are only looking at efficiency gains @ 2% or less of the 60% efficiency of the intercooler.

The best thing you can do is to make sure you have a heat shield around your turbo. I can’t stress this enough. The heat shield seems to be a worthless piece of metal but it drastically reduces engine temperature The people that remove the heat shield and still run a top mount intercooler are dramatically lowering the intercooler’s efficiency.

Most of the variables are out of our control: ambient temperature , pressure of turbo system, and engine temp( to a point). We can do some things to lower engine temperatures by doing the following:

• using a heat shield around the turbo.
• ceramic coating or heat wrapping of the exhaust manifold.
• heat wrapping of the up-pipe and the hot side of the turbo.
• Lowering the boost

 

basically ryan, the speed you need to go to keep the intercooler at its peak efficiency could be not moving at all some days that it is incredibly cold. and days that it is hot it would take some air shoved down its throat to keep it at optimum efficiency. depending on the day conditions it will change also remember that some days when it is hot and your engine is running you will not be able to keep the intercooler at great efficiency without Co2 or NOS sprayed onto the intercooler, which i wouldn't recommend either really, if a rock hits your intercooler after being sprayed it could put a nice hole through your IC. Ice works kinda..... i used it at a really hot day at the track and the ice just melted and never got the intercooler could.. i mean my cobb accessport was telling me intake temps of 137 degrees Fahrenheit.

Ryan~

 

I heard that thr scoop really only cools the car during slow or city driving under 35mph. The 08 and up wrx/sti get the most air because of the hoodscoop placement.

 

wow thanks for the quality post / info

I know past xx mph the scoop is getting as much air as it can so you cant do anymore i think its around 60 or higher


to add i am water cooling my comptuer right now and screwing around with fan speed. The faster it goes the better the cooling and the head pressure is what im getting into now

the delta temperature depends on how hot it is coming in that you have to measure. out of the turbo and into the hood scoop and out of the inter cooler.

teh intercooler will never get to ambient temps on a fan or driving. you are always adding in heat from teh turbo

 

to minimize heat soak... get a front mount

 

....what a silly argument. Neither of you have proof and your #'s are pure speculation. I could understand being curious but until you have proof or do your own testing, I see no point in arguing about it.