V2Rocket

Is there a general rule of thumb for sizing heat exchangers to an AWIC core?

namasgt

What does AWIC stand for ?

tveltman

The front cooler is the least important part of the IC system as it is doing most of its work when the vehicle is not operating under boost

danglerb

Air Water Inter Cooler. Instead of putting the intercooler up in front of the regular radiator, you put a small coolant filled radiator in any good spot for air flow and circulate the coolant to a intercooler located in a more convenient area for the flow of boosted air.

No clue on the sizing, guessing you try what everybody else uses and update if its too small.

V2Rocket

i think i remember reading somewhere that the HE's should be at least larger than the IC core, and like 2x as much frontal surface area was good.

can someone tell me how to calculate the total internal surface area of a bar-plate cooler? it apparently isnt as simple as LxWxH of the core.

tveltman

You would have to know the geometry of the internal components of the core. The reason that the heat exchanger isn't very important is because the car isn't run under boost for large periods of time but rather a few seconds of acceleration at a time. Most of the actual cooling is prformed by the resevoir because, while the water will heat up quickly, the fluid capacity of the system will insure that "fresh" water will be supplied for several seconds before the temperature of the bulk fluid increases to the intake charge temperature. At this point, the heat exchanger will cool down the bulk fluid over time. If you had a very large exchanger, then your time limit for cooled air charging would be larger, bit at some point, that time frame becomes unnecessarily large.

tveltman

LxWxH would result in the volume of the box the core fits in. Calulat the surface area by calculating the surface area of each component and then multiply by the number of components. Internal surface area isn't the only issue. The actual design ofthe core internal will determine how well charge air and cooling fluid can exchange heat through the core, and the core material makes a diference as well (copper is better than aluminum). When the airflow is more turbulent (and thus slower), the air will be more willing to exchange it's heat into the cooling fluid. (The cooling surfaces that serve to slow down the air are called turbulators, I believe). Often the design of the core is much more important than the actual surface area. I was recently recommended Corky Bell"s book on turbocharging, and it has pretty thorough information on all aspects of buildin a boost system. I would advise you to find a copy of it and give it a read. Good luck!

V2Rocket

bump, carl faussett, any of the sc company guys have any input?

blau928

No rule of thumb that I am aware of. You need to consider how much power the system will be producing and size accordingly. Power = heat, and the AWIC system is there to act as a thermal reserve, and to remove the heat from the intake charge using coolant.

The cooler mfg. wil be able to tell you what the heat rejection rate is for their coolers, and you can use that as a guide.

Other variables to consider are the coolant pump's flow rate, the size of tank, the size of the lines, and of where will the radiator for the system be placed..

Again, don't know how much power you plan to make, how hot the air will be, and so forth.. I calculated ny own requirements for my setup. Spearco has lots of tech charts, and maybe they can help you get a more "rule of thumb answer." However, I am sure they will ask the same questions...

Hope that helps..

hacker-pschorr

You also need to take into account how much water your system holds and the flow of your pump.

The system most people are using holds over 3 gallons of water (928 windshield washer tank) which is sitting in the fender at close to ambient temperature. Until you reach a point where you are heat soaking all of the water before coming off the throttle, the front mounted cooler isn't terribly important. The only people I know who can sustain boost levels for that long are the open road racers.

Size of the cooler is far less important to the quality of the cooler.
In addition to the quality of the cooler is proper duct work directing air through the cooler. You can have the largest cooler hanging out in the breeze that will be less effective than a smaller (of equal quality) with good duct work.

On top of everything is what will fit in the locaton you plan to use? You really need to figure that out first.
You can "compensate" for a slightly undersized cooler with a larger pump.....
You do not have a lot of room in the nose of the 928 unless you want to start cutting things up, dropping the A/C, moving the radiator etc....

So, step 1 is find out what fits, work backwards from there.

V2Rocket

this is for my 944 sc project. using an eaton M90 (non-teflon rotors) at about 10psi. intercooler is taken off a jaguar xjr6.

pump is a bosch cobra. will be using a late 944 windshield washer tank which is just over a gallon, the intercooler might hold half a gallon (it is large, do not know for sure). currently i have two setrab oil coolers taken off a volvo to use for heat exchangers, i might add a third or put a larger one between them in front of the radiator/AC. the oil coolers will be where the 944 NA foglights normally are, with some ducting from the opening to the outer edge of the cooler (so air has nowhere else to go but through the cooler)

power should be around 240-260hp

hacker-pschorr

Data logging, data logging, data logging

Spend some money to accurately measure intake air temperature before / after IC and water temp before / after heat exchanger.

I say accurately measure since most I see are using temp senders that are way too slow to accurately measure air temperature and give false positives.

This is the setup I'm using:
http://www.stealth316.com/2-autometer3373.htm
http://www.vividracing.com/catalog/a...e-p-26353.html

V2Rocket

i have air temperature sensors (from the jaguar the IC came from) for those locations and will be using water temp sensors before the ic, after the ic, and probably after the HE's.

Imo000

You could use a small motorcycle battery with a fan already attached to it.

V2Rocket

que?