Intercooler sizing theory

[thomasbl]

In most cases linden, im sure you're probably right. The benefits of cooling as much as possible most likely outweight the negatives of a denser cooler mixture. I have however heard of people having tuning issues and flat spots lower down caused by the cooler mixture not burning as well, and the throttle plate not thinning the mixture enough. Just another thing to think about in the whole 'intercooler sizing theory' i suppose. As with all theories too, its important to remember they can be different in actual application and results from real testing. Lindens testing and results might be a case like this.

[oldcorollas]

radiator is different.
heat loss works by temperature difference.
ideally, you would have a single row, and the air temp after it goes past that row is (at the inlet of the row) the same as the air/water to be cooled.
if you had a second row (with this ideal situation) there would be no temp difference between the air before and after the second row, and thus it CANNOT cool.

if you find 4 rows make a difference over 3, it means each row is inefficient.

this is for steady state cooling, (ie radiator cooled by stream of air)

for air to air charge cooler, as mentioned it is more to do with it being a heat sink.
this is because there is usually a pretty low temp difference, and the lower the temp difference, the lower the heat transfer.
if you are running at high speed and have a large volume of air flowing over core, then you can start to lose a lot of heat, even tho the temp difference is low.

in normal car situation, you want, low restriction (higher cross-section for air to flow, and row inlet losses), low airspeed (to increase residence time), and high mass (so the alloy can absorb a lot of heat before it gets too hot and reduces the temp difference further)

think of the mass like a brake disc, the extra weight takes longer to heat up. longer to cool also.

what direction are the tubes and what is the cross-sectional area between the two IC's?
more shorter tubes, or larger tubes in same direction, will increase residence time and decrease airspeed/losses (perhaps).

another factor is the surface area... there must be a balance between the passages cross-sectional area, the passages surface area, and the frictional losses...

thomas, is that with carbied cars or fuel injected?
thinning the mixture?

[thomasbl]

That is a good way of explaining it. The example i was using was referring to a carbied turbo monster. I suppose it would be different again with injection.

[oldcorollas]

That is a good way of explaining it. The example i was using was referring to a carbied turbo monster. I suppose it would be different again with injection.

yeah, carby needs heat in manifold to evaporate the fuel if it hits the port walls when the air turns.
if injectors aim at valves, then they are hot enough to vapourise (well.. not vapourise but..) the fuel and the manifold can stay cold. ish

[Norbie]

A street car is also different to a race car. When you're racing you've got your foot down nearly all the time so an intercooler needs to be shedding heat constantly. On the street you're only giving it a hit occasionally and the rest of the time you're just cruising, so the heatsink effect is far more important. Therefore a thicker intercooler is going to work better, even if it can't shed heat any faster than a thinner one.

[whatthe?]

Wouldnt a thicker intercooler retain more heat due to reduced airflow in street conditions? I chose a thicker intercooler for the supra because it's always going to get good flow when in use. Dont know if I would have gone the same for a daily though

[oldcorollas]

Wouldnt a thicker intercooler retain more heat due to reduced airflow in street conditions?

yes, but because there is more thermal mass, it takes longer to heat up. it does take longer to cool down, but you shouldn7t be on throttle for long on the street (if you want to keep licence), so it is short term gains you are after....
heck, even 10 seconds is a long time (too long) for accel on the street.. for some toymods cars

[Norbie]

Yep, 10 seconds on max boost gets me well into cut-up-the-licence territory, and a few more seconds will get me jail time, so in reality an intercooler is only going to see short bursts of hot air followed by several minutes (at least) to cool down again.

[JustenGT8]

For a street car, mass as heat sink is what you want for sure so bar and plate FTW. They don't flow as well as tube and fin so just size up from what you calc you need. This calc isn't as simple as first appears so the easier option is just fit the biggest IC you can

For race cars where weight is everything and you have constant high air flow then definitely tube and fin is the way to go.

Just keep all your flow paths as tidy as you can and pretty well assured of a good result. Not something to agonise over.