Jet Jockey/A4 Pilot

First of all I do not own a S4 but a B6 A4 1.8t.
I'm asking these questions on the S4 forum because I know from reading it,that some of you guys have some serious engine mods. done to your cars and I feel you can perhaps answer these quetions. I saw a Greedspeed A4 with a larger lower grill mid-mount intercooler in a car magazine replacing the OEM I/C in the left fender and I called them on it. They basically told me that if I'm running a K03 or K04 on the car it's a waste of money, no gain in performance. I thought that a bigger I/C would cool down more air going into the intake. What are your thoughts on this? What does the size of the turbo have to do with it?

Audi uses two I/C on the S4, the TT, RS4, RS6 and B6 A4 (190hp in Europe). What are the pro and cons of two I/Cs versus only one bigger I/C?
My thoughts on this are, one I/C means less weight, less plumbing and alot less chances of a pneumatic leak in all that extra plumbing between I/Cs and the intake. Again what are your thoughts?

TIA

Mike

vegasS4

probably for a big honking turbo

s4what?

The more sustained the boost, the bigger the IC needs to be. For street use it is not that important to have a large IC. Too small an IC though and you won't get enough cooling even with a short spurt of boost. Two IC parameters are frontal cooling area and flow cross sectional area. The frontal area needs to be large to get rapid cooling. The flow cross section needs to be large to keep the pressure drop down. There are rapidly diminishing returns on oversizing an IC. I was not aware that single turbo 1.8 engines have two turbos. S4s have two because they have two turbos.

VonK :: Retired

Well put. :-)

sj6sp

I'm sure lots of folks on here have good info on intercoolers and going larger.
I'm going to the larger RS4 IC's for a few reasons:
1. Reduced pressure drop. From what I have read, this particular set-up will reduce drop across the IC by about 1psi. My turbos don't work as hard to move the same mass of air.

2. Cooler intake temps. Don't know how much to expect but lower is better.

3. Stock IC's have plastic end tanks fitted to aluminum core. These have been found to leak precious boost. Aftermarket IC's use aluminum end tanks welded to the core.

Because of the first two items above, increased air mass is possible from the same boost settings BUT I've read on this board and in some online publications that our computer controlled engine will pull back boost when air mass targets are met. So dramatic power increase is not guaranteed.

Some will argue that bigger IC's mean more volume to pressurize. Again, the option I'm going with has a negligable increase in total intake volume. Bigger is probably better until you reach a point.
Any system, as a whole, needs to be well designed and reduce the number of tight bends in the flow path through the whole intake.

Jet Jockey/A4 Pilot

Thanks for the info, yes the TT as a 1.8t engine with a K04 with two I/Cs.Audi is releasing a B6 A4 in Europe with two I/Cs.

Jet Jockey/A4 Pilot

So if I get this right, two smaller I/Cs will have the same cooling affect but a lesser drop in pressure which in turn is better/easier for turbo to move around.

By the way thanks for the info.