View Full Version : ***034Motorsport Tech Article: Intercooler Case Analysis, B5 A4 20vt ***

11-23-2010, 02:56 PM
Here at 034Motorsport, while building a lot of crazy Audi and Volkswagens, we get a chance to do a lot of product testing. This is the first of a series of articles we will be sharing with the B5 community.

Here Today, We Look at a B5 A4 20vt Case Analysis, Optimizing Intercooler Cross Sectional Area for Better Flow, Improving Cooling Capacity for Lower Air Intake Temps

We built and tuned a customer B5 A4 recently, here are some of the relevant specs:

* Built 2.0 bottom end with 92.8mm crank and forged rods and JE Pistons
* SPA Turbo Top Mount Cast Manifold
* Shrick 252/260 billet Camshaft set, built ADR cylinder head
* Precesion 5557 CEA Turbo capable of 600+ HP
* Full 034Motorsport 3" downpipe and exhaust system
* Custom 034Motorsport Motronic tuning with RC 550cc injectors and upgraded fuel system.

And the one part the car came to us with, that in the interest of saving a few dollars, was left in palce for the time being:

* Race Tech FMIC - Ultimate Intercooler Kit (http://www.racetec-us.com/)

This car had all the parts and tuning that we knew made power, we know this from the dozens of B5 A4's we build and many of these parts are even used on our own Time Attack A4.

After spending many hours tuning and eliminating any problems we could, we ended up with approximately 325 wheel HP and 275 ft/lbs TQ, and boost hitting 20psi and tapering off to 14 by redline, not very characteristic of the PTE 5857 turbo that we're used to running at 30+psi all the way pas 8500 rpm in our Time Attack Car.

The last remaining part that had not been changed on the car was the Race Tech front mount intercooler.

Specs on the Race Tech FMIC:

* Core dimensions - 2" thick, 10" tall, 17.5" long

http://gallery.034motorsport.com/d/53185-2/DSC_0556.JPG http://gallery.034motorsport.com/d/53252-5/DSC_0553.JPG http://gallery.034motorsport.com/d/53258-2/DSC_0554.JPG

* 2" inlet and outlet


* Ligh density heat transfer fits on outside of core, light density turbulators inside tubes.


Specs on stock B5 A4 intercooler are:

* 2.5" thick, 7" wide, 9.5" long
* 2.2" inlet and outlet
* Medium density turbulators inside and out for good heat transfer

We did suspect that the intercooler was the bottle neck in an otherwise totally unrestricted engine system, the dimensions alone of this intercooler were suspect. A crude calculation of the core volume results in only 350 cubic inches. Even a stock B5 A4 intercooler is approximately 200 cubic inches. Though the Race Tech core has a decent core volume, and would likely cool a street driven engine like this to a degree, there is a much bigger consideration to note, the cross sectional flow area.

The cross sectional flow area of the intercooler is calcuated by multiplying the core thickness by the core height - the end of the intercooler where engine intake charge flows through.

The stock intercooler is 17.5 square inches, the Racetech is actually 20 square inches. This is a very important consideration when upgrading any intercooler, though the core volume dictates the cooling capacity of an intercooler, the cross sectional area and tube length determinie flow. The smaller the cross sectional area, the less the flow, the longer the tubes, the less the flow.

When comparing the Race Tech intercooler to the stock intercooler in terms of flow, its clear the Race Tech unit flows martinally better than the stock intercooler due to a marginally larger sectional area, and mainly due to longer tube length - it may actually flow worse.

Bottom line, its no better than the stock intercooler in terms of flow. It may have more cooling capacity than the stock intercooler, but due to the severe flow restriction posed by the Race Tech core, cooling capacity becomes a far second priority. If air cannot flow the the intercooler it can't be cooled.

In order to accomodate the relatively high flow of this built 2.0 20v motor with a large 600HP turbo, the intercooler must be properly sized in cross sectional flow area. A properly spec'd out intercooler would be our 034Motorsport B5 A4 Large Core Intercooler Kit.


Specs on 034Motorsport B5 A4 Large Core Intercooler Kit:

* 3" thick, 10.5" tall and 18" long
* 2.5" inlet and outlet
* High density turbulators for efficeient heat transfer

http://www.034motorsport.com/oscthumbwm/w/650/h/621/q/95/f/jpg/fltr/wmi|phpThumb/watermarks/034watermark|C|20|0/hash/0e1b17f10139a2fd40e98c80ec57c79c/src/images/IntercoolerCoreLarge.jpg http://www.034motorsport.com/oscthumbwm/w/600/h/580/q/95/f/jpg/fltr/wmi|phpThumb/watermarks/034watermark|C|20|0/hash/dd596fa6a74f2f28939b02747017145f/src/images/IntercoolerTurbulator1.jpg

A quick look at the new core reveals some large improvements:

* Core volume is up to 567 cubic inches, a 60% improvement over the Race Tech for greatly improved thermal capacity
* Cross sectional area is 31.5 square inches, a 57% increase in flow area
* 2.5" inlets and outlets, an approximate 56% improvement in flow area
* All piping is 2.5" for much less flow restriction compared to 2" piping for Race Tech system

The benefits are clear here, 57% increase in flow area allows for massive gains in flow, an added benefit is that the 034 core is only .5" longer than the Race Tech core meaning that there is no additional flow restriction added by the tube length, and only gains over cross sectional area.

2.5" inlets and system plumbing allow for 56% improvements in flow through the entire system. High density internal turbulators mean that the air interacts with more aluminum for better heat transfer into the heat sink, meaning better efficiency. Granted, the larger core requires some cutting of the bumper core support area to make room, but the gains in flow and efficiency are well worth it.

After installing the new intercooler system, the car was put back on our dyno to test if any imporvements in power were made. Though all these numbers look great on paper, if they don't mean more power at the engine then there really is no benefit.

After a baseline pull, the results were clear:



* 62.62 ft/lbs of torque at the wheels gain at 3700 rpm
* 53.29 horsepower at the wheels gain at 6400 rpm
* 500 rpm faster turbo spool up
* HP and TQ gains everywhere from 2500 rpm to 7000+ rpm
* on average approximately 30-40 HP and ft/lbs TQ gain from 3500 rpm to redline
* 6 psi boost gain by 7000rpm

The gains are truly shocking, from the HP and TQ gains, to spool up gains, to the boost gains up top. Clearly this engine was flow restricted by the Race Tech intercooler, with no other change than the 034Motorsport intercooler kit, these gains were realized.

For more information on the 034Motorsport B5 A4 Large Front Mount Intercooler kit: http://www.034motorsport.com/engine-components-18t-intercooler-kit-b5-a4-large-core-p-2399.html

034Motorsport Tech Articles (http://www.034motorsport.com/img-srcart03gif-t-3.html?osCsid=26sgv818lv9nq833i9u7np4027)

Kyle H
11-23-2010, 03:16 PM
Wow, 500rpm faster spool with the bigger intercooler is crazy. Seems like the racetec is meant for k04-ish setups.

Thanks for doing these tech articles [up]

11-23-2010, 03:44 PM
What core do you guys use? Garrett? Bell?

11-23-2010, 04:11 PM
Excellent writeup and explanation! My car showed similar improvements with a larger FMIC (increased from 2" to 2.5" inlets/outlets too) and piping....albeit from a butt dyno, haha....PLEASE keep em coming......we need more stuff like this in the B5 A4 section

Papa Stone
11-23-2010, 04:22 PM
I love if you do a comparison with this core

It would be a nice comparison.. I know that it doesn't come as a kit, but that can be done very easily

11-23-2010, 05:03 PM
What core do you guys use? Garrett? Bell?

We use a Garret core for this kit

Papa Stone
11-23-2010, 06:32 PM
So then testing the one I ask for makes no sense.. Great product Javad

11-23-2010, 07:26 PM
I run the 034 Big intercooler kit. The only downside to the setup is the silicon piping. I changed mine out for aluminum. It is overall a great kit.

Max, when I ran the SPA manifold (with the silicon 034 piping) I needed an extention to reach my turbo. Did you guys do the same with the customers car? Any pics?

Keep up the good work 034.

11-24-2010, 09:06 AM
Rob, we use a simple aluminum tube extension to connect the 034 hose to the new turbo position, sorry no picture handy.

Thank you,

11-24-2010, 09:15 AM
Rob, we use a simple aluminum tube extension to connect the 034 hose to the new turbo position, sorry no picture handy.

Thank you,

I will snag some pictures when i get a chance.


11-24-2010, 02:50 PM
Rob, we use a simple aluminum tube extension to connect the 034 hose to the new turbo position, sorry no picture handy.

Thank you,
Cool I was just wondering. I rigged up a similar setup when I was running my old 3071 on SPA. [up]