Background:

When I purchased the AMD intercoolers AMD had informed me that they do not offer shrouds.  I inquired as to why that was and they explained that there had been negligible difference when they had tried using shrouds.  The thought was that because of the large frontal area of the core, the AMD frontal area is larger than any other SMIC I have got figures on except for the Wagner RS4 – which requires extensive modification to the car to fit, this larger frontal area leaves little room for air to go anywhere except through the core.

The Setup:

After driving with the AMD intercoolers for a few days I became curious to see if I could record any difference in IAT with a shroud in place.  I wasn’t willing to spend a couple hundred dollars on a set or ER intercooler shrouds, the only ones I thought might be close to covering the AMD core, so I decided to use my stock IC shrouds.  This was not the ideal setup, but if shrouds were to make any difference I thought stock shrouds may be sufficient.

I had a well laid out course to drive where speeds could be tightly controlled.  Part way through, at about 25 minutes in, I parked on the side of the road with the motor running for two minutes, then resumed the drive for four minutes whereupon I rolled into a FATS pull.  From there I spent a few minutes driving the car back to the garage.

The Results:

The results of the two drives are shown below:

Conclusion:

Results look mixed to me.  At the start the setup with shrouds shows a slight improvement over the non-shrouded drive, and the ambient temperature was a couple of degrees warmer when the shrouds were installed.  But around the midway point of the drive the difference disappears and never returns.  This could possibly be attributed to the type of driving being done, the first half was steady state cruising while the second half had some significant dynamic changes and an overall slower pace.

The main question I have is how the results would have looked if a larger shroud had been used.

With my recently delivered AMD intercoolers on hand (shout out to Jason at AMD for setting me up with this rare set of his intercoolers) I made some data runs to compare them with the Audi B5 S4 stock intercoolers utilizing the same fixed wastegate duty cycle tune on my FrankenTurbo F4H-BT setup.  Ambient temperatures were close to being the same; 68F on the stock IC day and 60F on the AMD IC day.  Neither intercooler was aided by water injection.

The fact that water injection was not used is important to note because Jason made clear to me prior to the purchase that his intercoolers are optimized for large turbo, high horsepower setups that are using water/methanol injection where minimal pressure loss is critical.  Just how well these intercoolers perform in that regard is evident by their first place position on the intercooler face-off rankings for flow.  This is what is called expectation management – I should not be looking for outstanding temperature control like ER’s provide.  By not using w/m injection I was purposefully handicapping the AMD IC’s, I was also operating in a boost regime that was not what these are targeted at, a 21 psi flatline to redline.

Results:

Results of the data collection are shown in the charts below.  The first chart illustrates the additional boost pressure that is realized at the intake manifold due to the reduction in pressure drop that the AMD intercoolers provide.  Because the tune was operating at a fixed wastegate duty cycle any changes in boost pressure are a product of factors outside of the ECU manipulating boost via the N75 valve.

It should be pointed out that these two products are as far apart on the flow chart as any two intercoolers that I have tested, and therefore these results are illustrating an extreme case.  Two more equally matched intercoolers, such as ER and AWE, would not be expected to show such a significant difference.

The chart below is the calculated wheel TQ based upon vehicle acceleration for each intercooler setup.

Finally, a comparison of the acceleration rate of the S4 when equipped with the two different intercoolers.

The trend line has been added to the two charts above to help give a sense of the scale of difference between the two intercoolers on these tests.

Conclusion:

It doesn’t come as much of a surprise that the manifold boost pressure is higher when using a better flowing intercooler.  The degree of improvement in wheel torque and acceleration is significant, especially in light of the relatively low boost pressure that the tests were performed at.  Even though the intake air temperatures were fairly similar the improved airflow through the AMD intercooler nets some decent performance gains.

Substituting a high flowing, good cooling intercooler for the S4’s stock IC’s is likely to deliver measurable improvements in performance.