AWE Manifold Dyno Session

With having collected enough performance data on the street about the effect of the AWE Exhaust Manifolds on boost onset and pre-turbine back pressure, there was not much left that I was interested in seeing.  Still, with installing exhaust manifolds being a bit of a chore, I decided I would take advantage of having the AWE product installed and dyno my S4.

AWE-Tuning Tubular Exhaust Manifold
AWE-Tuning Tubular Exhaust Manifold

I was thinking of ways to make the session a bit more productive other than to just gather more data on the AWE manifolds.  I chose to also test the effect that the water-methanol injection system’s nozzle placement has on Intake Air Temperature and the effect, if any, that the Fluidampr harmonic dampener has on torque and power production.

With those three tests planned I arranged for a dyno session at ET Tuning in Union Missouri.  As a precursor to the dyno test procedure, and to get an estimate of the amount of time it would take to swap the harmonic dampener, I swapped my S4 back to the OEM part.

First up was a pull with the car configured as I’ve driven it lately – BorgWarner K04 turbochargers, AWE-Tuning tubular exhaust manifolds, and dual 0.4mm Aquamist WMI nozzles placed in the up-pipes.  One exception was the OEM harmonic dampener being installed, lately I have driven with the Fluidampr, although my last dyno with the BW K04’s was done with the OEM dampener in place.   The tune is unchanged from the last K04 dyno session.


In a post from the day of the dyno I explain the absence of the bumper and headlights.  A comparison of the better pull from the earlier session (red line) with the better of the first two (of several) on this day (blue line) is shown below.

exhaust manifold comparison dyno chart
BorgWarner K04: Stock S4 vs AWE-Tuning Tubular exhaust manifolds

Nothing particularly remarkable stands out.  The torque with the stock S4 manifolds builds more quickly, this could have been expected based on the data that showed the boost building more quickly with the stock exhaust manifolds.  On the dyno the boost profiles are (solid lines stock, dashed lines AWE):

Stock Exhaust Manifolds vs AWE-Tuning Tubular: Boost Onset

With the AWE-Tuning manifolds the boost is about 200 rpm behind that of the stock exhaust manifolds, although the curves do start slightly later with the AWE manifolds.  The initial boost swing of the stock curves is not a byproduct of the stock exhaust manifolds as I only saw that response on the dyno the day the first logs were recorded.

Tabulating the peak torque and horsepower numbers from all the runs on both days and comparing them, with the stock exhaust manifolds the car made 8 more wheel TQ and 5 less wheel HP than when equipped with the AWE-Tuning exhaust manifolds.

Notably from the datalogs, the AFR during the AWE manifold runs was almost three-quarters of a point richer than the stock manifold runs – potentially altering the power numbers from where they would have been (higher) had the AFR been the same between sessions.


This test produced no surprises.  Aftermarket exhaust manifolds predominantly are built to improve airflow, or more correctly reduce pressure losses at high airflow rates, a result of this is a reduction in air speed through the manifold runners as compared to the stock manifolds.  This lower air speed decreases the available energy for spooling up the turbochargers giving the delayed boost onset and slightly reduced low-end torque in favor of better top end horsepower.

In my case, with a small turbocharger and a modest boost profile the effects are minimal, but present.

The next test was to find if the location of the water-methanol system nozzles would affect the intake air temperature.

wmi_nozzle_drawingOne of my concerns with the placement of the nozzles in the up-pipes is the potential for a significant amount of the injected fluid to impinge the side walls or opposite side and collect in a stream that does little to help cool the charge air.  This concern had prompted a request for a set of intercoolers with wmi bungs located in the end tanks such that the injection of water-methanol would be almost directly into the oncoming airflow, thus gaining better mixing of the fluid and air.  This placement in the end tanks is shown below.

WMI Nozzles in SMIC end tanks
WMI Nozzles in SMIC end tanks
WMI Nozzle - Passenger Side IC
WMI Nozzle – Passenger Side IC
WMI Nozzle in driver side IC end tank
WMI Nozzle in driver side IC end tank

Several pulls were conducted with the wmi nozzles in the bipipes and the SMIC end tanks.  A compilation of the intake air temperature data is shown below:

Nozzle placement comparison
Nozzle placement comparison

There does not seem to be any obvious difference in the temperature profile with change in nozzle placement.

Flow rates were also unaffected:

Pulls 1-2
Pulls 1-2
Pulls 3-7
Pulls 3-7

Note that on pull 2 (F2-V2) on the top chart and pull 5 (F3-V3) on the lower chart that these pulls are after the WMI hose line was swapped and the initial spike in flow rate is on account of the line being filled.

The last test was the most involved labor-wise.  Swapping out the OEM harmonic dampener for the Fluidampr.

Preparing for Fluidampr swap
Preparing for Fluidampr swap

Ready to install the Fluidampr:

OEM (top) and Fluidampr (bottom) harmonic dampeners

As it turned out, the Fluidampr pulls proved to be the most involved to decipher.  When comparing the peak numbers of the OEM harmonic dampener versus Fluidampr the swap caused the torque to drop 8 ft-lbs and the power to drop 13 horsepower.

The immediate deduction was the added mass of the Fluidampr is slowing the rotation rate of the crankshaft and diminishing the output.  Knowing how the intake temperatures can affect power production I looked into how the power numbers changed with the smallest recorded IAT of the pull.


The correlation is very strong, so much so that I needed to do more than a simple comparison of peak numbers to deduce what the Fluidampr may have done to engine performance.

In the chart above the green dots are with the OEM harmonic dampener and the red dots are with the Fluidampr.  The orange dot is also with the Fluidampr, but was the first pull after the hour-long break while swapping the parts.

If the number of Fluidampr data points is limited to the pair that have IAT’s similar to that with the OEM part then the difference is only a drop of 3 ft-lbs and 10 horsepower.

Unfortunately one of the two good IAT datapoints happens to be the orange dot, the pull that was first after having the car sitting, and cooling, on the dyno for an hour.  If I take the single reliable datapoint for the Fluidampr, the difference is 1 ft-lb and 4 wheel horsepower, a minuscule difference when comparing values of around 430 ft-lbs wtq and 400 whp.

The dyno chart for this ‘best case’ comparison is shown below with the Fluidamp pull highlighted by the green line.

OEM vs Fluidampr
OEM vs Fluidampr

Results with the Fluidampr are not conclusive, but it does not seem engine power production was increased with the aftermarket harmonic dampener.  This is not all that surprising since the function of the part is not to increase power but help to control harmonic vibrations.

Thermal Imaging on the Dyno

Today the Silver S4 went back to the Dyno for a series of pulls with some hardware configuration changes.  Data from that is still under evaluation.

10/21/2016 Dyno Session
10/21/2016 Dyno Session

Because I was changing some hardware configurations I removed the front bumper and headlights for the morning.  This allowed me a clear view of the intercoolers, or more correctly the thermal camera a clear view of the intercooler.

I snapped these images during one pull, the left image is from the early part of the pull and the right image is from the last part of the pull as the dyno operator lets off the accelerator.

Side Mount Intercooler Thermal Image on Dyno
SRM SMIC Thermal Image During Dyno Pull

As makes sense, the lower part of intercooler, where the charge air enters the core, is rising in temperature more rapidly than the upper part of the core, where the cooled air exits.

Timing Belt Completed

Today I completed work on the timing belt and water pump replacement.


I did not use any RTV on the water pump gasket, which is how the install is advised to be done in the Blau Parts video, and which is something I’ve also heard recommended by other owners.  I made sure to torque the water pump bolts to 10 nm, then had the engine sit overnight.  The next day I checked the bolts again to make sure the gasket had not compressed and that 10 nm was still on there.


One of the bolts on the harmonic dampener had been close to being stripped when I removed the bolts, but Blau Parts kit includes two of these, just for this possibility, so I ended up using one of their replacement bolts when I put the parts back in place.

I also re-installed the exhaust manifolds with new gaskets and nuts.


Coolant O-Ring Replacement

Today’s effort was directed at the engine that will be going into the Silver S4, the former Nogaro engine with 91k on it.  At some point in the recent past the timing belt was replaced, but on account of me not knowing when in the past it was done I decided to update the baseline.  The valve covers were also done recently, but I know those were within the last 3,000 miles so I’m not concerned about being dead on with the mileage that they were replaced at.

With the engine out and a number of components removed I decided this would be a good time to replace the coolant hardpipe o-rings.


I purchased the O-rings as part of a servicing kit that ECS Tuning offers, along with a few other parts I was in need of.

I can’t recall seeing pictures of where these O-ring are located in a picture of the engine, so I took a few pictures as I went along.







In preparation for installing the new thermostat and water pump I put a polishing wheel on my dremel and cleaned up the surfaces that the water pump gasket and thermostat o-ring will be seated against.


B5 S4 Survivor Results

This post will be updated occasionally as more entries are submitted to the Audi B5 S4 Survivors poll.

As of 10/12/2016 there have been 450 entries submitted.







A concern that was raised about the results related to the data not being unbiased.  If the results are biased, trying to apply them to the entire population of B5 S4’s could make for incorrect conclusions.  To try to assess if there is some data bias I graphed the percentage of Tiptronic transmissions out of all the samples, as the number of entries increased.

Tiptronic transmission percentage of all entries
Tiptronic transmission percentage of all entries

The increasing percentage of Tiptronic transmissions does suggest that this data is ‘enthusiast’ biased, on account of B5 S4 enthusiasts being more inclined to buy manual transmissions.  The majority of early contributions to the survey were made by members of B5 S4 car forums and Facebook communities – enthusiasts.

With the continuance of time I have entered B5 S4’s that I have seen listed in for sale ads and on insurance auto auction sites.  These cars are more likely to be representative of the overall population, and as their numbers are increasing in the poll, the percentage of Tiptronic transmissions is increasing.

Another measurement that can be looked at in a similar fashion is the body style, something less likely to be influenced by an enthusiast, or non-enthusiast, owner.

Body style percentage of all entries
Body style percentage of all entries

In this case the percentage of Avant body style out of the the overall sample population has remained fairly consistent, around 15%.


Audi B5 S4