It’s been some time since I tested any parts for the B5 S4 but when I was contacted by Torque Factory (TF) Consulting wondering if I would be willing to flow test a Y-pipe they are developing I agreed to.
Y-Pipe Flow Testing
Previously I have tested the stock S4 Y-pipe as well as the B5 RS4 Y-pipe. For this test the products would consist of the Torque Factory prototype as well as The Tuner Y-pipe.
The Tuner Y-pipe
Two MAF pipes were supplied, one 4″ and the other 4.5″ in diameter. The 4.5″ pipe contains a removable flow straightener.
Because these products are larger than the S4/RS4 parts I have previously tested I needed to make a new adapter to attach the products to the flow bench.
Flow Bench to MAF Pipe Adapter
3D printing comes in handy for creating the adapters needed to join parts with the flow bench.
Test Procedure:
Prior to measuring the airflow through the parts a calibration plate is installed on the flow bench to check for accuracy. Once that has been completed the Y-pipe is attached to the MAF pipe using a silicone coupler and the MAF pipe is attached to the flow bench using another silicone coupler that attaches to the flow bench adapter.
A MAF sensor is installed in the MAF pipe and the PCV port on the Y-pipe is blocked off.
The previous testing with the S4/RS4 Y-pipe had been performed at a depression of 10″ of H2O. I found with the larger components used during this test that the flow limit of the bench, roughly 650 cubic feet per minute (CFM), was being met before reaching 10″ of pressure drop through the test article.
THE-Tuner Y-Pipe Flow Test
For this reason 6″ of H2O was chosen as the default test depression for taking measurements.
Several combinations of Y-pipe and MAF pipe were flow tested.
Torque Factory Consulting Y-pipe Flow Test
Test Results:
The table summarizes the readings for each of the combinations tested:
Y-Pipe Test Case
MAF Pipe
Flow Straightener
Airflow @ 6″ of H2O
TF-1
4.5″
Yes
641
TF-2
4.5″
No
686
TF-3
4″
N/A
644
THE-1
4.5″
Yes
560
THE-2
4.5″
No
537
THE-3
4″
N/A
518
This data is presented in bar chart format along with the measurements for the S4 and RS4 Y-pipes:
Flow Test Results Summary
A calculation can be made with the measured data to predict the airflow at a higher depression than what was tested.
Because the S4 and RS4 Y-pipes were tested at 10″ of H2O an extrapolation is made with the data for the Torque Factory and THE Tuner Y-pipes to estimate what they might flow at a depression of 10″ of H20.
The predictions are shown on the chart below, represented by the segment of the lines that are dashed.
Conclusion:
A flow bench test was performed to measure the airflow through different combinations of Y-pipe and MAF pipes using a Torque Factory Consulting prototype Y-pipe and a production version Y-pipe manufactured by THE-Tuner.
Comparing the results of this test with previous results using the S4 and RS4 Y-pipes both the Torque Factory and THE-Tuner Y-pipes flowed significantly more air at the test depression.
Of the various combinations tested, the Torque Factory prototype using a 4.5″ MAF pipe without a flow straightener produced the highest airflow, 686 CFM @ 6″ of H20.
About 48 months after picking up the S4 Avant from a fellow Audi enthusiast they contacted me offering to buy the Avant back if I ever was thinking of selling it.
Audi B5 S4 Avant
As it turned out I had not been driving it very much. I’d picked up a Mk7 GTI as a daily driver to replace my Miata. The Mk7 GTI is very similar to the S4 with respect to exterior dimensions and comes in a few hundred pounds less weight.
VW Mk7 GTI and B5 S4 Avant
The turbo engine and abundance of aftermarket parts options were another bonus, offering the opportunity to test with a different platform.
The opportunity to return the Avant to the previous owner made the decision to see it off easier to make.
First though there would be a final turbo swap, removing the Frankenturbo F21 v3’s for a pair of TiAL 605s’.
Turbo Swap Prep.
Engine Removal Prep.
Knowing this would likely be the last time I was removing a 2.7T engine made it a bit easier to undertake what is probably the dozenth engine pull I’ve worked through.
Audi Engine Removed
Swapping turbos to the TiAL 605.
Passenger Side Turbo Installed
Driver Side Turbo Installed
The engine only has about 50k on it, but having it out I took the opportunity to replace a few coolant hoses that have been in use for a number of years.
After run coolant pump hoses
Back in it goes.
Engine Installed
Nearly done…
2.7T Engine Installed
With the Avant back with the prior owner and the GTI a family favorite daily driver a replacement project car was needed. The Mk7 Golf R was what I settled on. Similar to the B5 S4 but with enough differences to launch a new round of tests at MyGolfMk7.com
