Continuing the evaluation of the candidates for best stock motor turbo, I installed The Turbo Engineers TTE550 turbochargers on my Audi B5 S4. No changes were made to the car’s hardware other than swapping the turbochargers.
Tale of the tape – TTE550 vs FT21:
All readings are made at 6500 rpm and 24 psi of Manifold pressure.
- MAF: TIE at approximately 400 g/s
- EGT: TIE at approximately 840 degC
- Exhaust Backpressure: 40.2 psi (TTE550) vs. 42.5 psi (FT21)
- Compressor Outlet Temperature Rise: 188 degF (TTE550) vs. 186 degF (FT21)
- Downpipe Temperature Pre-Cat: 1178 degF (TTE550) vs. 1147 degF (FT21)
If it is not obvious from those numbers, there is very little difference between these two turbochargers in the areas that I have measured.
I attribute the overall slightly better spool-up of the TTE550 to the Exhaust Backpressure measurement. It looks as though the TTE550 is just a bit more efficient at converting exhaust side energy into charge side pressure.
TTE550
Functional Requirements Verification Matrix| Number | Functional Requirement Description | Verification Method | Pass / Fail |
|---|---|---|---|
| 1 | Rapid acceleration at 2000-3000 rpm. | Demonstration | Fail |
| 2 | Maintain strong acceleration from 5500-6500 rpm. | Demonstration | Pass |
| 3 | Biturbo configuration. | Inspection | Pass |
| 4 | Does not require unique parts. | Inspection | Pass |
| 5 | Equal or exceed RS4 K04 performance. | Test | Fail |
| 6 | N75 DC <80% at 6800 rpm | Test | Pass |
| 7 | Wastegate modulation of boost at part throttle. | Test | Pass |
TTE550
Technical Requirements Verification Matrix| Number | Technical Requirement | Verification Method | Pass / Fail |
|---|---|---|---|
| 8 | Charge air temperature < 300 degF | Test | Pass |
| 9 | Exhaust back pressure:Manifold pressure ratio <= 1.5 | Test | Fail |
TTE550
Supportability Requirements Verification Matrix| Number | Supportability Requirement | Verification Method | Pass / Fail |
|---|---|---|---|
| 10 | Reputable vendor with good product support | Demonstration | Pass |
| 11 | 12 month warranty | Inspection | Pass |
| 12 | Cost competitive with alternatives | Inspection | Fail |
| 13 | Price not greater than 20% over RS4 K04 | Inspection | Fail |
TTE550
Performance Specifications| Number | Specification Description | Verification Method | Pass / Fail |
|---|---|---|---|
| 14 | Develop 20 psi of manifold pressure by 3100 rpm | Test | Pass |
| 15 | 2-11 psi time should be <= K04 time at all rpm | Test | Fail |
| 16 | Maintain >= 25 psi to 7000 rpm | Test | Pass |
| 17 | <= 45 psi of exhaust back pressure at 6500 rpm and 25+ psi of manifold pressure. | Test | Pass |
| 18 | Mass Airflow Rates >= 375 g/s at 6000 rpm | Test | Pass |
| 19 | FATS time <= 3.5 sec (Sea level, 60 degF) | Test | Pass |
| 20 | Torque >= 400 ft-lbs | Test | Pass |
| 21 | Wheel power >= 400 whp | Analysis | Pass |
| 22 | MTBF >= 48 mo. or 50,000 miles | Analysis | Pass |
Note: Ambient temperatures during measurement taking for the TTE550 have been warmer than when readings were taken for the FT21 and BW K04. This will affect the comparison. If readings for the TTE550 were made under the temperature conditions like those of the FT21 and BW K04 it is probable that 20 psi @ 3100 rpm (Number 14) would have been a PASS.
UPDATE: I took advantage of some cold weather and obtained additional readings. The TTE550’s reached 20 psi @ 3100 rpm, passing this criteria.
TTE550 Requirements Summary
| REQ. # | BW K03 | BW K04 | FT21 | SRM RS4+ | TTE 550 |
|---|---|---|---|---|---|
| 1 | Pass | Pass | Fail | Fail | |
| 2 | Fail | Pass | Pass | Pass | |
| 3 | Pass | Pass | Pass | Pass | |
| 4 | Pass | Pass | Pass | Pass | |
| 5 | Fail | Pass | Fail | Fail | |
| 6 | Fail | Pass | Pass | Pass | |
| 7 | Pass | Pass | Pass | Pass | |
| 8 | Pass | Pass | Pass | Pass | |
| 9 | Fail | Pass | Fail | Fail | |
| 10 | Pass | Pass | Pass | Pass | |
| 11 | Pass | Pass | Pass | Pass | |
| 12 | Pass | Pass | Pass | Fail | |
| 13 | Pass | Pass | Pass | Fail | |
| 14 | Pass | Pass | Pass | Pass | |
| 15 | Pass | Pass | Fail | Fail | |
| 16 | Fail | Fail | Pass | Pass | |
| 17 | Fail | Fail | Fail | Pass | |
| 18 | Fail | Pass | Pass | Pass | |
| 19 | Fail | Pass | Pass | Pass | |
| 20 | Fail | Pass | Pass | Pass | |
| 21 | Fail | Fail | Pass | Pass | |
| 22 | Pass | Pass | Pass | Pass |