TTE550 vs FT21

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.

Picture of TTE 550 Compressor Housing and Wheel
TTE 550 Compressor Housing & Wheel

 

TTE550 2 to 11 time vs. FT21 and BW k04
TTE550 2 to 11 time vs. FT21 and BW k04

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
NumberFunctional Requirement DescriptionVerification MethodPass / Fail
1Rapid acceleration at 2000-3000 rpm.DemonstrationFail
2Maintain strong acceleration from 5500-6500 rpm.DemonstrationPass
3Biturbo configuration.InspectionPass
4Does not require unique parts.InspectionPass
5Equal or exceed RS4 K04 performance.TestFail
6N75 DC <80% at 6800 rpmTestPass
7Wastegate modulation of boost at part throttle.TestPass

TTE550

Technical Requirements Verification Matrix
NumberTechnical RequirementVerification MethodPass / Fail
8Charge air temperature < 300 degFTestPass
9Exhaust back pressure:Manifold pressure ratio <= 1.5TestFail

TTE550

Supportability Requirements Verification Matrix
NumberSupportability RequirementVerification MethodPass / Fail
10Reputable vendor with good product supportDemonstrationPass
1112 month warrantyInspectionPass
12Cost competitive with alternativesInspectionFail
13Price not greater than 20% over RS4 K04 InspectionFail

TTE550

Performance Specifications
NumberSpecification DescriptionVerification MethodPass / Fail
14Develop 20 psi of manifold pressure by 3100 rpmTestPass
152-11 psi time should be <= K04 time at all rpmTestFail
16Maintain >= 25 psi to 7000 rpmTestPass
17<= 45 psi of exhaust back pressure at 6500 rpm and 25+ psi of manifold pressure.TestPass
18Mass Airflow Rates >= 375 g/s at 6000 rpmTestPass
19FATS time <= 3.5 sec (Sea level, 60 degF)TestPass
20Torque >= 400 ft-lbsTestPass
21Wheel power >= 400 whpAnalysisPass
22MTBF >= 48 mo. or 50,000 milesAnalysisPass

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 K03BW K04FT21SRM RS4+TTE 550
1PassPassFailFail
2FailPassPassPass
3PassPassPassPass
4PassPassPassPass
5FailPassFailFail
6FailPassPassPass
7PassPassPassPass
8PassPassPassPass
9FailPassFailFail
10PassPassPassPass
11PassPassPassPass
12PassPassPassFail
13PassPassPassFail
14PassPassPassPass
15PassPassFailFail
16FailFailPassPass
17FailFailFailPass
18FailPassPassPass
19FailPassPassPass
20FailPassPassPass
21FailFailPassPass
22PassPassPassPass

Audi B5 S4