Within the last few days a couple of dyno charts have been put forth showing some impressive performance from the TTE 550 and FT 21 turbochargers.  Since both of these turbochargers are strong candidates for going onto my B5 S4 I decided to try and match up the results.

This is an exercise that must be approached with a great deal of consideration for the significant differences underlying the dyno charts.  These differences include:

1. The dyno’s the cars were recorded on
2. The conditions when they were produced
3. The way measurements are reported
4. The cars
5. The fuel

There are enough points of difference here that a comparison should only be considered a ballpark estimate for how the turbochargers may compare under more controlled conditions.  Those more controlled conditions will hopefully be realized on another day, so for now I’ll charge onward with a crude comparison.

What I do know about the respective charts and vehicles.  The TTE 550 turbo’s were installed on a well modified B5 RS4 operating on 99 RON fuel with WMI spraying washer fluid.  The dyno chart displayed results at the engine, using an approximate 20% drivetrain loss.

The nature of the dyno readings meant that I needed to convert from NM to ft-lbs, and also apply the drivetrain  loss, more calculations than I’d like to do when trying to match performance, but necessary given the way data was presented for each vehicle.

The FT 21 turbochargers were installed on a stock motor B5 S4 operating with E85 fuel.  Dyno recording was made on a Mustang dynamometer and reported at the wheels.

And the comparison results…

Based on these *rough* curves it looks as though these two turbochargers match up well, but this comparison is far from being definitive.