New option from SRM

With the passage of a few months a new candidate has entered the scene.  I noticed that Silly Rabbit Motorsports has introduced a K04 hybrid variant to provide another option for me.

SRM K04 RS4+ (K04 Hybrid Turbo)
SRM K04 RS4+ (K04 Hybrid Turbo)

These SRM turbo’s bring a new twist to the candidate pool because they are similar in size to the FrankenTurbo F21 and ProjectB5 RS4-X on the compressor side, though the SRM uses a billet compressor wheel, but on the turbine side it is using a clipped wheel.

This is a very interesting development since I have theorized that one of the reasons my experience with the FrankenTurbo F4H-BT did not show much gain in the upper rpm’s, despite pushing 25psi out to redline, was that the airflow through the turbine side began to back up lowering the engines VE.  Perhaps a clipped turbine wheel would allow this size turbocharger to hold that 25+ psi and flow better, netting greater top end horsepower results.

Since the product is a recent introduction it remains to be see how they perform, but for now they will stay on the candidate list:

  • BorgWarner K04
  • FrankenTurbo F21
  • ProjectB5 RS6-X
  • SRM Billet K04

Note: As of July 2015 I have yet to see any results of how the SRM billet K04 turbocharger performs.

Next: TTE 550 Another Contender

6th engine pull

Getting ahead of the game, I’ve got plans to put some different turbochargers in the car but at the moment haven’t established exactly what they’ll look like.  The motor is coming out so I can work on a few accessories and swap exhaust manifolds then hopefully within a couple of weeks will have a different set of turbochargers to evaluate.

audi b5 s4 engine pull
6th time the motor has come out of my S4

A lesson learned from this time around, figure out how you are going to plug the braided stainless slave cylinder line BEFORE you install the product.  I wanted to leave the metal slave cylinder in place since I had put some RTV around the housing to keep dust from getting into the bell housing around the slave cylinder.  This meant disconnecting the AN fitting that goes to the metal slave cylinder.  With the stock unit I had a small tube that would slide over the end to plug it when disconnected, not so with this AN fitting.  After disconnecting the fitting and not having any luck holding the line up to keep the fluid in, or being able to find a suitable plug, I let the end of the line drain into a waste container.  Next time around I’ll have a proper plug to put on the end of the line.