Starting on New Years Day I am taking advantage of some extra free time to get ready to swap the Frankenturbo F21s into the S4.
FrankenTurbo F21 version 3S4 Engine Pull Preparation
The S4 sits on a set of dollies so it can move about the garage easily for positioning. The car is at an angle in the garage when the engine hoist removes the engine.
S4 Engine Pull Preparations
Spending Friday evening removing the engine.
S4 engine out
Saturday is turbo swap day. This took a bit longer than usual on account of the Mamba wastegate bracket on the passenger side being too big.
Mamba Wastegate Bracket
Some cutting and filing of the bracket is done so that it will fit in place because the unmodified bracket contacts the cylinder head and/or starter.
Mamba Wastegate Bracket Modified
On go the new F21s.
Frankenturbo F21v3 Driver SideFrankenturbo F21v3 Passenger Side
Before installing the engine the wastegate preload is set to 12 psi. The setup is using the Yellow springs from the Mamba collection of springs.
With a number of different turbocharger pairs sitting in boxes, and a good pair on the car, I’ve had trouble deciding what to do next with my S4.
BorgWarner RS6 – FrankenTurbo F21 – TiAL 605
Then there is an incomplete engine sitting in the corner of my garage that will open some opportunities on account of the 2.8 heads and built bottom end.
Engine Cleanup
After several months of no progress on either I took some free time on New Years day to start preparing the car to pull out the engine.
Engine Pull Prep-work
The built engine is not ready so that option is out for now. My goal with the TiAL turbochargers is to have them made over into 770’s, so that leaves me with a choice between the BW RS6 turbo’s:
BorgWarner RS6/K04
Or prototype FrankenTurbo F21 with ceramic coated turbine housings and Mamba wastegate actuators.
Frankenturbo F21 with Mamba wastegate
I’m leaning toward the F21s on account of them being an easy transition from the Turbo Concepts Stage 1 turbos that are presently on the car.
After putting in a solid three months to the Silver S4 that drove away in August I’ve been eyeing this engine that is sitting in the corner of my garage.
Istook Built Engine
The Past:
The story of this build goes back to the early days of the B5 S4 when the S4 and driver (Don Istook) were actively racing.
Istook’s Motorsports in Fort Worth Texas took on the project that was envisioned to match a B5 S4 engine block, A4 2.8L cylinder heads, and a Supercharger.
The Engine:
The engine underwent a substantial amount of work consisting of:
Modification to the oil pump
Micro honed engine bores
Polished engine bearings
Boat tail crank saddles
Lightened crankshaft flyweights
Cryo treated and micro polished crank
Pauter rods
Thermal ceramic treated pistons and skirts
Engine Cleanup
The Heads:
The 2.8L cylinder heads saw some work as well:
Port & Polish of the heads
Multi-angle valve/seat work
Before and after flow testing
New springs with Cryo treatment
Surfaced cylinder heads
Thermal ceramic treated exhaust ports
Istook Motorsports worked 2.8L Cylinder Heads
On the back sat an Unorthodox Clutch Kit:
Ultra G Aluminum Flywheel
Ultra G Feramic 6 paddle spring disc
Ultra G high force pressure plate
Date Marking
The Body:
After all that work the engine was placed in an unassuming B5 A4 and parked outside a shop waiting to be finished.
Audi B5 A4
And there it sat and waited, and waited, and waited. Then I was contacted and asked if I’d be interested in trying to complete the project, only now doing so with Turbochargers instead of a Supercharger.
It isn’t often that something new and unusual comes along with the B5 S4, and this was unusual. I said yes and headed off to pick up the engine.
Istook Motorsport Engine Retrieval
The Present:
Now back in my garage this piece of Audi history is again slowly progressing towards completion.
