The twin scroll housing allows the header builder to separate the engines exhaust pulses so the exhaust stroke on one cylinder will not cross contaminate an adjacent cylinder that is on overlap. The helps volumetric efficiency. By keeping the exhaust pulses discreet, the turbine can be hit with evenly spaced discrete pulses of exhaust energy. This boosts turbine efficiency and speeds spool, typically by at least 500 rpm.
With all of these high tech features to speed spool and improve response, Essa Autosport was able to select a high flowing 1.05 A/R turbine housing. Higher A/R’s flow better and make more power but typically spool at a higher rpm and spool more slowly. With a high tech EFR turbo, it was possible to get both worlds, good flow and power but with good response and lots of low end torque!
The turbo manifold is a Doc Race top mount twin scroll unit. Doc Race worked directly with Essa Autosport to develop this manifold. The all stainless steel Doc Race manifold comes with a T4 twin scroll flange or an optional V-band twin scroll flange and is set up for twin wastegates, one for either side of the twin scroll system. This assures optimal pulse separation and best pulse conversion efficiency.
Twin low profile 38mm Tial MV-S wastegates are used. The wastegates are placed where they will get decent airflow and are not exposed to excessive heat, away from the excessively hot parts of the turbo system. Not to many people know, but you should always try to shield your wastegates from excessive heat as it can damage the diaphragms or cause valve sticking. This is especially important for competition cars that see a lot of flow through and heat into the wastegates.
After the turbo, the exhaust flows through a 4″ titanium exhaust system. This bit saves 20 lbs off of the car. Check out the smooth pie cut bends! That is a lightweight Drive Shaft Shop carbon fiber driveshaft next to the exhaust.
An HPF intake manifold was modified to take a throttle body. The S54’s ITB’s were gutted to turn the intake system into a large plenum with a single throttle body.
9 comments
Some very nice little details – I very much like the adaptation of the blade swaybar end to the splined bar, and the use of multiple batteries as not-technically-ballast amuses me. There’s definitely a feel like… about a well sorted car where there’s not much excess, which you would figure.
It’s interesting how some shops swear by using the latest in performance bearings for their rods or mains. And then there are the ones who check their clearances and successfully run stock bearings (not even WPC etc. treated).
In my experience a crank with too much runout or oval/worn journals is the main culprit of bearing failures, not the mechanical properties of the bearing itself.
I’ve even noticed that some performance bearings have less crush height than OEM ones, especially on Honda engines.
PS:
Using performance bearings in daily driven engine is also a recipe for disaster. They just don’t absorb contaminants as well, leaving them float around in the oiling system and grind away on your precious polished crank journals.
Great article Mike! The E46 has quite a long wheelbase (2720mm) relative to its overall external dimensions. The current Mustang is also in the 2720mm range. The BRZ (2570mm) and S15 (2520mm) are significantly shorter in wheelbase
The A90 Supra has a 2470mm wheelbase.
As horsepower and speeds increase in top level competitions do you anticipate more competitors moving to long wheelbase platforms for improved high speed stability.
Would the short wheelbase of the A90 Supra hinder it’s high speed stability to a significant degree? Is the BMW E92 Coupe at 2760mm.wheelbase the new benchmark platform for top level drifting?
I think the wheelbase sweet sport is around 100 inches.
The power steering cooler looks like a low pressure unit but it does not look like a CSF product… possibly a Setrab ProLine STD range cooler?
Curious as to why 6 speed transmissions are starting be the norm. I’m not aware of many tracks where a 4 speed would not suffice
Most sequential transmissions with enough torque capacity are six speeds.