2008 Impreza 2.5i Turbo Kit Prototype

2008 Impreza 2.5i Turbo Kit Prototype
About 10 years ago, Ross of AVO came over to the states for an extended R&D trip, creating
one of our most famous turbo kits for the Subaru Impreza 2.5 RS. The 2.5 RS was a great car
from Subaru that had all the trappings of the STI turbo models in Japan with it's aggressive
hood scoop and sporty 2-door styling. Unfortunately, the situation under the hood was not quite
so sporty, as Subaru opted to only offer it with a 2.5-liter non-turbo motor in America. Given
AVO's 38 years of turbocharging cars that hadn't been turbocharged in the first place, this was a
natural job for us.
That project is, as they say, history. We still provide the kit to RS 2.5 owners, and it's been a
steady, strong performer through this entire time. While it is still available, there is less and less
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2008 Impreza 2.5i Turbo Kit Prototype
2.5 RS Impreza's available as the years go by. We had been looking at doing a turbo kit for the
newer models from Subaru, but have been waiting for the right timing. With the release of the
Accessport for the 2008 Impreza 2.5i, the timing was now right.
What makes the Accessport so important to this project? Engine management is actually one of
the thornier issues when building a turbocharger kit, as so many areas need to be modified to
make it work. Problems that come up when you turbocharge a car that was not turbocharged in
the first place are multiple. When a manufacturer builds a car these days, they usually build it to
very tight specifications with only a minimum level of necessary equipment. Fuel injectors and
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2008 Impreza 2.5i Turbo Kit Prototype
the fuel pump are one of those areas that are built to a minimum specification only, which meant
both will need to be replaced with higher flowing units due to the fuel demands of turbochargers.
That is just but one of the issues that come up when we are creating a turbocharger kit. We
solve the fuel pump issue with the AVO 245l/hr fuel pump, and anticipate using 500cc injectors.
So once we knew we had a engine management solution in place, we were ready to start
building the prototype. We already had in mind the basic specifications for the package. The
turbocharger we chose for this application is a Garrett dual ball-bearing AVO350 (based on the
GT28) for it's combination of quick spool up and good mid-rpm performance. It flows about
39lbs/min of air - more than enough for cars running on a complete stock engine, and with
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2008 Impreza 2.5i Turbo Kit Prototype
headroom for people that choose to swap in a STI shortblock to run more boost and make even
more power. That said, the newer NA cars have much better built engines than in the past, and
can run at higher boost levels than the 2.5 RS motors that were available back in 1999. A
stainless steel downpipe and uppipe will be used, and we are looking into using a
California-compliant OBD-II sports cat on the downpipe.
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2008 Impreza 2.5i Turbo Kit Prototype
A big design change from our previous kit was moving from using a top mounted intercooler to a
front mounted intercooler. When we designed the kit for the older cars, they already had a hood
scoop in place, with a simple, removable plate blocking airflow. This made it a no-brainer to
specify a TMIC to go under than hoodscoop, taking advantage of resources that were already
available. Subaru stopped using hoodscoops on any non-turbo car however, and this created a
new problem. Anybody that wished to fit the kit would need to purchase a new or used hood
from a turbo model if we designed the kit with a TMIC.
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2008 Impreza 2.5i Turbo Kit Prototype
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2008 Impreza 2.5i Turbo Kit Prototype
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8 / 11
2008 Impreza 2.5i Turbo Kit Prototype
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2008 Impreza 2.5i Turbo Kit Prototype
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2008 Impreza 2.5i Turbo Kit Prototype
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