Nerd’s Eye View: Inside Fredric Aasbo/Papadakis Racing’s Amazing V8 eating 2AR Toyota Engine

Nerd's Eye View: Inside Fredric Aasbo/Papadakis Racing's Amazing V8 eating 2AR Toyota Engine

By Mike Kojima

A couple of years ago, a lot of knowledgeable people, myself included declared that the turbocharged small displacement 4 cylinder engine was dead in the sport of Pro Drifting.  Dead, uncompetitive and obsolete.  We sung the praises of the latest new generation of domestic V8's like the Chevy LS, the Chevy SB2 and the Ford Coyote.  For a while it seemed so even though others like our own Eric Hsu predicted otherwise.

This year things are changing, turbochargers are coming back to the delight of fans and challenging the rule of the V8.  One of the most intriguing and successful applications of new turbo technology is the Toyota 2AR engine developed by Papadakis racing and driven by Fredric Aasbo.

The 2AR is a 2.5 liter all aluminum inline 4 that is both lightweight and stout at the same time.  Papadakis racing has proven that it can not only make competitive power with good driveability but also operate reliably for a long time at exceedingly high power levels.  It's taken about 2 years for Papadakis racing to hone and develop the 2AR into the potent package it is today and the story and parts behind it are interesting indeed.  Check it out!

When the development process first started on the 2AR, the engine's Achilles heel was the valvetrain.  If the engine hit high revs or if the revs changed quickly the engine would spit its valve lash caps and rockers off.  If luck was with the team that would be it but sometimes the rockers could cause a valve to drop and BOOM!   Part of the problem was the engine's hydraulic lash adjusters pumping up and lifting the valves off the seat.  A big part of fixing the problem was eliminating the hydraulic adjusters.  Surprisingly, the mechanical lifters the team used shown here are from a GM Ecotec racing engine.  They dropped right in place of the Toyota parts!  Lash caps with deep pockets for the valve stems were also designed.  The deep pockets make it a lot harder to spit them off the valve stem.  You can see just how deep they are here.
The valve lash is adjusted via select fit shims that go under the solid lifters.  Sweet stuff!
The roller rockers are modified with taller rails to accommodate a taller valve stem and lash cap.  The deep pocket created by the taller rails make it harder to dislodge the rocker if spring surge is encountered.   A smaller base circle camshaft is also required when modding the rocker in this fashion.
The titanium retainers are made by Supertech to Papadakis Racing's specs.  Besides being super light, the retainers have to allow clearance for the sides of the deep rocker arm pocket and stonger than stock 6mm  stem diameter valves.
Supertech dual valve springs are used with a custom inner spring seat that gives more spring preload.  The valvetrain is good for a safe maximum of 8400 rpm with a typical working rev limit of 8100-8200 rpm.

 

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