posted on June 11, 2013 00:30
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.
Tuesday, June 11, 2013 4:34 AM
This is truly an impressive motor from a design aspect. Perhaps it might be because I'm so used to seeing old Japanese 4 cylinder motors that I've overlooked some clever engineering that now comes standard in newer 4 cylinder motors.
Also, it's great that the TC got the 2014 facelift.
Tuesday, June 11, 2013 6:34 AM
Some interesting details on that; I like the chamber shape machined into the pistons. Squirters too - it always amazes me that Subaru guys talk of them as being useless, maybe it's just the factory implementation. Separate cam carrier reminds me of the old Cosworth BD motors, though they obviously set valve lash differently. I really do like all the turbo guys using nitrous as a sort of antilag system - definitely seems like it works and maybe the missing link to the old small displacement engines coming back into being competitive. Also, 105mm stroke and an 8400rpm redline is pretty darned good.
Are you sure the lift numbers on the cam card aren't given after the 1.7x multiplier from the rocker ratio? I just ask because from what I've seen, 0.418" lift at the valve is in line with an aggressive 4-valve head of this sort of bore, while I've never seen 0.710" lift at the valve in anything short of a big bore domestic V8.
Tuesday, June 11, 2013 6:54 AM
I have nothing but praise for this motor, i came across one in 2009 (keep in mind, it first became available in the 2010 model year) and got it for a song from the junkyard. i dropped it in my 24hours of lemons race car and i've been beating it up ever since with nothing but oil changes (about 7000 miles of racing now). the motor runs super cool under all conditions with the stock oil cooler and we get 12mpg around the track. this motor is downright awesome even in stock form.
here it is in the MR2: http://www.frankensteinmotorworks.com/2AREB61MKI/IMG_0559.jpg
the motor mounts are trivial also, like most toyota products the 3 motor mounts are on the transmission and the 4th is on the engine, but in this case the engine mount location is perfectly flat so it's easy. the whole thing was in my car in a day and then another day for the 6 speed shift linkage.
i recommend this motor for swaps all day long.
Tuesday, June 11, 2013 8:13 AM
Awesome article, thanks Mike! Not sure if I missed this, but what cars does this engine come in?
Tuesday, June 11, 2013 12:04 PM
Which 2AR is this? I assume the 2AR-FE?
So a Camry/RAV4 motor?
Tuesday, June 11, 2013 12:11 PM
yeah, that car was built before the FXE direct injected motor and the heads don't show ports for the direct injectors. so it's a 2ar-fe
Tuesday, June 11, 2013 5:04 PM
Kenku, you are right and I am wrong, Steff tells me that the lift is with the rocker ratio considered.
Tuesday, June 11, 2013 6:24 PM
What a cool engine. The plastic cooling jacket diffuser and cast upper pan assembly just blew my mind. That's the kind of stuff that I love to see on high production engines.
I feel the urge to dump one of these into a Factory Five '33.
Tuesday, June 11, 2013 10:49 PM
Too bad the motor doesn't already come in something fun.
Tuesday, June 11, 2013 10:59 PM
Surprised at the THREE oil squirters per piston. I wouldn't think the engine would be that stressed in it's normal use. I guess if it does towing.
Wednesday, June 12, 2013 6:28 AM
I wonder if Toyota had some interesting R&D data trickle down from when they were in F1 - Race Engine Technology article on the last generation F1 V8 had the thing with something like 3 squirters per piston too. It's not like the engines are similar at all, but maybe they came up with some clever idea regarding piston alloys and crown temperatures. Or, okay, I just want to imagine a world where F1 technology actually trickles down, is that so bad? ;)
Wednesday, June 12, 2013 1:26 PM
I was amazed with the 3 squirters myself.
Wednesday, June 12, 2013 10:28 PM
I wonder what this engine would do in stock stroke hi comp form with ITB's. Looks like. Good replacement for the 3SGE dual beams in my Altezza one day.
Thursday, June 13, 2013 6:33 AM
you can see in this graph i made for toyota motors that it's already better than the beams:
those are all the torque curves from toyota's technical documentations re-scaled to have the same range (which is why some look blury, i did not redraw the lines)
there are horsepower lines in the back also so you can read torque and horsepower.
as you can see, the 1ar and 2ar both have about the same amount of horsepower, the beams has a few more above 6750 or so to it's redline, but overall the 1ar and 2ar have significantly more area under the curve.
what that graph does not say is just how much each motor opens up when you uncork the stock exhaust. the 2gr-fe shows gains of about 70hp when you let it breathe with the stock ECU.
Thursday, June 13, 2013 2:26 PM
The wastegate exits through the hood? Was this grandfathered in or something (based on current rules)?