Rota D-Force Wheels for STI

D-Force test-fit on STI

If you follow this blog you've probably seen me complain that there aren't many wheels available that are both wide and high-offset to fit the GR-chassis STI.  Although there ARE lots of 5x114 wheels around, most of them have the wrong offset -- typically around +35mm -- and would stick out on the WRX STI.


In an effort to remedy this situation we worked with Rota to spec out a wheel that would be nice and wide, but still fit under the fenders of the wide-body STI.  We just got them the other day.  They're called D-Force, and they're 18x9.5", +40.  They have a very large (2.75") lip, which is really unusual for wheels that fit the big Brembo brakes of the STI.  At 22.6 pounds, the weight isn't too bad, either.

D-Force

For now, we only have this wheel in flat black.  Other colors to come will certainly include "Hyper Black," which is a smokey silver color.  I'm open to suggestions on what other colors you'd like to see.  Also, we could do the wheel with a polished and clear-coated lip.  Comment at the bottom of this post if you have an opinion either way.

Want them?  As I write this post, they are in stock and you can buy them.  You can find them at our web site.

GT Performance dyno video

This is the video from the second tuning session with the GT Performance race car.  With boost peaking at about 22 psi, tapering to 20 psi, the car made 565 horsepower at the wheels.  It's running 100 octane fuel.

Video here: http://www.youtube.com/watch?v=PhoMgVCjKuY

Tuning an STI to higher horsepower levels

We had the opportunity recently to tune a beautifully prepared 2006 WRX STI that was put together by GT Performance in Maryland.  Among other goodies, the car sports a fully-built 2.6-liter block with custom dry-sump oiling, a built-up dog-gear transmission, a complete roll cage, and even air jacks.  A Garrett GT35R turbocharger pushes air into a Cosworth intake manifold, and through Cosworth heads.  The car made a whopping 565 whp on our dyno.  Here's a look at an earlier dyno run -- a mere 500 whp:

http://www.youtube.com/watch?v=aKD8wztdHnA

Here's the car on the track at Summit Point:

http://www.youtube.com/watch?v=iiFtBMDpfEw

We look forward to working with the GT Performance crew some more in the near future.

Driving the Mach V STI

I took the Mach V STI home and ran a few errands.  Hauled a big PC to work, took the kid to school.  The car is still its usual self for around-town driving.  The exhaust note might be a tiny bit louder at idle and low speeds, but it's hard to tell.

Full throttle is another story.  When the 20G-XT-equipped STI gets up above 3500 rpm, everything starts to happen really fast, and it sings a baritone Subaru full-throttle song that turns heads -- in a good way if those listening are car fans.  (I got a thumbs-up from a guy in a BMW Z3 M roadster.)  But maybe that noise is not so good if you're trying to keep a low profile on the road.  Not like the car in its current form is subtle -- what with the multi-vented hood, huge wheels, and all that.

The power is pretty fun.  At freeway speeds you can still dip into the gas in sixth gear and get a good dose of passing speed, although there is more lag than there used to be.  Dropping a gear gets the car up into insta-boost range and you'll quickly be at extra-legal speeds.

Which brings me back to the thought of losing my driver's license.  I'm going to have to get the car to the track to see what it's like to drive it really hard at this power level.

Blouch 20G-XT on the car

We bolted the new Blouch 20G-XT turbocharger to our STI, and rolled it back onto the dyno for some more pulls.  The turbo delivered as advertised.  Spool was a little slower than the Tomei ARMS turbo we had on the car before, which is understandable given how much larger the turbine outlet is on the 20G-XT.  The car made a lot more horsepower at the same boost levels -- 33 more hp and 30 lb-ft of additional torque to the wheels.  An added benefit that isn't seen on the dyno graphs is that off-boost throttle response is better -- the more wide-open turbo outlet probably is the reason.  The exhaust note is a bit louder now, too!

Most of the time when we put a 20G on a car we've also done a turbo induction hose, TGV deletes, and headers, none of which are on our car.  When we do get those mods done, we'll dyno again.  I'd expect another 10+ hp at that time.

Needs More Turbo

Although the Tomei ARMS turbocharger on our STI made decent power, and spooled very nicely compared to the stock hair dryer, we just can't leave well enough alone.  We asked our friends at Blouch Turbo if they had any suggestions for something with just a little more oomph, and we got a Blouch 20G-XT: A Mitsubishi 20G compressor housing and center section mated to a custom Blouch turbine side that will bolt on to any 2002-07 WRX, and any 2002+ WRX STI.  But wait, there's more.  The compressor wheel is not cast like traditional wheels.  Instead it's CNC milled from a block of billet aluminum.  That means it can be made lighter and more efficient than old-school compressor wheels.  The upshot is supposed to be more power and better spool.  We'll find out next week when we bolt the turbo on and roll the car back on the dyno.

The 20G turbo has always been my "go-to" turbo for 2.5-liter cars.  It spools almost like a stock turbo, but has massively more top-end.  If you have a 2.0-liter car, the 18G is probably a better choice, as the 20G takes a while to get going with only a 2.0 engine blowing on it.  Blouch also has an 18G-XT available.  Watch our web site for more details on purchasing these turbos soon.

Trickle-Down Economics, Subaru Style

Today Subaru announced that the 2011 WRX sedan will get a wide body look that borrows the front fenders of the current STI hatchback.  The car will be on display at the up-coming New York Auto Show.

What does this mean?  Well, besides the obvious benefit of a 1.5"-wider track for WRX sedan buyers (the car also gets a more aggressive front end, blacked-out grille, and wider 17 x 8" wheels), it seems to me that it would be easy and cheap to just make an STI sedan, now that the body work is taken care of.  Our customers have pined for the lack of an STI sedan since the old one retired back in 2007.  I hope they haven't been holding their collective breath since then, but I'd wager there will be a 2011 STI sedan available alongside the hatch.

We've been working with our suppliers to get larger and wider wheels available for the current WRX STI -- now we'll renew those efforts, since the wider WRX will also allow for those bigger fitments.  (We've seen STI hatch models run wheels as wide as 10".)