Great Lakes Divisional Championship Video

Tuesday, August 10, 2010 by Tire Rack Motorsports
Here are the video highlights from last weekend's Great Lakes Divisional Championship event in Peru, Indiana.

Our team used the event to get ready for the upcoming Tire Rack SCCA Solo Nationals held in Lincoln, NE in early September.

Project STR Captures THREE Divisional Championships

Monday, August 9, 2010 by Tire Rack Motorsports
It’s been a busy two weeks for Project STR.

Our first outing took us to Miller Park in Milwaukee, WI for the CENDIV Divisional Championship. This area has been a hotbed for street tire competition with plenty of fast drivers to help us gauge our performance. GRM/Tire Rack drivers Chris Harvey and John Rogers traded fast times both days. Chris pulled out the win with really quick times on his fourth and fifth runs.

Fast forward one week to the Great Lakes Divisional Championship in Peru, IN. This site is the best simulation of the Nationals course surface we can find east of the Mississippi. The battle was tight all weekend, with Chris Harvey out in front after day one by just 0.060 seconds. The course on day two was fast and hard to visualize in a few spots, but that didn’t slow down team STR. John Rogers threw down a crushing second run that no one could match, but it wasn’t enough to make up for his deficit from day one. Chris Harvey was second-quick for the day just 0.4 second back with autocross legend Jim McKamey less than a tenth behind.
Nick Jackson experimented with a wing on his S2000, and ultimately went faster without it. After two days, the three trophy spots were covered by a scant 0.078 second, with Chris Harvey, Nick Jackson and John Rogers finishing first through third respectively. Tire Rack driver Angie Rogers also got her first taste of the MX-5 this season, winning the STR Ladies championship and getting primed for Nationals next month.

If the competition at the Tire Rack SCCA Pro Solo Finale and Solo National Championship in Lincoln, NE next month is this tight, it’s going to be a heck of a battle to see what driver/car/tire combination comes out on top. We think we’re ready for the challenge.

Controlling the contact patch is job-one to going fastOur efforts to fine-tune the suspension set-up on Project STR are paying off, as shown by our recent success in competition. A close look during maximum cornering shows just how well the KW Coil-Overs and Hotchkis Anti-Roll Bars maximize the footprint and cornering power of the Dunlop Direzza Sport Z1 Star Spec tires on our MX-5.

Another Victory for Project STR at the Toledo ProSolo

Friday, July 23, 2010 by Tire Rack Motorsports
Project STR is ready for actionAs our 2010 Mazda MX-5 autocross project continues to evolve, we’ve been hard at work on Project STR, installing and testing suspension components and adding some go-fast graphics.

We’ve also tried to answer the question about what tire and wheel size produces the quickest lap times. One thing we did confirm is that what feels good isn’t always fast, and what’s fast doesn’t always feel good.  The MX-5 has been a great test bed to find out what fits, and what works. A full report will appear in the next issue of Grassroots Motorsports magazine.

Meanwhile, the battle for the top positions in the SCCA’s Street Touring Roadster class are turning out to be intense, with just a few tenths of a second separating the trophy positions at most SCCA National level events this season. The Toledo ProSolo was no exception with the margin of victory for Project STR driver Chris Harvey coming in at a scant .087 seconds over runner-up Jason Wong in his well-prepped Honda S2000. Just .389 seconds back was David Corsaro, piloting his Honda S2000 CR to third place.
Project STR sits in post-race impound, allowing competitors to inspect the car--and wonder how it goes so fast.
Along with finding ways to make the car go faster, another fundamental part of this project is keeping the car streetable. To that end, our driver, Chris Harvey, drove 250 miles to and from the event on the same Dunlop Direzza Sport Z1 Star Spec tires and Kosei K1TS wheels he raced on—just like we did for the Peru National Tour two weeks earlier. No tire change at the event was needed. The rest of our gear for the weekend was packed into the car. Chris’s only complaint: what to do with all of his spare time at the event. Could going fast get any easier?

Project STR scores at the Peru National Tour

Monday, July 12, 2010 by Tire Rack Motorsports
Chris Harvey drives to the finish at the Peru
 National TourThe blog has been a little quiet while we were hard at work installing and testing “go-fast parts” on the Project STR MX-5. In addition to the KW Variant 3 Coil-Overs and Hotchkis Sport Anti-Roll Bars, we’ve been experimenting with different sizes of Dunlop Direzza Sport Z1 Star Spec tires to find out what makes our MX-5 faster. A full tire test report will be appearing in the next issue of Grassroots Motorsports magazine on newsstands in a few weeks.

To put our efforts to the test, we competed in the Tire Rack SCCA National Tour autocross in Peru, Indiana. 15 drivers showed up in an array of vehicles – Honda S2000s, Pontiac Solstice, BMW Z3 and our Mazda MX-5. Day One saw Mike Lillejord jump out to a half-second lead in his Pontiac Solstice over Matt Glagola in his S2000. Our MX-5 was less than 2/10ths further back with Chris Harvey at the wheel, while John Rogers was just another 1/10th of a second behind in 4th place.

Sunday dawned a new day with a revised course layout that featured a six-cone slalom and several fast, decreasing radius turns. Chris and John changed tire pressure and shock settings to help the MX-5 put down more power when driving off the corners. Our drivers used this to their advantage, posting the two quickest times of the day in the STR class. When the dust settled, the margin Mike and Matt gained on Day One was too much for our MX-5 to overcome, leaving Chris and John in 3rd and 4th respectively, about 0.4 seconds behind the winner.

As a reference point for how the project is progressing, this weekend 2nd place finisher Matt Glagola was driving the Honda S2000 that won the Dixie Tour earlier in the year where we were over eight seconds behind in our bone-stock MX-5. At least on this day, on this course, we’ve closed the gap to his car down to a scant 0.015 second margin. We still need to figure out how to chase down Mike and his Solstice. I guess we have a little more work to do.

<Click on the photo for a video of Chris Harvey's FTD run>

Hotchkis Anti-Roll Bar Upgrade

Thursday, May 6, 2010 by Tire Rack Motorsports
Since the beginning we have noticed significant lateral body roll in the Project STR MX-5. Installing the KW Variant 3 Coil-Overs with the stiffer spring rates improved it marginally, but we feel it still needs to be reduced further. Past test experience has shown us that tuning the anti-roll bars can have a significant positive impact on responsiveness and cornering power.

Front Bar Comparison - Hotchkis vs. O.E.So, the next logical step in our build-up was to install a set of Hotchkis Anti-Roll Bars. For this application, the tubular bars are larger diameter than the O.E. bars. They're also 3-way adjustable front and rear, which should help us tune the balance of the car to our liking, and to work well with the rest of the suspension and wheel and tire upgrades we’ve already made.

Project STR gets its first Tire Rack SCCA Pro Solo win!

Monday, May 3, 2010 by Tire Rack Motorsports
After a few local autocross events to gain valuable seat time, Chris Harvey made the 10 hour drive to Lincoln, NE for the 2nd Tire Rack SCCA Pro Solo event of 2010 driving the Grassroots Motorsports/Tire Rack Project STR Mazda MX-5. The site is the same used for the year-end Pro Solo Finale and National Championship events, making this a great advanced look at how the car will do at the big dance later this year.
Project STR ready for action
Call it a coming out party, or call it a battle. Either way, Chris was challenged by Brandon Davis in his lightweight ’99 Miata all weekend. Keeping everyone in suspense, Chris was able to pull out the win on his final run on each side of the course. As they say, it ain’t over ‘til it’s over. In addition to scoring victory, Chris learned a lot about how the car performs in the heat of battle and the direction we need to go as the project develops.

KW Variant 3 Coil-Overs Tested

Friday, April 23, 2010 by Tire Rack Motorsports
Now that the KW Variant 3 Coil-Over suspension has been installed and the car re-aligned, it was time to see what sort of improvement in lap times the suspension upgrade brings. KW’s installation and tuning information included with the kit provide initial recommendations for ride height, as well as rebound and compression settings. Figuring this was the best place to start, we dialed in the system to their recommendations, and headed for the track.

We ran the car on both the O.E. Bridgestone Potenza RE050A tires, as well as on our wide Dunlop Direzza Sport Z1 Star Spec competition tires. As expected, both configurations went faster than the last time we drove the car with the stock springs and shocks. Interestingly, the Dunlops gained more than the O.E. tires did, suggesting they have more potential not realized with the O.E. suspension. Subjectively, the car now feels more at home on the track, responding to driver inputs with greater authority than before.

Project STR Gets a Suspension Upgrade

Tuesday, April 20, 2010 by Tire Rack Motorsports
The next step for project STR is a suspension upgrade to replace the Mazda shocks and springs. We’ve settled on the KW Variant 3 Coil-Over system. It offers flexibility in adjustments, with separate controls for compression and rebound settings. Ride height is adjustable, too. All together, this system should do a good job helping to control the increased grip of the Dunlop Direzza Sport Z1 Star Spec tires we’ll be competing on.

KW has a reputation for winning – with plenty of victories in Europe, chosen as the O.E. supplier for the Viper ACR suspension, as well as on some of the best AMG package Mercedes on the road.

Wider Proves to be Faster

Wednesday, March 31, 2010 by Tire Rack Motorsports
So, now that we have tires and wheels installed, it’s time to find out how much quicker around our test track this combination is versus the O.E. tires and wheels. To simulate the total lap time of a typical national level autocross event, we combined 2 flying laps of our standard test course.

First setting a baseline reference with the factory 205/45R17 Bridgestone Potenza RE050A tire/O.E. wheel package, we then bolted on the 255/40R17 Dunlop Direzza Sport Z1 Star Spec  tires on 17x9.0 TRMotorsports C3 wheels and ran a few comparison laps. With nothing else done to the car, and no real tuning done Project STR testing tiresto optimize tire performance, we went well over 2 seconds a lap faster, on a 55-second course. Steady state lateral g-forces were improved, too.

We’re looking forward to installing the coil-over suspension, so we can better control the performance of the Dunlop tires.

First Outing for Project STR

Wednesday, March 31, 2010 by Tire Rack Motorsports
Project STR Mazda MX-5 saw its first competitive action over the weekend at the Tire Rack SCCA Solo National Tour in Georgia. To capture a baseline before the upgrades begin, Chris and John drove the car in stock trim – with nothing more than an Project STR at Tire Rack SCCA National Touroptimized alignment. They competed against fully prepared S2000s and a few MR-2 Spyders using the MX-5’s factory tires and stock suspension.  After 2 days of competition, they finished up 8th and 11th out of 13 drivers, just over 8 seconds behind the winner. Based on this we need to find 4 seconds per day on a 60 second course.

The next step will be to try on some proper tires and wheels at the Tire Rack test track to see how much of the gap we can make up right out of the gate.

Project STR Comes To Life

Wednesday, March 31, 2010 by Tire Rack Motorsports
Tire Rack has teamed up with Grassroots Motorsports magazine to prepare a car for competition in the Sports Car Club of America’s new STR autocross class. This class allows common bolt-on performance improvements to an otherwise stock street car, such as wider performance tires and wheels, suspension upgrades and an engine ECU retune. Sticky R-compound competition tires are not allowed, so we’ll be competing on “regular” street tires.

A 2010 Mazda MX-5 will serve as the foundation for the project, offering a good blend of power, handling and modest weight. The Grassroots Motorsports/Tire Rack Mazda MX-5 will compete head-to-head with similarly-prepped Honda S2000s, Toyota MR2 Spyders and other 2-seat sports cars. Throughout the 2010 season we’ll be measuring the performance gains of our parts installs on the Tire Rack test track and in the heat of battle during select Tire Rack SCCA National Tour and Pro Solo competition. The project will culminate at the Tire Rack SCCA Solo Nationals and Pro Solo Finale events in Lincoln, NE this fall.

You can follow the project here on the Tire Rack blog, our Twitter site and at

Tire and wheel installation

Tuesday, March 23, 2010 by Tire Rack Motorsports
The first upgrade has to be tires and wheels. So it’s off with the old and on with some more serious rubber. Using the widest size allowed by the class rules, we’ve installed 255/40R17 Dunlop Direzza Sport Z1 Star Spec tires mounted on 17x9.0 ET48 TRMotorsports C3 wheels. This is a very aggressive custom fitment, which required some work to get to fit. The white chalk mark seen in the photos is to check for any tire interference with the bodywork of the car. It was worth the effort to make it fit, and boy it sure looks good! We can’t wait to see how well it works out on the test track.