Grassroots Motorsports

Several factors led them down the path to a 5.0-liter Ford V8 rather than a Chevy. As Jeremy explains, “[The Ford engines] are cheaper than 350 Chevys and are easier to hook to a manual transmission; they are very light and compact; and they have forged pistons and a roller cam from the factory and can handle large quantities of nitrous.”

The Mouse House

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After years of rallying, autocrossing and ice racing, Jeremy and Mark were ready two years ago for something that was a bit easier on the wallet. They began thinking about less expensive ways to go racing. They needed a change.

“We watched the Challenge grow every single year,” Jeremy says. The first Grassroots Motorsports Challenge was held back in 1999. “But in the early years,” he continues, “we were so busy with our other racing and repairing our rally cars that we did not have time to build a Challenge car. But as rallying grew more expensive, and we spent less time rallying and more time talking about Challenge ideas—we really got the bug.”

Once the bug had bitten, it was time to find the right car. After a few sessions spent discussing what was needed in a competitive Challenge car, the pair set some parameters for their potential vehicle.

“Having the car look good was very important,” Mark explains. “We benchmarked lots of other competitors: originally an 11.99 quarter-mile, a respectable finish in the autocross, and a high finish in the concours.” They also wanted their car to be a street sleeper with a quiet exhaust and full interior. Plus, in order to save as much money as possible, they decided to look for a hardtop model that wouldn’t require a roll cage.

The pair had several platforms already in mind when Jeremy’s former boss offered up his failed Mazda RX-7 race project. It had sat in a barn for nine years and needed a new home. Its blown engine had been removed some time earlier, while the interior had acquired some full-time inhabitants: mice.

“The price at first was $2000,” Jeremy says, “and I politely passed on that. I did not even bother looking at it. But the price kept coming down each week, and the list of modifications kept growing as he started remembering what he did to the car.”

The two finally came to terms. “Finally the price was 600 bucks, and even if the car was a total wreck, I could sell off the parts and break even,” Jeremy recalls. “So I decided to buy it and tear into it.”

Soon after purchasing the car, Mark and Jeremy decided that its rotary powerplant was just too far gone to rebuild, especially on a Challenge budget. (The cap for that 2004 event was set at $2004.)

Besides, even with a hot rebuild and nitrous, they knew it would be hard to break into the 11s at the drags with the rotary engine in place. So they began researching V8 engine swaps.

There are several commercially available V8 swap kits for the RX-7, but these also proved too expensive for a Challenge car. Most of them required altering the steering rack location and also wouldn’t work with the stock hood. So in true penny-pinching form, Jeremy and Mark decided to tackle the transplant on their own.

Now they just had to decide what they would use to power their car. “We wanted a manual transmission because we thought it would work better at the autocross portion of the event,” Jeremy recalls.

Several factors led them down the path to a 5.0-liter Ford V8 rather than a Chevy. As Jeremy explains, “[The Ford engines] are cheaper than 350 Chevys and are easier to hook to a manual transmission; they are very light and compact; and they have forged pistons and a roller cam from the factory and can handle large quantities of nitrous.”

The Rat Trap

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Once they had a solid plan in mind, Mark and Jeremy set out to bring their creation to life. After securing their desired Ford engine plus transmission, clutch, bell housing, shifter and accessories, they began construction in the summer of 2003.

Naturally, a used engine needs help, and during the rebuild a few little problems popped up, like when one of their new piston rings broke during installation. Solution? The team had to reuse the best one that came in their engine. It’s not ideal, but moves like this kept them under the budget. And just in case the freshened V8 wasn’t enough to motivate the chassis, a used nitrous system was installed for that extra oomph during the drag race.

While things like broken piston rings were easy to fix, the team had to get a little more creative when it came time to actually fit the engine in the car. The engine’s oil pan sump wouldn’t clear the steering rack and chassis crossmember.

A Sawzall solved that problem, as the team cut away the firewall and moved the engine 4 inches toward the rear of the car. This plan of attack allowed the engine to fit behind the steering rack and thus preserved the geometry.

Engine mounts were then fabricated for the powerplant’s new location. The new custom mounts were formed from “cheap parts-store 1970s Ford motor mounts” along with scrap pieces of square tubing—a low-tech solution, but it did the job.

The relocated firewall did bring a few complications. “It was a lot of work to get the dash, heater system and driver controls back in with a bunch of room missing under the dash,” Jeremy says. And that’s not the only place where space was tight: Since the V8’s stock fuel injection now wouldn’t fit under the hood, the setup was ditched in favor of a carburetor pieced together from two used units.

But after they cleared the hurdles and got the engine installed, the car ran. Everything fit and the car drove without any hiccups.

Now it was time for the hard part: making it all pretty. As enjoyable as the V8 growl sounded, it was time to completely tear everything apart and start all over again, this time with an eye toward producing a tidy engine bay and showroom-floor finish. They weren’t about to show up with a race-winning car, only to be defeated in the looks department.

“Too many people either ignore the concours or have the wrong ideas about what it takes to do well,” Mark says. “We wanted to have the car look as factory as possible and very clean, not hacked-up. Basically, a real sleeper.”

Jeremy and Mark spent the majority of their 1000 man-hours on their project’s cosmetics, fixing the body and cleaning the interior and engine bay. In order to create a factory look, Jeremy spent “way too many hours” snipping and soldering together the wiring harness.

While Jeremy was conquering the wiring mess, Mark set about repairing the body. Years spent collecting dust in a barn and serving as a home for many mice had taken a toll on the RX-7. The body was full of small, rusty dings and scratches, and each one had to be fixed. And since the car had been home to several generations of mice, it smelled bad. Really bad.

“Some people could not believe we won the concours because we had the original interior in the car,” Mark says. “Scrubbing, cleaning and reinstalling the original, mouse-infested interior was one of the hardest parts of the entire project.”

Time to Shine

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With the car now rodent-free and finally all one color, the team enlisted Mark’s old rally co-driver, Al Zifilippo, to help them come up with some graphics and a visual theme for the project. Subtlety was the key, as simple, gray “G.T. 302” decals on the RX-7’s rocker panels recalled classic Shelby stripes and were the only visual clues as to what was lurking under the hood.

Mark and Jeremy finished the car in time for the magazine’s 2004 event, where they finished a respectable third in their first Challenge outing.

They knew that just a little tweaking could move them up a rung or two for the 2005 event, so they sold off some parts to create some room in the budget. (An extra dollar is added to the budget each year, so all teams could spend a maximum of $2005 at this year’s event.) Newer rubber for both the autocross and drag race made a huge difference in terms of on-track performance.

The changes paid off: In addition to taking first place in the concours, the car was the third-fastest in the drag race with an 11.676-second quarter-mile time—fast enough to beat most of today’s supercars. Jeremy and Mark also came home eighth in the autocross, racking up enough points to take the top award of the weekend.

On top of the trophies, the car earned itself many fans. The team’s fellow Challenge competitors were often overheard discussing the Mazda, and how it looked just so darn stock.

And that was Jeremy and Mark’s plan all along.