AP’s Spec Corvette: Ferrari Fill-In For Forty Large

After a lifetime spent racing karts, Outlaws, and everything in between, AP Miranda decided to take a good chunk of the change he’d made over his career as a professional pilot and buy a Ferrari Challenge car. However, he found that the Challenge drivers he met weren’t too welcoming to his outlaw attitude. The series he’d dreamed about for so long quickly lost its luster, and he was curious if there was a better way to spend his money.

AP decided to seek out a cost-conscious alternative among a more welcoming bunch. “I met a couple of the Spec Corvette guys at a Speed SF weekend and they pulled me right in. They were a bunch of renegade guys looking to have a lot of fun — so I signed up and I haven’t looked back.”

Within a few months, he’d built a budget club racer with V8 power, a large footprint, and more than enough performance to keep a driver with racing experience in twin-turbo Ferrari entertained. Best of all, he’d done it for about a sixth the price of his old Ferrari.

The C5 Corvette doesn’t have to be expensive to run. Well, it’s always going to be hard on consumables, but compared to other cars running in the 1:37s on the old Laguna Seca, this version of the C5 Corvette can’t be called pricey. Simple, too — the formula for Spec Corvette is meant to be basic so that the fields can be fairly fat without too much expected from the participants in terms of vehicle prep.

This meant that the competition would likely be close, and so AP put some more money into a knowledgeable instructor to help him get the most from his new old car. He hired Tim Moser, a respected coach with a background in Formula Dodge-Barber, LMP3, and other serious machinery, to show him how to extract all the potential from his low-downforce, high-torque middleweight.

Strengths

Building a Spec Corvette requires little. There is the sole aero item — a three-inch ducktail spoiler from Trackspec Motorsports, but the car is compliant, stable, and predictable without major aero. This is due in part to a set of one-way Penske 8300 dampers and monoballs replacing the OEM bushings. If there’s one thing which the C5 needs to be less of a transporter to the pitch and putt and more of track scalpel, it’s removing the factory rubber.

The factory brakes are fair, but the Wilwood six-pistons are a great budget upgrade, and their rotors will last a year of racing before needing replacement. Even though the minimum vehicle weight is just 3,200 pounds, the Wilwood pads can last six weekends without losing their competitive edge. Retain the stock brakes and you’ll be working on them a lot of the weekend, but the stopping power is sufficient.

In the interest of keeping costs relatively low, the series has mandated a 200-treadwear Nankang NS2R tire, which should last three weekends or so. Considering the power and weight, that’s a relatively long life.

It doesn’t matter if the donor car is powered by an LS1 or an LS6 — either motor shouldn’t have much difficulty making the maximum 380 horsepower and 380 lb-ft of torque at the rear wheels as per the Spec Corvette rules. Both motors are under stressed, consistent, and easy to work on.

There are two options if the car comes with the less-desirable LS1. It can use the intake manifold, heads, and camshafts from the LS6 to make the allowed power, or, if the LS1 is kept totally stock, a set of long-tube headers are allowed. The LS6 only needs to retain the factory headers to make the desired output, so it’s the better choice. Plus, its “batwing” style oil pan is broad, shallow, and sufficient for Spec Corvette usage. In fact, it’s fine for just about any application which doesn’t involve slicks and wings.

However, G-forces and sustained high-revs will still cause oil to accumulate in the LS6’s heads, and to avoid this problem, some use reduced diameter pushrods, some drill holes in the lifter trays to drain oil to the sump faster.

Those are the essentials, though there are a couple preferred changes a cost-conscious owner/driver would consider. Though differential and transmission coolers help extend the lifespan of some of these consumables, they’re not necessary to ensure consistent performance over a single race — or even over a single season. The one last potential issue in this area is, thankfully, solvable with an OEM part. The LS7’s clutch is a cheap and easy replacement for an LS6’s clutch which struggles with the increased power output. Impressively, a Spec Corvette can be built with all new components for just $40,000 — quite inexpensive for the sort of lap times it’s capable of.

“The shocks work pretty well; we barely touch them over the course of a weekend,” Tim says.

Weaknesses

Now, while it would be unfair to say the car leans on its power advantage — which is enough to make it a contender in NASA ST3 — it does have some shortcomings in other areas. The braking performance is fair, though having to run the stock master cylinder makes the pedal feel a little softer and over assisted than a real race car ought to. That, combined with the oft-derided ABS system, forces the driver to learn all the braking system’s shortcomings. “You’ve gotta have the wheel totally straight if you’re going to brake aggressively,” Tim elaborates. Consider that this braking handicap would likely be worsened if the rules allowed the car to have all the camber it could use.

There is the famous lack of visibility to deal with, too. The combination of a low roofline, thick a-pillars, window nets, and a halo seat makes it tough to get a sense of what’s around you. Factor in the C5’s long overhangs and somewhat vague steering, and it might not be the easiest car to place precisely.

Such a small window opening makes rapid extrcationg an act achievable only by contortion artists.

Nevertheless, that’s a short list of shortcomings for a car with so many strengths. Tim’s coaching and Speed SF’s open lapping groups have helped AP feel at ease in the car. “We used the last event at Laguna for passing practice since we’re usually up front at race weekends and don’t get enough naturally. Everyone we drove with was courteous and aware, which made it easy to run nose-to-tail for several sessions that day.

We loved the low-key atmosphere; normally someone complains when you’re driving in such close quarters with someone else. We didn’t get any of those problems with Speed SF, and we got all our time thanks to every session running on-time.”

No major mechanical issues, close driving with plenty of opportunities to practice managing traffic, and a strong series of lap times in the low 1:37s made their last training weekend at Laguna Seca a total success. We hope Tim and AP join us again and give us a demonstration of racecraft in one of the best performance bargains around today.

AP plans to start renting these cars out on an arrive-and-drive basis to those interested in the coming months.