Hard Rock Camaro, Part 1

By Dave Emanuel

Since the very first Z/28 Camaro set tire to pavement, it has been imbued with a performance image. That's as it should be. RPO Z/28 was developed specifically to provide Chevrolet with an entree into the Trans/Am road racing series. But in the 1970s, fabricated oil shortages and newly instituted exhaust emissions mandates, combined with corporate apathy, cut the heart and soul out of the Z/28. What had been a pulse-quickening performance icon, became nothing more than a package of striping tape. Then it disappeared.

RPO Z/28 returned for the 1977 model year, wounded, but still breathing. It wasn't until the introduction of the Third Generation Camaro, for the 1982 model year, that a true revitalization began. Although it was a far cry from the original version, the Third Generation brought with it a positive move towards performance credibility. In 1986, a 350 engine became available and Z/28 horsepower took a significant step upward.

Yet even with Tuned Port Injection, stock Z/28 Camaros with 350 cubic inch engines residing beneath their hoods are hard pressed to click off mid-14-second quarter mile times. By comparison, Fourth Generation Z/28s have no trouble rumbling through the quarter in 14-seconds flat. This was the car about which Chevrolet asked, "What would you expect from the country that invented rock and roll?"

Considering the ingredients that comprise a 1986-1992 350 Tuned Port engine, a Third Generation Z/28 should be able to run rock and roll right along side its more youthful replacement; it should produce the type of performance that brings some white to your knuckles and a smile to your face. And it should be able to fulfill the need for speed without running afoul of emissions laws. It can-- it's just a little harder to squeeze horsepower out of an L98 Tuned Port engine than it is an LT1, hence the name, the "Hard Rock Camaro". This project originally appeared in Popular Hot Rodding magazine and serves as a blueprint for building exceptional performance.

For people raised on carburetors and mechanical distributors, late model vehicles can be a bit intimidating. But in spite of computerized engine management systems, electronic fuel injection and emissions control equipment, an internal combustion engine is still an internal combustion engine. It requires air and fuel, administered in the proper amounts to produce horsepower. Consequently, for maximum performance, the formula for short block preparation is the same as with any other type of high output engine; precise machining and assembly practices are required. However, emissions requirements and a limited rpm range (with the manifolding that's part of Tuned Port Injection assembly, maximum horsepower is typically achieved at 4750-5000 rpm) dictate judicious piston, piston ring and camshaft selection.

According to Garry Grimes of Grimes Automotive Machine, building a high performance engine for a late model emissions-controlled vehicle requires the same type of preparation as a race engine. He states, "When you build a high performance street engine, durability has to be a major consideration, but you also can't afford to give away any horsepower, because you're limited in terms of modifications. If you want the engine to pass an emissions test, cam timing has to be conservative and compression ratio must be set to match."

Grimes's formula for a streetable small block that can click off impressive numbers at the drag strip begins with careful preparation of a four-bolt main block. He states, "When you get up into serious horsepower levels (above 500) I like to start with a Bow Tie block. But with a street/strip car, where horsepower is realistically going to be in the 350 to 450 range, a solid production block that has been sonic checked is suitable."

Once block preparation was complete, Grimes assembled the engine using Keith Black hypereutectic pistons which he fit with a Speed-Pro moly piston ring set. Hypereutectic piston alloys contain a high concentration of silicone which improves strength and also offers excellent insulating properties. In fact, heat transfer through hypereutectic pistons is reduced enough that wider piston ring end gaps are required than with conventional cast or forged pistons. This reduction in heat transfer translates to potential power increases because combustion pressures above the piston don't bleed off as quickly.

Obviously, pressure must be contained above the piston, so ring seal is of paramount importance. Use of top quality rings is therefore vital to maintaining maximum performance and minimum exhaust emissions.

The remainder of the reciprocating assembly consists of reconditioned production connecting rods and a production cast crankshaft. Although a forged crank is standard fare in most high performance engines, the anticipated power level of this engine, and its relatively low rpm range, (below 6000 rpm) will not place extreme stresses on the crankshaft. A cast crank should survive with no problems, but just to add some insurance, Grimes installed a Fluidampr 6-1/4" vibration damper.

Considering the projected power level, this may seem like a bit of overkill, but according to Grimes, "One point that's often overlooked when an engine is built using stock type components is that stock harmonic balancers are tuned to control the torsional vibrations of a stock rotating assembly. When you install aftermarket pistons, recondition the rods and lighten them, When that's done, rotating weight is altered enough that the stock balancer is no longer correctly tuned. That may or may not be a problem, but it doesn't pay to gamble. We know the Fluidampr does the job."

Another component known to get the job done is the ZZ9 hydraulic roller camshaft from TPI Specialties. Developed specifically to optimize the performance of late model fuel injected engines, while keeping exhaust emissions at acceptable levels, the ZZ9 provides 212 degrees of intake and 226 degrees of exhaust duration (at .050" lift) combined with .483" of intake and .520" of exhaust lift. (The lift numbers jump to .515" and .555" with 1.6:1 rocker arms.) A Competition Cams roller timing chain and gear set drives the cam which is mated to stock Chevrolet hydraulic roller lifters.

Although a solid short block is a requisite for durability, the true arbiters of horsepower are the cylinder heads, intake and exhaust systems and camshaft. Several viable cylinder head options exist, but since the ultimate goal was to make the engine suitable for competition in the National Muscle Car Association's EFI class, use of stock castings was advantageous since they didn't incur any "power adder" penalties.

Discussion of the situation with Pete Incaudo and Bob Hudgins of CNC Cylinder Heads Inc. led to the selection of a set of 1988-1991 Corvette aluminum L98 castings. Incaudo has developed highly efficient ports and combustion chambers for these heads and their resulting air flow capacity is sufficient to meet the demands of engines producing 350 to 450 horsepower. Hudgins has translated Incaudo's designs into digitized data that allows them to be precisely reproduced on the company's 5-axis simultaneous CNC machining center.

Incaudo designed the L98 port contours to function with stock valve diameters (1.94" intake, 1.50" exhaust). But in this case, a little bigger is a little better. He states, "We've had amazing results with stock valves and with just a slight increase in diameter, air flow is even better, and so is horsepower. That's a point a lot of people miss. It is possible to increase air flow and decrease horsepower because the quantity of air flow isn't as important as the quality. In these heads, we took REV stainless 2.02" intake and 1.60" exhaust valves and cut them down to 2.00" and 1.56". With these diameters, all you have to do is machine the stock valve seats-- if you go any larger, the seats have to be replaced. I like the REV valves because they're manufactured of exceptionally strong severe duty stainless steel material and the quality of machining is always excellent. They consistently hit their mark on the flow bench too, and they're reasonably priced so they're affordable for street applications."

After the CNC porting was completed, the heads were assembled using Competition Cams dual valve springs, steel retainers and 10-degree locks. Comp Cams guideplates and 7/16" rocker arm studs were also installed along with 1.6:1 ratio Pro Magnum roller rocker arms. Sealing the heads to the block are a pair of Fel-Pro part number 1010 head gaskets. These gaskets are designed for aluminum heads and incorporate a copper wire beneath the stainless steel armor around the bore openings.

The ideal mate to the CNC-ported Corvette aluminum heads is a TPI Specialties "Big Mouth" intake manifold, large tube runners and ported plenum and 52mm Throttle body. Although other intake systems are available, this configuration offers a combination of torque, horsepower and drivability that's hard to beat. According to Myron Cottrell of TPI Specialties, "The Big Mouth base, large tube runners and ported plenum is probably the best combination for a car that is street driven. It fits better with a mild engine combination, stock gearing and street type torque converter. We also offer the Mini Ram intake manifold, but it's designed more for top end horsepower than mid-range torque. It requires a significantly different engine/driveline combination for maximum performance."

On the exhaust side of the heads, a set of ceramic coated Hedman emissions-legal headers, with 1-5/8" diameter primary tubes, were connected to a pair of Random Technology Super High Flow catalytic converters. A Random Technology cat-back exhaust system with dual 3" tail pipes is attached to the converter outlets.

After the engine was installed in the Camaro's vacant engine bay, a TCI "Street Fighter 700-R4 transmission and Super Street Fighter 12" torque converter were bolted to it. This transmission was modified to use TCI's Universal Lock-up Kit, which takes torque converter lock-up control out of the hands of the vehicle's ECM and puts it into the driver's. Under normal driving conditions, the converter clutch locks when the transmission shifts into overdrive and steady throttle pressure is applied. However, a switch mounted in the passenger compartment, allows normal control to be over-ridden. When the switch is flipped, the converter clutch applies as soon as the transmission shifts into second gear. Experience has shown that locking the converter through second and third gears is worth a tenth of a second and one mile per hour in quarter-mile clockings.

The final link in the Hard Rock Camaro's driveline is a stock 7-5/8" 10-bolt housing that was fitted with a USGear 3.42:1 ring and pinion set and Auburn High Bias limited slip differential. Previous experience with 3rd and 4th Generation Camaros has demonstrated that these components offer surprising strength and durability. With a ring gear diameter of only 7-5/8", there isn't a lot of material to absorb the stresses of aggressive drag strip launches. But in previous projects, USGear ring and pinion sets have held up to continued abuse and survived admirably. Auburn's limited slip differentials have also survived very well. One of the common denominators in our previous experiences has been Red Line Synthetic's Shockproof gear lubricant. The Shockproof formulation seems to offer an extra margin of protection that's vital for prolonging the life of rear end components.

Of course, having completely gone through the engine and driveline, it just wouldn't do to go off to the drag strip with stock paint. One ofthe premier custom painters in the Southeast is Ernie Ritchie of Omni Automotive Graphics in Conyers, GA. Ernie agreed to not only apply the paint, but to develop a distinctive, conservative paint scheme. If beauty is in the eye of the beholder, so is "conservatism". The paint scheme doesn't exactly exemplify the dictionary meaning of "conservative", but it is certainly attractive, and never fails to illicit favorable comments from anyone who sees the car. In addition to preparing and painting the body, Ritchie also did the finishing work and installation of a Harwood fiberglass hood.

Following installation of the engine and driveline, the requisite number of proper break-in miles were accumulated before the Camaro was loaded up for a test session at Silver Dollar Raceway in Reynolds, GA. Check out the next feature to see the results.

Dyno Test Results

Hard Rock Camaro 350 Tuned Port Engine
RPM Torque HP
2000 333 127
2100 340 136
2200 343 144
2300 347 152
2400 349 159
2500 356 170
2600 364 180
2700 374 192
2800 376 201
2900 378 209
3000 386 220
3100 394 232
3200 399 243
3300 400 252
3400 401 260
3500 402 268
3600 406 278
3700 404 285
3800 412* 298
3900 412 306
4000 405 309
4100 399 312
4200 395 316
4300 394 323
4400 391 328
4500 386 331
4600 381 334
4700 373 334
4800 369 337*
4900 354 330
5000 344 327
5100 331 322
5200 317 314
* Maximum readings
All results corrected to 29.92 in/Hg, 60F., dry air


Auburn Gear
Auburn Drive
Auburn, IN 46706

Competition Cams
3406 Democrat Road
Memphis, TN 38118

CNC Cylinder Heads, Inc.
6400 53rd Street North
Pinellas Park, FL 34665

Federal-Mogul Performance Parts
P.O. Box 1966
Detroit, MI 48235

Fel-Pro Incorporated
7450 North McCormick Blvd.
Skokie, IL 60076

11980 Walden Ave.
Alden, NY 14004

Grimes Automotive Machine
215 Tidwell Drive
Alpharetta, GA 30201

Harwood Industries
17824 State Highway 31 East
Tyler, TX 75705

Hedman Hedders
730 Branch Drive
Alpharetta, GA 30201

Keith Black Pistons
4909 Goni Road
Carson City, NV 89706

Random Technology
1313 Temple Johnson Road
Loganville, GA 30052

Red Line Synthetic Oil
3450 Pacheco Blvd.
Martinez, CA 94553

REV Inc.
4704 NE 11th Ave.
Fort Lauderdale, FL 33334

TCI Automotive
One TCI Drive
Ashland, MS 38603

TPI Specialties
4255 County Road 10 East
Chaska, MN 55318

US Gear/Strange Engineering
9420 South Stony Island Ave.
Chicago, IL 60617