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NHRA Sport Compact Engine Builds

When you're looking for something different than your typical small block rebuild, you might want to check out one of the newest types of drag racing. NHRA Sport Compact Drag Racing engines can be challenging as well as profitable for shops willing to learn what it takes to make these screamers into winners

By Brendan Baker

It may be a cliché to talk about the movie "The Fast and The Furious" when speaking of the sport compact market, but for lack of time and space it describes the scene pretty well. If you don't know about this little movie from 2001, think Honda Civics on nitrous. On the surface, the movie had a bad plot and very poor character development. However, for its cheesiness, it offered rather decent insight into this new hot rod lifestyle. And most notable was this: performance doesn't have to include eight cylinders, four-barrel carburetors or posi-traction.

You can't go far these days without noticing the proliferation of suped-up Hondas and other sport compacts on the street. Many of the cars are all show and no go, but some Gen-X'ers and Gen-Y'ers who are more addicted to speed, take their cars to the drag strip. Angela Proudfoot is one such case. Although when she first bought her car Proudfoot says she never intended to actually race it, one trip down the measured quarter-mile changed her mind.

"I was always into cars," she explains. "I wanted a fast street car but I couldn't afford the car I really wanted, so I bought a Honda Civic. I had heard they could be made to go fast. I took it to the drag strip after owning it for only a week. That's when I got the speed bug. I wanted the car to go faster, so I took it to a local import tuner/engine builder and had them build a 550 hp engine. I think I was their biggest paying customer ever," Proudfoot recalls.

Proudfoot today races an 850 hp Honda Civic in the National Hot Rod Association's (NHRA) Summit Racing Sport Compact Drag Racing Series Hot Rod division. Cars in this series are often exotic racecars, typically running four- and six-cylinder engines fed by turbochargers and nitrous oxide. Racecars in the fastest classes can cover the quarter-mile in as few as six seconds at more than 200 mph, but NHRA also offers novice and intermediate categories for every level of racer.

Most people think sport compact is only for imports, and in the past this was mostly true. Today, however, there are a number of successful domestic sport compact cars that compete and win in NHRA's Sport Compact Drag Racing Series.

Evolution
Though import owners have been street racing for years, the first organized racing events for imports were held in the early '90s. "The first ever sport compact event was called 'Battle of the Imports'," says Javier Ortega, NHRA Sport Compact Series event director. "Then after that was the NIRA series, which was owned by Peterson and later merged with Primedia. Eventually, Primedia wanted to get out of the event promotion business and worked out a deal with NHRA."

According to Ortega, NHRA's Sport Compact Series has grown to a whole other level in the past couple of years. "We're starting to see full-time sport compact racers and teams, becoming more professional every year. The teams are getting more funding (with sponsorships and manufacturer support) and are able to run more professional organizations. A few of the well-funded teams either have a hired gun to build their engines, or they have an in-house engine builder."

Ortega notes that there are still plenty of teams on the grid that do not build their own engines "The most organized teams have their own dedicated machinists and engine builders, but, the smaller, less well-funded teams are still sending engines out to be built." Simply put, there is a great deal of opportunity for engine builders who want to get into this market.

In the past, teams could often get by without much effort, Ortega says. Now, however, the technology and the progress of engine development in this series have made it much more difficult for teams to be competitive without first taking their skills up a notch or several.

"Teams like Mopar and GM have a lot of knowledge and engine building prowess," says Ortega. "These teams have taken the sport compact powerplant to a whole new level," Need proof? Both GM and Mopar factory teams have each built engines that produce over 1,000 hp from a production based four-cylinder engine with power adders (e.g., turbochargers, superchargers and nitrous oxide).

NHRA Class Structure
There are five "Heads-Up" classes and several sportsman-level classes in the NHRA Sport Compact Series. The sportsman classes probably offer the most opportunity for engine builders because these teams are usually self-funded and do not typically rebuild their own engines. Although sportsman teams are every bit as serious on race weekends as the heads-up teams, they typically run much smaller operations. Because these drivers and teams do not race for a living, they usually don't have as many resources available to them.

"The sportsman classes are for guys who just want to have fun, non-professionally," says Ortega. "These guys typically all work regular full-time jobs and just come out on weekends to play weekend warriors. And they usually only race within their home regions."

Sport Compact Sportsman classes range from Sport RWD (rear wheel drive) and FWD to Street Stock and Quick Sixteen classes.

The Sport RWD class is for four- or six-cylinder or two-rotor rotary engines with a turbocharger, supercharger or other power adder (i.e., nitrous oxide).
The Sport FWD class is basically a four-cylinder front-wheel drive platform with one or two power adders. Two power adders typically means either a turbo and nitrous or a supercharger and nitrous.
The Street Stock class allows virtually no modifications except for safety.
The Quick Sixteen class is made up of the fastest 16 qualifiers. These racers make the final rounds instead of the usual eight qualifiers.

NHRA's five "Heads-Up" classes are mostly purpose-built racecars for those classes. The All Motor class is open to four-cylinder or rotary engines without power adders. The All Motor class can either be FWD or RWD using either gasoline or methanol.

The Hot Rod class is FWD only with minimal modifications and tube frames are prohibited. Only four-cylinder turbocharged engines with nitrous oxide are permitted in this class.

Moving up to the Modified class, these cars are full tube-frame chassis and back-half rear wheel drive cars powered by four- or six-cylinders or rotary engines with turbochargers and nitrous.

Finally, the two Pro classes are Pro RWD and Pro FWD. In Pro FWD the cars are purpose-built Pro-Stock-style cars with some rule restrictions. The chassis are tube frames powered by four-cylinder engines only. Turbos and nitrous are the accepted power adders for this class. In Pro RWD the rules are similar to Pro FWD except the engines you can use are not limited to four-cylinders. You can use rotary, four- and six-cylinder engines with turbos and nitrous. This class is the quickest class in the Heads-Up category.

"For a long time the most popular classes were All Motor or Hot Rod, but it really varies now," says NHRA's Ortega. "It depends on what part of the country you're racing in. You could race in California for example and have 28 cars trying to qualify for a 16 car field."

Cylinder Sleeves
Cylinder sleeves are a big component of the NHRA Sport Compact drag racing. Since the advent of cylinder sleeves and their subsequent use in popular import engines such as Hondas, sport compact drag racing has been able to reach new levels of power and attract a healthy fan following.

The ability for a shop to install cylinder sleeves is a big plus in this market. Except for the occasional cast iron block, most of the engine blocks used in this series are aluminum. Because aluminum blocks cannot handle the high cylinder pressures and the heat that accompanies such pressure, cylinder sleeves made of super high strength ductile-iron are used and machined into place in the cylinder block (see February 2003 Engine Builder, page 30 for more on sleeving).

With an engine sleeve, teams can now add monstrous turbochargers and nitrous oxide induction and run upwards of 55 psi of boost pressure through the cylinders without grenading the engine.

"It used to be really tough trying to make power with a stock block," says NHRA's Ortega. "Especially when you have floating sleeves. You could make power for a little while but if you got any detonation - boom - it was over. The sleeves helped a lot. Many teams are running alcohol now, which in itself makes a lot of power. You couldn't run alcohol in an aluminum block without a sleeve."

Most teams no matter how much machine work is done in-house, send out for sleeve work to be performed by a qualified machine shop. Currently there are two companies that seem to hold the most market share in this division of racing because of their ability to properly install cylinder sleeves.

Rebuilding Intervals
There are many different formulas to determine how many passes a team can run before an engine rebuild is necessary. Like all racing stories, you have to read between the lines. Some say 45-55 passes is acceptable before a rebuild. Others say a rebuild is critical every couple of races. The truth? It really just depends on how much stress and strain is put on a specific engine.

"Right now we get anywhere between 45-55 passes on one engine," says Kenny Tran, who races the Quaker State Honda Civic in NHRA's Hot Rod Class. Tran owns a tuning/engine building shop where he mostly builds sport compact street rods for customers, so he counts on durability in his engines. "Internally, the only things we've upgraded on our B18 VTEC Honda engine are the cylinder sleeves, of course, and the connecting rods have been upgraded to powder rods. We've also upgraded the pistons to forged pistons, and we went with high-strength head studs and main studs. Everything else is basically stock. We use a stock forged Honda crank; we just balance it and pop it in. We're currently using stock bearings as well. The rod bearings are coated from the manufacturer but the main bearings are not. So far we've not had any trouble using stock bearings. Our motto here is, 'If it's not broke, don't fix it.'"

Tran tears the engine's top end apart to rebuild at about the same intervals as the bottom end. He uses most of the stock valvetrain from Honda with the exception of the valves, springs and retainers. He uses stainless steel valves, stiffer springs and titanium retainers for lightness and durability. But he still uses the stock camshaft.

Angela Proudfoot, on the other hand, uses many upgraded aftermarket parts and also changes mains and rod bearings every couple of races. "We take it apart and look at it all the time. Our pistons lasted all year last year, but we were running the wrong head gasket, which was one of our biggest problems." Proudfoot notes that she also ran a stock crank only to find that it was flexing, causing one of the pistons to hit the cylinder head. After she switched to an aftermarket crank those problems disappeared.

Our experts say that NHRA's Sport Compact drag racing series is still growing. There is a lot of interest in the series right now, which is evident by the manufacturer support in teams like Mopar and GM. Engine builders are starting to understand these powerplants more and more. One engine builder says that tuning one of these sport compact engines is a totally different animal than traditional drag racing engines. And there is almost no crossover between sport compact drag racing engine building and traditional V8 drag race engine building. But that can be a good thing for engine builders looking to get into the sport on equal footing - there's not a lot of competition right now, so the door is wide open.

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