Smog Test History and Its Impact on Modified Cars in America

Jun 22, 2023

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I love cars. I always have. More than that, I love to mess around with cars—to fix them up, change them, make them look better, and make them run better. I am a hot rodder, and I probably always will be.

At the same time, however, I run several miles a week. I love to hike, camp, bicycle—do things outdoors. I breathe. I live in Los Angeles. I hate smog. I detest it.

America has been nurturing a love affair with the automobile since its inception. While lots of us may grumble about traffic, commute time, loan payments, or repair bills, nearly everyone—hot rodder to stay-at-home parent—has a particular affection for his or her personal car. Moreover we would argue that hot rodding, the freedom to personalize your own car and make it work better, is part of the fabric and spirit on which this country is founded. Hardly anyone here is anti-car.

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Yet we all know that cars make smog. And anyone who says they like smog is crazy. It appears we are perched on the horns of a dilemma.

Not quite. In the first place, personal cars are only a partial contributor to smog. Trucks, airplanes, trains, buses, boats, tractors, lawnmowers, and countless other combustion-powered vehicles add to "mobile source" pollutants. More basically, any burning of organic material contributes to air pollution: factories, forges, refineries, mills, coal-fed electric plants, home heating furnaces, burning leaves in your backyard. Moreover, many industries or products emit vapors which contribute to pollution—paint and chrome-plating being just two examples.

How much do cars contribute to smog? In Southern California, which has the highest concentration of cars in the country, automobiles account for only one-third of all pollution-causing emissions (see accompanying charts, above and below). This is a very important point. Many people—politicians, environmentalists, government agency employees intent on tracking down every last gram of tailpipe pollution—seem to think that if all auto emissions were squelched today, smog would disappear tomorrow. That just ain't so.

Furthermore, in the past 20 years auto emissions from new cars have been reduced drastically: 96% for hydrocarbons (HC) and carbon monoxide (CO), and over 75% for oxides of nitrogen (NOx), nationally (California reductions are even greater). According to Dr. Arthur Winer of the Statewide Air Pollution Research Center at the University of California, Riverside (one of the world's leading smog research centers): "The tailpipe emission levels attained today for HC and CO are as far as we can go on a cost-effective basis. Further reductions aren't practical." Dr. Winer feels that oxides of nitrogen must be further controlled in Southern California; however, current NOx standards suffice for most of the rest of the country, where climatic and geographic conditions make NOx much less of a problem. (Admitted one Environmental Protection Agency official, perhaps rashly, "L.A. is unique in having a NOx problem. NOx is not an EPA problem. ")

The point is that passenger cars are not the primary source of air pollution. And the federal Clean Air Act, which has set increasingly stringent emissions standards at the manufacturer level since 1968, is highly effective at curbing pollutants from new cars. And yet, because most states have been unable to reduce overall air pollution to meet National Ambient Air Quality Standards, the EPA is ordering states across the country to invoke a dreaded "I/M" (Inspection and Maintenance) Program which is coming down on individual automobile owners like the Spanish Inquisition.

I/M is supposed to catch "gross polluters" cars with missing or poisoned catalytic converters, cars with other smog equipment removed or "tampered," or cars severely out of tune. Programs vary from state to state, most employing either an underhood visual check (Inspection), or a tailpipe emission check and tune-up, if necessary (Maintenance), or both. So far 26 states have I/M Programs already operating. More will follow.

We would be foolish to attack the I/M Program as a bad thing. That is, we hot rodders keep our cars well-tuned and we shouldn't be afraid or annoyed about taking an annual tailpipe sniff test, with everyone else, in the mutually beneficial interest of keeping our air breathable. However, along with all car owners, we must first ask whether I/M is equitable, and whether it is cost-effective.

Nearly all I/M testing exempts trucks, buses, motorhomes, motorcycles, diesels, boats, planes, and trains (not to mention police cars, fire trucks, and ambulances). The burden of cleaning up the air falls only on private car owners. The cost for an I/M test and certificate averages $20-$30 per car, plus another $30 for the tune-up if the car fails. Most states put a ceiling of $50-$100 on necessary repairs if none of the smog equipment has been tampered.

In California the Bureau of Automotive Repair (BAR), which operates the new program there, stated that they expect 13 to 14 million cars to be tested (out of 17 to 20 million in the state), and that 50% would fail and require a tune-up or repairs, at an average cost to owners of $50 per car. That's a lot of time and money.

Now recall that cars contribute only about 33% of active air pollutants. Add that only about 75% of the vehicles in California will be tested. Then consider that the entire California I/M Program, according to Senate Bill 33 which enacted it, calls for "...the average reduction in emissions of hydrocarbons and carbon monoxide from inspected vehicles [to be at least] 10 percent" after three years of the program. That's 10% of 75% of 33%—a "hoped for" net emissions reduction of less than 2-1/2% for the entire California I/M Program!

The EPA expects an average emissions reduction of 25% from cars tested in nationwide I/M Programs, but California's program indicates that EPA projections might be optimistic.

I/M obviously isn't cost-effective, but we could still live with an I/M Program requiring annual tune-ups, or even specified smog controls for all cars. That's not what scares us. It's the particular method of inspection in the new program in California—plus the specter that this program will be imported to other states—that has hot rodders suddenly angered and bewildered.

Californians were caught off guard, largely because the state cried "Wolf!" so many times before. Fifteen years ago a new vehicle code (VC 27156) made it illegal to "disconnect, modify, or alter" any part of the smog-control equipment which originally came on a car, and the Highway Patrol set up inspection traps at various surprise locations on public highways to try to enforce this law (if caught, you had to replace the parts and pay a hefty fine). But the public became enraged by these Gestapo tactics, raised an outcry, and the enforcement was scrapped… though the law remained on the books.

Basically, this law makes nearly any external engine modification to any 1966-or-later California car illegal. Yet, lots of things rodders do to their cars are technically against the law (modified exhaust, lowering, no fenders, etc. ); sometimes they result in selectively-enforced nuisance tickets. But generally the "smog law" lay dormant for years.

Then, suddenly last March, they sprung the I/M Program with as little warning as those highway traps years ago. Every two years California cars must not only pass a tailpipe sniff test for HC and CO (plus NOx in Los Angeles), but they must also pass an underhood inspection to verify that all original smog equipment is in place, unmodified, and working properly. Furthermore, the California law is being interpreted to mean that any part which might increase emission levels on any car for which state or federal tailpipe emission levels were set ('66-or-later California; '68-or-later "49-state" cars) is not allowed. That means no nonstock multiple carburetion, no blowers, no aftermarket air cleaners, no lots of things. We explain the California I/M Program more fully elsewhere, but here's the bottom line: if you can't pass the test, both visual and tailpipe, you can't register your car! You can't drive it.

Yes, to a large extent, the California I/M Program does outlaw hot rodding. Specifically, Vehicle Code 27156 made most engine modifications to '66-and-newer cars illegal for years; then Senate Bill 33 made effective enforcement of this law possible. Just like that.

Actually—surprisingly—the wording of VC 27156 tries to make allowance for modification:

In plain words, this clause says that any modification is OK as long as you don't disconnect any smog-control equipment or increase tailpipe emissions from your car. We'll buy that. It sounds reasonable to us. However, it's the phrase "found by resolution of the State Air Resources Board" (the ARB) that screws things up.

Ever since the passage of VC 27156, the California ARB has been given the authority to judge whether aftermarket parts meet the letter of the law, and they have taken the firm position that all such parts are guilty until proven innocent. In most cases, to prove that an individual aftermarket component (an intake manifold, a carburetor, a turbocharger, etc.) does not adversely affect smog-control apparatus or increase emission levels, the manufacturer of that part must pay an independent testing lab (usually several thousand dollars) to run the part through a full EPA driving cycle "Federal Test Procedure," and submit the data to the ARB for "consideration." The ARB can accept the results, giving the part an "E.O." (exemption) number; it can reject the data; or—as it has in many cases—it can call for further testing (at the manufacturer's expense).

Getting any vehicle to "certify" for HC, CO, and NOx in an EPA Full Test Procedure is difficult, complicated, and expensive. But the worst part is that, in most cases, if the part passes it is given an exemption only for the model on which it was tested. For example, a BAE Turbocharger is exempt for "1980 gasoline-powered VW Rabbit, Scirocco, and Jetta passenger cars with manual transmission and three-way catalyst." Other examples of turbo exemptions include two for pre-'80 Dodge 440 motor homes, one for pre-'80 MoPar 360 trucks, and one for '75-'76 Mercedes 240 diesels. Several aftermarket ignitions are exempt, mostly for pre-'75 models, but listen to a sample "limitations" description for the Mallory Unilite #502:

Obviously the ARB certification system discourages manufacturers from getting exemptions for aftermarket parts. The ARB-approved parts list (as of early '84) includes no intake manifolds, no superchargers, no carburetors, no camshafts, no cylinder heads, and one brand of headers. That doesn't mean these parts are necessarily illegal (some are currently accepted as "replacement" aftermarket parts), but right now we're not really sure what is legal and what isn't. So far, the ARB has been policing VC 27156 at the manufacturer and point-of-sale level, trying to get blatant "tamper" parts (such as "test tubes" to replace catalytic converters) off the market, and to make sure that all "modification" parts are sold with a disclaimer that they are "Not Legal for Use in California on Smog-Controlled Vehicles." To this end, the ARB freely admits sending undercover agents to speed shops, muffler shops, and other such places to catch illegal sales or modifications (they can impose fines of up to $2,500).

Fortunately, however, a different agency was selected to implement and oversee the I/M Program in California, and they take a slightly more liberal interpretation of VC 27156. The Bureau of Automotive Repair (BAR) is a branch of the Department of Consumer Affairs, and they now have the ultimate authority to pass or fail vehicles at registration time. The BAR, thanks to strong lobbying by the Specialty Equipment Market Association (SEMA) and other concerned aftermarket or replacement parts manufacturers, currently is allowing aftermarket intake manifolds, carburetors, headers, ignitions, and other equipment as original-type replacement parts, as long as these parts retain all smog-control apparatus and are "marketed by the manufacturer for street use."

However, the BAR still enforces a list of "Illegal Modifications" drawn up by the ARB, including any non-original multiple carburetion, any blowers or turbos without an "E.O." exemption, centrifugal-advance-only distributors on most models, "Removal of catalytic converter for any reason," and "Installation of add-on devices not exempted by the ARB." Does this sound like 1984? Listen, brother, it is 1984, and this is happening.

Obviously the I/M Program in California is taking a very direct shot at "hot rods"—i.e., modified vehicles—and we can expect the same all across the country. It's not surprising. Hot rods, often for totally unexplainable reasons, have been the target of pointedly discriminatory laws or legal harassment for decades.

The problem, believe it or not, stems in part from the fact that hot rods have become accepted as an American tradition. Everybody knows what hot rodding is. Also, hot rods are very conspicuous. People see them everywhere (or at least they think they do).

Admittedly, our hobby/sport/industry is big. It involves a lot of people and a lot of business. HOT ROD Magazine is the largest automotive publication in the world. Auto racing—a direct derivative of modified cars—is a bigger spectator sport than football or baseball.

But let's back up for a minute and count some numbers. There may be a lot of hot rods in America, but there are a whole lot more "stock" vehicles. Statistics on the actual number of modified cars in the country are hard to come by. However, the California ARB has been running traffic spot checks for years to determine (among other things) what percentage of on-road vehicles have at least one piece of aftermarket engine equipment (even if it's only a chrome air cleaner). We had been told that 1.2% of the vehicles in California are modified.

However, according to an ARB memorandum dated July 20, 1983, which compares an estimate of emissions from all modified cars in California to an estimate of emissions from these vehicles if smog controls were added, the percentage of modified cars is even lower. The ARB's estimate of emissions from modified vehicles, in tons per day, is:

Compare these numbers to the 1983 emissions inventory for all on-road vehicles:

Simple arithmetic will tell you that modified vehicles—according to the ARB's own estimates—account for only 0.84% HC, 0.94% CO, and 0.35% of NOx emissions from on-road vehicles. Less than one percent! In fact, these figures compare uncontrolled "hot rod" emissions to emissions from "stock" vehicles with smog controls, so we can assume that the percentage of modified cars in California is actually far less than one percent. On a national level, the EPA has estimated that only about one-half of one percent (0.5%) of vehicles on the road are modified.

The purpose of the ARB memorandum was to show that emissions from modified vehicles could be reduced 75% to 85% if all were forced to install smog-control equipment. Using their own figures, let's see what the ARB would achieve by "going after" all hot rods. For hydrocarbons, we'd get an 84% improvement of 0.84% of on-road emissions, which are less than 50% of combined mobile/stationary sources, giving us a net emissions reduction of less than 0.35%. The reduction in carbon monoxide would be about half a percent, and NOx would improve only about a tenth of a percent. These numbers are actually quite conservative, plus they are based on ARB sources, which we feel may presume inflated emissions levels from modified vehicles in the first place.

The point is that hot rods are not gross polluters. Hot rods may be highly visible, but they actually constitute a virtually insignificant minority. If the EPA, the ARB, and the BAR could stop the sale of all aftermarket equipment, and remove all modified parts from any cars on the highway today, we could not possibly measure any improvement in ambient air quality. All the experts will agree on that.

In a word, no. In a democracy the majority rules. The only way I/M will be stopped or diverted is if the general public sees it as a waste of money, or as an unwarranted inconvenience.

As hot rodders, we aren't going to change the laws by hitting them head-on. In California we must deal with a program that's already in place; in other parts of the country you might be more effective at diverting disaster before it strikes. However, in either case we're probably going to find that logical argument—or even hard numbers such as we've presented here—are weak weapons. Governments are often moved by elements other than logic. We suggest—both for the sake of pragmatism and for the sake of cleaner air—that we try compromise instead.

If we thought logic or practicality had a chance, this is the plan we would submit: Since the EPA has already set emission standards for all cars for the last 16 years on a national level, and since the EPA requires new car manufacturers to warranty all smog-control parts for five years, we feel it would be much more feasible to require new car buyers to bring their vehicles back to the dealer annually for a low emissions tune-up to maintain their warranty. The dealer could charge for the tune-up at the current rate (about $30), but repair or replacement of parts would be covered by warranty. Nearly 50% of passenger cars on the road nationally are five years old or less (and that percentage will increase for the next few years as Detroit pulls out of its recent sales slump), plus one to five-year-old cars travel about 30% more miles annually than six to 10-year-old cars, and considerably more than cars even older. Remember, we're still dealing with percentages of percentages here. If they want I/M checks to keep these cars tuned and running clean, they should use the legislation already in place on a federal level and tie the testing into the new car warranty. If they feel they really need to go after more cars, they could require a 10-year warranty on smog controls (with pro-rated replacement or repair cost), and possibly a biennial mandatory tune-up.

If the above system were adopted, the small minority of new car owners who wished to modify their engines would simply void their warranty (modification has always voided engine warranties).

However, we also know from experience that once a bureaucracy is established (such as the I/M Program), it is very difficult to displace. Therefore—assuming that the above suggestion would not be accepted—we propose the following modification to the I/M Program as enacted in California: (1) Allow modified vehicles to install any functional smog-control equipment, rather than the specific items which came on the car originally. Such equipment should probably include catalytic converters, an evaporation canister, and a thermal air cleaner, with the possible addition of an air injection pump and EGR valve. Thus the modifier could select high-performance control apparatus, such as a Z28 or H.O. Mustang dual inlet air cleaner, or, hopefully, approved aftermarket smog-control systems. Then each modified vehicle would have to pass a tailpipe sniff test for HC and CO, possibly with levels set by model year, or even with a set standard for all modified cars.

Or, (2) Allow modified vehicles to pass a tailpipe emission test only. In most states a test for HC and CO at idle and at 2,500 rpm "cruise" should suffice. In Los Angeles or other designated NOx areas, the modified car owner could elect to take their vehicle to a test station equipped with a chassis dyno (perhaps for a higher test fee), to take a "loaded" NOx tailpipe test on the rollers. Such stations are already in place in Southern California.

Given the computerization of current I/M testing, the above suggestions would certainly not complicate the program. In fact, testing modified cars could be simpler than testing other types. At the beginning of the check, the owner would state that the vehicle is modified (and perhaps the year), the operator would key this category into the computer, and the test would be run to a pre-determined set of standards.

Some of you may be surprised—perhaps angered—that we are not calling for outright exemption from smog-control equipment and testing for modified vehicles. We do stand fast behind our statement that banning all "hot rod" parts would produce no measurable improvement in air quality, anywhere. But we know that we can't be an exception to the rule just because we're a minority.

Furthermore, we believe that as hot rodders—as auto enthusiasts—we should do our part to help reduce the serious air quality problem the automobile is contributing to in this country. Let's clean up our act.

Most of us believe that smog control and high-performance won't mix. One look at quarter-mile times turned by Detroit's latest "clean" muscle machines should convince you otherwise. The fact is that most smog-control equipment has little or no effect on horsepower, especially at wide-open throttle (WOT) engine operation.

A typical pre-computer smog-control system could include a catalytic converter (CAT), an air-injection pump (AIR), a thermal air cleaner (TAC), a closed crankcase and positive crankcase ventilation (PCV), exhaust gas recirculation (EGR), and an evaporation control canister (EVAP).

Let's start with the AIR pump. This is simply a mini blower that pumps air into the exhaust manifold runners near the exhaust ports to help burn any raw fuel left in the exhaust gas and to convert CO to CO2. Since it doesn't pump against pressure, there is negligible drag on the belt that drives it. And, although it can sometimes cause funny popping sounds in the exhaust system, it actually has no effect whatsoever on the operation of the engine.

The catalytic converter also does its job outside the engine. Without going into the chemistry of it, the CAT is almost like a magic wand. Simply passing the exhaust gases over the platinum and palladium embedded honeycomb surfaces converts HC and CO into harmless carbon dioxide (CO2) and water vapor (H2O). New three-way catalysts also convert NOx into free nitrogen and oxygen, the two primary components of fresh air. The catalyst itself never gets used up. Sounds perfect, doesn't it? But there are two drawbacks. First, as we know, lead poisons the catalyst, thus requiring unleaded gasoline in the car. Since the EPA has just announced a near-total phase-out of all leaded fuel, arguing for leaded premium is now a moot point. We'll all have to live with unleaded gas and non-lead octane boosters. Second, a single catalytic converter—especially a pellet-bed type—can cause considerable exhaust backpressure on a healthy V8. The solution? Dual high-volume catalytic converters for performance cars. A couple of CAT manufacturers are currently working on "high-performance" models. Hopefully the aftermarket can also compete with more affordable units.

We hardly need to discuss the closed crankcase and PCV system. Most street rodders use PCV to keep breathers from leaking oil in the engine compartment, and racers know the benefit of pan evacuation.

EGR is a problem. Admitting exhaust gas into the fuel/air mix in the manifold lowers the engine's volumetric efficiency, and it lowers combustion temperature (to reduce NOx formation), thereby lowering the engine's thermal efficiency and power output. We question whether the reduction of NOx attained by EGR is worth the fuel wasted by the system; plus we question whether EGR is the best NOx control system (there are several other ways to reduce NOx emissions—including the three-way catalyst). We would suggest that performance cars be allowed to select other forms of NOx control; however, since EGR was installed on most '73-up cars, current I/M checks such as California's require it to be in place. Many aftermarket intake manifolds now have EGR passages, making them "acceptable" in I/M tests. What we need is a high-performance EGR valve, possibly of an adjustable type, which will "override" (close the EGR passage) at wide open throttle. Many factory EGR systems already work this way.

Finally, we have the thermal air cleaner and the evaporation control system. The TAC is simply a sealed air cleaner housing with a snorkel inlet and a heat-controlled flapper. At cold start, the flapper remains shut and the engine draws warm air from the "stove" around the exhaust manifold. As soon as the engine warms up, the flapper opens and the TAC draws fresh air. The only drawbacks to a TAC in a rodder's opinion are (1) that they are big and ugly, and (2) the single snorkel on most types doesn't afford enough breathing capacity for a performance engine. However, we have been trying to convince rodders to install fresh-air inlet systems for years, rather than open, underhood air cleaners. A TAC is perfect for this. All we need are large-capacity snorkels (such as the dual inlets on new Z28s and H.O. Mustangs), and ducting to a fresh air source, such as the front grille or fenderwells. With a low-restriction element inside, and the flapper doors open after warm-up, such a TAC would actually give better performance than your typical aftermarket underhood open air cleaner.

The TAC also works in conjunction with a charcoal canister to contain hydrocarbons emitted to the air from the gas tank and the carburetor bowl. According to U.C.R. 's Dr. Winer, today's cars are so clean at the tailpipe that, on a 24-hour basis, they can emit as much pollution by evaporation as from running the engine. It's a simple problem to remedy, with no adverse effects on engine performance whatsoever (especially when the car's sitting in the garage). Every hot rod should have an EVAP system.

Hot rodding has been operating on 1950's mentality and technology for far too long. We at HOT ROD Magazine have been just as guilty as the rest.

We won't go so far as to call the I/M Program an outright crisis for hot rodding, but it is certainly a jolt that should help us wake up to the times. The basic smog-control equipment we describe above is exactly that—basic. In fact, it's pretty crude. We seriously hope that our aftermarket industry will also be awakened by this challenge, and will respond with our own brands of high-performance, high-tech smog control systems. In a sidebar ["Hot Rodding: Some Inevitable Changes," below] we have asked Jim McFarland, a former editor of this magazine and (as chief of development and design at Edelbrook Corporation) one of the few members of the performance aftermarket industry to acknowledge the need for smog-control compatible products years ago, to discuss future high-performance potential using computer-controlled systems and modern electronics, especially Electronic Fuel Injection and turbochargers.

This has been a lengthy discussion, but there is still much left to say. In our opinion, this article merely breaks the ice on many topics we have ignored for too long. We will follow up with numerous articles and projects showing how to build "clean" performance engines, exploring possibilities for more effective and efficient smog-control equipment, and beginning what we are sure will be a lengthy educational process for hot rodders into the field of electronics.

Legislators, environmentalists, or petty government agents who think they might be able to kill hot rodding are in for a surprise. We think we might just teach them a few things instead.

We heard of an interesting I/M test and decided to watch. John Dahl of Riverside, California, was taking his '70 Chevy Nova to Jim Meyer's (former MoPar Pro Stock racer) R.V. Specialties tune-up/repair/smog check shop for certification. The clean orange "weekend cruiser" has a 65 396 with J.E. 8.4:1 pistons, Total Seal gapless rings, a Schneider 290 degree/.480 lift/112 degree lobe center hydraulic cam, a Hampton 6-71 blower, and two 750 Holley #4779 carbs. The car came with an EVAP canister, and this is hooked up, along with closed crankcase and PCV on the motor.

In cases of engine swaps, the BAR has ruled that motors installed before March 1984 must retain all smog equipment that came on the motor; those swapped after March '84 must be fitted with all controls that came on the car. You need a receipt, or other proof of the date of the swap, which John had (dated March '78). Therefore John didn't need a thermal air cleaner, since the 425-horse 396 (which this was), didn't originally have one. Necessary smog controls were in place, and the car should pass I/M if the tailpipe emissions were below those for a '70 Nova. Meyer had checked this with the BAR office ahead of time. Then, on the day of the test, the local BAR office called back saying "You can't pass that car" because the intake manifold had been changed to a non-stock type. Dahl disagreed; but either way, the car had to be failed on the "visual" test and sent to a referee station because of the engine swap.

Now here's the kicker. The car still had to complete the tailpipe portion of the test and have the data recorded (this is true in all cases). The idle standards for a '70 V8 are 500 ppm HC and 6.50% CO, with no "cruise" limits. John's Nova registered 44 ppm HC and 0.10% CO at idle, and 25 ppm HC and 0.06% CO at 2500 rpm "cruise." This is well under the limits for a 1984 V8 with full smog controls and catalytic converter!

At the referee station, on the next day, engine numbers were checked to verify it as a '65. It was, and the referee passed the car, since new-car tailpipe emission levels were never set for pre-'66 California (or pre-'68 49-state) vehicles. Consequently such cars (or engines) only need to have original smog controls in place to pass I/M. If John's engine had been a '66 or later (since the car was originally sold in California), neither the blower nor the dual carbs would have been allowed since they could possibly increase tailpipe emissions, and they don't have ARB exemption numbers. In other words, John's car passed on a very fine-line technicality. But get this: at the referee's it registered even lower actual tailpipe emissions. This was not a special car "doctored" to pass the test. He simply drove it in the way he drives it on the street. We have seen similar tailpipe results from most modified cars which have been tested.

Most hot rodders regard laws the way stock car drivers regard NASCAR rules—the challenge is to use your ingenuity to see how much you can do without breaking the letter of the law. Assuming that a "worst case" I/M Program (i.e., one like California's) is invoked in your state, what kind of hot rods can you still legally build and drive?

Loosely defined, smog is dirty air. The term comes from industrial revolution-era London, where factory smokestacks produced "soot fog." Currently the EPA measures for seven principle air pollutants: ozone (O3), carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen (NOx), sulpher dioxide (SO2), particulates, and lead. As we describe elsewhere, air pollutants come from many sources and different geographical areas have different types of smog. For instance London, like other coal-burning areas, has a much greater SO2 problem (which causes acid rain) than a NOx problem.

Gasoline-powered vehicles emit HC, CO, and NOx. Diesels emit much less HC and CO, but produce much more NOx and particulates. Particulates, as the name implies, are any tiny solid particles suspended in the air (soot, dust, pollen, etc. ); they can discolor the sky, and certain sizes can lodge in your lungs.

These emissions are called primary pollutants. Hydrocarbons are any of several compounds containing hydrogen and carbon, including most products made from petroleum: gasoline, benzene, octane, toluene, etc. Carbon monoxide is a colorless, odorless, poisonous gas (this is what kills you if you run your tailpipe into the car and roll up the windows). Oxides of nitrogen (NOx) emitted from cars are about 90% nitric oxide (NO), a colorless, oderless, non-toxic gas, and 10% nitrogen dioxide (NO2), which is brown, pungent, and toxic.

However, these emissions, when acted on by sunlight or in combination with each other or other elements in the air, produce secondary pollutants which are the really nasty elements of smog. The worst is ozone (O3), which is simply a molecule of three oxygen atoms. Oxygen would prefer to link up in pairs (O2), as it does in the air we breathe. Ozone is a highly-reactive "oxidizer"—it likes to attach its extra oxygen atom to other substances (remember that burning is an oxidation process). Ozone eats rubber and chrome, it kills crops, and it causes respiratory and other problems in people (it makes your lungs hurt on smoggy days). Ozone is produced when a mix of hydrocarbons and NOx are acted on by the energy of sunlight.

Secondary pollution can get complex. For instance NO2 (a byproduct of any combustion) combines with hydroxyl (OH) to form nitric acid (HNO3) which can be deposited from the air. Nitric oxide (NO, which is 90% of auto NOx emissions) will actually reduce ozone (O3 + NO = NO2 + O2), which some people think is good. However, the NO2 produced by this reaction breaks down into NO plus O when acted on by sunlight, and the highly-reactive O molecules combine with O2 in the air to make more ozone (O3).

If you're like most of us, you have pulled lots of smog-contol parts off of cars, but you have never had to consider putting the back. Suddenly you are faced with the task not only of finding smog pumps and EGR valves and catalytic converters, but of trying to remember just what came on your car. The real problem, of course, is different makes and models had different equipment—there are no universal rules. But to give you a general idea of the chronology of smog control, here is a very loose and unofficial rundown on equipment used on most Chevrolet models.

California's I/M Program is the scariest for hot rodders, but don't think for a minute that I/M is just a California problem. I/M is a nation-wide program that will very likely affect you. Briefly, here's how it comes down.

The Federal Clean Air Act was passed by Congress way back in 1963. It has been amended many times. In the mid-'60s it established emission levels for all new cars, at the manufacturer level, which were implemented nationally in 1968.

In 1970 the Environmental Protection Agency (EPA) was established, and they immediately set National Ambient Air Quality Standards (NAAQS) for all regions of the U.S. A 1977 amendment to the Clean Air Act required all states not meeting NAAQS—and this includes all or part of most states in the country—to submit a plan by 1979 (to be implemented by 1982) to improve air quality to "attainment levels." If the state demonstrated in '79 that it couldn't meet standards for ozone and carbon monoxide by '82, then the federal law requires the state to implement an I/M Program for on-road vehicles (as well as some other clean-up programs) in order to get a five-year extension (to 1987) for meeting air quality levels.

Each state is allowed to design its own plan, including details of the I/M Program. But once the plan is approved by the EPA, it cannot be revoked or changed, unless a new plan is submitted and approved by the EPA. In other words, the I/M Program is essentially federal law. To enforce it, the EPA is empowered to withhold federal highway funds from non-complying states.

As of this writing, 26 states had implemented I/M Programs (most of them just since 1981) and another five or six are expected to begin shortly. Connecticut, District of Columbia, Louisiana, Maryland, Missouri, New Hampshire, Oregon, Utah, Virginia, and Wisconsin, besides California, require passing the I/M test in order to renew vehicle registration. In other states, cars without I/M compliance stickers can be stopped and fined by police. In Idaho, a computer network will spit out all eligible vehicles which have failed to take the test, so owners can be summoned to court.

Individual programs vary as to the years of cars tested, and whether an under-hood check for "tampering" is included. The testing in California, Oregon, Idaho, Louisiana, Massachusetts, Missouri, North Carolina, Virginia, and Wisconsin appears the strictest so far. (In New Hampshire, only vehicles with side pipes are checked for catalytic converters!) In the Chicago area, the Environmental Control Department has been staging on-highway spot checks for removed or tampered smog equipment, and is trying to pass a statute in Cook County making individual car owners punishable for such offenses under the Clean Air Act.

All of this is happening very quickly, and most of it can change—for better or worse—at a moment's notice.

Here's another suggestion. We're looking for ways to keep hot rods legal within the parameters of I/M. We all know that supercharged killer cars and muscle machines with 5.38 gears aren't grocery-getters or 30,000-mile-a-year commuters. Regardless of what comes out the tailpipe, such vehicles cannot possibly be considered gross polluters on a gram-per-mile basis.

Therefore, why not allow hot rods, show cars, special interest autos, or other similar weekend "hobby cars" to apply for a limited use registration (possibly even with a special license plate)? A maximum annual mileage would be set for such cars, say 5000 miles a year, and they would be exempt from I/M testing.

Immediately the typical bureaucrat will ask, "What's to keep you from disconnecting the speedometer?" Silly question, oh cigar-smoking fat one; you've already passed a law making it illegal to disconnect or alter an odometer, and requiring "tamper proof" speedos on new cars. Second, it should be patently obvious that chrome-plated, supercharged, high-dollar cars aren't going to rack up even as much as 5000 miles a year. Third, this system is identical to one used for years by most major auto insurance companies to reduce rates for limited-use cars. You see, we'd all be better off if all hands were on the table. —Kevin Boales

The performance enthusiast is experiencing significant changes in the basic vehicle with which they have to work. Futuristic fuel control and spark ignition, in combination with smaller displacement engines and turbocharging, are changing the face of today's new cars. And since the performance enthusiast uses what Detroit provides as a starting point for modification, these systems bear examination as indicators of what we can expect in the performance aftermarket in the next few years.

First of all, we are seeing extensive use of electronics. Initially intended to accomplish the dual function of fuel economy boosts and exhaust emissions reductions, we now find that optimum engine efficiency is also obtainable with electronic controls.

Throttle body injections systems, first criticized as being subject to the so-called "walk home" mode are now being examined by leading manufacturers of aftermarket parts. The atomization efficiency potential of this method of fuel entry has proven superior to conventional carburetion. The finer the fuel droplets, the more efficient the delivery condition of the mixture. T.B.I. seems to be a step in the right direction.

Buick's introduction of a coil-less spark ignition system is a clear indication that a "tailored" individual spark program is an improvement over the long-standing Kettering method. You'll see much more of this shortly in the aftermarket.

We're also now seeing tubular, often stainless steel, exhaust manifolds on new cars. Pontiac, Buick, Mustang, and Corvette applications prove that these types of "headers" will not only meet exhaust emissions but also improve performance.

Also in the parts aftermarket we are seeing increased research pertaining to mass air flow sensing (of the hot wire variety), induction systems that embody multi-tuned volumetric points (relative to engine rpm), and the beginning of carbon fiber parts development that not only reduces components weight but offers some benefits in engine power and efficiency. And to really tweak your head a little, there is an advanced project by a major original equipment manufacturer that involves a typical V8 engine that has no camshaft, valve lifters, or pushrods. The valves are operated by a network of computer-controlled solenoids that can respond to either a pre-programmed set of operational limits or to variable valve timing as requested by the vehicle operator as the car goes down the road.

While you are recovering from all this futuristic stuff, we'll mention that the constantly variable transmission (C.V.T.) that allows an engine to run at a constant rpm (typically at or near peak efficiency) will be available in Europe next year and on selected U.S. models by 1986… according to all the crystal balls in our view.

Simply to stay in business, progressive manufacturers of aftermarket parts must develop derivatives of this technology, and make it available for application to older cars and performance vehicles. Movement to this end is underway. —Jim McFarland

Last March I/M cracked down suddenly in all major urban areas of California. After a couple of false starts and lots of threats and rumors over the last decade, we didn't believe it was really going to happen… but it is.

Here's how it works. Every other year, when your registration comes due, you must take your car to any of hundreds of independently operated "smog check" stations to take the I/M test and get a "compliance" certificate. Most any tune-up or repair shop can become a "smog station" by taking a one-day course and buying any of several approved computer test machines. The cost of the test is unregulated; it averages $18-$20 here. Cost of the certificate is another $6. All gasoline or dual-fuel powered vehicles, 20 years old or less, and under 8500 pounds, must be tested. Also on change of title (sale of car), or initial registration (if you bring a car into the state), all 1955 and newer domestic cars and all '65-up imports must pass the I/M test.

When you bring your car in, the operator first lifts the hood to check that all original smog equipment (or any required to be retrofitted over the years) is in place, untampered, and working properly. To make this determination the operator must rely on their own memory and experience, or they can refer to any of several handbooks or engine guides—neither process guaranteeing 100% accuracy. The problem is that all the different makes, models, and engine options over the past 20 years have been fitted with a wide variety of smog equipment. There is no "official" list or catalog of required equipment for each make and model. One certified test operator told us, "It's still an honor-type system. I can make a car fail, or I can make it pass."

The operator begins the test by entering the owner's name and address and the vehicle's make, model, year, and I.D. numbers into the computer. Once a test has begun, it cannot be stopped (you either pass or fail), and the results are retained on the computer memory. If you pass all the categories on the visual inspection, then the operator inserts a sensor probe in the tailpipe(s) and runs a "sniff" test for HC and CO, either at 2500 rpm cruise speed (for 30 seconds) followed immediately by an idle test, or just at idle (on earlier cars). Given the year, model, and engine of your car, the computer decides whether you meet the prescribed levels. (In L.A. and Ventura you must also pass a NOx inspection, either by a mechanical test of the EGR valve, or a tailpipe reading at a dyno-equipped shop.) If you fail the tailpipe test, the operator (or anyone) must try to tune the car to meet the levels, but he can only charge a maximum of $50 for the tune-up and repairs. A typical "low emissions tune-up" (which often consists only of resetting the idle mixture screws) costs about $30. If this brings the car in line, they can run an immediate retest on the computer (some shops re-charge for this, but most do it free if they did the tune-up) and issue a pass certificate. If $50 worth of tuning or repairs won't clean up the car, the operator has to try to lower emissions at least 10%, and then issue an exemption for the car.

Now here's the kicker. If your car flunks the visual inspection because the operator determines any smog equipment is missing, disconnected, or modified (that means if one of the vacuum hoses has fallen off your air cleaner, or if the operator judges your intake manifold or carb to be a non-replacement type), then you forfeit the $50 maximum repair limit. Regardless of the emissions at the tailpipe (which are recorded in every case), you must spend whatever it takes to put your engine back to stock to pass the test and get your registration renewed.

You can take the test as many times as you want (at $20 a shot), and hope that one shop will pass your car.

However, if you feel you have failed unjustly, or in any instance requiring a special judgement (such as engine swaps or home-built vehicles), you go to a BAR "referee station" for a ruling. As you can see, subjective decisions play a big part in the tests.

Money has a way of making people do funny things. California, a state which has steadfastly refused annual auto inspections, suddenly capitulated when the EPA froze "$600 to $800 million" in federal highway expansion funds due certain regions of the state. In political terms, California bartered the I/M Program for this money.

But how much will the program cost the taxpayers? At the outset, the BAR estimated that 13 to 14 million cars would be tested in a two-year cycle, at an average total cost of $50 each. That's up to $700 million right there. Add on top of this sizable annual budgets for the EPA, the ARB, and the BAR to oversee the program (the BAR budget alone is $22 million a year earmarked just for (I/M). Then figure what it costs the taxpayers in terms of man-hours estimating 14 million times about two hours each to take the test—not to mention the cost of test equipment to I/M shops or possible lost revenue to aftermarket parts manufacturers and sellers. These are all costs born by the public.

But look at the other side. At a $6 certificate fee per test, the BAR actually nets a $40 million profit over two years. The state really doesn't have to pay anything for I/M, but they get $600-$800 million in return. Independent shop operators pay several thousand dollars for I/M computers and training, but stand to earn considerably more by testing and tuning cars. Everybody makes money on the deal at the expense of the taxpayer. And that might be O.K., if the program really helps clean up the air. —Kevin Boales

(EDITOR'S NOTE: This article was originally published in the October 1984 issue of HOT ROD Magazine. It was written by Pat Ganahl | Illustration by Barry Jackson)

Is the '68 Dodge Charger the "best car" like David Freiburger says? Maybe, but the General Mayhem is definitely one of the most iconic Roadkill cars. Watch as Roadkill Garage hosts Freiburger and Steve Dulcich give it tons of body upgrades and engine-saving modifications before hitting the road for proper break-in procedures—aka burnouts! Sign up for a tree trial to MotorTrend+ and start watching every episode of Roadkill Garage today! Video created by Little Dot Studios.