Project Nissan 200SX 1.6: Part 2

Project 200SX 1.6 is sort of a John Hughes-ish coming-of-age story of a homely girl (er, car) that is overlooked by the crowd, remakes herself and ends up joining the popular crowd. Or so we hope.

In the December issue, we gave Project 200SX 1.6 dancing lessons of sorts for the track. Now that she can get down and boogie, we are going to focus on making her fast--a little bit at least.

In this installment, we're going for bolt-on modifications just to see how effective they are in this platform. These bolt-ons are relatively inexpensive and are simple to install compared to internal upgrade parts. This keeps with our premise of making Project 200SX 1.6 novice wrench friendly, at least for now.

At this level, well-designed bolt-ons usually have no negative effect on drivability or mileage, and in fact, often help both. This is unlike other upgrades like camshaft swaps that can produce negative side effects with the increased power gains--such as rough idle and decreased fuel mileage. The mods that we will cover in this issue are ones that help the engine breathe by eliminating restriction in the intake and exhaust systems. This reduces pumping losses (a parasitic loss of power) and also helps scavenging (the engine's ability to rid itself of burnt exhaust in the cylinders more easily). These mods simply help the engine's all-around efficiency, giving something for nothing.

These mods will not cause the engine to pollute excessively as all smog equipment is retained. Since none of these parts have CARB approval as of yet, their legality on a street-driven car may be subject to the interpretation of local laws. In spite of this, the parts we will be working with in this installment should pass a local smog dyno test with flying colors. Because our 1995 200SX SE is also equipped with an OBDII-type emissions system, we will be taking pains to keep the system intact to avoid the notorious check engine light and the test-failing DTC codes.

The GA16DE that comes as standard equipment on '91 to '99 Sentras and 200SXs was not designed for performance like its big brother, the well-known SR20DE. The GA's role in life was to be clean-burning, smooth, quiet and to provide excellent fuel economy. At these chores, it excels, providing excellent mileage and worry-free reliability. With its VTC variable intake cam timing system, it is also relatively peppy. The quick nature of the engine was apparent when we took it to the local drag strip, as the spunky little car seemed to hold its own against other competitors in its class. The only other stock subcompacts that could spank Project 200SX 1.6 were its bigger SE-R brother and the powerful Civic Si.

To start with, we brought Project 200SX 1.6 to R&D Dyno Service in Gardena, Calif. to get a baseline power run after a tune-up. To our dismay, the little engine was only able to lay down 91 hp and 89 lb-ft of torque to the wheels. What a start. This inauspicious beginning gives Project 200SX 1.6 the dubious distinction of being the weakest project car to grace the pages of this magazine. We figured that there had to be more power in that block of iron just waiting to be unleashed, so we went at it, jumping in with both feet.

Because the GA16-powered Sentra/200SX has been virtually ignored by the performance aftermarket, (much like the SE-R was before we gave the aftermarket a prod with our project cars) we were going to have to convince some folks that the GA was indeed worthy. After hitting up some companies by showing the much larger production numbers for the GA, (SE-Rs averaged a tiny six percent of Sentra/200SX production) we were able to convince a few to step up to the plate.

One of the first up to bat was Hotshot. Hotshot is famous for making high-quality headers and air intakes for niche-market vehicles. Need a header for your Saturn, ZX2 or Neon? Hotshot has it. Hotshot shared our enthusiasm for the GA16 project and agreed to help. By the time you read this, Hotshot should have all of these parts into production.

Cat-Back Exhaust
One of the first bits of high-performance hardware purchased by the budding hotrodder is a cat-back exhaust. An exhaust system gives good sounds and cool looks. It is also easy to install. However, despite claims to the contrary, we often find that cat-back exhausts, especially on performance models, do not usually give big horsepower increases. After all, building a free-flowing exhaust system does not cost the manufacturer any more than a restrictive one and most OEM engineers understand that free flow is free power. In our testing, an aftermarket exhaust usually extracts only a horsepower or two, not much for the noise penalties that exhaust systems often incur.

When testing Project 200SX 1.6 on the dyno, we noted the car's exhaust sounded very stifled, like the engine was running underwater. Since the car was marketed as an affordable luxury car when it was introduced, we figured that in order to produce an ultra-quiet car, Nissan went to town with the baffling of the exhaust to kill every extra decibel on the stock system.

Our prototype Hotshot cat-back was constructed of 2-inch, mandrel-bent aluminized tubing. Mandrel bends are superior to crush bends, as they do not narrow when they are required to bend around parts of the chassis. The 2-inch tubing replaced the tiny, crush-bent 1.5-inch to 1.75-inch tubing that made up the car's exhaust system. The exhaust features a polished, stainless-steel, 4-inch tip with a straight-through, perforated core main muffler and pre-silencer. Perforated cores have a lot less backpressure than the traditional louvered cores found in old-school, glass-pack mufflers. The straight-through construction also gives lower backpressure than reverse-flow or turbo-type mufflers, popular in the '80s and early '90s.

After bolting on the exhaust, we were pleased with the mellow exhaust note, not loud but still pleasantly audible. A trip to R&D's dyno proved this exhaust made an exceptional increase in power. The exhaust bumped us to 97 hp and 92 lb-ft of torque, a big increase of 6 hp and 3 lb-ft of torque, which was a lot for a cat-back exhaust system! The power gain was proportional, starting at 1 hp at 2000 rpm and maxing out at a 7-hp gain at 6600 rpm. This is one of the biggest gains for an exhaust system that we have yet to see on a naturally aspirated street car.

Cold Air Intake
We have gotten very good results with cold air intake systems (or CAI) on several of our other project cars. CAIs help power by letting the engine breathe cold air, unheated by radiation from the engine and hot air from the radiator, from outside of the engine compartment. Every 10 degrees of drop in the intake air temp can result in approximately 1 percent more power, due to the increased air density. CAIs can also relieve intake restriction on OEM intake systems that are crippled by small openings and convoluted bends. Many times, the air filter of the OEM system is undersized and restrictive. CAIs usually utilize free-flowing air filters. Finally, the long tubes used in CAIs can have a resonance tuning effect to use the tuned length to help ram air into the engine much like the fundamental note of a musical instrument.

Our Hotshot CAI is unusual because it uses a stepped diameter. From the free-flowing K&N cone air filter to the mass airflow meter, the tubing is a large 3-inches in diameter, the same as the larger SE-R. From the airflow meter to the throttle body, the tubing is a smaller 2.5-inches in diameter. Although this would seem to preclude the effects of any resonance tuning, Hotshot assured us that this configuration was better in its testing.

Installing the CAI was easy, although we had to enlarge an existing hole in the fender apron for the intake pipe to fit through. This was accomplished in a few minutes with an air-powered die grinder but a dremel or even a drill and tin snips could easily do the same thing in a bit more time.

The Hotshot CAI gave the car a nice intake roar that was not at all unpleasant. At cruising speed it was still silent. At RD, the CAI was good for a respectable 3 hp gain, bringing our total up to 99 hp and 94 lb-ft of torque. The CAI made good gains in the much-used mid-range with gains of almost 5 hp occurring around 4500 rpm. There were no power losses anywhere in the powerband. We were pretty impressed for the power gain that this easy-to-install piece created.

Underdrive Pulley
Since we saw big results for very little investment with an Unorthodox Racing underdrive pulley in Project SE-R, the installation of it in Project 200SX 1.6 was going to be mandatory. The anodized aluminum pulley is well made with cool details, like a steel sleeve in the front main seal area to maintain a leak-proof seal with the front main seal.

The underdrive pulley works by reducing the speed at which an engine's accessories spin by reducing their drive ratio in relationship to the crank. This reduces friction and frees power. Since the amount of underdrive is mild--on the order of 10 percent--there is no trend to discharge the battery, overheat or lose power steering effectiveness. On Project SE-R, the underdrive pulley freed up 6 hp at the wheels!

There is some controversy about the pulleys, as they are not equipped with the harmonic balancer that the stock pulley has. We feel the risk of removing the balancer on certain engines is not really a risk. Inline, four-cylinder engines for the most part have short, stiff crankshafts. These do not need a balancer as much, because of their high natural frequency. Engines with long, whip-like cranks, like inline six-cylinders, need balancers to prevent failure, but most four cylinders do fine without them.

Nissan four cylinders, with the exception of the vibration-prone KA24, can do fine without a balancer. We have had underdrive pulleys on many SR20 engines, some with more than 1,000 track miles, with no problem whatsoever. Nissan four cylinders are also internally balanced, which reduces the need for a harmonic balancer. Many cheaper engines, on the other hand, need to have a built-in imbalance on the pulley to make up for a lack of an internal counterweight. Like the SR20 engine, the GA16 engine actually felt smoother and revved more freely with the underdrive pulley installed.

At R&D, we were somewhat disappointed with the dyno results from the pulley. At peak, we gained 1 hp for a total of 100 hp and 95 lb-ft of torque. Between 5000-5500 rpm, the power gain was a respectable 4 hp, keeping the positive power trend to the very peak. Although this is not as good as what we got on the SR20, it was still a very acceptable gain for an inexpensive part that has no detrimental effect.

Why was the SR20 more responsive to the pulley? We theorize that the SR20 has a poorly designed water pump that runs into cavitation above 6500 rpm. An underdrive pulley keeps the water pump on the SR out of cavitation and thus frees up more power on these engines than our GA16.

Headers
The GA16 is cursed with one of the worst exhaust manifolds we have ever seen. Cylinders 1 and 2 and cylinders 3 and 4 are paired together. Each set of adjacent exhaust ports dump into a crude funnel which flows into an oversized stubby pipe and then feeds into a close-coupled catalytic converter. This is about the worst arrangement possible for the production of power, although it probably does cut down cold start emissions.

We replaced this power-sucking monstrosity with Hotshot's tri-Y header. The header pairs cylinders 1 and 3 with 2 and 4 to create an interference branch in addition to the normal, tuned length of the unpaired primaries. This is what helps tri-Y designs usually have a broader powerband. Tri-Y's are also less sensitive to changes to the engine's tuning than a race-style 4-into-1 header design. These attributes usually make the tri-Y better suited for street use and for when the header designer does not have control over the final specifications of the engine, the most common situation in street engines.

The Hotshot header features ceramic-coated, thick-walled, steel construction and is obviously a quality piece. The header comes with a blow-out-proof, soft copper gasket between the primaries and secondarys, but no head flange gasket. It seems no dealer or parts store stocks gaskets for the GA16, so don't remove the stock exhaust manifold late at night like we did, only to find no head flange gasket in the box. The Hotshot header fit beautifully, with a minimum of effort on our part with the EGR tube bolting right on and the O2 sensor fitting perfectly. Since we lost our close-coupled cat when we installed the header, we had to add a new catalytic converter under the car.. Though it may be tempting to remove the cat altogether, don't do it. We have found time after time that cats do not hurt horsepower in mildly tuned engines. The world is rapidly becoming a small place and all of us must do our part to reduce pollution. Removing the cat can turn a clean car into a gross emitter that spews the pollution of literally hundreds of normal cars.

We installed a Random Technology catalytic converter from an SE-R onto our headers collector and spliced it into our exhaust system. A stock SE-R cat would do just as well in this case. We also welded a boss for the rear OBDII sensor just behind the cat. The purpose of this sensor is to check if the cat is working or not, and it must be installed behind the cat if a check engine light is to be prevented. If you are duplicating our work on your car, any local muffler shop should be able to assist you.

The header really changed the exhaust note, turning our pleasant mellow tone into a headache-inducing, raspy roar. This was unacceptable, so we changed our pre-silencer to a longer one, which reduced the noise. This change will be incorporated into Hotshot's system by the time it goes into production.

At the dyno, the header produced an impressive gain of 6 hp with a maximum gain of nearly 9 hp in the 5500-rpm range for a total of 106 hp and 100 lb-ft of torque. The header is the biggest, peak-power contributor to our package.

Timing Adjustment
While on the dyno, we did a little impromptu dyno tuning by advancing the timing. We found the biggest gains by turning the timing up 5 to 6 degrees. Doing so had no ill effects with no detonation on 92-octane pump gas. The results of this freebie adjustment were pretty impressive. Although we gained only 1 hp for a total of 107 hp, we gained a bunch of torque, now peaking at 104 lb-ft. The adjustment made the biggest gains in the mid-range where the engine picked up around 5 hp at 5000 rpm.

JWT ECU
If you read our Nissan performance articles at all, then the name JWT does not require any further introduction. Jim Wolf Technology is probably the premier Nissan tuner in this country. JWT's Clark Steppler is a genius at bending electrons to the will of performance nuts. Clark thinks in hexadecimal code and can work wonders with the stock Nissan ECU. Can JWT's ECU beat our freebie, advance-the-distributor trick?

The JWT ECU does more than advance the timing on the GA16, it alters the air/fuel ratio, leaning it here and enriching it there. It also raises the pesky factory rev limiter to 7300 rpm and eliminates the irritating, 109-mph speed limiter. Many a Nissan has been humiliated by a Civic when the speed limiter was hit, ending the festivities. Since the additional timing is built into the ECU's program, we had to turn our timing back to stock when installing the JWT part.

On the dyno, the JWT ECU increased the peak power by 2 hp, bringing us to 108 hp and a whopping 107 lb-ft of torque. Although the peak power gains are not huge, what the ECU does in the mid-range is very impressive. At 5000 to 5500 rpm, the JWT ECU increases the power output by an amazing 10 hp. This is fat, usable power right in the middle of a hard gear pull.

As far as increasing the amount of power under the power curve, the JWT ECU is the king of all the mods we have done so far. But remember: It is the area under the curve that propels you down the track, not peak numbers. This is the biggest difference of any ECU that we have seen for any naturally aspirated car.

The ECU also improves drivabilty and throttle response considerably, making the car feel eager to leap ahead with only a light touch of the pedal.

So far we have gotten 17 more hp and 20 more lb-ft of torque without going into the engine, an impressive gain of 16 percent. Mid-range power gains are even better; at 5000-5500 rpm, the power gains are in the order of 22 hp. The car feels a lot better, more responsive and much more willing to please. It even gets better mileage to boot.

Will we have more in store for Project 200 SX 1.6? You bet; stay tuned to this channel.

The prototype Hotshot exhaust system features 2-inch mandrel-bent piping and free-flowing, perforated-core mufflers. On the GA16, the exhaust gives a sizeable power gain.

The Hotshot Cold Air Intake has an unusual staggered pipe diameter. From the filter to the MAF, the pipe is 3 inches. From the MAF to the throttle body, the pipe is reduced to 2.5 inches.

The Unorthodox Racing Underdrive pulley reduces frictional power losses caused by the accessories by simply slowing the accessories down.

Here is the route exhaust gasses take as they exit the head. Note that the output of two cylinders funnel through here!

The stock exhaust manifold was obviously designed only to provide low cold-start emissions. The short pipes sharing two exhaust ports each are to light off the cat quickly. Power generation seemed to be the last to be considered in its design!

The Hotshot header reserves a separate primary tube for each exhaust port, no neck down here. The tubes are also tuned for better power production. The catalytic converter is located just after the header flange.

The Hotshot header is a far cry from the poorly designed (as far as power production goes) stock exhaust manifold. The header is a tri-y type which is 4 into 2 into 1.