Ultimate Guide to S13 Silvia Test Pipes: Flow Better, Make More Power

Understanding the S13 Test Pipe

The test pipe is an important emissions component found on the Nissan Silvia S13 (1989-1994). Replacing the restrictive stock catalytic converter with a less restrictive test pipe is a popular modification for increasing horsepower and performance.

What is a Test Pipe?

A test pipe is essentially a straight pipe that replaces the stock catalytic converter and offers less resistance to exhaust flow. By removing the catalytic converter, the test pipe reduces back pressure which allows the engine to breath better and make more power.

Test pipes are popular in racing applications or off-road use where emissions compliance is not required. However they are not street legal since they remove the catalytic converter which helps reduce harmful exhaust emissions.

Benefits of an S13 Test Pipe

There are several key benefits of installing a test pipe on an S13 Silvia:

• Increases horsepower and torque - By reducing exhaust restriction, the engine can operate more efficiently.
• Enhances turbo response - Less back pressure allows the turbo to spool up faster.
• Better throttle response - With less resistance to exhaust flow, the engine reacts more quickly to throttle inputs.
• Improved engine sound - Gives the exhaust note a deeper, more aggressive tone.

With the CA18DET engine found in many S13 Silvias, owners can see horsepower gains of 15-25 WHP from installing a quality test pipe and tuning the ECU accordingly.

Installing an S13 Test Pipe

Putting a test pipe on an S13 is a relatively straightforward bolt-on modification, but there are some important steps to follow:

Choose a High Quality Test Pipe

Not all test pipes are created equal. Look for a TIG welded, mandrel bent test pipe made from stainless steel or aluminized steel tubing. This ensures strength, proper exhaust flow, and increased durability compared to a cheap welded pipe.

Trusted brands like ISIS, HKS, and RS*R make high end test pipes designed specifically for the S13 CA18DET or SR20DET engines.

Ensure Proper Fitment

Verify that you order the correct test pipe for your S13's motor (CA18DET or SR20DET), chassis, and drive orientation (RHD/JDM or LHD/USDM). Getting the proper fitment ensures the test pipe bolts up correctly without issues.

Include New Gaskets

Don't reuse old exhaust gaskets, install new ones on the slip joints to prevent exhaust leaks. High quality gaskets made from multi-layer stainless steel are best for turbocharged engines generating extreme heat cycles.

Get a Professional Tune

After installing the test pipe, get the ECU professionally tuned on a dyno. This allows adjusting fueling and timing maps to match the engine's new airflow and ensure optimum performance.

A proper tune is crucial to avoid potential issues with lean air fuel ratios that can cause detonation or damage after removing the catalytic converter.

CA18 vs SR20 Test Pipes

There are some notable differences between test pipes designed for the CA18DET versus SR20DET S13 engines:

CA18DET Test Pipe

• 2 inch piping diameter
• Less expensive option
• Compatible with stock CA18 turbo or upgraded TD06 turbos
• May require custom tuning depending on turbo choice

SR20DET Test Pipe

• 2.5 to 3 inch piping diameter
• More expensive, higher-flow option
• Works best with upgraded SR20 turbo upgrades
• Needs a custom ECU tune to match bigger turbo

As shown above, test pipe requirements differ quite a bit between the CA and SR motors. Make sure to get the proper test pipe optimized for your S13's engine setup.

Complimentary Modifications

While a quality test pipe provides meaningful power gains on its own, there are supporting mods that further boost performance:

Larger Intercooler

An upgraded front mount intercooler reduces intake air temperatures for denser air flow and more power when paired with a free-flowing test pipe.

Intake & Exhaust

Higher flowing intake and turbo-back exhaust systems force even more air through the engine to capitalize on the reduced back pressure from the test pipe.

Engine Management

As mentioned before, a proper ECU tune customized for the test pipe, fueling upgrades, and other supporting mods is crucial to optimized performance.

Turbocharger Upgrade

An upgraded turbo capable of higher boost levels can fully utilize the increased exhaust flow capability from an S13 test pipe at higher rpms.

On stock frame turbos, the limits of the compressor wheel and turbine housing are quickly reached even with a higher-flowing test pipe.

Conclusion

Installing a quality test pipe provides excellent performance benefits on a modified S13 Silvia. Just remember these key points when installing a test pipe:

• Properly match the test pipe to your exact S13 motor and chassis
• Only install with proper supporting mods like tuning, injectors, etc
• Work with a performance shop experienced with test pipes for best results

With some upfront research and expert assistance, adding a test pipe to your S13 can take your build to the next level without compromise.

FAQs

Are test pipes legal to run on the street?

No, test pipes are not street legal since they remove the catalytic converter which helps filter harmful emissions. Test pipes should only be used for racing/off-road applications where emissions compliance is not enforced.

What type of power gain can I expect from an S13 test pipe?

You can expect 15-25 WHP gains on a stock S13 CA18DET with supporting modifications like intake, exhaust, intercooler, etc. Larger power gains are possible with upgraded turbochargers.

Do I need an ECU tune when installing a test pipe?

Yes, always get a professional ECU tune when installing a test pipe. This allows properly adjusting fueling, timing maps, and other parameters to match the engine's new airflow characteristics.

Should I upgrade my turbo when installing a test pipe?

Upgrading the turbo is recommended to take full advantage of the increased exhaust flow from a higher flowing S13 test pipe. The limit of the stock turbo compressor wheel and housing will be reached faster.