Peterbilt 330/335/337 Engine & Performance Parts

Frequently Asked Questions About Peterbilt 330/335/337 Engine & Performance Parts

What engine options are compatible with Peterbilt 330, 335, and 337 models?

Peterbilt 330, 335, and 337 models typically come with Paccar PX-7 or Cummins ISB engines. The 330 and 335 models (2005-2021) commonly use the Paccar PX-7 (6.7L) or Cummins ISB 6.7L. The 337 models can accommodate larger engines including the Paccar PX-9 (8.9L) or Cummins ISL 8.9L. When selecting performance parts, verify your specific engine model and year as mounting points and specifications can vary between engine families and model years.

Will aftermarket air intake systems void my warranty or affect emissions compliance?

Most aftermarket cold air intakes and performance air filters are designed to maintain factory emissions standards and typically won't void your warranty when properly installed. However, any modifications that alter emissions components or engine calibration may impact warranty coverage. We recommend checking with your dealer before installing performance chips, tuners, or exhaust modifications. For commercial vehicles operating in California or other CARB states, ensure any parts you purchase have appropriate EO numbers for legal compliance.

What are the most common installation challenges when upgrading exhaust systems on these models?

The most frequent installation challenges include clearance issues with the frame rails and aftertreatment components on 2011+ models with DPF/SCR systems. Many customers report needing to modify exhaust hangers or relocate heat shields. For 330/335 models with shorter wheelbases, ensure your chosen exhaust system accounts for the tighter packaging. Professional installation typically takes 2-4 hours, and you'll need basic hand tools plus a reciprocating saw for removing the old system.

Which performance upgrades provide the best fuel economy improvements?

Based on customer feedback, the most effective fuel economy improvements come from combining a high-flow air filter system with a quality engine tuner. Customers typically report 0.5-1.5 MPG improvements with these modifications. Free-flowing exhaust systems can add another 0.3-0.5 MPG when paired with proper tuning. However, results vary significantly based on driving conditions, load weight, and maintenance habits. Avoid aggressive tuning if fuel economy is your primary goal, as maximum power settings often decrease efficiency.

Are there specific coolant system upgrades recommended for these medium-duty trucks?

Heavy-duty aluminum radiators are highly recommended for 330/335/337 models used in demanding applications like refuse, construction, or heavy towing. The factory plastic-tank radiators are prone to cracking after 150,000-200,000 miles. When upgrading, ensure the radiator matches your engine option and includes proper mounting brackets. Many customers also upgrade to silicone coolant hoses and a lower-temperature thermostat (180?F vs stock 195?F) for improved cooling capacity in hot climates or stop-and-go applications.