VIDEO
HIGHLIGHT
Log InSign up
When Subaru Put a “Jet Engine” In Their Exhaust | Rocket Anti-Lag Explained!
SummaryTranscriptChat

When Subaru Put a “Jet Engine” In Their Exhaust | Rocket Anti-Lag Explained!

Introduction

The video introduces the topic of anti-lag systems and specifically focuses on the rocket anti-lag system used in Subaru's WRC program.

What is an Anti-Lag System?

  • An anti-lag system keeps the turbocharger spinning fast enough to produce boost by causing combustion in the exhaust manifold when the driver is off throttle.
  • Turbochargers compress intake air by using exhaust gas to spin a turbine wheel. The more we compress the air going into the engine, the more boost we make and the more power we can make.
  • Turbo lag affects drivability and is especially problematic for rally cars where drivers need on-demand power to control their car on difficult surfaces.

Throttle Bypass System

  • A throttle bypass or throttle kick system cracks open the throttle just a little bit to still allow some airflow into the cylinders on the intake stroke. It adds a little bit more fuel than usual and slows down firing of spark plug so that it happens when piston is already moving down during combustion stroke.
  • Running too much air through engine during anti-lag can make for some drivability issues as it makes engine still making a fair amount of torque.

Air Injection System

  • An air injection system or fresh air system routes compressed air directly from our turbo to a valve connected to exhaust manifold. This valve can be precisely controlled by our ECU via solenoid which eliminates torque surge from other systems and gives us more control over combustion and how much we keep turbo spinning.
  • This type of system was common on WRC cars until they recently banned it in rally 1.

Rocket Anti-Lag System

The video discusses the rocket anti-lag system used in Subaru's WRC program.

How it Works

  • Rocket anti-lag system works by injecting fuel and air into the exhaust manifold through a secondary set of injectors. This creates a small explosion that keeps the turbo spinning.
  • The rocket anti-lag system was unique because it used a separate combustion chamber to create the explosion, which reduced stress on the turbocharger and exhaust manifold.
  • The rocket anti-lag system also had an adjustable valve that allowed for precise control over how much air and fuel were injected into the exhaust manifold.

Common Myths

  • Myth: Rocket anti-lag systems are dangerous and can cause fires. Reality: While there is always some risk involved with any high-performance technology, proper design and implementation can minimize these risks.
  • Myth: Rocket anti-lag systems are illegal. Reality: While some forms of anti-lag systems have been banned in certain motorsports, rocket anti-lag systems are not inherently illegal.

Conclusion

The video concludes by summarizing key points about anti-lag systems and the rocket anti-lag system specifically.

Key Takeaways

  • Anti-lag systems keep turbochargers spinning fast enough to produce boost by causing combustion in the exhaust manifold when drivers are off throttle.
  • Throttle bypass or throttle kick systems crack open the throttle just a little bit to still allow some airflow into cylinders on intake stroke while air injection or fresh air systems route compressed air directly from our turbo to valve connected to exhaust manifold.
  • Rocket anti-lag system uses separate combustion chamber to create explosion that keeps turbo spinning and has adjustable valve for precise control over air and fuel injection.
  • Rocket anti-lag systems are not inherently dangerous or illegal, but proper design and implementation are important to minimize risks.

How Anti-Lag Systems Work

This section explains how anti-lag systems work in cars and how the Rocket Anti-Lag System is different from other systems.

Anatomy of the Rocket

  • The rocket has two main sections: an intersection where exhaust flows through and an outer pocket area where intake air can flow throughout.
  • There are holes that let intake air enter the intersection from the outer pocket, diagonal tubes that inject air into the chamber in a swirling motion, and a central tube that takes air from the outer pocket and flows it down.

Combustion Process

  • Exhaust carrying unburnt fuel enters the rocket and mixes with intake air entering through holes. This starts combustion process.
  • As mixture flows down into center section, diagonal tubes come into play to inject air into chamber in a swirling motion creating toroidal vortices of gas and air within annular region.
  • Vortex rings move along rocket due to rotational movement reducing friction between ring and surrounding air allowing for high velocity stream of gases discharging through outlet rather than irregular explosions in exhaust manifold.

Benefits of Rocket Anti-Lag System

  • Steady consistent stream of gas coming out of rocket like thrust from jet engine which can be precisely controlled to spin up turbo however much desired.
  • Air flowing along edges insulates metal protecting it while also cooling rocket as it flows downstream resulting in less exiting exhaust gas temperatures preserving lifespan of turbo.
  • Air layers create barrier for flame preventing it from being extinguished allowing for sustained flame inside rocket keeping things going.

Common Myths Surrounding The Rocket

This section debunks common myths surrounding the Rocket Anti-Lag System.

  • The rocket is not a jet engine but works similarly to suction of a jet engine where combustion occurs in combustor.
  • Jet engine combustors have their own internal fuel injection and ignition systems whereas the rocket needs neither of those.

Subaru Rocket System: Debunking Myths

In this video, the presenter debunks myths surrounding the Subaru rocket system. The presenter clarifies that the system does not have a boost storage tank and explains how the boost control system works.

Boost Control System

  • The tank mistaken for a boost storage tank is actually part of the boost control system.
  • Two airlines connect to the wastegate of the turbo and intercooler piping.
  • Three solenoid valves and a sensor wire are used to control wastegate pressure.
  • The ECU controls wastegate with this system, allowing precise control over how much rocket gas enters it.

Efficiency and Precision

  • Precise control makes the rocket system efficient when properly tuned and calibrated.
  • Engineers had to be smart to get everything dialed in perfectly.
  • Air injection systems are simpler from a control standpoint and don't require precision fabricated inconel rocket tubes.

Bonus Myth: Air Pump on Reservoir

  • A mechanic using an air pump on a reservoir in an engine bay is likely trying to raise pressure in the car's cooling system, not related to anti-lag or rocket systems.

Overall, this video provides insight into how the Subaru rocket system works while debunking common myths associated with it.

Video description

Anti-lag systems help a turbocharger to continue producing boost when a driver is out of the throttle, but did you know that the Subaru rally team had one that could fully spool a turbo at idle? The Subaru Impreza WRX STi S11 and S12 WRC generations featured a unique system dubbed Rocket Anti-Lag. Using patented technology from Prodrive and similar principles to a jet engine combustor, the cars were fitted with a separate combustion chamber in the exhaust. The system that drivers like Petter Solberg and Mads Ostberg got to enjoy has puzzled people for some time, so I decided to read through the patent documentation and try to understand how it works. So let’s learn how anti-lag works, then go over all of the awesome engineering behind the rocket system! This is Subaru’s Rocket Anti-Lag explained! Timestamps: 00:00 Intro 00:45 How a Turbo Works 01:06 What is Turbo Lag? 01:45 What is Anti-Lag? 02:19 "Throttle Bypass" Anti-Lag 03:40 "Air Injection" Anti-Lag 04:21 How "Rocket Anti-Lag Works! 09:04 Busting Myths About Rocket Anti-Lag Credits and References: https://pastebin.com/hTPUQYRU Music List: https://pastebin.com/EwaRHmhA ------------------------------------------------------------------ Copyright Disclaimer: Under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. This video intends to follow and obey the guidelines set forth pertaining to fair use by using the original content in a transformative way to tell a new story. If you are the original copyright owner of material used in this video and disapprove of its use, please email the business email listed in the channel description and I will be more than glad to resolve any issue.