Walnut Shell Blasting

Walnut Shell Blasting Service – FAQs, Explanations & Answers

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Here at SoCal BMW Installs, one of the most common services we perform is the Walnut Shell Blasting service on BMW Turbo engines (N20, N54, N55, N63, S55, S63). This service is a scheduled maintenance required on Direct Injection vehicles in order to clean the Carbon buildup on the Intake Valves. The interval that this service should be completed is every 40k-50k miles during normal driving (unmodded). We have made this post to educate customers and the community about the various aspects that surround this service. If you are ready to schedule an appointment, or had any questions that are not answered feel free to contact us at (714) 485-9794.

1. What is Walnut Shell Blasting?

Walnut Shell Blasting is a service that involves shooting a mixture of compressed/pressurized air and walnut shells into the Intake Valve track in order to clean Carbon Deposits and Buildup that occurs slowly over time.

2.Why does my Direct Injection Turbo BMW need this service?

Direct Injection style Fuel system (Injector is after Intake Valve)

As we all know, BMW is quite a powerhouse brand and has the ability to incorporate a high level of engineering in every project they work on. Modern day BMW’s use a myriad of new technologies that are well ahead of their time; one of these technologies is the use of a Direct Injection style Fuel Injection system. This style of Fuel Injection has become very popular over the last few years as many manufacturers and vehicle models are using similar Fuel Injection technology and following suite of BMW. Just as the name implies, the Direct Injection fuel systems work by “directly injecting” fuel into the cylinder combustion chamber. This enables the vehicle to be much more gas efficient all around and helps manufacturers to meet CAFE mileage requirements and goals. The Direct Injection fuel system is designed to have the Injectors within the Cylinder (after the Intake Valves, and before the Exhaust Valves). Prior generation fuel systems use a traditional Port Injection style, which injects fuel prior to the Intake Valves. The Port Injection style fuel system has its benefits since the Intake valves do not require Walnut Shell Blasting and cleanup as a scheduled maintenance. Since the fuel is injected prior to the Intake Valves, these valves get cleaned with the detergents or cleaners found in most pump gasoline fuels (i.e. Chevon Techron, Shell V-Power, etc). In the newer Direct Injection style fuel systems, since the fuel is injected AFTER the Intake Valves, these valves do not get cleaned by the detergents and cleaners found in most gasoline. This eventually leads to a large amount of Carbon buildup over time on newer BMW Turbo engines which requires the Walnut Shell Blasting service.

3. What would my Intake Valves look like before a typical cleaning? Is there anyway you can provide videos to give me an idea of what I should be expecting?

Sure! We have attached a couple videos to hopefully give you a better visualization of what to expect before and after a typical cleaning.

4. How often should I perform this service? When do I need it?

The Walnut Shell Blasting service is regular maintenance item that should be performed every 40-50k miles. This interval is the recommendation for vehicles that are stock and unmodded, as well as lightly driven vehicles. For any vehicles that are modded, tracked or driven in a more spirited fashion it’s recommended to have this service performed every 30-35k miles.

5. What are the benefits to Walnut Shell Blasting?

Although the Walnut Shell Blasting service is just a required maintenance item, it does have advantages that come as “side” benefits. Some benefits include:

  • Increase in Horsepower (hp) and Torque (tq) – It has been proven by dyno that if the Carbon buildup is particularly bad, you can recover roughly 15whp+/20twq+ of “lost” power by making the engine breath better.
  • Gas mileage increase in efficiency – Also due to the engine “breathing” better, you stand to make the car a bit more efficient in the gas mileage department. It has been proven to increase mileage by roughly ~2-3mpg overall which quickly adds to a lot of gas and cash saved!
  • Ease of diagnosis of issues related to Carbon Buildup – Once the Walnut Shell Blasting service in completed, you have peace of mind that the building was not causing any common issues such as Rough Idle, Misfires, Cold Start Issues, etc. This helps to eliminate the Carbon buildup as a potential variable and makes the diagnosis to issues increasingly

6. How much does the Walnut Shell Blasting service cost?

The cost of the Walnut Shell Blasting service is $250 for BMW N54 and N55 engines (please contact for custom quote on other engines). This price includes replacement of the OEM BMW Intake Manifold gaskets, which must be replaced every time the Intake Manifold is removed and reinstalled. We always stock these gaskets due to the sheer volume of these services we perform every week. In addition, we have wrapped the cost of the gaskets into one low affordable price of $250 for the service.

7. How long does the Walnut Shell Blasting service take to perform?

The Walnut Shell Blasting service takes about 3-3.5 hours to complete.

8. How many of these Walnut Shell Blasting services have you done exactly?

We are proud to say we have done over 100 of these Walnut Shell Blasting cleaning services for various local (and out of state) customers since 2013. We are confident in our work and guarantee all work performed with a warranty.

9. So you do all of this out of your garage? How much experience do you have and can I trust you? I am on the fence since I want to be confident in who I am taking my vehicle to.

We do work out of our garage indeed! We have been working on local BMWs within the Southern California area since 2013 and are very well known within the local Southern California community. We have created a section for “Review & Feedback” to help new customers gauge the quality of work we provide here at SoCal BMW Installs. We feel posting this unedited feedback in this section is the best way to display how customers truly feel about the work we provide. In addition, we provide a warranty on all Walnut Shell Blasting service and guarantee our work.

10. How does this work exactly, do I drop the car off or can I stay and wait?

Glad you asked! We are happy to accommodate for customers in any given situation or circumstance. Your welcome to drop the car off, or you can stay and wait while we perform the service.

Drop Off: If you drop the car off, we will perform the Walnut Shell Blasting service and be sure to take videos of the Intake Valves before and after the cleaning. This ensures that the work was done to your satisfaction and will show you proof that the Intake Valves are completely clean.

11. Have more questions?

Any other questions? We are happy to help answer them for you, feel free to reach out to us directly at (714) 485-9794. Thanks!