Diesel Tuner's Blog

What you need to know about Boost Testing your truck!

Posted by Paul Wilson on May 6, 2016 9:00:00 AM

So many truck come into our shop with high EGT's, turbo lag, excessive smoke output, and bad fuel mileage which are all symptoms of a boost leak. It is so common to devlop boost leak that we now require all trucks to have a boost test done prior to strapping them down on the dyno. What's funny, is that no one shows up knowing they had a boost leak. The reality is that even if you can hit peak boost, you may have a leak, especially if you have a variable vane turbo. Variable vane turbos will change vane position and other operations to try and achieve a desired boost number which may cover up a leak in the charged air system. 






Leaks can be developed by corrosion of the intercooler pipes, blown or torn boots, loose clamps on intercooler piping, or even a cracked intercooler. Many times a leak starts small but over time becomes more prevalent. Again, most people do not know they have a leak until the charged air system is pressurized. Soapy water and looking for bubbles is strenuous and time consuming, feeling each boot does not tell you anything, and running a smoke machine through the intercooler piping does not pressurize the system hard enough to expose all of the potential leaks. 

 HD Regulator

This is why boost leaks kill diesel engines. Boost leaks can result in a smokey, laggy, dog-of-a-truck, which runs hot and burns excessive fuel. Basically, the exact opposite of what you want from your diesel.

Boost Testing your diesel is essential! Every truck that comes in the shop, gets a boost test. Most of the time customers report still seeing peak boost on their gauges despite a boost leak. However, common symptoms of a boost leak include Increased Smoke, Higher EGTs, Excessive Lag, and Loss of Power.

If you work with diesel trucks long enough, you’ll see leaks just about everywhere in the charged air system at one time or another. Remember, the charged air system includes anywhere from the turbocharger to the intake manifold. Your Intercooler system, Exhaust Gas Recirculation components, and even the Turbocharger compressor cover can all develop boost leaks.

Over the years, our team has used just about everything you can think of to boost test a truck. From PVC pieces to smoke testers, and just about anything else you can think of. There are a few kits out there that will help, but nothing that truly tests the entire system accurately and is made of premium parts.  

That’s why we spent the resources to develop the Stealth Boost Tester. You can now easily and accurately test your entire charged air system. The kit is made entirely of premium parts, designed to last, and built to rigorous standards. 

You can choose either a Compressor Inlet Adapter or Turbo Faceplate Adapter to go along with your kit.

Holset Compressor Inlet Adapter

The Compressor Inlet Adapter is a billet adapter that connects to your Compressor Inlet with a heavy-duty, 4ply boot, and 2 high strength T-Bolt clamps. Removing a Cold Air Intake in most trucks is a job that only takes a few minutes and requires the most basic mechanical skill. The same goes for installing and using the Compressor Inlet Adapter. Your billet adapter even comes with how many inch-pounds the T-bolts need to tighten too.

The Turbo Faceplate Adapter connects directly to the inlet of the turbocharger.  If you have a sheet metal intake that’s not designed to hold compressed air, or a brand new turbo upgrade, you may prefer this option. Just as the name implies, the billet adapter connects directly to the face of your turbocharger.

Both the Compressor Inlet Adapter and Turbo Faceplate Adapter feature a conveniently placed and sealed fitting, allowing them to work with our high-quality regulator. This regulator is a crucial component when using the kit. If you have ever used a bad or failing regulator you know how frustrating it can be. You’ll notice the liquid-filled gauge here. That prevents erratic reading from pressure spikes and external vibrations. And of course, the regulator made from high-quality materials designed to last.

The unique advantage to this setup is we can accurately test the entire charged air system very quickly.

I know our mechanics like it because they prefer to use premium tools that are easy to use and provide accurate results.

LB7 Stealth Boost Tester

Do not put a test plug in the hot side pipe, this takes the y-bridge out of the test loop (a common leak spot). The engine will hold the pressure.

 If you hear any hissing, find it and you'll find your boost leak.  Fixing it will lower EGT's, improve spool up, and improve peak power. 


Stealth Boost Tester



Topics: Duramax Performance, duramaxtuner, Duramax, Duramax Power, Charged Air System, Boost Leak, intercooler, Trouble Shooting Duramax, Boost, Turbo, Boost Test