With many of today’s diesel engines, the boost pressure is less than the drive pressure. This has to do a lot with the emissions levels that they need to reach. It is a pretty simple concept. Higher pressure will flow into the lower pressure area.
Since the exhaust gas is designed to flow into the engine during a wide range of conditions, the OEM must ensure that the drive pressure is always higher than the boost pressure. Otherwise they run the risk of releasing boost pressure into the exhaust (which wouldn’t be the worst thing), which could greatly reduce the power of the engine.
So, while having a boost pressure gauge is great and it gives you a decent look into the health of your engine, it is really only telling you part of the story. To get a better picture, a drive pressure gauge should, also, be used. Now many of us have been running boost pressure gauges as drive pressure gauges. So, it isn’t like there was no way to achieve it in the past. However, what Auto Meter has accomplished, is to provide a high quality reliable system for the market.
Auto Meter has released two systems, a mechanical system and a digital system.
Exhaust gasses are hot (you know, you watch them all the time. It is pretty common to see 900 to 1300 degrees at any given time) so you have to cool them down somehow. Auto Meter’s kit includes 6’ of 1/8” cooper tubing to act as a cooler. The tubing is connected to the exhaust manifold and coiled up. The 6’ of tubing helps to cool the EGT’s down to a more manageable temperature.
Once the EGT’s are cool, there are two options. Hook up the Nylon tubing or connect an exhaust (drive) pressure particle trap kit (this is a good idea). What the particle trap does is basically filter the exhaust to ensure that the Nylon tubing or the gauge itself doesn’t get stopped up with soot.
After the exhaust is cool and possibly filtered, the Nylon line is connected to a mechanical gauge to read the pressure.
On the digital side of things, the exhaust is cooled down the same away as above. The same 6’ of cooper line is used. From there, we would recommend opting for the particle trap kit. Either way, the electronic gauges use a pressure sender that sends a signal to the gauge. The gauge then reads the pressure and you are good to go. No worries about having any soot or exhaust leaks in the cab.
The kit does come with a complete wiring harness to hook up the gauge and the gauges are available in multiple series.
Really no matter how you want to run it, knowing how much drive pressure and boost pressure will let you know how your turbo is running and give you a picture of the overall health of the engine. Check out Auto Meter’s website for more info.