Filter Minders for Dummies

[davidbrady]

Anytime Pete. You know I can't stay away from this stuff for too long.

I didn't notice any appreciable change in boost levels after doing the exhaust. I didn't really notice any turbo spool up time change or any fuel mileage increase either. It may be there, if so it just wasn't significant enough for me to see a difference. I also replaced my charge air cooler (CAC) with a Duralite CAC.

What I did notice was a significant drop in exhaust gas temperatures and I think this was mostly due to the repair of the CAC but the new exhaust system may have added to it.

My original CAC suffered a fatal blow when the bus suspension air was dumped and the CAC came down on an obstacle. I had a nice crack in my OEM CAC. I worked with Duralite to have a new one made to fit the LXi. If anyone wishes to have a Duralite CAC for their LXi the part number is: BLUDAC-350B. This is a bolt on replacement for you Radiator Specialties unit.

When a CAC leaks the engine is starved of air. This results in a drop in boost pressure. To get the pressure back up to where the ECM wants to see it, the ECM dumps fuel in the cylinders. The result is black smoke out the pipe and excessive exhaust gas temperatures (EGT's). This is what got me on this kick of understanding what an electronically controlled diesel will do.

The same is true for the exhaust and intake systems. Making either of these freer flowing will result in less pumping loss and more air to the engine. This means to achieve a given boost the ECM can taper off the fuel delivery a smidge. With the change I made to the exhaust system I wasn't able to identify any increase in mileage (engine efficiency) and I think the same would be true of the small changes in intake flow that some are proposing. Unless the stock system is overly restrictive in intake or exhaust I think the differences will be unnoticeable in terms of efficiency.

I never saw a boost increase with either the CAC or the exhaust system upgrade. This is due to the smarts of the ECM. A given ECM program (flash) with a given set of injectors wants to see a predetermined boost level at a given engine load and rpm. A 500 HP Series 60 wants to be 500 HP.

You can throw all the intake and exhaust tricks you want at an electronically controlled engine and you won't see an increase in boost or power. The only way to get that is to alter the fuel map and the expected boost and that requires an ECM reflash and new injectors. You may see an increase in efficiency as the ECM tapers off fuel delivery but with the LXi it's going to be slight to unnoticeable.

The beauty of my Silverleaf VMSpc videos is that they are real factual numbers coming from real engine sensors. This isn't seat-of-the pants, or third party heresay, or jawflapping. This is the real deal. These numbers don't lie.