6.5 Turbo Diesel

Greetings,

The turbo for the 6.5 was smaller in diameter and had a lower boost pressure than on either the Cummins or the Powerstroke so it wasn't always easy to hear, but I could barely hear mine at harder acceleration just before the shift.

I can't tell yet if is working due to the way it was set up. I bought it and it had 2.25" exhaust ... yes 2 1/4" that was done by one of the muffler shops. It was so restricted I don't think that enough exhaust could get out to spin it up. We removed the clogged cat and put on 3.5" back to the rear so far, we have to bend up some pipes for over the rear and out the back. Also replaced the clogged air filter... hoping to see a major improvement. When we replaced the air filter we also removed the small restrictive air intake out of the fender. While we had that off we also reached in and spun the turbo it spun very free with no drag I hope that is normal and good. When I bought it the guy said it gets bad fuel mileage and low power. I hope this fixes it all, then we can start throwing extra parts at it. It is a F code and from what I read that is the H.O. Turbo ??? Does anyone know what is different in them ?

Greetings,

If you want better exhaust flow overall the key component to replace is the downpipe from the turbo outlet on the exhaust side to the cat inlet. This S-shaped pipe had some pretty restrictive bends and was not radius bent from the factory (it has "crimps" on the inside curves of each bend) and no matter how much you opened up the exhaust after the downpipe or the cat it was always the chokepoint for flow. You can find an aftermarket replacement that has smooth, constant diameter bends and is fairly easy to install.

The other thing to check is the dump valve on the turbo itself. Make sure it is free and able to move from fully open to fully closed. Disconnect the vacuum line at the turbo and move the valve rod back and forth with a pair of pliers. Don't hesitate to clean it up and lube it. A valve that is stuck open could rob you of power. Since it is vacuum operated check the vacuum pump (they do wear out and I had to replace mine at least once), the vacuum solenoids (three on the driver's side of the motor on top) and the vacuum lines (they like to get cracks and leak).

Cheers - Jonathan

So the 6.5 uses vacumme to operate the wastegate on the turbine????? Thats dumb...way to go GM. That outta be a boost sensing line to control the wastegate.

.....FYI its called "mandrel" bent tube that you want for exhaust.