Subnostr

Ehh, possibly with the billet wheels, but on 6.4s pedal response is mostly in your tuning, especially with a tiny little VGT. You will usually see lower average EGT though when going to billet wheels.

Blow off valves are for useful for throttled engines (gas engines) because when the throttle snaps shut all of that energy stored in the charge air needs a place to escape, so it goes back out the compressor side causing a large pulse of shear force on the shaft or even causing the wheels to spin in reverse, then another huge spike in the positive direction after that column of charge air escapes.

In diesel engines without throttles (yeah I know the cali emissions 6.4s had "throttle" blades but they aren't used for throttling) that charge air just gets stuffed into the cylinder and doesn't do anything, just raised AFR which again is just fine for a diesel engine. So you turbo and your engine will be fine, a blow-off valve is pretty much useless!

Because diesel engines are fuel metered, you can stuff as much air as you want into the cylinder and it will only make as much horsepower as fuel is available in the cylinder. (horsepower is a function of cylinder pressure btw)

Fiat Shenanigans 🤡🌎 1y ago

I see. So question:

When I would accelerate hard and then pull my foot off the throttle the boost pressure would spike for a split second. Like it was hitting 35 at a little over 3000 RPM and would spike to about 40-41. The last time that happened it blew off one of the intercooler hoses and that's when I discovered the turbo was leaking oil into the intake and decided to replace it. Do you know what was causing that?

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Discussion

ChipTuner 1y ago

Hmmm, tricky. I haven't seen that before but most of my time was with 7.3ls. Typically when letting of the accelerator the PCM would "close" the vains in the VGT charger which might cause that spike but it seems unlikely because of the time it happens. 1. usually the VGT would be much slower to respond than the energy lost when fuel is reduced. 2. usually the EBP pressure would prevent the vains from closing too slowly.

1. I could be wrong about the throttle body, but I'm fairly confident that's not the case

2. I wonder if the compound configuration might cause a pulse if the VTG is closing fast enough, and/or the low pressure charger's wastegate closes too quickly.

Also the low pressure charger should be wastegated iirc which usually helps prevent that

Second. It's normal to see oil in your charge pipes because if the crank case vent. Not a lot but more than you'd expect, just throwing that out there. You may want to wiggle shafts to make sure they don't have any play in them if you havent already.

Fiat Shenanigans 🤡🌎 1y ago

Hmmm. It was originally a Canadian truck. So would it have the same throttle body as a Californian truck maybe? I'll have to take a look at the throttle body to see. There was quite a lot of oil in the charge pipe and around the turbo inlet. The turbo inlet was clean when I installed the cold air intake just a few weeks ago so this was a new problem. And the turbo felt a little stiff when I tried to turn it with my finger.

ChipTuner 1y ago

It looks like I may be wrong, I was basing this off my 6.0L knowledge, which that was the case. It was used for EGR by reducing manifold pressure under higher loads. TMK it was never used for any other purpose and should be wide open most of the time. All 6.4Ls may all come with throttle bodies from what I can tell. It's mounted to your intake manifold and where your cold-side boot clamps too.

If oil was sitting in the inlet, more than likely I suppose, but end-play is usually your best tell-tale of a failed bearing.

Fiat Shenanigans 🤡🌎 1y ago

Thanks for all the information by the way. I take appreciate it.