[JPMC]

Follow this link and watch the build story. You'll see in episode 4 when they get the dyno tune that because of the lack of CAT/DPF it is over boosting to 27psi.

https://youtu.be/DNL-NMBpF-g

 

[freemansteve]

I suspect there is some confusion here between the use of turbos for diesels (no throttles) and petrol (with throttles) where with the latter you can get stress on the fresh air impeller if the throttle is closed quickly. That does cause a "back-pressure" on the compressor, as there is a lag until the exhaust pressure reduces and until the wastegate can open. But I see no issue on the exhaust side in any situation...

 

[freemansteve]

Follow this link and watch the build story. You'll see in episode 4 when they get the dyno tune that because of the lack of CAT/DPF it is over boosting to 27psi.

https://youtu.be/DNL-NMBpF-g

Yes a little bit of extra boost for a short while until the electronics regulate it , when using a free-flowing exhaust, but easily adjusted to any required level depending on the map as was said. I doubt it is a catastrophic issue for the turbo (as was stated previously), even without altering boost in the map to compensate. Don't forget any proper remap for more torque would have to up the turbo boost anyway and this does not seem to have caused turbo failures - it does however stress the whole drivetrain a bit more. Also, variable-vane systems are much faster to respond that normal wastegates.

 

[JPMC]

Yes a little bit of extra boost for a short while until the electronics regulate it , when using a free-flowing exhaust, but easily adjusted to any required level depending on the map as was said. I doubt it is a catastrophic issue for the turbo (as was stated previously), even without altering boost in the map to compensate. Don't forget any proper remap for more torque would have to up the turbo boost anyway and this does not seem to have caused turbo failures - it does however stress the whole drivetrain a bit more. Also, variable-vane systems are much faster to respond that normal wastegates.

These turbos aren't variable-vane (only the D40's were) that's why they have two.
Over boosting stresses the turbo and also causes the engine to run lean. These engines actually adjust themselves to derate when intake temps get to high. (Running lean causes heat)
Have you ever noticed the ute feels sluggish on a hot day especially in heavy traffic?
This is because the heat soak raises temps so the ECU retards the engine to protect it and keep EGT's down.
You say it can be adjusted to the required level depending on the map which is the point I'm making. If you de-cat/dpf you need to remap. If you don't then down the track it's going to come back and bite you.
By mapping you have the ability to run bigger boost as you can adjust the other parameters to match but then you also need to look at changing the intercooler also.

 

[mrw27]

I'll need to come back to this later guys. I gotta head out for a while.

 

[mrw27]

A miserable one and a half pounds of torque gain before the re-map; and you're telling me there's significant back pressure!

There is no mention of turbo damage anywhere in the video, not part 3, or 4, and especially not from the point of a lack of back pressure destroying it!!

The tuning specialist mentions over boost a few times, that's simply because the exhaust is now so much more efficient. They do not mention damage to the turbo. A simple map sorts over boost, but not to save the turbo, just to maximise efficiency and performance by changing engine control parameters to suit the new setup.

There is so much science to engine exhaust systems that it would melt your mind. I'll introduce another few concerns when trying to design/tune an exhaust, that's something called "scavenging" and "Exhaust Velocity". They are basically the other part of exhaust science, since they all work in relation to one another. What's described as a "Linear Relationship" between these particular parameters.

So, you showed me a video made by a few guys in a shed (although off point, it was very interesting) HERE is a video made by engineering scientists.

Another extremely short video HERE.

 

[mrw27]

I should say; over boost is not the ideal situation to hold a turbo in, but this is where we agree. A remap should be performed when trying to tune an exhaust, it would be absolutely stupid not to.

 

[freemansteve]

I agree. My point was to say that all other things remaining same, then making a more free flowing exhaust may allow more boost in a turbo, but this is quite quickly electronically controlled. In any case, a decent remap will up the boost to a greater level than simply improving exhaust flow alone - this will not "blow a turbo" either. Sure, the two together may give you more than a safe level of boost, affecting all sorts of drive-line components.

Frankly, if one has no working knowledge of Navier–Stokes equations, and about 8 other PhD-level topics related to flow and acoustic resonances, one is probably a trial and error meddler, when it comes to exhaust gas flows. Nothing wrong with trial and error though!

 

[mrw27]

I agree. My point was to say that all other things remaining same, then making a more free flowing exhaust may allow more boost in a turbo, but this is quite quickly electronically controlled. In any case, a decent remap will up the boost to a greater level than simply improving exhaust flow alone - this will not "blow a turbo" either. Sure, the two together may give you more than a safe level of boost, affecting all sorts of drive-line components.

Agree 100%.

Frankly, if one has no working knowledge of Navier–Stokes equations, and about 8 other PhD-level topics related to flow and acoustic resonances, one is probably a trial and error meddler, when it comes to exhaust gas flows. Nothing wrong with trial and error though!

Precisely.

 

[mrw27]

One other point to bear in mind; in the video you linked to, the final gain in power was 40.6KW (that's another small car worth!!). In your opinion, what do you think they did to the turbo (map side) in order to create such a massive gain in power?

Your logic, as you mentioned:
Turbo working hard - 118.9KW
Turbo working less hard - 159.5KW

That's 34.15% gain in power.

I do realise redesigning a map isn't quite as simple as "turning something up or down", but this highlights a serious error in your thinking.

What other major change on the map could have allowed such an insane power gain, targeting which components, or adjusting which parameters?

Or, do you think they lowered the parameters for the turbo in order to gain more power?

The requirement of back pressure is a myth, fact. The important things, as mentioned above, is exhaust Scavenging and Velocity.

I think you will find, the error you made whilst assuming that the turbo can be directly damaged by a lack of back pressure, is that you failed to consider that over boost generally causes damage to many other components. Not the turbo. It is designed to be under stress, because that's what it is for, it's a compressor. The turbine, or torsional stress on the shaft, bearings... isn't the concern, it's pipework and intercooler etc, things like that will blow with over boost (or more severe things). That being said, as the Free Man mentioned above, re-map or no re-map, the waste gate/turbo vanes are governed by many parameters, as soon as the ECU decides there's too much pressure, it will let it go or adjust the vanes (very quick to respond).

If the turbo was under the level of stress you mention, enough to damage it, then something else would pop first, make no mistake.


(all figures above are taken from memory, please excuse errors after the decimal point. Although it should be accurate to one unit at least, close enough for argument)

 

[Jackmck]

Some great replies above as to over-boast etc.

With DPF removal you MUST do a re map to delete it out of the ECU otherwise it will try do a burn and find nothing happens. It will keep trying to do a burn pumping more diesel into the exhaust creating a lot of back smoke but the ECU will pick up nothing is happening and shut it all down. This will lead to limp mode and possible boost shut off giving u a ute with about 2kw to try get home. Driving any long distance with dpf delete not tuned out will result in towing your car home and maybe some tears.

Tuning is another thread altogether. But a simple reply would be when tuning go to a professional with a good track record. They determine your engines life or death literally. They are not turning up just the boost and diesel pump but rather altering the curves and get a most power within the factory perimeters. You can always install an EGT gauge to monitor the temps which is the main killer of you turbo or turbos in my case

 

[mrw27]

Very interesting read, nice info.

Also, I couldn't agree more about choosing a specialist who actually has a proven record. Not just because of the risks, which are important enough, but also to maximize the gain. Just as an example, one tuner could decide that for a given transducer, changing it's output by altering it's response range by just 0.18Ω may result in a gain of 1.2HP at one particular point of the graph, Another guy may miss that.

 

[Jackmck]

Hi all, Just a quick update on my NP300.

So i have put in a delete pipe finally. Note when purchasing the unit from PPD it is not all direct bolt in. You will need to run new pressure hose as the existing will need reach and also lengthen the existing pipe after the DPF as its to short a pipe and the sensor hits the floor pan and snaps. Not good. Few things you will need are 1m of 10mm Heater hose and 3 hose clamps. Also a brass 10mm hose joiner. maybe a resonator of some kind.

The result power wise is good. It has noticeably more torque and will pull harder down low. The noise thou is very loud. It sounds like a Jet!! I haven't yet tested it on any long climbs with a load to see if it keeps cooler or not. Stay tuned for an update.

I'm planning to fit a catalytic converter or resonator this week to try quieten it down. The whistle is cool but makes your ears ring after 5mins

 

[Jackmck]

a Few pictures of the install. Including a home made tool to get the sensor out.

 

[LAY_2036]

I have a 2017 NP300 and I have unbolted the dpf and everything detached but I still can't remove it, it's wiggling around but not enough room to remove it I'm stuck? Has anyone removed one before will I have to unbolt the cross-member?