[Dyno]

Referring to the attachment above...

The shape of those curves is very interesting. If they are accurate, it looks like RaceChip was able to push the torque peak up to a much higher rpm (i.e., the peak torque speed). In fact, the "chipped" curve shows that peak torque occurs way up near the redline.

This is evidence that the T6 engine has a turbo which is much larger than what is typically found on a turbo-only engine. The supercharger gave them the ability to do this without sacrificing low-speed torque.

 

[pocholin]

Referring to the attachment above...

The shape of those curves is very interesting. If they are accurate, it looks like RaceChip was able to push the torque peak up to a much higher rpm (i.e., the peak torque speed). In fact, the "chipped" curve shows that peak torque occurs way up near the redline.

This is evidence that the T6 engine has a turbo which is much larger than what is typically found on a turbo-only engine. The supercharger gave them the ability to do this without sacrificing low-speed torque.

I don't know if the turbo is much larger, but it does make sense that it reaches torque peak because boost peak is achieved much earlier.

Looking more in depth at the CSV files, I can see RC is making the turbo achieve maximum factory boost much earlier than under P*. P* achieves max boos ~22.5-22.6 PSI @ 5,500 RPM, while under RC the max boost (still ~22.5-22.6) is achieved as early as 3,500 RPM. I can also see that ECU pulls timing in order to throttle down the boost but RC quickly corrects and pushes back to max boost.

 

[lamarguy]

Looking more in depth at the CSV files, I can see RC is making the turbo achieve maximum factory boost much earlier than under P*. P* achieves max boos ~22.5-22.6 PSI @ 5,500 RPM, while under RC the max boost (still ~22.5-22.6) is achieved as early as 3,500 RPM. I can also see that ECU pulls timing in order to throttle down the boost but RC quickly corrects and pushes back to max boost.

It reaches peak boost much earlier because the supercharger is being overdriven in map 7 (superheated air), and the ECU is compensating for knock by temporarily pulling timing during the handoff to the turbo. That's why I'm requesting a map 4 run - I suspect you'll see a slightly later torque peak with little-to-no timing being pulled during the handoff.

Tuning on the T6 appears to be limited by the supercharger. Changing to a 5:1 pulley would allow for higher boost from the turbo.

 

[pocholin]

It reaches peak boost much earlier because the supercharger is being overdriven in map 7 (superheated air), and the ECU is compensating for knock by temporarily pulling timing during the handoff to the turbo. That's why I'm requesting a map 4 run - I suspect you'll see a slightly later torque peak with little-to-no timing being pulled during the handoff.

Tuning on the T6 appears to be limited by the supercharger. Changing to a 5:1 pulley would allow for higher boost from the turbo.

I feel like it does the same in map4, I will get you the readings, hopefully this weekend.

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[Dyno]

It reaches peak boost much earlier because the supercharger is being overdriven in map 7 (superheated air), and the ECU is compensating for knock by temporarily pulling timing during the handoff to the turbo. That's why I'm requesting a map 4 run - I suspect you'll see a slightly later torque peak with little-to-no timing being pulled during the handoff.

Tuning on the T6 appears to be limited by the supercharger. Changing to a 5:1 pulley would allow for higher boost from the turbo.

I don't think any of that made sense.

 

[lamarguy]

I don't think any of that made sense.

Very enlightening.

Have you looked at SPA data logs? Did you read why TDI Tuning (and some other piggyback tuners) hasn't developed a T6 tune - citing supercharger tuning "issues"?

 

[Dyno]

OK, some of it made sense to me, but...

1. How does chip tuning overdrive a mechanically-driven supercharger?
2. How is the supercharger the limiting factor if it's out of the picture by 3500 rpm?
3. What is that supercharger superheated air comment about? Again, I don't see how the SC behaves any differently with tuning -- except perhaps by altering the conditions where it is bypassed.

I admit I have not studied logs or are particularly familiar the T6 Drive-e control strategies.

 

[pocholin]

OK, some of it made sense to me, but...

1. How does chip tuning overdrive a mechanically-driven supercharger?
2. How is the supercharger the limiting factor if it's out of the picture by 3500 rpm?
3. What is that supercharger superheated air comment about? Again, I don't see how the SC behaves any differently with tuning -- except perhaps by altering the conditions where it is bypassed.

I admit I have not studied logs or are particularly familiar the T6 Drive-e control strategies.

I think your questions are valid, the super charger is deactivated around 3400-3500 RPM, if I remember correctly, so it has no effect on the turbo.
https://www.swedespeed.com/features/Technical_Features/volvos-2-0l-t6-makes-power-per-liter-ferrari/

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[Dyno]

That's a good article.

One thing I picked up is that because they've got the turbo to handle things in the upper half of the rev range, they can really gear up the supercharger so that it spins much faster than if you had to rely on it all the way up to redline. They simply disengage it once it's spinning too fast and gets inefficient.

I can't tell where the supercharged air goes, though. Does it get plumbed to the turbo compressor inlet or is it in parallel? Does the supercharged air go through the intercooler or only the turbo's air? Hard to tell from just a couple of photos.

 

[pocholin]

That's a good article.

One thing I picked up is that because they've got the turbo to handle things in the upper half of the rev range, they can really gear up the supercharger so that it spins much faster than if you had to rely on it all the way up to redline. They simply disengage it once it's spinning too fast and gets inefficient.

I can't tell where the supercharged air goes, though. Does it get plumbed to the turbo compressor inlet or is it in parallel? Does the supercharged air go through the intercooler or only the turbo's air? Hard to tell from just a couple of photos.

There's another article with photos that shows air flows under each of the chargers. I'll try to find it tonight.

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[lamarguy]

1. How does chip tuning overdrive a mechanically-driven supercharger?
2. How is the supercharger the limiting factor if it's out of the picture by 3500 rpm?

It's driven until the ECU decides to disengage the clutch. And, that's where piggyback controllers confuse the ECU.

Most assumed the factory programming had a hard cutoff at 3500 rpm, but that's not the case. It factors in target manifold pressure too. So, when the piggyback underreports the MAP sensor voltage, the ECU waits longer to disengage the clutch (until the target pressure is reached).

TDI wrote about this issue and I corresponded with the Vaitrix tuners about it. I was curious how they solved the supercharger speed/efficiency limitation and they hadn't. Their tune pushed the supercharger cutoff to 3,900 - 4k (3.9k * 6 = 23.4k).

Eaton TVS R410 specs

3. What is that supercharger superheated air comment about? Again, I don't see how the SC behaves any differently with tuning -- except perhaps by altering the conditions where it is bypassed.

The supercharger has a max rpm rating of 24k. At maximal speed and pressure, it's only ~50% efficient (vs 90% at lower rpm).

Why does efficiency matter, because lower efficiency produces hotter, compressed air and increases parasitic drag. Why does hot intake air matter? I'll leave that one to the scholars.

 

[lamarguy]

An ideal T6 tune would (1) maintain the supercharger's efficiency range AND (2) extract more work from the larger turbocharger (within its efficiency range).

A proper tune (cracked ECU) would prevent the ECU from pulling timing and possible supercharger damage from exceeding its max rpm. Lacking that, I would be very hesitant to run a piggyback at its most aggressive mapping.

 

[Dyno]

Thank you!

The key to my understanding was your comment about under-reporting MAP, which would then unintentionally delay the supercharger disengagement point, pushing the operating point farther away from the peak efficiency island, resulting in a lot more heat but not so much more air (which is pretty much the textbook definition of "poor efficiency") .

By the way, hotter intake air is less dense than colder air at a given pressure (the Ideal Gas Law and all that), so it's like having less boost. Also, hotter air is more conducive to knock -- the mortal enemy of turbocharged engines.

 

[pocholin]

An ideal T6 tune would (1) maintain the supercharger's efficiency range AND (2) extract more work from the larger turbocharger (within its efficiency range).

A proper tune (cracked ECU) would prevent the ECU from pulling timing and possible supercharger damage from exceeding its max rpm. Lacking that, I would be very hesitant to run a piggyback at its most aggressive mapping.

You cannot expect much computing input/output to the car's ECU from two harnesses, one connected to air intake sensor and the other to boost sensor. I don't disagree with you though on what a proper tune or elaborated piggyback like the one from Heico should do...however, that is +$1,500 USD more than Racechip.

 

[lamarguy]

You cannot expect much computing input/output to the car's ECU from two harnesses, one connected to air intake sensor and the other to boost sensor. I don't disagree with you though on what a proper tune or elaborated piggyback like the one from Heico should do...however, that is +$1,500 USD more than Racechip.

Ya, and I'm not trying to be negative toward piggyback tunes for the T6. I think it's a reasonable alternative for the ROI. I'm just advocating caution with regard to overdriving the supercharger. :beer:

 

[pocholin]

Perhaps a map 4 run too?

I suspect map 7 is overboosting the supercharger (past 4k rpm) and the ECU is pulling timing.

Here's the Map7 vs Map4 results.

 

[lamarguy]

Here's the Map7 vs Map4 results.
View attachment 71655

Thanks.

The blue line is map 4, correct? If so, there's definitely more power produced "under the curve" (without the ECU pulling timing).

 

[pocholin]

Thanks.

The blue line is map 4, correct? If so, there's definitely more power produced "under the curve" (without the ECU pulling timing).

Yes, it is. It certainly seems to be the case. I'll do some 0-60 passes and report back.
In 4th gear I still feel the timing being pulled back but it might be lesser than in map7. I'll report back in a few days.

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[pocholin]

Recorded a 5.6 sec in 0-60 in map4, same area where I previously recorded 5.4 on map7.
I did a second recording of Map4 and power bands are fairly the same with one another. See below image, today was colder, reflected in the SAE corrections.
View attachment 71715

 

[Power6]

In 4th gear I still feel the timing being pulled back but it might be lesser than in map7. I'll report back in a few days.

I'm curious your experiences in 4th gear. I have tracked my T6 S60 and logged OBD2 data, simple throttle angle and boost. It's very obvious that there is programmed in power limiting 4th gear and up at WOT. Solid 22psi goes to a sort of bouncing around of the throttle angle and boost while my foot is WOT on the pedal as you might expect on the track. I assume there is a torque target as typical engine control strategy. throttle and boost are manipulated to meet that target. You can see here, on the front straight, shift to 4th about 80mph.

Probably a good compromise for Volvo for longevity, most people aren't going to care about WOT over 80, the upper gears are a lot of load. It's noticeable though on the closed course where you got space to run!