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This will be the primary factor. I grabbed some Garrett compressor maps to illustrate the point. Figure the base turbo is operating at around a pressure ratio of 2.5 and a flowrate of 25lbs/min which has a compressor efficiency of about 60%. Stepping up to the bigger compressor at the same operating point has a compressor efficiency of 71%. Therefore, the air coming out of the bigger compressor will be about 42F cooler if I did my math right. On top of that, because the bigger compressor is more efficient at the same operating point, it requires less shaft power from the turbine which ultimately means less back pressure on the turbine side. So even if you just put the bigger GTS turbos on while keeping the same tune, the car should run cooler and be more happy on track. And actually make more power because the ECU doesn't have to derate as much due to high IATs along with the lower exhaust backpressure which should reduce any ignition timing correction/retard.
You guys are tempting me! Any difference in the heat generated between the small base turbo and the bigger GTS turbo? Is one set-up more or less likely to heat soak before the other? (Assuming both running stock intercooler)
Here are peak IAT's, running GTS turbo's, APR 100oct tune, AMS intercoolers, Tial inlets/elbows, without intercooler water spray.
Tyler at APR says the ecu begins pulling drastic power at 131F.
Here is what he told me in 2020 from his track testing.
The inlet pipes are great, they really help with some efficiency on the compressor. However it is not going to make a huge difference on the IAT. Now running the M660 with the inlets like I do on my e85 file where I really keep the boost lower than normal, will make the car more oem like and make it trap 160+ at Road Atlanta whether or not it is hot and cold. This type of setup makes it repeatable and consistent, but even with these mods and tuning I still have IAT problems at the track. The biggest problems is the ducting to the intercoolers and not being able to shed the heat, and these hybrid turbos discharge temps are just too much with the increased mass flow for the intercoolers to keep up. Ideally it needs a real turbo that can operate in a much more efficient manner than a modified stock housing. Don't get me wrong the Tial's are great, but hybrids leave much to be desired for the Road Course guys that want 30+ minutes of abuse at the same pace. I am looking into water injection as well to try and help with the IAT issue, but I have not found the right injection setup yet, also need the controller to be updated on the software so I can actually have it do what I want.
Long story short the Tial stuff is a great product, but no matter the GTS or the Tial parts you are still going to run into iat issues with the car without making some other changes. The thermal capacity of the system is just not there. I do not ever recommend running the wrong hardware with software designed for another setup. The calibration is setup for that specific hardware, and when you change turbos the calibration changes were quite significant. So no I would not just put on hybrids and run the stage 1 file.
Hope this helps answer some questions. Biggest problem for this platform is heat rejection. If we could make a solution for that, the sky would be the limit.
My World's intercooler water sprayer are reducing peak IAT's by 25 at 80deg, 30 at 90deg.
Tyler at APR says the ecu begins pulling drastic power at 131F.
I do not ever recommend running the wrong hardware with software designed for another setup. The calibration is setup for that specific hardware, and when you change turbos the calibration changes were quite significant. So no I would not just put on hybrids and run the stage 1 file.
My World's intercooler water sprayer are reducing peak IAT's by 25 at 80deg, 30 at 90deg.
This is your 100 octane, 600hp tune right
I agree and disagree with Tyler on the hardware vs calibration. Going from big turbo to small, hard no. Going from small turbo to big, doable but not optimized for max power and response. And how big of a step is also a factor. In a way, going to a bigger turbo is like having a much better flowing intake and exhaust. Ideally, recalibrate to optimize the A/F and timing, but it should be safe from a knock/detonation viewpoint. I feel this is doable on the modern ECU control system with mass airflow measurement and constant wideband A/F measurement which allows the ECU to make any fuel trims as necessary. Old cars working on speed density systems and narrow band O2 sensors would also be a hard no on doing significant hardware changes without a new calibration/tune.
I agree and disagree with Tyler on the hardware vs calibration. Going from big turbo to small, hard no. Going from small turbo to big, doable but not optimized for max power and response. And how big of a step is also a factor. In a way, going to a bigger turbo is like having a much better flowing intake and exhaust. Ideally, recalibrate to optimize the A/F and timing, but it should be safe from a knock/detonation viewpoint. I feel this is doable on the modern ECU control system with mass airflow measurement and constant wideband A/F measurement which allows the ECU to make any fuel trims as necessary. Old cars working on speed density systems and narrow band O2 sensors would also be a hard no on doing significant hardware changes without a new calibration/tune.
Yes, the APR 100oct GTS tune.
I'm pretty sure I've seen people on this forum running the APR tune on the 660 turbos. Like you said, probably safe, but not ideal. But no way Tyler is going to recommend that to an APR customer.
@spdracerut Thanks for the math, I agree, it is sexy! LOL
Speaking of APR, I am working directly with them now, In fact, they have shipped me their new Ultralink product, arriving tomorrow. The tunes for the 991 are not public yet, but the Beta test is nearly complete and I am getting early access to all of the 991 tunes that are compatible with the new Ultralink. I think the public release is still scheduled for next week, absent last minute surprises.
I'm really excited about this as I have always been a huge fan of APR's tunes and this will give me the ability to play around with the various tunes and their impact. So initially I'll be playing with octane levels, and then potential hardware changes. (Not sure why I said 'potential', I am too weak to resist a turbo upgrade LOL). Everything will be recorded and reported back here .... so stay turned !
I also think a water sprayer is in my future. It's interesting, I always thought I'd be chasing suspension mods next but there is no point in increasing cornering speeds and more time at WOT if it will only result in heat soaking faster. Really have to solve this Achilles heel first.
You guys are tempting me! Any difference in the heat generated between the small base turbo and the bigger GTS turbo? Is one set-up more or less likely to heat soak before the other? (Assuming both running stock intercooler)
We see higher oil temps with the smaller turbos, not a massive difference with IATs but it seems that the smaller units retain more heat.
The folks at APR were kind enough to send me an advance copy of the new Ultralink product for the 991. This will allow dealers and consumers to flash various APR tunes to their cars at their leisure, anywhere with an internet hook up. I'll be experimenting with several of the tunes, including the 100 octane tune. The public release should be coming VERY soon, Beta testing has gone splendidly and is being wrapped up. More to come, but here is the un-boxing for the final consumer version. One point of differentiation, the tunes lie on a special APR website, so the module goes to the OBD, cable between laptop and module, and internet connection to APR to complete downloads. It's not a self contained unit like the Cobb, but hey, many of us believe the APR tune is superior so I'm thrilled at this option!! Plus, you can program multiple cars, different models and even different manufacturers, with this unit. This will be fun.
The folks at APR were kind enough to send me an advance copy of the new Ultralink product for the 991. This will allow dealers and consumers to flash various APR tunes to their cars at their leisure, anywhere with an internet hook up. I'll be experimenting with several of the tunes, including the 100 octane tune. The public release should be coming VERY soon, Beta testing has gone splendidly and is being wrapped up. More to come, but here is the un-boxing for the final consumer version. One point of differentiation, the tunes lie on a special APR website, so the module goes to the OBD, cable between laptop and module, and internet connection to APR to complete downloads. It's not a self contained unit like the Cobb, but hey, many of us believe the APR tune is superior so I'm thrilled at this option!! Plus, you can program multiple cars, different models and even different manufacturers, with this unit. This will be fun.
Jake - Will the APR unit need to remain attached to the OBD after the tune is flashed, or will you be able to remove it after the flash is completed? If still attached, would you be able to quickly flip between maps on the fly? My only complaint about my Cobb unit is that it can’t quickly flip between maps on the fly as reverting to a stock tune still takes about 3-4 minutes and vis versa for stage x.
Jake - Will the APR unit need to remain attached to the OBD after the tune is flashed, or will you be able to remove it after the flash is completed? If still attached, would you be able to quickly flip between maps on the fly? My only complaint about my Cobb unit is that it can’t quickly flip between maps on the fly as reverting to a stock tune still takes about 3-4 minutes and vis versa for stage x.
The dongle is only attached while the programming is going on. Unfortunately, I am not aware of any way to shift programs on the fly as only one program is stored on your ECU at a time. This week I hope to do some flashing and I'll have a better idea how long the process takes and also how much customization APR enabled for us. One of the APR's greatest advantages has always been the flexibility in their tunes. For example, you can have a very aggressive torque curve for launches or something more linear which is better on a race track. I'll dig in and see what they left in there for this "at home" version of their tune.
Any questions I can't answer directly I'll find out for everyone as I have a very direct line into their team now. I accidently butt dialed one of their tech guys this weekend, while he's on vacation, and got an immediate call back! LOL I can't say enough what a pleasure it is to work with them and what an incredible level of service they provide to all of their customers!!
The APR tune on GTS turbos is fantastic. Here my 60-130mph posted on draggy with my manual Carrera T on pump gas. I did add Tial inlets and a few other mods but wanted to stick with oem turbos (even if tempted to further upgrade those lol)
IMO, the best tunes available for our cars come from APR, and now with their new Ultralink product the process could not be easier! With their product in hand, a laptop, and an internet connection you can tune your car in under 5 minutes!
After creating your profile on the special Ultralink website, you are greeted with these options:
The first you must do is Update Ultralink. Without that, the dongle won’t talk to the car. So Ultralink hooked up to laptop and dongle NOT connected to the car, you hit that button and it does it’s think automatically. Next hook up the dongle to the OBD port and Create a Tune:
The device immediately recognized my VIN and knew I already had an APR Stage 1 flash in it. That gave me access to the other octane choices available for Stage 1 at no charge. So after selecting Stage 1, it showed me those options:
I went with 93 octane, up from my current 91. The plan is to run here for a bit until I fill it with 100 octane and then try that one out. It’s great that I can go back and forth, and even back to stock, with no fuss. Love it!
I was hooked up to a charger, but turns out it only took 4 minutes to flash. For safety, it does a voltage check before letting you flash:
And once the flash I done you get this confirmation screen:
One final nice feature is the website will keep track of your history, letting you know when and which flashes your car has seen:
Driving impressions will come shortly, so stay tuned (pun intended)
Thanks for the detailed summary for APR tuning process. I tried there website for 991.2T ultra link tune, but couldn't find the price. Also is "ethanol" tune a E85 tune? That could be fun 😊.
05-08-2024 | 02:44 PM
