APR Stage 2 with Stock Turbos?
03-29-2022, 12:48 PM
#11
Super-Duper User
Thread Starter
I don't know if this helps, but a few fellow members and I recently had our cars dyno’d.
Mine is a 2016 S8 Plus with the APR Stage One tune (that’s all, no HW changes). I was using Costco 93 octane fuel and here is the result: 586hp & 674 ft-lb of torque.
Randy’s is a 2016 S8 Plus with the APR Stage Two tune (downpipes and using 100 octane fuel map). His result was: 661hp & 674 ft-lb of torque.
Here is a link to APR’s website specifically for a 2013 A8 4.0: https://www.goapr.com/products/softw...U-40T-EA824-A8
The horsepower will jump around 110 over stock, but the torque jumps 185 ft-lbs. This will DEFINITELY push you in the seat when the throttle is matted! My recommendation is get the APR Stage One tune (it’s only $799) and see how you like it. If it is still not enough, then move to Stage Two.
Mine is a 2016 S8 Plus with the APR Stage One tune (that’s all, no HW changes). I was using Costco 93 octane fuel and here is the result: 586hp & 674 ft-lb of torque.
Randy’s is a 2016 S8 Plus with the APR Stage Two tune (downpipes and using 100 octane fuel map). His result was: 661hp & 674 ft-lb of torque.
Here is a link to APR’s website specifically for a 2013 A8 4.0: https://www.goapr.com/products/softw...U-40T-EA824-A8
The horsepower will jump around 110 over stock, but the torque jumps 185 ft-lbs. This will DEFINITELY push you in the seat when the throttle is matted! My recommendation is get the APR Stage One tune (it’s only $799) and see how you like it. If it is still not enough, then move to Stage Two.
Thanks Dave. I thought you knew I had APR Stage 1 from my sig. I was probably their last customer at $1500 before the price dropped
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It would be most interesting to see the results if you both use the same fuel!
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Last edited by A8L_New_England; 03-29-2022 at 12:53 PM.
03-29-2022, 01:19 PM
#12
Super-Duper User
Thread Starter
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I am in fact in a CARB state, Massachusetts. It's part of my reasoning to stick with cats, and I prefer to avoid the Ricky Racer style engine compartment to retain saleability of the car.
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The other reason I'm holding off on hardware mods is that there is plenty of additional performance to be had without doing any. One post comes to mind where the (seemingly authoritative) author stated that the stock downpipes were more than adequate for up to 650 HP. Another post stuck in my memory is one where the author complemented VAG for particularly good intake performance. I have some experience with intake design, and may implement something there, though.
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Yes, I get that about the DS1. Sorry for the imprecise language. I haven't gotten my feet wet yet, though, and will dig into it soon!
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Gentlemen, thanks for your input, as usual.
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I am in fact in a CARB state, Massachusetts. It's part of my reasoning to stick with cats, and I prefer to avoid the Ricky Racer style engine compartment to retain saleability of the car.
.
The other reason I'm holding off on hardware mods is that there is plenty of additional performance to be had without doing any. One post comes to mind where the (seemingly authoritative) author stated that the stock downpipes were more than adequate for up to 650 HP. Another post stuck in my memory is one where the author complemented VAG for particularly good intake performance. I have some experience with intake design, and may implement something there, though.
.
Yes, I get that about the DS1. Sorry for the imprecise language. I haven't gotten my feet wet yet, though, and will dig into it soon!
.
Gentlemen, thanks for your input, as usual.
.
03-30-2022, 12:06 AM
#13
AudiWorld Senior Member
I don't know if this helps, but a few fellow members and I recently had our cars dyno’d.
Mine is a 2016 S8 Plus with the APR Stage One tune (that’s all, no HW changes). I was using Costco 93 octane fuel and here is the result: 586hp & 674 ft-lb of torque.
Randy’s is a 2016 S8 Plus with the APR Stage Two tune (downpipes and using 100 octane fuel map). His result was: 661hp & 674 ft-lb of torque.
Mine is a 2016 S8 Plus with the APR Stage One tune (that’s all, no HW changes). I was using Costco 93 octane fuel and here is the result: 586hp & 674 ft-lb of torque.
Randy’s is a 2016 S8 Plus with the APR Stage Two tune (downpipes and using 100 octane fuel map). His result was: 661hp & 674 ft-lb of torque.
03-30-2022, 07:45 AM
#14
Super-Duper User
Thread Starter
03-30-2022, 09:09 AM
#15
AudiWorld Senior Member
I agree, but time didn't permit us to do so. We were all limited to three "pulls" and there were quite a few of us there.
03-30-2022, 11:43 AM
#16
AudiWorld Senior Member
These are very different cars.. I dont do ricer math.. I am not requesting further testing either... 80HP up top with downpipes installed sounds good but we cant just say its the one piece that's making the power..
03-30-2022, 12:21 PM
#17
Moderator
Downpipes and Tuning! "100 octane fuel map" equals he used race gas right? Running race cats right
These are very different cars.. I dont do ricer math.. I am not requesting further testing either... 80HP up top with downpipes installed sounds good but we cant just say its the one piece that's making the power..
These are very different cars.. I dont do ricer math.. I am not requesting further testing either... 80HP up top with downpipes installed sounds good but we cant just say its the one piece that's making the power..
03-30-2022, 02:33 PM
#18
W12 Aficionado
You don’t exactly gain power by removing the downpipes alone. It will shift the torque curve as the turbos can spool faster, but the tune must reflect the hardware change to take advantage of it. Same as bigger turbos or race fuel, they work in tandem with software and not alone
Going purely on what Unitronic offers for the A8’s version of the 4.0T the downpipe gets you +14hp and +51lb-ft.
What’s much more important is how that power is delivered. That extra 51lb-ft is available by about the same time as stage 1 peak torque but now we don’t have a dip directly following peak torque (stage 1 looks like it hits peak torque then drops about 30lb-ft right away. So at 3,500 rpm the stage 2 has ~80lb-ft more than stage 1 and 134 more than stock). Instead the curve has a very gradual taper with almost peak torque lasting through 4,500. This is going to pull noticeably smoother and harder.
I reread the initial question. Is factory downpipe sufficient for a stage 2 tune.. well, no. If you don’t have hardware changes then you only have a stage 1 tune. You can get a custom stage 1 tune but you’ll only go so far. Either your torque curve gets super funky, or you run into reliability issues (super high boost, for example)
Perhaps the question is: what is peak power to be had on custom stage 1 tune vs OTS stage 2 tune with supporting hardware? Even if we could ascertain what the max power is, without the graph we don’t know how it’s going to perform. If the power isn’t where we can use it, and doesn’t last, then we have a slower car. The DP removal is key for flattening the curve. As it’s been said, inlets are beneficial mods too. Even if there was zero peak power gain with the downpipes then the open DP car will still be faster because it has more power more of the time.
I swear I never set out to type so much every time I go to respond…
Going purely on what Unitronic offers for the A8’s version of the 4.0T the downpipe gets you +14hp and +51lb-ft.
What’s much more important is how that power is delivered. That extra 51lb-ft is available by about the same time as stage 1 peak torque but now we don’t have a dip directly following peak torque (stage 1 looks like it hits peak torque then drops about 30lb-ft right away. So at 3,500 rpm the stage 2 has ~80lb-ft more than stage 1 and 134 more than stock). Instead the curve has a very gradual taper with almost peak torque lasting through 4,500. This is going to pull noticeably smoother and harder.
I reread the initial question. Is factory downpipe sufficient for a stage 2 tune.. well, no. If you don’t have hardware changes then you only have a stage 1 tune. You can get a custom stage 1 tune but you’ll only go so far. Either your torque curve gets super funky, or you run into reliability issues (super high boost, for example)
Perhaps the question is: what is peak power to be had on custom stage 1 tune vs OTS stage 2 tune with supporting hardware? Even if we could ascertain what the max power is, without the graph we don’t know how it’s going to perform. If the power isn’t where we can use it, and doesn’t last, then we have a slower car. The DP removal is key for flattening the curve. As it’s been said, inlets are beneficial mods too. Even if there was zero peak power gain with the downpipes then the open DP car will still be faster because it has more power more of the time.
I swear I never set out to type so much every time I go to respond…
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03-30-2022, 02:42 PM
#19
Super-Duper User
Thread Starter
03-30-2022, 02:55 PM
#20
Super-Duper User
Thread Starter
You don’t exactly gain power by removing the downpipes alone. It will shift the torque curve as the turbos can spool faster, but the tune must reflect the hardware change to take advantage of it. Same as bigger turbos or race fuel, they work in tandem with software and not alone. Going purely on what Unitronic offers for the A8’s version of the 4.0T the downpipe gets you +14hp and +51lb-ft. What’s much more important is how that power is delivered. That extra 51lb-ft is available by about the same time as stage 1 peak torque but now we don’t have a dip directly following peak torque (stage 1 looks like it hits peak torque then drops about 30lb-ft right away. So at 3,500 rpm the stage 2 has ~80lb-ft more than stage 1 and 134 more than stock). Instead the curve has a very gradual taper with almost peak torque lasting through 4,500. This is going to pull noticeably smoother and harder. I reread the initial question. Is factory downpipe sufficient for a stage 2 tune.. well, no. If you don’t have hardware changes then you only have a stage 1 tune. You can get a custom stage 1 tune but you’ll only go so far. Either your torque curve gets super funky, or you run into reliability issues (super high boost, for example) Perhaps the question is: what is peak power to be had on custom stage 1 tune vs OTS stage 2 tune with supporting hardware? Even if we could ascertain what the max power is, without the graph we don’t know how it’s going to perform. If the power isn’t where we can use it, and doesn’t last, then we have a slower car. The DP removal is key for flattening the curve. As it’s been said, inlets are beneficial mods too. Even if there was zero peak power gain with the downpipes then the open DP car will still be faster because it has more power more of the time.
So much there, and thank you. But cutting to the chase, I need to stick with cats, and believe they are good for a decent flat torque curve within my target. DP removal is crucial for lower exhaust backpressure, of course, but I don't think that it will come into play for this project. I am going to have a good hard look at the intake, though.
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