It's fast
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Joined: Apr 2013
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What I want to know is simple, and I ask because I'm interested in the subject of what makes a car faster than another. Which components of the ACR deserve the most credit for allowing it to best the previously quickest cars around MRLS and other tracks? I previously pointed out (hopefully with some level of accuracy) that the downforce of the ACR is in the same ballpark as the P1. And the data points in the Motortrend analysis show that the ACR is braking later and pulling more lateral G's than either the 918 or P1. Enough to actually overcome the huge power deficit on the straights. I find it hard to believe that the brakes on a $120k car are more effective or advanced than those on million dollar hypercars, so my gut tells me it must be the tires that give the ACR the edge in braking as well as cornering. Or at least the tires are a big part of the equation.
Again, I'm curious what others think about this. I acknowledge that tires are not an excuse for making a production car faster (or slower) than another, since tires are a crucial component of the engineering that goes into a performance car. If you make a very fast car and then give it hardened dog turds for tires (like the base Continentals on the new NSX) then that's too bad for you.
Joined: Aug 2005
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Okay I see what you mean, now.
I'd say that the single biggest factor is the tuning of all the parts to work in unison. It's relatively light, produces considerable downforce, has a long wheelbase, a wide track, a low center of gravity, and all the rest, but it's the way that it all works together that makes it so awesome.
A good analogy would be the 911 GT3 RSRs that used to race in the ALMS. They were the knife brought to the gun fight. Down on power, not the best weight distribution (unless we're talking braking and acceleration), small engines, large frontal area, less than stellar dimensions, mac struts, unibody chassis, etc., yet they won consistently. The reason for this is Porsche's ability to make the simple recipe work perfectly while everyone else had a more complex recipe. Every car in their field was more car on paper.
I'd say that the single biggest factor is the tuning of all the parts to work in unison. It's relatively light, produces considerable downforce, has a long wheelbase, a wide track, a low center of gravity, and all the rest, but it's the way that it all works together that makes it so awesome.
A good analogy would be the 911 GT3 RSRs that used to race in the ALMS. They were the knife brought to the gun fight. Down on power, not the best weight distribution (unless we're talking braking and acceleration), small engines, large frontal area, less than stellar dimensions, mac struts, unibody chassis, etc., yet they won consistently. The reason for this is Porsche's ability to make the simple recipe work perfectly while everyone else had a more complex recipe. Every car in their field was more car on paper.
Joined: Nov 2007
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From: SoFlo
The P1 produces 600 kg (1322 lbs) of downforce at 160 mph. The ACR produces 1800 lbs at 177 mph. I'm no physics expert but isn't downforce loosely proportional to velocity squared? In which case the ACR produces ~22% more downforce at 177 mph than it does at 160 mph, meaning it should produce around 1470 lbs at 160 mph. That's sort of in the same ballpark as the P1, which leads me to believe the tires (size, compound, or both) perhaps give the ACR as much (or more) of an edge vs downforce.
Purely conjecture but it's very interesting to think about.
Purely conjecture but it's very interesting to think about.
So it's hard to compare the P1 & ACR's quoted DF numbers. Because the ACR has serious gains above 75mph and similar cornering speeds below 75mph, I would still guess it has an aero advantage, especially when you consider the cord length and span of the ACR's wing vs. the P1, let alone the splitter and dive planes. Visually the ACR makes more DF.
Okay I see what you mean, now.
I'd say that the single biggest factor is the tuning of all the parts to work in unison. It's relatively light, produces considerable downforce, has a long wheelbase, a wide track, a low center of gravity, and all the rest, but it's the way that it all works together that makes it so awesome.
A good analogy would be the 911 GT3 RSRs that used to race in the ALMS. They were the knife brought to the gun fight. Down on power, not the best weight distribution (unless we're talking braking and acceleration), small engines, large frontal area, less than stellar dimensions, mac struts, unibody chassis, etc., yet they won consistently. The reason for this is Porsche's ability to make the simple recipe work perfectly while everyone else had a more complex recipe. Every car in their field was more car on paper.
I'd say that the single biggest factor is the tuning of all the parts to work in unison. It's relatively light, produces considerable downforce, has a long wheelbase, a wide track, a low center of gravity, and all the rest, but it's the way that it all works together that makes it so awesome.
A good analogy would be the 911 GT3 RSRs that used to race in the ALMS. They were the knife brought to the gun fight. Down on power, not the best weight distribution (unless we're talking braking and acceleration), small engines, large frontal area, less than stellar dimensions, mac struts, unibody chassis, etc., yet they won consistently. The reason for this is Porsche's ability to make the simple recipe work perfectly while everyone else had a more complex recipe. Every car in their field was more car on paper.
0.02
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Joined: Aug 2008
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From: Philly Burbs
Originally Posted by Zygrene' timestamp='1447131113' post='23799593
The P1 produces 600 kg (1322 lbs) of downforce at 160 mph. The ACR produces 1800 lbs at 177 mph. I'm no physics expert but isn't downforce loosely proportional to velocity squared? In which case the ACR produces ~22% more downforce at 177 mph than it does at 160 mph, meaning it should produce around 1470 lbs at 160 mph. That's sort of in the same ballpark as the P1, which leads me to believe the tires (size, compound, or both) perhaps give the ACR as much (or more) of an edge vs downforce.
Purely conjecture but it's very interesting to think about.
Purely conjecture but it's very interesting to think about.
So it's hard to compare the P1 & ACR's quoted DF numbers. Because the ACR has serious gains above 75mph and similar cornering speeds below 75mph, I would still guess it has an aero advantage, especially when you consider the cord length and span of the ACR's wing vs. the P1, let alone the splitter and dive planes. Visually the ACR makes more DF.
Okay I see what you mean, now.
I'd say that the single biggest factor is the tuning of all the parts to work in unison. It's relatively light, produces considerable downforce, has a long wheelbase, a wide track, a low center of gravity, and all the rest, but it's the way that it all works together that makes it so awesome.
A good analogy would be the 911 GT3 RSRs that used to race in the ALMS. They were the knife brought to the gun fight. Down on power, not the best weight distribution (unless we're talking braking and acceleration), small engines, large frontal area, less than stellar dimensions, mac struts, unibody chassis, etc., yet they won consistently. The reason for this is Porsche's ability to make the simple recipe work perfectly while everyone else had a more complex recipe. Every car in their field was more car on paper.
I'd say that the single biggest factor is the tuning of all the parts to work in unison. It's relatively light, produces considerable downforce, has a long wheelbase, a wide track, a low center of gravity, and all the rest, but it's the way that it all works together that makes it so awesome.
A good analogy would be the 911 GT3 RSRs that used to race in the ALMS. They were the knife brought to the gun fight. Down on power, not the best weight distribution (unless we're talking braking and acceleration), small engines, large frontal area, less than stellar dimensions, mac struts, unibody chassis, etc., yet they won consistently. The reason for this is Porsche's ability to make the simple recipe work perfectly while everyone else had a more complex recipe. Every car in their field was more car on paper.
0.02
Joined: Aug 2005
Posts: 6,281
Likes: 119
Originally Posted by Zygrene' timestamp='1447131113' post='23799593
The P1 produces 600 kg (1322 lbs) of downforce at 160 mph. The ACR produces 1800 lbs at 177 mph. I'm no physics expert but isn't downforce loosely proportional to velocity squared? In which case the ACR produces ~22% more downforce at 177 mph than it does at 160 mph, meaning it should produce around 1470 lbs at 160 mph. That's sort of in the same ballpark as the P1, which leads me to believe the tires (size, compound, or both) perhaps give the ACR as much (or more) of an edge vs downforce.
Purely conjecture but it's very interesting to think about.
Purely conjecture but it's very interesting to think about.
So it's hard to compare the P1 & ACR's quoted DF numbers. Because the ACR has serious gains above 75mph and similar cornering speeds below 75mph, I would still guess it has an aero advantage, especially when you consider the cord length and span of the ACR's wing vs. the P1, let alone the splitter and dive planes. Visually the ACR makes more DF.
Okay I see what you mean, now.
I'd say that the single biggest factor is the tuning of all the parts to work in unison. It's relatively light, produces considerable downforce, has a long wheelbase, a wide track, a low center of gravity, and all the rest, but it's the way that it all works together that makes it so awesome.
A good analogy would be the 911 GT3 RSRs that used to race in the ALMS. They were the knife brought to the gun fight. Down on power, not the best weight distribution (unless we're talking braking and acceleration), small engines, large frontal area, less than stellar dimensions, mac struts, unibody chassis, etc., yet they won consistently. The reason for this is Porsche's ability to make the simple recipe work perfectly while everyone else had a more complex recipe. Every car in their field was more car on paper.
I'd say that the single biggest factor is the tuning of all the parts to work in unison. It's relatively light, produces considerable downforce, has a long wheelbase, a wide track, a low center of gravity, and all the rest, but it's the way that it all works together that makes it so awesome.
A good analogy would be the 911 GT3 RSRs that used to race in the ALMS. They were the knife brought to the gun fight. Down on power, not the best weight distribution (unless we're talking braking and acceleration), small engines, large frontal area, less than stellar dimensions, mac struts, unibody chassis, etc., yet they won consistently. The reason for this is Porsche's ability to make the simple recipe work perfectly while everyone else had a more complex recipe. Every car in their field was more car on paper.
0.02
I wasn't comparing it to anything, just saying that those are its characteristics and that they all work together. However, I think you may be looking at inaccurate weight figures for the P1. Weight figures of cars are all suspect, but I've seen the P1 quoted as having a dry weight in the neighborhood of what you're suggesting. Again, though, I wasn't comparing the two.
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Joined: Mar 2014
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The brakes got huge kudos from both car and driver and R&T, but I believe they were more responding to just how well the whole thing works together. On tighter tracks the cornering speeds and braking distances were much more on par with a normal car, like Z07 Z06 for example.
The most interesting thing about the R&T article (performance car of the year, where the viper finished second to the new mustang 350R or whatever it's called) was the editor and other drivers all agreed that only the viper felt like it could continue at the pace it set lap after lap. It's hard to be the fastest and the most reliable (in the sense of overall reliability and reliably producing consistent lap times). I think this is the real 'trick' of the acr....it's not a one lap wonder. It's a, run it until it runs out of gas wonder.