Viper ACR vs GT2 RS stock to stock on same rubber at Thunder Hill

[Snakebit10]

The first vid was out for a while. The second one with the data just dropped 2 weeks ago. Very interesting and backs up the European test between these two beasts. Tracks with lots of long straights, the GT2 RS will win. Tracks with lots of turns, medium straights and more technical, the Viper will win. You might recognize the players.

Part 1:
https://www.youtube.com/watch?v=e0_FxDu8NFQ

Part 2:
https://www.youtube.com/watch?v=rIZPmteNpEs

European test from a few years ago at Zolder:
https://www.youtube.com/watch?v=-4Mh-Y9h1y4

[ViperNC]

Fun facts and fun to watch.

[Exhlr8n]

Thanks for making the Video and sharing..! Looks like a blast. Hope to get back to Thunderhill soon (it's been years).

Great job representing the Snake Todd!

[mikesax]

Todd always has a blast on the track! Great VIDS !

[Lawineer]

Why did the ACR have iron rotors (2:43 in part 2). Was that an option? Weight savings of CCB is a decent edge for a pro driver.

Kind of odd they went with 315/345 tires on the Viper, and I dont know why they wouldn't get a little more seat time with the Viper so it was equal (they said they drove the Porsche harder because they had got more sessions with it to get comfortable).

Super fun video to watch though! Crazy how much ground the GT2 makes up due to ACR drag.

[Snakebit10]

But, if the ACR-E was a decent bit faster on Thunderhill with much less seat time, not the best tire size, iron rotors and all that drag, then its a good thing for the GT2 RS lol.

I would love to see what a bone stock ACR-E would do with an good DCT only addition. Even the least powerful GT3 Porsches and the S models leave the Vipers for dead on the straights. Two great cars though and it was a pleasure seeing this comparo. Cant go wrong with either for track duty.

[Bill Pemberton]

Pretty simple why the ACR has iron rotors, more availability of tire sizes as one can even fit an 18 inch rim up front. Kumhos up front on 19s were limiting tire choices and many with CFRs have purchased custom wheels for varying tire choices.

Kumhos have not been the most reliable tire in having supplies over the last decade or more, imho.

[Lawineer]

Well the front tires are 20mm wider and rear are 10mm narrower, IIRC. So overall, more rubber and I'd imagine it benefits more from more up front. Probably a wash with the loss from iron rotors or close to. But running 75% instead of 85% is probably a good bit of difference there.

That GT2 really made up a lot on the straights. I wonder if the ACR (non-E) or a TA would have been faster.

[Scott_in_fl]

Great videos! Any time that we can see our Vipers hanging right there with the best that anyone else can offer, it says a ton about how this car was designed. Both cars are beasts on a racetrack.

I've commented in the past that this is how track tests should be performed (same tire, same track, alternating experienced drivers) as this is how they test sportbikes (and have forever).

Now I'd like to see the NFGT do a similar test. I still feel like that car has been all looks and only middling track ability (Ford marketing trying to convince everyone that their V-6 decisions into the GT and the Raptor were anything other than abysmal decisions has been laughable, imo).

[Snakebit10]

That GT2 really made up a lot on the straights. I wonder if the ACR (non-E) or a TA would have been faster.

I doubt the non-E or TA would have been faster on this track than the ACR-E or the GT2. The Viper ran away from the Porsche in the turns while the Porsche caught up on the straights. The ACR-E df is responsible for that. TheGT2 RS would probably have kept up with the TA and non-E in the turns and then monstered them on the straights. GT2 should win on this track against any non ACR-E Viper in a test like this imho.

[TheWessss]

Love that track!!!

[Scott_in_fl]

I doubt the non-E or TA would have been faster on this track than the ACR-E or the GT2. The Viper ran away from the Porsche in the turns while the Porsche caught up on the straights. The ACR-E df is responsible for that. TheGT2 RS would probably have kept up with the TA and non-E in the turns and then monstered them on the straights. GT2 should win on this track against any non ACR-E Viper in a test like this imho.

Agreed, and this is supported by test data from lots of tracks. The ACR-E is a record holder at many road courses because of its df. Non-E's and TA's have been driven at similar tracks, by competent drivers, and cannot get close to the ACR-E time. Laguna is one very evident example with Randy Probst driving both.

[Arizona Vipers]

Agreed, and this is supported by test data from lots of tracks. The ACR-E is a record holder at many road courses because of its df. Non-E's and TA's have been driven at similar tracks, by competent drivers, and cannot get close to the ACR-E time. Laguna is one very evident example with Randy Probst driving both.

The ACR is the record holder at all these tracks because Porsche doesn't take their cars there hehe.
Don't forget, the Kumho's are worth 2-3 seconds over the "normal" Pirelli's on the other Vipers.

[finalleaf]

fyi TA1 with slicks did 1:30.78 at laguna seca (3 seconds faster than the corsas), so still a couple seconds slower than ACR with kumhos but closes the gap quite a bit

[Cody's Car Conundrum]

fyi TA1 with slicks did 1:30.78 at laguna seca (3 seconds faster than the corsas), so still a couple seconds slower than ACR with kumhos but closes the gap quite a bit

Can confirm. It was part of the Motor Trend magazine issue featuring the Gen V TA back in... I want to say early 2014. I'll get a picture of the issue and the sentence when I have time. I want to add that, theoretically, a Gen V GTS or SRT on the same slicks could be in the high 1:31s or low 1:32s based on how the TA did (both with the slicks and the corsas). Which would put those no-aero Gen Vs right with the very aero'd C7 ZR1 :cool: . Granted Randy's run with the ZR1 likely wasn't a full balls-to-the-wall manufacturer effort.

[finalleaf]

Can confirm. It was part of the Motor Trend magazine issue featuring the Gen V TA back in... I want to say early 2014. I'll get a picture of the issue and the sentence when I have time. I want to add that, theoretically, a Gen V GTS or SRT on the same slicks could be in the high 1:31s or low 1:32s based on how the TA did (both with the slicks and the corsas). Which would put those no-aero Gen Vs right with the very aero'd C7 ZR1 :cool: . Granted Randy's run with the ZR1 likely wasn't a full balls-to-the-wall manufacturer effort.

from what I heard from my friend who was volunteering at Laguna, the ZR1 actually ran a sub 30 afterwards, but unfortunately didn't comply with the hotlap rules of "best drivers car". Meanwhile I'm just happy I was able to get my GTS into the 39s my first time out :'(

[Cody's Car Conundrum]

from what I heard from my friend who was volunteering at Laguna, the ZR1 actually ran a sub 30 afterwards, but unfortunately didn't comply with the hotlap rules of "best drivers car". Meanwhile I'm just happy I was able to get my GTS into the 39s my first time out :'(

Well thanks for making me look like a fool :slap: :lol2: . Glad to hear the ZR1 did run a better time though! It never sat right with me that the C7 ZR1 was only a second and a bit faster than the C6 ZR1.

Hey! That's a very respectable time for your first time out IMHO! The corkscrew is no joke and Lagaun ain't a grippy track.

[Scott_in_fl]

Gotta say that, looking back at some of these old articles, whoever at FCA came up with the idea of running around the country every couple of weeks to hot lap the car, was a freakin' genius. These records are still pretty damn amazing, at some pretty damn amazing tracks.

52538

[Snakebit10]

The ACR is the record holder at all these tracks because Porsche doesn't take their cars there hehe.
Don't forget, the Kumho's are worth 2-3 seconds over the "normal" Pirelli's on the other Vipers.

If you look at the non-ring tracks the GT2 RS and ACR ran on, you will see nigh equal times, some favoring the GT2 RS and some favoring the ACR, depending on track figuration. For instance, look at the Zolder vid I posted and the Laguna times. In both those tests, each car was on different rubber, the GT2 being on newer, better rubber. The GT2 has a faster time on both those tracks but its literally by 1-2 tenths, which is too close to say either one can't beat the other. That could just be a tire choice variable or just taking a turn slightly better and either could be the victor.

The Laguna and Zolder test was not on equal rubber like this test Todd put on so this test speaks volumes about both cars strengths and weaknesses one toward the other. Long fast tracks the ACR doesn't have a chance since the delta between the acceleration is much greater than the delta between the handling. But on tracks like TH, the ACR will clearly win, given equal rubber.

[Arizona Vipers]

fyi TA1 with slicks did 1:30.78 at laguna seca (3 seconds faster than the corsas), so still a couple seconds slower than ACR with kumhos but closes the gap quite a bit

Was that with Pobst driving?

[finalleaf]

Was that with Pobst driving?

yup, the same day when the TA1 set the lap record (with the corsas), they decided to throw on slicks just to see what happens

at the end of this article they mention it
https://www.motortrend.com/reviews/2014-srt-viper-ta/

[Lawineer]

If you look at the non-ring tracks the GT2 RS and ACR ran on, you will see nigh equal times, some favoring the GT2 RS and some favoring the ACR, depending on track figuration. For instance, look at the Zolder vid I posted and the Laguna times. In both those tests, each car was on different rubber, the GT2 being on newer, better rubber. The GT2 has a faster time on both those tracks but its literally by 1-2 tenths, which is too close to say either one can't beat the other. That could just be a tire choice variable or just taking a turn slightly better and either could be the victor.

The Laguna and Zolder test was not on equal rubber like this test Todd put on so this test speaks volumes about both cars strengths and weaknesses one toward the other. Long fast tracks the ACR doesn't have a chance since the delta between the acceleration is much greater than the delta between the handling. But on tracks like TH, the ACR will clearly win, given equal rubber.

Even a pro will have laps vary by more than a tenth or two. Heck, the track can speed up/slow down by a full second, easily, within an hour or two.

Goes to show you how fickle the Lightning Lap times are. Their drivers (editors, not pros) were a full 4 seconds off the pace of a pro. Now, that's not to say they're not good drivers (that's pretty good for an am), but they're definitely a gentleman driver in a real race and probably not super consistent like a pro.

[Arizona Vipers]

Even a pro will have laps vary by more than a tenth or two. Heck, the track can speed up/slow down by a full second, easily, within an hour or two.

Goes to show you how fickle the Lightning Lap times are. Their drivers (editors, not pros) were a full 4 seconds off the pace of a pro. Now, that's not to say they're not good drivers (that's pretty good for an am), but they're definitely a gentleman driver in a real race and probably not super consistent like a pro.

My car is always around 2 seconds faster first session, versus end of the day 20-30* hotter, same as most cars. I don't even do any sessions after the first one as I know I won't go faster unless it's a new track that I'm learning.

[Lawineer]

I’m often fastest in my second session. Track warms up a bit, lay some rubber down and work some rust off. But, same for me. 8am session to 4pm session is typically 2 sec

[serpent]

The ACR is the record holder at all these tracks because Porsche doesn't take their cars there hehe.
Don't forget, the Kumho's are worth 2-3 seconds over the "normal" Pirelli's on the other Vipers.
I'd love to see what Jeff Cook (driver in this video) can do in the ACR with the Cup2R that are magical on Porsches and the AMG GT Black Series.

At the 5 minute mark in the part 2 video the Cup2 R are 1-1.5 seconds faster than the R7. The Kumhos are .1-.2 seconds faster than the R7. I wonder if the Cup2R are capable of running 1:27s at LS in the ACR.

[ACRSNK]

Cool videos!

[Arizona Vipers]

I'd love to see what Jeff Cook (driver in this video) can do in the ACR with the Cup2R that are magical on Porsches and the AMG GT Black Series.

At the 5 minute mark in the part 2 video the Cup2 R are 1-1.5 seconds faster than the R7. The Kumhos are .1-.2 seconds faster than the R7. I wonder if the Cup2R are capable of running 1:27s at LS in the ACR.

Yeah those tires are nuts, it's why the GT3 took such a leap in time at the Nurburgring. If they are worth 1.5 seconds over an R7 at Laguna, they'd be 7+ seconds at the 'Ring over R7's.

[Lawineer]

Yeah those tires are nuts, it's why the GT3 took such a leap in time at the Nurburgring. If they are worth 1.5 seconds over an R7 at Laguna, they'd be 7+ seconds at the 'Ring over R7's.

They're kind of bullshit tires from what I've read. After 3-4 laps at most tracks, they overheat and get greasy. They're hero lap tires.
I'd imagine on something like an ACR with 2-3x the downforce, it wouldnt last long at all.

It would be cool if all spec races went to the same tire (just different sizes) and they became a "benchmark" tire.

[13COBRA]

They're kind of bullshit tires from what I've read. After 3-4 laps at most tracks, they overheat and get greasy. They're hero lap tires.
I'd imagine on something like an ACR with 2-3x the downforce, it wouldnt last long at all.

It would be cool if all spec races went to the same tire (just different sizes) and they became a "benchmark" tire.


I believe they do this with motorcycles, as far as lap comparisons go.

[Lawineer]

I believe they do this with motorcycles, as far as lap comparisons go.

That's nice. Though, motorcycles are probably a lot easier since they all have the same size wheel and, within a class (600, 1000, etc) same size tire.

[13COBRA]

That's nice. Though, motorcycles are probably a lot easier since they all have the same size wheel and, within a class (600, 1000, etc) same size tire.

Correct! Just making a statement haha

I don't care on cars if they're the same size or not, but the same compound would be ideal.

[Lawineer]

Correct! Just making a statement haha

I don't care on cars if they're the same size or not, but the same compound would be ideal.

Yeah, I just meant in terms of logistics and availability.

Given the countless size combinations for width, aspect ratio and rim size, it would be near impossible to ever execute. Cars in the Lightning Lap probably range from 17" wheel to 21" wheel, 245 width to 345 width, all kinds of aspect ratios and etc. I doubt any two cars even have the same size tire most years. And on top of that, everyone has a different offset, lug pattern, etc so you couldn't even try to get a few different wheels with different widths (ie: a bunch of 19s).

Stinks that it's so impractical, but it sure would be nice.