Opinions wanted on 9L and ACR

[38D]

So I am considering doing the 9L or 9L extreme upgrade to my 2016 ACR-E. Has anyone who tracks an ACR done this upgrade? I’m specifically wondering what it does to the balance of the car. I find the car to be very easy to drive and very well balanced...I don’t want to kill this by adding power. Also wondering if this hurts the functionality of the traction control at all (all the modes). How about tire wear (which is already horrid with the Kuhmos)?

Also, what do folks think this would do to the long term value of the car?

[ACRSNK]

Not sure of anything else you asked, but as to long term value, I bet it would take away from the same just like it always does. People that collect cars love to have them stock.

[Jack B]

So I am considering doing the 9L or 9L extreme upgrade to my 2016 ACR-E. Has anyone who tracks an ACR done this upgrade? I’m specifically wondering what it does to the balance of the car. I find the car to be very easy to drive and very well balanced...I don’t want to kill this by adding power. Also wondering if this hurts the functionality of the traction control at all (all the modes). How about tire wear (which is already horrid with the Kuhmos)?

Also, what do folks think this would do to the long term value of the car?

1. You will pull better in 4th/5th gear.

2. You may be able use a higher gear at low speeds, therefore, shifting less.

3. isn't most tire wear on the fronts. therefore, any change would be minimal.

You should contact Arizona Viper, he has the 9 liter.

[ViperGeorge]

I've been interested in this as well. As to value, mods typically DO NOT ADD value to the car when selling unless you happen to find a buyer that wants the exact mods you have. Usually buyers look at mods as a detraction not a plus. Ask Bill Pemberton, he will tell you the same thing. If you are worried about resale don't mod it unless the mod is easy to reverse.

[Terminator02]

These are packages not some random mods. A TT Viper will sell more than a 9L And the 9 more than HC. There is plenty of interest in these setups. Random mods, I agree do not have ROI. We have had HC vipers sell already and they were at premium no doubt. A white TA HC car went about 10k over average white TA cars and if anything the argument would be stronger of how modding a limited edition would lower value. Maybe long term value will be lower at BJ.

[stradman]

Agree more or less with a lot of the comments. My ACR is a track slag and I'm getting Prefix to do the 9L along with a few other mods to optimise car on track in a couple of months. I'm pretty sure I'm not going to get my money back after doing all that. But I don't care because car will be awesome and I'm not planning on selling anytime soon. I am fed up of Mclarens, Porsches having more grunt than me in the straight(Ok i know I have them in the twisty bits and ultimately will set a better lap time, but still can't stand the sight of them leaving me in the dust in the straights). And remember there are more and more cars coming out that can outpower us in the straights. So need a bit more under the hood imv.
Have a look at me during a dual with a 675LT(which is a bit slower than a 720s) and you'll understand. Don't even want to talk about the new GT2RS or Ferrari Pista coming....

[Bruce H.]

My ACR is a track slag and I'm getting Prefix to do the 9L along with a few other mods to optimise car on track in a couple of months.

I'd be very interested to hear your strategy to optimize performance, perhaps in a future thread so as not to derail this one. I think the most significant challenges are non-power related, and see that in your video. Hope to see you and others blaze new trails!

[stradman]

I'd be very interested to hear your strategy to optimize performance, perhaps in a future thread so as not to derail this one. I think the most significant challenges are non-power related, and see that in your video. Hope to see you and others blaze new trails!

Yeah well I'll keep it brief. Along with the 9 Liter, obviously fifth gear needs to be altered as will the final drive. Will also change to Nth moto clutch, Wavetrac LSD, and Accusump(to avoid draining oil too much in those high speed long left and right hand turns). And will of course continue to improve my driving skills hopefully too!

[q8blueviper]

Agree more or less with a lot of the comments. My ACR is a track slag and I'm getting Prefix to do the 9L along with a few other mods to optimise car on track in a couple of months.

enjoyed the video every bit of it ...... thumps up and nice driving

[Jack B]

Yeah well I'll keep it brief. Along with the 9 Liter, obviously fifth gear needs to be altered as will the final drive. Will also change to Nth moto clutch, Wavetrac LSD, and Accusump(to avoid draining oil too much in those high speed long left and right hand turns). And will of course continue to improve my driving skills hopefully too!

My 0.8 fifth and 0.5 sixth gears have just come in, should have the trans installed soon. I do not know if i was running out of fuel or it was just the wind resistance, but, the WOT shift into fifth seemed to slow the car down. Have Prefix add the high volume fuel pump when your car is there. I have the new pump and will install it once I have the trans back in.

[stradman]

My 0.8 fifth and 0.5 sixth gears have just come in, should have the trans installed soon. I do not know if i was running out of fuel or it was just the wind resistance, but, the WOT shift into fifth seemed to slow the car down. Have Prefix add the high volume fuel pump when your car is there. I have the new pump and will install it once I have the trans back in.

Thanks Jack. Will do. Cheers

[Scot@Prefix]

Thanks Jack. Will do. Cheers

Alex, the high volume fuel pump comes standard with the xtreme package!

[stradman]

Alex, the high volume fuel pump comes standard with the xtreme package!

Thanks Scot. So can I ask in the viper is there ever a need for a fuel surge or swirl pot tank for track work? Cheers Alex

[ayousef]

Yeah well I'll keep it brief. Along with the 9 Liter, obviously fifth gear needs to be altered as will the final drive. Will also change to Nth moto clutch, Wavetrac LSD, and Accusump(to avoid draining oil too much in those high speed long left and right hand turns). And will of course continue to improve my driving skills hopefully too!

Is there any reason to believe the Wavetrack LSD is better than the factory diff?

[stradman]

Is there any reason to believe the Wavetrack LSD is better than the factory diff?

Well according to Matt Bejnarowicz who is one of the top viper chassis setup guys:

"The problem with speed sensing diffs is that they are really delayed in reacting. I kind of view them as a reactive differential while a torque sensing is more of a predictive/pro-active principle. A proper torque sensing diff reacts to the driver’s inputs and therefore is changing before the car transitions into its future state. Good drivers learn to manipulate the car through the differential. A Porsche, for instance, requires the driver be very aware of what they are doing with the gas, brake, downshifts as the car needs to be manipulated through the diff to perform at peak performance.

With the speed sensing diff – they transition smoothly, but you need to have differential wheel speed for them to do anything. Therefore, they really don’t do much of anything as the car transitions into the first part of the corner (from straight to turn-in). Only pre-load of the clutch plates is helping you here. The street Viper typically suffers from entry instability or lacks confidence here. This is mainly because the speed sensing differential is not reacting to help the car on early corner entry. On corner exit – the differential does not set until some wheel spin occurs. When I was driving the street cars – you can feel this. It is a bit of “2-step” in the rear. You transition to the power, the car moves a little in the rear then settles, and then you can roll into the gas further. This is the differential operating in the street car – it needs some differential speed to work.

Of course a speed sensing diff does do better when one wheel is in the air or has very limited traction. The best solution here is to avoid this situation in the first place as the tire cannot generate grip if it’s not touching the ground properly in the first place.

So in my experience, a proper race car needs:

1st: A ramp/plate style torque sensing differential. Good ones are ramp, friction surface, and pre-load adjustable.

2nd: If it is legal or allowed in the budget – a hybrid diff (viscous coupled with ramps) is the best. The VC helps smooth transitions and catch wheel flairs.

3rd: A solely speed sensing diff is the worst for racing and driver confidence. They are good for street cars and off roading. You won’t find any pro-level GT cars with only speed sensing diffs.”

And there you have it!

[Jack B]

Thanks Scot. So can I ask in the viper is there ever a need for a fuel surge or swirl pot tank for track work? Cheers Alex

All the vipers are a pump in a bottle, the new pump does not change that.

[ViperGeorge]

Well according to Matt Bejnarowicz who is one of the top viper chassis setup guys:

"The problem with speed sensing diffs is that they are really delayed in reacting. I kind of view them as a reactive differential while a torque sensing is more of a predictive/pro-active principle. A proper torque sensing diff reacts to the driver’s inputs and therefore is changing before the car transitions into its future state. Good drivers learn to manipulate the car through the differential. A Porsche, for instance, requires the driver be very aware of what they are doing with the gas, brake, downshifts as the car needs to be manipulated through the diff to perform at peak performance.

With the speed sensing diff – they transition smoothly, but you need to have differential wheel speed for them to do anything. Therefore, they really don’t do much of anything as the car transitions into the first part of the corner (from straight to turn-in). Only pre-load of the clutch plates is helping you here. The street Viper typically suffers from entry instability or lacks confidence here. This is mainly because the speed sensing differential is not reacting to help the car on early corner entry. On corner exit – the differential does not set until some wheel spin occurs. When I was driving the street cars – you can feel this. It is a bit of “2-step” in the rear. You transition to the power, the car moves a little in the rear then settles, and then you can roll into the gas further. This is the differential operating in the street car – it needs some differential speed to work.

Of course a speed sensing diff does do better when one wheel is in the air or has very limited traction. The best solution here is to avoid this situation in the first place as the tire cannot generate grip if it’s not touching the ground properly in the first place.

So in my experience, a proper race car needs:

1st: A ramp/plate style torque sensing differential. Good ones are ramp, friction surface, and pre-load adjustable.

2nd: If it is legal or allowed in the budget – a hybrid diff (viscous coupled with ramps) is the best. The VC helps smooth transitions and catch wheel flairs.

3rd: A solely speed sensing diff is the worst for racing and driver confidence. They are good for street cars and off roading. You won’t find any pro-level GT cars with only speed sensing diffs.”

And there you have it!

Interesting write-up. I believe the Gen 5 has the GKN Visco Lok diff, is that the same as a viscous coupled one in your number 2?

[stradman]

Interesting write-up. I believe the Gen 5 has the GKN Visco Lok diff, is that the same as a viscous coupled one in your number 2?

GKN is a speed sensing diff. ie number 3..

[IHOP]

A 9.0L ACR is the ultimate Viper IMO, as for value I'm sure it would hurt the value except for a few select buyers. But AZ Viper's 9.0L track car is just the ultimate beast!

[Arizona Vipers]

Agree more or less with a lot of the comments. My ACR is a track slag and I'm getting Prefix to do the 9L along with a few other mods to optimise car on track in a couple of months. I'm pretty sure I'm not going to get my money back after doing all that. But I don't care because car will be awesome and I'm not planning on selling anytime soon. I am fed up of Mclarens, Porsches having more grunt than me in the straight(Ok i know I have them in the twisty bits and ultimately will set a better lap time, but still can't stand the sight of them leaving me in the dust in the straights). And remember there are more and more cars coming out that can outpower us in the straights. So need a bit more under the hood imv.
Have a look at me during a dual with a 675LT(which is a bit slower than a 720s) and you'll understand. Don't even want to talk about the new GT2RS or Ferrari Pista coming....

You should have kept it in 2nd gear at 1:43 at 92mph, the next turn you would have killed that McLaren. You dropped to 58 mph in 3rd gear, which dropped you about 125 hp compared to 2nd gear. You were already bouncing off the rev limiter, just had to do that another tenth of a second and you would have blown post him on the (left) outside. Coming out of a corner at 58mph in 3rd gear you may as well have been in a Yugo.

[stradman]

You should have kept it in 2nd gear at 1:43 at 92mph, the next turn you would have killed that McLaren. You dropped to 58 mph in 3rd gear, which dropped you about 125 hp compared to 2nd gear. You were already bouncing off the rev limiter, just had to do that another tenth of a second and you would have blown post him on the (left) outside. Coming out of a corner at 58mph in 3rd gear you may as well have been in a Yugo.

What are you talking about AZ? At 1:43 at 92 in second you're well into the cut out. And yeah sure I could have made a move on the left just after that but remember I wasn't racing buddy and wasn't going to make an aggressive move at that corner as I knew he then had to move out to the left anyway himself around that corner. Just a bit of fun AZ. We don't need to both end up with very expensive repairs at the end of this buddy!
Btw would love to see some videos of your moves! Any links?

[F2V]

<<Also, what do folks think this would do to the long term value of the car?[/QU>>

Depends what you consider long term is. I'd say in 10 years not much, may even add value. The 9.0L "upgrade" is by Arrow, the people who make the Viper engine. I'm guessing in the long run, this will go a lot further price wise, than a third party "modification" imo.

[Scott_in_fl]

^^^ There are modifications, and there are modifications. The Arrow HC kits and 9L kits are going to be highly regarded because they are as close to OEM spec, design, testing, tuning, etc. as you will get. If you are worried about future value, these are the only mods I would consider.

That said, modding a '17 ACR-E, especially an SE car or other highly desired spec, is taking a larger gamble because the cars are potentially collector-worthy and most collectors want a bone stock car at auction time (with little to no miles). Thus, if your endgame is maintaining the highest possible value, you really need to not drive it anyway -- so why mod it?

Now, I think these kits make far more sense on a car that already has miles anyway. Or, say a '16 ACR with standard colors. Those cars do not stand out for their stock spec, but might actually stand out (and be more desirable) because of an awesome Arrow upgrade like the 9L.

I'm caught in the middle. I have a great stock spec on a final year car, but I plan on driving the wheels off the thing and never selling it. So, I like the idea of the 9L and my only real concerns are long-term reliability and parts availability.

[ViperGeorge]

Prefix should have given the 9.0L Vipers a special name. Something like was done with the Yenko Chevys or Shelby Mustangs. Those cars command big $ compared to their factory counterparts. They did make a Shelby Gen 2 Viper at one point and I believe they command higher prices. Who can come up with a good name for a Prefix modded 9.0L Viper?

[F2V]

Prefix should have given the 9.0L Vipers a special name. Something like was done with the Yenko Chevys or Shelby Mustangs. Those cars command big $ compared to their factory counterparts. They did make a Shelby Gen 2 Viper at one point and I believe they command higher prices. Who can come up with a good name for a Prefix modded 9.0L Viper?

Interesting comment. I'd take a stab at "Dick Winkles Special". A metallic screw/bolt on badge, to be affixed where the GTS stick on badge is located. Available from Prefix (only) to those cars that are equipped with BOTH packages HC and 9,0L, which they would verify with the installers.