SRT Viper GTS vs Chevrolet Corvette ZR1! - Head 2 Head

[hrcslam]

No, that's not all things being equal, that's all things being optimized for the larger engine, and that's the part I disagreed with. If you were to literally keep the same heads, ports, cam, and valves and simply increase displacement, for example going from a 327 to a 383, then you'd have the same airflow capability through the engine and the same overall horsepower, but the torque would come on earlier and be higher. Like this.
http://www.truckinweb.com/tech/engin...d/viewall.html




Now that part I agree with.

Actually, no; I still disagree. Increasing bore and stroke only is not all things being equal. A 2" bore would perform absolutely horribly on a head designed for a 4" bore. The 4" bore however would fare better on a 2" bore designed head than the 2" on the 4". So all things being equal does include scaling up the entire engine equally. A 3.1L V-8 based on the LS3 would push less than half the power of a 6.2L LS3.

In other words, an engine made for a larger bore and stroke made smaller in displacement would fare worse than an engine made for smaller displacement and bored out. If the engine is optimized for smaller displacement and made larger than it wouldn't fare as well as an engine made for the larger displacement. But if an engine was optimized for larger displacement and made smaller it would perform like utter crap.

But this is never the case. And we end up increasing displacement with just bore and stroke, then trying to maximize air flow for that particular engine displacement with the port shapes and volumes available.

Engine power can be moved up and down the rpm without adjusting displacement at all too. That's done with cam lift vs duration and overlap plus timing and port flow length, shape, and cross sectional area. A LT1 Camaro can have a 1500-5800 rpm power band then go to a 2500-6500 power band with nothing more than a cam swap and tune. But, if the engine were designed to be a high revver the builder can optimize the rest of the intake and exhaust track to match the cam.

This is without even considering the area vs volume advantage that grow exponentially as displacement grows. The bigger the displacement the smaller the frictional surface area to volume relation gets.

[Slideways]

A 3.1L V-8 based on the LS3 would push less than half the power of a 6.2L LS3.

No, it would produce half the torque. Assuming the same bore it would still be capable of flowing the same airflow, (300+ cfm) it would just have to rev ridiculously high to produce power, but it would produce LS3-like horsepower.


Displacement represents the potential to make torque, cylinder head flow represents the potential to make power.

[hrcslam]

No, it would produce half the torque. Assuming the same bore it would still be capable of flowing the same airflow, (300+ cfm) it would just have to rev ridiculously high to produce power, but it would produce LS3-like horsepower.


Displacement represents the potential to make torque, cylinder head flow represents the potential to make power.

Assuming same bore wouldn't make all things equal. But in that case, I agree.

[Slideways]

Assuming same bore wouldn't make all things equal. But in that case, I agree.

In that case, we're not arguing about engines anymore, just the definition of "all things being equal". I'm OK with that.

[63GrandSport001]

The math on a 3.1L LS3 engine, the current LS3 engine produces 436BHP @ 5,900rpms which means it makes 388ft-lbs at 5,900rpms. If we cut that in half it would produce 217BHP @ 5,900rpms, with that kind of torque in order to make the same amount of horsepower this 3.1L LS3 would have to rev to 11,500rpms to make 430ish BHP.

[hrcslam]

In that case, we're not arguing about engines anymore, just the definition of "all things being equal". I'm OK with that.

Yeah, I think we do agree.

The math on a 3.1L LS3 engine, the current LS3 engine produces 436BHP @ 5,900rpms which means it makes 388ft-lbs at 5,900rpms. If we cut that in half it would produce 217BHP @ 5,900rpms, with that kind of torque in order to make the same amount of horsepower this 3.1L LS3 would have to rev to 11,500rpms to make 430ish BHP.

Right, but half the displacement doesn't equal half the torque either. It's less than half because of other losses; like lower air velocity intake speeds.

[CaddyLac10]

The Viper is a very fine vehicle and in almost every case, it would be considered utterly dominating against all challengers, but the ZR1 finds a way to make it seem somewhat of a let down.

Make no mistake, SRT aimed right at the ZR1 as benchmark. The spec similarities are uncanny. Yet, after almost five years, the ZR1 still came out on top.

I would never call the Viper a failure because it isn't a great car, but when you have a clear target and your product is five years newer, I would expect the outcome to be different. When GM developed the ZR1, there was a 599 right next to it and there was never any question as to which car was superior.

There have been discussions about Ferrari holding back for the Viper for the sake of the Berlinetta and believe there may even have been some official comments regarding it. I don't doubt that may have been the case and it could certainly be a legitimate reason why the Viper came up a little short if it were true.

First, no ceramic brakes on the Viper? They knew what the ZR1 was capable of doing, yet they still use Stop Tech brakes? Plus, there's no reason why the Viper shouldn't have been well above 640hp. Brembo ceramics and anywhere near 700hp would put the Viper dangerously close to the Berlinetta, if not besting it in some measurements.

[mchicha]

It's about as expected, the Viper is designed to be brutish (though not as bad in the newer car), and though the Zr1 is getting a little long in the tooth it's an amazingly well balanced car.

I think we are going to see that the C7 Z51 is going to put down road course times simular to the C6 Z06. It won't beat it in te quarter mile but, if you look at what GM did with the ZL1 it was pure magic. The car has a ton of weight to manage but it just puts power down so well that it is posting crazy lap times.We will see a huge jump in road course performance in the C7. The C7 has a lot going for it. The Brakes are putting out ZR1 like stopping distances (though I doubt they will get the fade resistance), the engine has a power band a lot like the LS7, and it has all the magical features found in the ZL1 (MRC, PTM) plus the ELSD. I think the car will be able to manage traction much better on and off corners.

The SRT (Dodge boys) made the same mistake Ford made with the 640 HP Shelby against ZL1. They put more power and on the first outing on the track with the ZL1 they got smacked down and embarrassed. You cannot just cannot get performance out of a car if you do not do the investment necessary to produce the proper performance beast.
Chevrolet has probably the most comprehensive racing program on the planet for a long time. They win more races on any given weekend than even Porsche. From indy, to Rolex to ALMS... they race their engines and their performance cars. All that stuff comes together in their road performance car. So if you are Dodge and you do not have a proper racing program that tells you what to improve on a car, a cheap engineering job plus more power will not help you.
This corvette (the ZR1) has the benefits of the LS motors running in all sorts of races from Baja to Down under to ALMS, Rolex etc... couple that with over 20 years of a corvette racing program (for example Camaro brakes are from the work Chevy does with Brembo on Rolex and ALMS programs) , all those things come beautifully in the 10 year old ZR1 and the newer ZL1.

More pawa cannot help the Dodge.(oops SRT) Chevrolet is serious about performance, they invest the time and the engineering resources and it shows.

Try bring something like a Jaguar XFR-S or AMG C63 black series against a ZL1 at Laguna SECA see what happens. All the F1 stuff cannot help Mercedes, because Rolex is where they need to be to improve their road going cars.

Giles has mentioned that the New ACR will have 1500lbs of Down force. that's a 500lb Increase from the 2010 ACR, that means its gonna have some massive Power update for a top trim Viper to have that amount of downforce

What everyone is failing to realize, the Vipers that's being Driving and Tested by Magazines are Pre-Production Vipers, Thats why they dont have the Production Seats giles mentioned on Twitter Viper #001 is the Metallic Red GTS Viper ( the one that's was built to giving to the person who won the Auction on Barrett Jackson) and the 50+ Inaugural GTS Viper (blue /w white strips) will be the 1st Production Vipers. . Both versions just started production last week.

In Theory, lets take a ZR1.
Remove all the sound deadening, all the electronic stuff like power windows, radio air conditioning, speakers etc, change the doors to carbon fiber, add the ALMS suspension and aero kits to the ZR1 complete with the diffuser and wing, then add even more grippy slicks to it, then add power to like 700 HP, (something one can easily do with the LSA) then bring the ACR, see what happens. That is what the ACR is, a true race car.

I am telling you the ZR1 would destroy everything short of an F1 in that form. It would run faster than ... fill in the blank here... __________________

[63GrandSport001]

Yeah, I think we do agree.



Right, but half the displacement doesn't equal half the torque either. It's less than half because of other losses; like lower air velocity intake speeds.

That is a given, I just removed that factor from the equation, though there are some things that they could do in order to add some of that back. For example the LS3 doesn't have VVT or direct injection not to mention other things to improve the performance of that engine. If you really wanted to you can probably get 300ft-lbs out of that little 3.1L V-8 engine. If you can get 300ft-lbs at lets say 9,000rpms then you would produce 514BHP @ 9,000rpms. Would sound interesting at that rpm as well....

For example Formula 1 engines produce around 300ft-lbs of torque from their 2.4L V-8 engine, at 18,000rpms 300ft-lbs is 1,028BHP (if that was where they peaked their torque at).

[hrcslam]

That is a given, I just removed that factor from the equation, though there are some things that they could do in order to add some of that back. For example the LS3 doesn't have VVT or direct injection not to mention other things to improve the performance of that engine. If you really wanted to you can probably get 300ft-lbs out of that little 3.1L V-8 engine. If you can get 300ft-lbs at lets say 9,000rpms then you would produce 514BHP @ 9,000rpms. Would sound interesting at that rpm as well....

For example Formula 1 engines produce around 300ft-lbs of torque from their 2.4L V-8 engine, at 18,000rpms 300ft-lbs is 1,028BHP (if that was where they peaked their torque at).

Yeah, but the conversation was about small vs bigger displacement. In which case the VVT and all that jazz could be added to the 6.2L again.

Certainly a 300ft/lb tq. @18,000 rpm 2.4L would produce 1,000+ hp. But if we compare that monster of a motor to lets say a 500cid 8,000 horsepower dragster motor it's producing the same amount of horsepower as the smaller engine per cylinder! That's 1000 hp per liter. Insane, and it's without VVT and all that jazz too. But I guess when building a purpose built race motor, the car doesn't need VVT and all that jazz....

[germeezy1]

The Viper is very appealing but I feel as if the bar was not moved forward far enough, and with Ferrari under the corporate umbrella there is no reason that the Viper should not be superior in every way to the outgoing C6.

[63GrandSport001]

Yeah, but the conversation was about small vs bigger displacement. In which case the VVT and all that jazz could be added to the 6.2L again.

Certainly a 300ft/lb tq. @18,000 rpm 2.4L would produce 1,000+ hp. But if we compare that monster of a motor to lets say a 500cid 8,000 horsepower dragster motor it's producing the same amount of horsepower as the smaller engine per cylinder! That's 1000 hp per liter. Insane, and it's without VVT and all that jazz too. But I guess when building a purpose built race motor, the car doesn't need VVT and all that jazz....

No doubt, when you are making a race engine you do not need VVT as that is really for street cars. Consider that the 5.0L push rod V-8 can hang (and won) against 5.0L DOHC BMW and Ford V-8 engines with the Corvette Daytona Prototype.

[JeffInDFW]

Journalist and car snobs, PLEASE read the following paragraph and spend the next 24 hours trying to understand it. Then, stop proving YOUR ignorance by continuing to belittle what is clearly superior design and engineering.

Please notice that all the high tech "modern" DOHC powered supercars with their "Eurro" and JDM BS are ALL slower than these "low tech" cam in block American cars. Speaking of common wisdom, all us snobs know that American cars might be fast in a straight line, but they can not handle like the superior Eurro and JDM cars. Please ignore the inconvienent FACT that the two fastest ROAD RACE TRACK cars at BOTH the Nurburgring in Europe AND at Laguna Seca CONTINUE to be the "low tech" CORVETTE AND VIPER.

[Butz]

0:21

love the fact the Viper has 2 more liters and cylinders but makes less torque and almost less net horsepower - must be embarrasing for SRT ...

You do know that the ZR1 is supercharged? Right?

[63GrandSport001]

Journalist and car snobs, PLEASE read the following paragraph and spend the next 24 hours trying to understand it. Then, stop proving YOUR ignorance by continuing to belittle what is clearly superior design and engineering.

Please notice that all the high tech "modern" DOHC powered supercars with their "Eurro" and JDM BS are ALL slower than these "low tech" cam in block American cars. Speaking of common wisdom, all us snobs know that American cars might be fast in a straight line, but they can not handle like the superior Eurro and JDM cars. Please ignore the inconvienent FACT that the two fastest ROAD RACE TRACK cars at BOTH the Nurburgring in Europe AND at Laguna Seca CONTINUE to be the "low tech" CORVETTE AND VIPER.

One thing that people who do not really know the Corvette or Viper really end up under estimating is how good they are on a race track. Sure in the past they may not have had all of the steering feel and they might have been a bit on the brutal side (but that is what some people want). However you can not deny the 7:19.63 lap time that the ZR1 Corvette put down on the ring besting most production street cars at that track. Most people think that the Viper and Corvette are very front heavy, pretty much when they think American car they think of the 5,000+ pound tanks. They think of a car that has really soft suspension tuning, has 60+% of its weight on the front, and has **** for brakes. They also think that American car companies can not innovate (when in reality American car companies have done most of the innovation in the industry). This is where reality has taken a back seat to perception, because since the 1980s American car companies were run like **** and didn't want to produce the right vehicles instead just produced excuses for their failures.

So that brings us to today, everyone who I know who think American cars are crap all want the new Corvette. Its making products like that once more (something that Lutz was an advocate for) that is going to change peoples perceptions. The Camaro won a lot of people over, the Corvette is going to win a lot more people over as well. These are conquest machines, this is what all 3 need right now (and Ford needs to get on board with this).