Andrew2KRT10
Enthusiast
http://www.autoblog.com/2006/12/28/2008-dodge-viper-srt-10-breaks-cover-ahead-of-schedule/
We are BACK !!!!
Andrew
We are BACK !!!!
Andrew
Lookee what I found !!!!!!!!!!!!!!!!!!!!!!!!!
- Thread starter Andrew2KRT10
- Start date
1TONY1
Enthusiast
Nice find.
Fast Freddy
Enthusiast
notice how the horsepower has increased by 90 but the torque has only increased 25 despite an increase in displacement to 8.4 litres as a result of a bigger bore. this is because of the variable valve timing (VVT). if they didn't have to do this in order to get the engine to pass the smog test you would have seen a way bigger increase in torque with the old skool valve train. the new engine even has 25% bigger valves on the intake side and 12% bigger valves on the exhaust side. this just goes to show how inefficient VVT is at lower rpm's where peak torque is made. my N/A heads & cam gen-2 engine only has 8.1 litres yet i dyno'd 542 rwhp and a whopping 577 rwtq with a mere 9.8:1 compression ratio. this new engine has 10.2:1 compression. when you adjust for your standard 15% drive train loss my engine is making aproximately 630 crank hp and a gen-4 butt kicking 685 foot lbs of torque! 
big-n-italian
Enthusiast
Tom F&L GoR
Enthusiast
We were only given the maximum torque value.
Even so, max torque is obtained at RPM of maximum volumetric cylinder filling efficiency. Upping the engine size from 8.3L To 8.4L brings a 1.2% increase in volume, so at least a 1.2% increase in torque should follow. In fact, the 25 ft-lb gain to 560 was a 4.7% gain. I would say "wow" instead of "only."
The variable valve timing doesn't limit torque, it is probably helping to get more torque (and horsepower.) It is adjusting on the fly to provide better opening and closing timing than a non-adjustable system would allow.
The disparate increase in horsepower and torque is because torque is a measure 'cylinder filling efficiency' and horsepower is 'cylinder filling multiplied by engine speed'. As speed increases, air consumption per revolution is still falling (less torque at higher RPM) but not as fast as before (more horsepower.)
Bluntly, it has to be helping because if you disabled it and left everything else the same, it would lose torque or horsepower somewhere. And having said all this, which sounds like I am correcting you, there are some interesting things you've done and I'm curious about them. Can you describe more of the differences you think exists between your Gen 2 and the new Gen 4? Thanks.
Even so, max torque is obtained at RPM of maximum volumetric cylinder filling efficiency. Upping the engine size from 8.3L To 8.4L brings a 1.2% increase in volume, so at least a 1.2% increase in torque should follow. In fact, the 25 ft-lb gain to 560 was a 4.7% gain. I would say "wow" instead of "only."
The variable valve timing doesn't limit torque, it is probably helping to get more torque (and horsepower.) It is adjusting on the fly to provide better opening and closing timing than a non-adjustable system would allow.
The disparate increase in horsepower and torque is because torque is a measure 'cylinder filling efficiency' and horsepower is 'cylinder filling multiplied by engine speed'. As speed increases, air consumption per revolution is still falling (less torque at higher RPM) but not as fast as before (more horsepower.)
Bluntly, it has to be helping because if you disabled it and left everything else the same, it would lose torque or horsepower somewhere. And having said all this, which sounds like I am correcting you, there are some interesting things you've done and I'm curious about them. Can you describe more of the differences you think exists between your Gen 2 and the new Gen 4? Thanks.
Blue Batmobile
Viper Owner
Finally!
Bat™
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