Makara
Viper Owner
You can use 1st, 2nd, 3rd or 4th but for a dyno pull - but why would you tune the car for 1st gear if your aim is to maximize performance in 3rd? Likewise, why would you tune in 4th gear if you rarely shift into 4th gear for your style of driving? Are viper owners so shallow that the only reason they dyno their cars is for bragging rights on threads like this rather than to improve performance?
You said that dyno pulls are should be done in 3rd gear because with the rear end, that gives the closest to a 1:1 ratio at the tires. That is so laughably incorrect and and when it was pointed out to you, you insisted that most cars are 1:1 in 3rd gear, which is not true or relavent to a discussion of dynoing a viper. Now you are changing it around to being more interested in maximizing performance in 3rd rather than take the typical viper owner route and just aim for the largest number possible. This is also shedding a lot of light on your understanding of what is going on. Maybe you should stop trying to rationalize why what you think/thought was correct and try listening and learning what is really going on. You will be a better person for it in the end. There is nothing foolish about being incorrect, but insisting that your mistakes are correct because of ego just makes you look like a fool.
I know right! What's with these "dyno experts" coming in here acting like their word is doctrine. Tuning a vehicle on a dyno is more art than it is science. If it were purely scientific there would be little or no discrepancies between the results you get with the various ECU tuners out there.
Are you saying that a dyno defies the rules of science? That could shed some light on your humerus theories on how it works. It is a science, follows the rules of physics, and there is no magic about it. The variables which are not typically controlled because of logistics absolutely affect the outcome and adhere to physics, not black magic that is inexplicable.
Sure, but it doesn't translate quite so linearly to actual performance. Since the power band of any automobile engine falls withing a predefined RPM range, the revs that you lose with taller gearing are not recuperated even though "technically" no power is ever given up.
Let's use my 3.00 and 4.00 theoretical final drive gears:
With 3.00 @ 6,200 RPM using direct drive (1:1) wheel speed is 2,067 RPM.
Same with 4.00 gears in rear axle, wheel speed is 1,550 RPM.
You can plug the wheel RPM into the HP equation to figure out what the theoretical WHP would be:
(Estimating Viper has ~500 ft-lbs of torque at the crank @ 6,200 RPM)
3.00 Gears (2,067 RPM * 1500 ft-lbs) / 5252 = 590
4.00 Gears (1,550 RPM * 2000 ft-lbs) / 5252 = 590
Even though no power is lost, you give up 25% of your revs because you are limited by the 6,200 RPM redline of the engine. In "real world" driving this means that taller gearing reduces the top speed in each gear as well as the overall top speed of the car, but the additional torque you gain allows you to reach the redline quicker thus making the car "feel" faster while driving it.
In drag racing this would mean lower trap speeds and possibly higher ETs (as long as you do not gain an extra shift due to gearing), while in road racing it would mean that your car is not going to pull as hard and you'll have to shift more often. You would start to get counterproductive effects if the taller gearing required you to shift into a higher gear at lower speeds, dropping the engine out of its powerband due to running out of revs in the previous gear.
That was a whole lot of wasted typing as this has nothing to do with dyno numbers changing because of parasitic loss from a different ration. Thanks for explaining that shorter gears change the way a car performs though. Good info to have! You are just going in circles, sometimes contradicting yourself.
Seacrest OUT!!!! I mean it this time.
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