Steve M
Enthusiast
Those numbers are realistic. What were the disappointed expecting, 0% drive train loss?
I don't think that's too much to ask.
Those numbers are realistic. What were the disappointed expecting, 0% drive train loss?
Those numbers are realistic. What were the disappointed expecting, 0% drive train loss?
I meant overrated in terms of HP. I know how great the car is, its a VIPER!If you're looking for a track only car you might be right. Mechanically not much has changed so you may as well go with the cheaper alternative.
To me the 13 is so much more than that though. When you look at the classics that have aged beautifully they have it all. Powerful engine and proper suspension, a curvacious timeless body shape, and a top of the line interior. All gen Vipers have had the power and suspension, Gen 1, 2, and 5 have the body (sorry 3 and 4 owners, they look great now but I think it's too angular to age well), but only the 5 has the interior. That's why I own one. And why I don't consider it overrated at all.
A car will also dyno higher with the 3.07 gears, compared with the 3.55 gears in the Gen 5.
I kinda began to think 13 is overrated.
The GEN IV was and still a legend.
Dyno pulls are done in 4th gear. If the gearing is shortened, as in numerically increased, going from 3.07 to 3.55 then measured power decreases. Calling a gen3,4 an S2000 is like calling a ZR1 a TR6 with a V8. By legend I think he means subjectively due to be the 'ring King, holding several spots in fastest lap records at numerous tracks, etc. Kinda just like the S2000. That's a whole lotta wrong in that post. Oh this gen5 forum is a weird place.
Third gear is usually 1:1 if no changes were made to the vehicle, and that's the gear used in a dyno test. If your car comes stock with 3.07 and you change to 3.55 or 4.10 gears then 3rd gear would no longer be 1:1 and you'd see higher dyno numbers, which would have to be compensated for to get accurate HP/TQ figures.
nope, the more power you gain at the crank, the more is lost due to friction in the driveline... 15% of 640 is more than 15% of 600
Third gear is usually 1:1 if no changes were made to the vehicle, and that's the gear used in a dyno test. If your car comes stock with 3.07 and you change to 3.55 or 4.10 gears then 3rd gear would no longer be 1:1 and you'd see higher dyno numbers, which would have to be compensated for to get accurate HP/TQ figures.
Why is this true? I would think that the amount of horsepower to turn the driveline would be a constant based on the design of the driveline. In other words why would two cars with the same driveline (say a Gen 3 and a Gen 4) require different amounts of absolute HP to turn the driveline? If a 500HP gen 3 lost 75HP to the driveline wouldn't a Gen 4 with the same driveline also lose 75HP to the driveline? In this example the Gen 3 would put 425 to the wheels and the Gen 4 would put 525 to the wheels.
Dyno pulls are done in 4th gear.
If the gearing is shortened, as in numerically increased, going from 3.07 to 3.55 then measured power decreases.
Calling a gen3,4 an S2000 is like calling a ZR1 a TR6 with a V8. By legend I think he means subjectively due to be the 'ring King, holding several spots in fastest lap records at numerous tracks, etc. Kinda just like the S2000.
That's a whole lotta wrong in that post. Oh this gen5 forum is a weird place.
Well, if a Gen IV is an S2000 with a V-10, then a Gen V is an S2000 with a V-10 and a nice interior. You are right...there's definitely a different vibe in here, and that doesn't appear to be a good thing.
4th gear is 1:1...it stays 1:1 regardless of rear axle ratio.
What Tony brings up is accurate for an inertial dyno (e.g. DynoJet)...a car originally dyno'd with a 3.07 rear end and then run again with the only change being 3.55s will show a lower output due to inertial losses. The dyno computer is told how to account for the change in gear ratios, but an inertial dyno only cares how fast you accelerated the drums. I've seen enough dyno results from cars with only gear swaps to know that this occurs pretty regularly and is repeatable. Put 3.07s in a Gen V, and you'd see those dyno numbers creep up probably around 10 or so HP at the wheels. Of course, it'd be a **** on the street with a retardedly tall first gear, but that's beside the point.
It doesn't really work that way. First off, fourth gear is a 1:1 ratio. That means the input shaft and the output shaft are spinning at the same rate.
This yields the least amount of parasitic loss. The final drive has nothing to do with the 1:1 figure. This is how much the driveshaft spins in relation to the wheels. The further you get from a 1:1 ratio, the more gears are spinning to increase or (far more likely in automotive applications) decrease the rate of wheel rotation, the more power is lost to heat. This is why the 3.07 will be slightly more efficient in power delivery than the 3.55. I don't believe that the difference is huge, but there should be a slight difference.
More power means a higher rate and/or more torque. In either case, more friction is encountered as gears are either spinning quicker or have more force being applied to them. Either scenario creates more heat.
Thanks PeerBlock. Exactly what I was saying.
The cars that I have had dyno tuned were done on 3rd gear of a 6-speed trans, although you're stating it as if it is the same for all cars it's not.
Third gear is usually 1:1 if no changes were made to the vehicle, and that's the gear used in a dyno test. If your car comes stock with 3.07 and you change to 3.55 or 4.10 gears then 3rd gear would no longer be 1:1 and you'd see higher dyno numbers, which would have to be compensated for to get accurate HP/TQ figures.
You made 1 post prior in this thread and you seem to be the one who thinks 1:1 in the Viper is 3rd gear.. No one else.
We are all on the same page here. We are talking about the Vipers. We are not talking about your previous cars or 5 speeds.
Oh, but I was talking about my other cars and cars in general as they pertain to dyno results, with the point being that the figures presented in this video are not indicative of the Gen 5 having optimistic power ratings. Whether or not you dyno the viper in 3rd or 4th gear is irrelevant - whatever gear puts you as close to 1:1 as possible is where you should be and if that's 4th gear on the viper, great...on a lot of the other cars I've owned it was 3rd gear.
Why get sidetracked with this minutia? You're not mad about the gen 4 being a fast S2000 thing, are you?
Oh, but I was talking about my other cars and cars in general as they pertain to dyno results, with the point being that the figures presented in this video are not indicative of the Gen 5 having optimistic power ratings. Whether or not you dyno the viper in 3rd or 4th gear is irrelevant - whatever gear puts you as close to 1:1 as possible is where you should be and if that's 4th gear on the viper, great...on a lot of the other cars I've owned it was 3rd gear. Why get sidetracked with this minutia? You're not mad about the gen 4 being a fast S2000 thing, are you?
That's great. And known. But we are talking about the Viper.
Not at all. My fast S2000 is like a circus on wheels. It seems to get all kinds of attention every time the garage door opens. I don't get it.
That's great. And known. But we are talking about the Viper.
Not at all. My fast S2000 is like a circus on wheels. It seems to get all kinds of attention every time the garage door opens. I don't get it.
The discussion is black and white, it is not about what is close to 1:1. There is always a gear that is exactly 1:1, Again, it is, black and white, in a T56 or 6060 fourth gear is 1:1. Everyone dyno's those cars in 4th gear. As was stated before, the input and output shafts are at the same rpm. In addition, as was stated previously, the parasitic losses are greater in a 3:55 versus a 3:07, however, the difference is almost inconsequential.
Yup the Gen 4 ACR Viper is the meanest looking viper period. If I park my ACR next to a Gen V . It would make the Gen V disappear.
Just watch it when your S2000 hits VTEC because it gets a bit squirrely with all those powers its producing.
It could be on certain transmissions but it is not always. Like I said before, it depends on the gearing of the transmission and it is usually 3rd or 4th gear, however that doesn't mean that it is a true 1:1 ratio. Sometimes you just have to settle for getting it as close as possible.
The taller gears post lower numbers on the dyno due to the way the dyno works. The dyno drum measures the time it takes a car to spin the drum up to a preset RPM. Taller gears require more revs to spin the wheels, and therefore the drum, so the engine has to spend more time overcoming its own inertia as well as that of the driveline.
The HP/TQ loss at the wheels isn't really about heat so much as it is the power required to accelerate the mass of the driveline components. Power (in physics) is "work" done over time, and since engines produce torque, and the amount of torque required to turn the drivetrain of a car does not increase as the power of the engine increases.
If you took a car that was rated at 600 ft-lbs @ crank stock, with 510 ft-lbs @ wheels (15% driveline loss), you can infer that it takes 90 ft-lbs of torque just to turn the drivetrain before the car would accelerate.
Let's say you slapped on a turbo to this engine and gained 300 ft-lbs at the crank, but did nothing to the rest of the car. The torque required to turn the drivetrain will not magically increase - it is still 90 ft-lbs. So now you have an engine with 900 ft-lbs @ the crank - what you should expect to at the wheels? The answer is 810 ft-lbs, which is only a 10% driveline loss.
The basic point is that as engine power increases you should see a decrease in the percentage of HP/TQ lost to the drivetrain. The common internet theory of the driveline loss being a fixed percentage regardless of power is incorrect. You'd actually want to calculate your driveline loss while the car is stock, then after doing any work to improve the power of the engine you would go by the static ft-lb value you got initially.
I don't think that's too much to ask.
You were saying the Gen IV are going to be written off by the vast majority of people as a fast S2000?
I was saying that it should take the absolute same amount of horsepower (or torque if you prefer) to turn the drive train in two cars with the same driveline design. It should not (and I believe it does not) depend on the amount of power the engine is able to create. Given I actually do have a degree in physics I would love for someone to show me the "physics" behind this number increasing just because the power of the engine increases.
No, we're talking about dyno numbers and how they pertain to the viper, as well as other vehicles...but feel free to try to keep telling everyone what they are talking about since you know better.
Just watch it when your S2000 hits VTEC because it gets a bit squirrely with all those powers its producing.
Not all transmissions have a 1:1 exact match gear. Not sure how to state that any more plainly. You could say that "many" transmissions have a 1:1 gear, but you are wrong to say that all do. The hang up on gear ratio is ignoring the point of the post - that dyno numbers are not a very good way to compare vehicle performance among various generations of a particular car or cars in general.
Yeah, it is pretty mean for a honda.
No. Go back and read my posts in this thread.
Jack's statements are correct. Dynojet inertial dynojet measure torque and monitor RPM, and use that to calculate horsepower. It is a simple mathematical formula.
HP = Torque x RPM ÷ 5252
Further proof to that, whenever you use a Dynojet and the RPM sensing lead doesn't work properly - you simply end up with a torque graph. Also, when you cannot get an RPM sensing lead on a diesel truck, you only end up with a torque graph.