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Road friction, wind and etc does not cause a loss of power , it simply increases "road hp", the power required to keep the vehicle moving at a steady speed on a flat surface at a certain mph. It used to be tested at 30,50 and 70 mph, not sure what it is now. The only place power losses can actually occur after the engine, is in the drivetrain.
I'm aware that these do not cause an actual power loss from the vehicle. I was speaking in general terms.
This is how Japanese companies used to manipulate their power figures to fit within the "agreement" though. That way they could say that the power was "equivalent" to 280ps on the road (known in the US as "rolling HP"), after these factors, even though it would dyno higher. It's the same basic concept used in weather with wind chill. It may be 50, but due to wind chill it feels like 45.
Here's an example of a calculator for figuring out the amount of aerodymanic and rolling HP required.
http://www.bgsoflex.com/aero.html

TSXtaxy said:
well said! simply physics, basically. Higher the Friction Force is, the higher the Applied Force needs to be.
That's the problem, physics are not simple. As you said, the higher friction force, requires a higher applied force.
Since, you're figuring this out for a vehicle's max hp, you do not have any more hp to apply. So the extra HP required to overcome that drag and friction, can be calculated as a Rolling HP loss.
 

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GTES-t said:
I'm aware that these do not cause an actual power loss from the vehicle. I was speaking in general terms.
This is how Japanese companies used to manipulate their power figures to fit within the "agreement" though. That way they could say that the power was "equivalent" to 280ps on the road (known in the US as "rolling HP"), after these factors, even though it would dyno higher. It's the same basic concept used in weather with wind chill. It may be 50, but due to wind chill it feels like 45.
Here's an example of a calculator for figuring out the amount of aerodymanic and rolling HP required.
http://www.bgsoflex.com/aero.html



That's the problem, physics are not simple. As you said, the higher friction force, requires a higher applied force.
Since, you're figuring this out for a vehicle's max hp, you do not have any more hp to apply. So the extra HP required to overcome that drag and friction, can be calculated as a Rolling HP loss.
"road Hp" losses alone would not bring such a car as say, the TT Supra, in line with it's supposed 276-280 whatever Hp rating. Road Hp on that car, even at 70 mph, was supposedly less than 25. Less than 20, if I remember right. Most regular cars total less than 20 road Hp. Only SUVs and very heavy high Hp luxury sport (SL55 AMG) cars have gone higher. Wind resistance is a big factor in road Hp, the Supras slick shape keeps it from losing too much.
 

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Looking at the Supra figure you posted earlier. You shouldn't have to factor in the road HP. As you said, it's at the flywheel, so it doesn't factor in the drivetrain loss. The power loss through drivetrain is usually anywhere in the range of 15-25% depending on who you talk to.
Giving the 326 bhp the 15% loss, that makes around 49 hp drivetrain loss. That gives it a 277 whp figure, which is pretty much the 280ps.
That fits right into the Japanese on paper figure.

The R34 GTRs were being driven right off the showroom floors, and dyno'ing around 300PS or more. These are cars that they did the extra factoring of road hp, so that they would be 280PS on paper.

These are just how the Japanese manufactures got their cars to fit in under their 280ps "agreement." I'm not saying they didn't fudge the figures a bit to do it (claim more drivetrain power loss, more road hp effect) because it's well known that they did.

Otherwise, it'd just be an amaxing coincidence that the 300zx tt, Skyline GTR's, top end Supras and NSXs all have exactly 280ps in Japan... on paper! :D
 

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interesting read up.. indeed :D

but this is NOT limited to Japanese production cars

lest we forget the domestics fudging the numbers for insurance reasons...


1969 Camaro Z28 with for example...
 

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GTES-t said:
Looking at the Supra figure you posted earlier. You shouldn't have to factor in the road HP. As you said, it's at the flywheel, so it doesn't factor in the drivetrain loss. The power loss through drivetrain is usually anywhere in the range of 15-25% depending on who you talk to.
Giving the 326 bhp the 15% loss, that makes around 49 hp drivetrain loss. That gives it a 277 whp figure, which is pretty much the 280ps.
That fits right into the Japanese on paper figure.

The R34 GTRs were being driven right off the showroom floors, and dyno'ing around 300PS or more. These are cars that they did the extra factoring of road hp, so that they would be 280PS on paper.

These are just how the Japanese manufactures got their cars to fit in under their 280ps "agreement." I'm not saying they didn't fudge the figures a bit to do it (claim more drivetrain power loss, more road hp effect) because it's well known that they did.

Otherwise, it'd just be an amaxing coincidence that the 300zx tt, Skyline GTR's, top end Supras and NSXs all have exactly 280ps in Japan... on paper! :D
With the AWD, though, drivetrain losses approach 20% or more. I've seen Skyline dynos of 325 to 368 Hp, all stock, no mods. But that's ON THE GROUND, given the nature of how a dyno works. That's after drivetrain loss occurs, because the dyno reads the Hp transmitted to it's rollers, in this case the ground. You can't fudge that. I would say it's more like the Japanese just have been outright lying for years, and the Hp agreement was pointless, since they've apparently not paid much attention to it anyway......
 

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With the AWD, though, drivetrain losses approach 20% or more. I've seen Skyline dynos of 325 to 368 Hp, all stock, no mods. But that's ON THE GROUND, given the nature of how a dyno works. That's after drivetrain loss occurs, because the dyno reads the Hp transmitted to it's rollers, in this case the ground. You can't fudge that. I would say it's more like the Japanese just have been outright lying for years, and the Hp agreement was pointless, since they've apparently not paid much attention to it anyway......

neither did many of the european car manufacturers who were the other party in the agreement. both sides took alitlte from the agreement, but they stayed around the same area.
 

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With the AWD, though, drivetrain losses approach 20% or more. I've seen Skyline dynos of 325 to 368 Hp
Wow. Where did you see that? I have never seen 368awhp for a stock GTR coming out of a properly calibrated AWD dyno (which tend to do strange things with ATTESA equipped cars even when properly set up).
 

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I've never seen stock GTR's dyno that high. I was in Japan 4 years, and the highest I've seen a stock GTR dyno was 320ps, and that was because the front driveshaft was disconnected. Other then that, all the awd dynos averaged around 300ps. Which puts Nissan the right area to fudge the numbers with rolling hp loss.
 

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You should have seen the outrageous dynos for R34s, then. 330-350 from the Vspec II and upwards around 400 for the Nur. This is, granted, recalculated to engine (IE flywheel) Hp, but with over 330 at the wheels. Maybe in range for fudging the numbers, but obviously with the big bump in torque the R34 has over the R33, there would be additional Hp as well. Soon as I find something definitive, I'll post it. There is a video I found of an R34 V-spec-II dynoing 360 kw with only filter mods, but I'm sure you guys wouldn't treat that as stock....
 

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You should have seen the outrageous dynos for R34s, then. 330-350 from the Vspec II and upwards around 400 for the Nur. This is, granted, recalculated to engine (IE flywheel) Hp, but with over 330 at the wheels. Maybe in range for fudging the numbers, but obviously with the big bump in torque the R34 has over the R33, there would be additional Hp as well. Soon as I find something definitive, I'll post it.
There are a number of videos and dyno plots out there which seem to be showing something insane at first, but are actually the result of the AWD dyno not being set properly (AWD dynos do not like cars which can do a 100/0 or 0/100 center torque split). When the Vspec and Vspec-II came out, a number of smaller Japanese car magazines jumped the gun and published articles claiming that Nissan was blatantly violating the 280ps restriction. It turned out later that these magazines were either using the results of an inconsistent run or were using a dyno which was not calibrated. Best MOTORing and Engine had a field day with that one.

The torque increase with the R34 doesn't affect peak power much. Transpose a R33 dyno chart over a R34 dyno chart and you'll see that the extra torque doesn't do too much around 6800 rpms, where the R34 GTR makes peak power.

There is a video I found of an R34 V-spec-II dynoing 360 kw with only filter mods, but I'm sure you guys wouldn't treat that as stock....
I think I know which one you're talking about. Let me see if I can find the one I'm thinking of.
 

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ReVerm said:
There are a number of videos and dyno plots out there which seem to be showing something insane at first, but are actually the result of the AWD dyno not being set properly (AWD dynos do not like cars which can do a 100/0 or 0/100 center torque split). When the Vspec and Vspec-II came out, a number of smaller Japanese car magazines jumped the gun and published articles claiming that Nissan was blatantly violating the 280ps restriction. It turned out later that these magazines were either using the results of an inconsistent run or were using a dyno which was not calibrated. Best MOTORing and Engine had a field day with that one.

The torque increase with the R34 doesn't affect peak power much. Transpose a R33 dyno chart over a R34 dyno chart and you'll see that the extra torque doesn't do too much around 6800 rpms, where the R34 GTR makes peak power.



I think I know which one you're talking about. Let me see if I can find the one I'm thinking of.
HERE Unfortunately the links no longer seem to be working. claims 360 bhp with just "breathers", whatever that means, but I'm assuming just filter mods.

If dynos are such inconsistent beasts, how can we expect to get accurate information from them...... Seems to me then it's probably just as good to plug your car stats into a G-tech or the equivalent, you have a better chance of getting accurate results. Kinda makes you wonder about these GNX guys claiming 1000+ Hp, maybe the dyno was helping a little.
 

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If dynos are such inconsistent beasts, how can we expect to get accurate information from them...... Seems to me then it's probably just as good to plug your car stats into a G-tech or the equivalent, you have a better chance of getting accurate results. Kinda makes you wonder about these GNX guys claiming 1000+ Hp, maybe the dyno was helping a little.
Dynos are inconsistent when the operators don't know what they're doing. The point I'm making is that getting proper measurements out of the ATTESA E-TS system is tricky because of the way it reacts to certain things (like % throttle open at a certain speed. Yep. It checks this with the latest gen ATTESA systems).

Although AWD dynos are finicky things to begin with. If you've ever seen one in action, you'll know.
 

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ReVerm said:
Dynos are inconsistent when the operators don't know what they're doing. The point I'm making is that getting proper measurements out of the ATTESA E-TS system is tricky because of the way it reacts to certain things (like % throttle open at a certain speed. Yep. It checks this with the latest gen ATTESA systems).

Although AWD dynos are finicky things to begin with. If you've ever seen one in action, you'll know.
Never seemed to be anything odd going on with the only one we have in Colorado, so I have no idea.
 
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