chenpin
02-11-2003, 09:00 PM
This is for all the kung fu masters out there :D . I came across this and was wondering if any of you can verify this.
The gear ratios and power curves for the RX-8 are available, so it is possible to do a comparison of acceleration between the 8 and the Z. Though it is just an "on paper" calculation, it is still a relatively good indication of how the cars will match up. The first interesting point is that the Z and the 8 have very similar torque curves. Second, Mazda seems to have chosen some funky gear ratios...not quite optimal for 0-60. Some people are guessing that this was done as a compromise in favor of economy...the car is a four door after all. After plotting acceleration through the gears for both cars, here are my predictions:
0-60, stoplight races, or anything at low vehicle speeds: The Z will own the RX-8. Like I said, the gear ratios are funky in the 8. If Mazda revises the ratios later for quicker low speed acceleration, Zs may have some difficulty.
Anything above 50: The 8 and the Z have nearly identical acceleration. What this means is, if you own a Z and want to race an 8, don't do it from a roll on the highway...neither one of you are likely to pull much on the other. This also means that if the 8's handling is up to snuff, the Z will have stiff competition on the road course.
Anyway, those are my predictions for a Z vs. 8 match-up. I'll be the first to say that this is entirely bench racing, so like many others have said wait until the 8 comes out before making any final judgements.
One final interesting note is that one of the reviewers who was present at the RX-8 Laguna Seca press day borrowed a 350Z to do a comparison between the cars. On the subject of torque, he said the 8 had "good low-down torque" while the Z "lacks much in the way of low-down torque". Things may not drive the way you expect them to, so wait till you can drive both before you make a choice.
Both cars carry 90% peak torque over a significant percentage of the rev range. But don't be fooled by the torque numbers...the Z doesn't really have all that much more torque than the 8. The area under the torque curve is what really matters for acceleration. While the height of the Z's torque curve is greater, it does not span the rev range that the 8's curve does. Compute the area under the curves, and you'll find that the torque of the two engines is much closer than you think. To make a more simplified comparison between the 8 and the Z, consider the 8 to make 240 lb-ft with a 6000 RPM redline and 90% peak torque coming in by 2166 RPM. This will tell you how the car drives and accelerates. Of course, 240 lb-ft is still less than the Z's 274, but please remember that the Z also makes ~40 more HP than the 8.
Like I said, I think the Z is going to own the 8 from a standing start...but the reason is because of the gearing Mazda has chosen, and not because of the Z's (perceived) torque "advantage".
the 350Z curve is much taller than that of the RX-8, but the RX-8 curve is significantly broader. Visually try to compare the area under the curves, and you'll see it's not that big a difference.
They don't use a similar amount of RPM range on each gear shift. As an example, the Z upchanges from 1st gear to 2nd at redline, and the tach drops to ~4250 RPM. That means that the entire 2nd gear pull will cover a rev range of 2350 RPM. In contrast, the RX-8 makes the upchange to 2nd at 9000 RPM in 1st, and the tach drops all the way down to 5250 RPM. The 2nd gear pull for the RX-8 will cover 3750 RPM on it's way back up to 9000. The RX-8 will sweep 1.6 times the revs the Z will during 2nd gear. That means the RX-8 torque to the wheels is getting multiplied ~1.6 X more than in the Z, since gearing directly multiplies torque. It's like the RX-8 was making 1.6 times it's torque with a lower redline...1.6 x 160 lb-ft = 255 lb-ft. Like I said, they really aren't that far off.
These were posted by "Red Rotory Rocket" on my350z.com. I think what he's saying makes sense, but i'm not a tech guy so can anyone comment on this?
The gear ratios and power curves for the RX-8 are available, so it is possible to do a comparison of acceleration between the 8 and the Z. Though it is just an "on paper" calculation, it is still a relatively good indication of how the cars will match up. The first interesting point is that the Z and the 8 have very similar torque curves. Second, Mazda seems to have chosen some funky gear ratios...not quite optimal for 0-60. Some people are guessing that this was done as a compromise in favor of economy...the car is a four door after all. After plotting acceleration through the gears for both cars, here are my predictions:
0-60, stoplight races, or anything at low vehicle speeds: The Z will own the RX-8. Like I said, the gear ratios are funky in the 8. If Mazda revises the ratios later for quicker low speed acceleration, Zs may have some difficulty.
Anything above 50: The 8 and the Z have nearly identical acceleration. What this means is, if you own a Z and want to race an 8, don't do it from a roll on the highway...neither one of you are likely to pull much on the other. This also means that if the 8's handling is up to snuff, the Z will have stiff competition on the road course.
Anyway, those are my predictions for a Z vs. 8 match-up. I'll be the first to say that this is entirely bench racing, so like many others have said wait until the 8 comes out before making any final judgements.
One final interesting note is that one of the reviewers who was present at the RX-8 Laguna Seca press day borrowed a 350Z to do a comparison between the cars. On the subject of torque, he said the 8 had "good low-down torque" while the Z "lacks much in the way of low-down torque". Things may not drive the way you expect them to, so wait till you can drive both before you make a choice.
Both cars carry 90% peak torque over a significant percentage of the rev range. But don't be fooled by the torque numbers...the Z doesn't really have all that much more torque than the 8. The area under the torque curve is what really matters for acceleration. While the height of the Z's torque curve is greater, it does not span the rev range that the 8's curve does. Compute the area under the curves, and you'll find that the torque of the two engines is much closer than you think. To make a more simplified comparison between the 8 and the Z, consider the 8 to make 240 lb-ft with a 6000 RPM redline and 90% peak torque coming in by 2166 RPM. This will tell you how the car drives and accelerates. Of course, 240 lb-ft is still less than the Z's 274, but please remember that the Z also makes ~40 more HP than the 8.
Like I said, I think the Z is going to own the 8 from a standing start...but the reason is because of the gearing Mazda has chosen, and not because of the Z's (perceived) torque "advantage".
the 350Z curve is much taller than that of the RX-8, but the RX-8 curve is significantly broader. Visually try to compare the area under the curves, and you'll see it's not that big a difference.
They don't use a similar amount of RPM range on each gear shift. As an example, the Z upchanges from 1st gear to 2nd at redline, and the tach drops to ~4250 RPM. That means that the entire 2nd gear pull will cover a rev range of 2350 RPM. In contrast, the RX-8 makes the upchange to 2nd at 9000 RPM in 1st, and the tach drops all the way down to 5250 RPM. The 2nd gear pull for the RX-8 will cover 3750 RPM on it's way back up to 9000. The RX-8 will sweep 1.6 times the revs the Z will during 2nd gear. That means the RX-8 torque to the wheels is getting multiplied ~1.6 X more than in the Z, since gearing directly multiplies torque. It's like the RX-8 was making 1.6 times it's torque with a lower redline...1.6 x 160 lb-ft = 255 lb-ft. Like I said, they really aren't that far off.
These were posted by "Red Rotory Rocket" on my350z.com. I think what he's saying makes sense, but i'm not a tech guy so can anyone comment on this?