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The RX-8 redlines at 9000 rpm! Yeah, max torque is a relatively puny 159 lb-ft, for a car that weighs almost exactly the same as the Saab(3058 lbs vs 3060 for a 2002 9-3 SE). But when you hit 5500 rpm in the Saab, you have to think about shifting, while in the RX-8, you're just hitting the power band.
Let's look at some numbers for fun:
In the Mazda, output at 5500 rpm is 159 ft-lb torque. First gear is 3.76:1, and final drive is 4.444:1, so torque to the wheels is 2657 ft-lb. The tires are 225/45R18, so force to the ground is 2452 lbf.
In the Saab, output from 2200-4800 rpm is 209 ft-lb (let's ignore the boost limits in first and second for now). First gear is 3.38:1 and final drive is 4.05:1, so torque to the wheels is 2861 ft-lb. On 205/50R16 tires, that's 2861 lbf of force to the pavement. Clearly, the Saab has better acceleration early.
But, at 4800, you shift up in the Saab. Now, you're in second, with a gear ratio of 1.76:1. You've got only 1490 ft-lb to the wheels, and 1490 lbf to the ground. The Mazda is still making 2452 lbf with 3500 rpm to go.
Ok, so let's look at some real-world situations. In the Saab, 2200 rpm in third is 32.9 mph. 4800 rpm is 71.7 mph. So let's look at that 50-70 time we all love. Force to the ground in third is 999 lbf. Acceleration will be 10.4 ft/s^2, or 7.12 mph/s. 50-70 time should be 2.81 seconds.
The lowest gear in which the Mazda can hit 70 is third. 50 mph is 4726 rpm. 70 mph is 6616 rpm. In the Mazda, we don't have a flat torque band, but with 238 hp @ 8500 rpm, torque is 147 ft-lb at 8500 rpm. Let's say the Mazda gets approximately 155 ft-lb from 4726 to 6616 rpm. That 155 ft-lb is 1046 lbf. Acceleration is 7.46 mph/s, which is 2.68 seconds 50-70.
Now, remember that that was the Saab at its best. Let's look at 40-60 times. The math for the Saab is all the same; it does it in third gear in 2.81 seconds. The Mazda can do it in second, though. Going through the math for the Mazda, you should find it takes only 1.94 seconds.
Real test numbers? The Mazda does 0-60 in 6.3. That's Viggen territory...actually, a bit better than the Viggen. The RX-8 is a sports car, especially once you've got it moving. Yeah, you have to keep the revs up to keep it going, but that's what a rotary engine is all about...and with a 9000 rpm redline, it's not a problem.
Matt
'99 base
posted by 12.101.2...
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