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Guesses about Gear Ratios and Wheel Torque
This Subaru video shows 97 km/hr @ 7300 and 61 km/hr @ 3200:
http://youtu.be/eP3SR1m_aRY That means redline is approximately at: 2nd 61 MPHIf we assume typical differences between gear ratios, we can speculate: 1st 40 MPHFor highway cruising, that puts 75 MPH in 6th at 3100 RPM. Peak wheel torque per gear, rounded to the nearest 10 lbf*ft, assuming 15% drivetrain loss: 1st 1700 lbf*ftNote that 4th-6th seem a little tall, but that's because 3rd is a bit tall in the video. Before noticing that 3rd was in the video, my guesses were: 3rd 86 MPHObviously redline won't be reached in 6th gear, and possibly not in 5th if rumors of a 136 MPH top speed are true. However, some of those rumors claim top speed is due to fuel cutoff (supposedly at 7450 RPM), which raises some questions. |
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Edit: Note that I revised 5th to redline at 144 rather than 141 |
I wonder why the wheel torque per gear never shows up on a dyno?
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Thanks, Dimman.
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I know this will sound like a very noob question and Im sorry if it does, but do you think the manual will be short throws? like I don't need to mod it with a Short shifter?
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Oh hey Deslock. Nice job on the calculations, I'll run some of mine here if you don't mind. Given the wheel RPM is known, 844 RPM @ 60MPH, I figure this car would need a 3.75 or so Final 5th gear ratio to pull 141MPH. That puts 6th gear around 0.78-0.80 if the 2500RPM at 60mph is true. Not exactly tall but it's not nearly as short as the MX-5/RX-8 gearbox.
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I happened to re-watch the video and noticed that 3rd gear is also shown, and estimated that it redlines at ~88 MPH (rather than ~86 as I initially guessed). So I added that information and revised my estimates assuming that 4th, 5th, and 6th are all *slightly* taller as well. Again, this is all guesswork.
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my car has less hp less tq and its drag ratio is .32 and i can hit 150 more tq and hp with a drag ratio of .27 should hit 150 prob topping out after 2-3 miles at 160-165 |
Suppose you can hit 61 at the top of second. This is interesting since they say the car was not designed for spec sheets. If your estimates are true it would make the 0-60 time look good on paper. Perhaps sub 6 sec to 60 mph if you beat the hell out of it and are a very very good driver.
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Those ratios don't seem very close, about 1.44 between gears :O by contrast an STi transmission is 1.386 (looking at 4th and 5th at least, assuming equal "spacing"). I think first is going to be a little more than 40 since that would put it more in line with the 2nd-3rd ratio. I think having all 6 gears equally spaced is kinda stupid if 6th gear cannot reach top speed, but that's just me (and Porsche?). |
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