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09-01-2015, 11:00 AM | #1 |
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Drives: E88 135i
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Location: Maryland
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Top Speed gearing for Auto 135?
I had my car out on a track recently and decided to see just how fast the car could go... I easily had it climb up to and past the 160MPH point on the speedo and was still only in 5th while still pulling hard. I couldn't get a good top end 6th run due to track size and all but even still, I didn't have a GPS Speedo running (bad planning on my part).
In any regards, does anyone know how fast the auto trans and rear diff are geared to run? I was shocked that I easily blew past 160 in 5th and still had a whole other gear to go! Just fueling my curiosity, maybe I should sign up for a standing mile run!
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09-01-2015, 06:46 PM | #2 |
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I don't know the answer to your question, but 6th gear isn't really a gear for putting power down. Maybe it is a necessity in your case since you would like to see the top speed of the vehicle, but not normally. 6th gear is an overdrive gear, much like every other car geared for road use, and that means its gear ratio is less than 1, so the power/torque output to the driveshaft is greatly reduced, as power delivery is not what it is meant for. I'm not even sure what could happen if someone were to put full throttle tuned power down in 6th gear. I am not sure, but in my head I think it would cause the engine and transmission heightened levels of stress since all that power is bottlenecked at the transmission and you wouldn't get much speed out of it.
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09-01-2015, 07:08 PM | #3 | ||
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V-Max...
Quote:
Quote:
First thing rhodesman the speedo does not report actual vehicle speed(unless you have it coded). The speedo reports a higher speed than actual. Second... IF your car doesn't have M-sport(which included option #840, speed sync) your car will be limited to 210 kph(or 135 mph). So sounds like your car has M-sport(seats & wheels?) which means you HAVE option #840 and your electronic speed limit is set to 250 kph(or 150 mph). Now with that all said... the bellow pic I took of my US spec, M-sport 135i(6 speed manual trans) when it was new and all stock. Even though the speed shows 155 mph... my GPS showed that I was only traveling at 240 kph. For me it doesn't matter IF I am in 5th gear or 6th. Most of the times I just leave the car in 6th and FLOOR IT! That means typically I will be driving as slow at 80 or 100 kph in traffic on the Autobahn... and then let the car rip up to V-Max. In 5th gear you will run out of revs, so V-Max is achieved in 6th for me. On my e39 535iA (3.5 liter V8, 5 speed ZF Auto) it will hold 4th gear until 240 kph and THEN it upshifts into 5th gear! I love that!! The highest speed I have seen with my old e39 is 256 kph(GPS). It has 437K kms on it too and doesn't burn any oil. Leaks it yes, but doesn't burn it. What's my V-Max? Well.. my car has a flash tune with 380 PS and 520Nm. The fastest I have seen on my same GPS is 285 kph. Thats about 6,400 rpms. But I know I've seen a few runs with me touching 6,600 rpms. I have no idea HOW FAST that is... but I suspect its around 295 kph. I have a few friends who also have tuned 135i's and they have also reported seeing 295ish out of their cars. So I think that is a legit V-Max. One of these days I will record it with a GoPro. Dackel PS: for more info on option #840... http://www.1addicts.com/forums/showp...67&postcount=2
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09-02-2015, 08:46 AM | #4 |
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Drives: E88 135i
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Thank you Dackel, yes I have option #840 so at the least, 155MPH is my car's top speed. Also I'm very familiar with the European speedos because my VWs of the past also reported faster than reality speeds (if I remember correctly there's a law somewhere in Europe that makes manufacturers do that).
My real question came down to the needle pegging 160 yet the car felt like it was still climbing in power. Now with the N54 engine, I was under the assumption that I had to get the Speed Delimiter on top of my JB4 to achieve a faster than 155MPH speed. However, in the past, most tunes would eliminate the Speed Limiter just by having the tune, so I guess my question is: do I still need the speed delimiter on top of the JB4 tune? From a "calculated" gear ratio + final drive + diff ratio, it seems the automatic cars can achieve 224.63MPH... but that's a CALCULATED top speed, not a realistic one as BMW135pls pointed out that a below 1 gear is going to be a strain on the drivetrain, thus not a true number. So I guess, 295kph (183.3MPH) will have to suffice as a good ACHIEVABLE top speed. THANKS!
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09-28-2015, 07:02 PM | #9 |
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IIRC, the manual is geared to about 200mph @7000rpm in 6th. The auto should be geared for about 220-230mph @7000rpm in 6th.
Reports from airstrip events have people hitting ~175-180 before drag ultimately stops them. Our cars are very comfortable cruising at 155mph.
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