Difference between Bluehdi 100 and 120

Engine, Exhaust, Drivetrain, ECU
FrankBullitt
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Joined: Sat Nov 14, 2015 9:32 pm

Re: Difference between Bluehdi 100 and 120

Post by FrankBullitt » Fri Aug 18, 2017 7:07 pm

The 6-speed gearbox does have a much nicer shift, PSA 5-speed boxes invariably feel like a Parisian with no mechanical sympathy has put 100k through the 'box when they are new.

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Softrider
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Location: Jutland, Denmark

Re: Difference between Bluehdi 100 and 120

Post by Softrider » Sat Aug 19, 2017 12:56 pm

The PSA 5-speed gearbox in the Cactus BlueHDi 100 is not a sophisticated gearbox, but it's significantly better when the car has run 50-60000 Km (about 35000 Miles). The PSA 6-speed gearbox in, for example, the C5 with the 2.0-liter HDI engine is very good and, in my opinion, better than the BMW's equivalent 6-speed gearbox in the F30 320d (and it says quite a bit)

I do not know how much torque the current PSA 5-speed gearbox can withstand without knowing what it's called internally at PSA, but it's not the gear ratios or the final drive ratio that is the challenge if you want more horsepower. The car has an extremely high gear ratio and, for example, the engine has no more than aprox 1700 rpm at 100 Km/h (62 mph) in fifth gear. The engine's maximum torque of 254 Nm (187 ft-lb) is developed at 1750 rpm. Maximum power of 100 horsepower is developed at 3750 rpm.
2017 Citroën C4 Picasso BlueHDi 120
History: 2002 Citroën C5 2.0 HDi, 2014 Citroën C4 Cactus BlueHDi 100

geokaps2005
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Re: Difference between Bluehdi 100 and 120

Post by geokaps2005 » Tue Sep 05, 2017 9:11 pm

Here is the Speed/1000 rpm

wp_ss_20170729_0002.png


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Softrider
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Location: Jutland, Denmark

Re: Difference between Bluehdi 100 and 120

Post by Softrider » Tue Sep 05, 2017 11:00 pm

You can calculate engine rpm vs. gear ratio by using the following formula (metric units - except for the size of the tires that are still stated in inches for some reason): rpm = (km/h x gearbox ratio x rear axle ratio x 5305) / ((25.4 x tire size) + (2 x tire width x tire profile))

For my Cactus BlueHDi 100 that has 195/65-15 wheels, the formula becomes at 100 Km/h in fifth gear:
rpm = (100 x 0.58 x 3.47 x 5305) / ((25.4 x 15) + (2 x 195 x 0.65))
rpm ≈ 1683
2017 Citroën C4 Picasso BlueHDi 120
History: 2002 Citroën C5 2.0 HDi, 2014 Citroën C4 Cactus BlueHDi 100

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