 Posted: Sun Dec 16, 2007 4:39 pm Post subject: |
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| Hi
On the unit I have you cannot map things like gear changes accuratly. They do the "V-Box Mini" which has provisions for external inputs such as a rev counter feed, but that is about 3 times the price. The Driftbox does has a provision for calculating the max power from the acceleration figures (and can display it on screen) but the people who make the unit are not really supportive of that being accurate. After all there are too many other variables (such as tyre slip and clutch slip), and it requires an accurate figure for drag coefficient and for weight. Then you have to realise that max power might only be over a VERY narrow band (for example on a bike we have, between 9000 and 10000rpm the power increases from just under 18hp to 25hp, about a 40% increase in 1000rpm). Also you are comparing the figures it gives to the brochure figures. Brochure figures are crank figures and a lot higher than the true figure at the wheel (which is meaningful). A 1.7 16V P4 has a claimed 137hp at the crank, but having seen one dynoed years ago it was under 90hp at the wheels. All the best Keith |
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| Posted: Sat Dec 15, 2007 11:24 pm Post subject: |
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| hi, i experienced a while ago a GPS-less solution! the principle of it is quite simple :
- make a current clamp by winding 10 turns of electrical wire around one spark plug wire - connect this to the line input of a laptop's soundcard - collect information about the car such as gear ratios, tyres, weight, ambient temperature, aerodynamics coefficient ; these are used to feed a smart software program - find a flat & straight road and drive from idle to the redline in 2nd or 3rd gear the software records how fast the engine revs increases, and deduces torque and power curves for the engine. At first i didn't think it would work but tried it on my 1.3 33 and guess what? after the test the computer gave me a max power of 90bhp, in accordance with manufacturer's specs. I've since tried it on a few cars and always enjoyed it. Unfortunately the required software ( http://www.powerdyn.fr/English/english.html) isn't free any more, but still cheaper than a GPS unit i think. Results are highly accurate and can be trusted, it's very useful on a car you modify, to know exactly what increase in performance you get from each of the mods. regards, zp |
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| Posted: Sat Dec 15, 2007 10:59 pm Post subject: |
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| Now to Hijack Keiths Thread..
The UHF Radio in my work Ute has a GPS feature, The Max Speed now shows 387kmph, Which I got up to in car park. Not bad for 2 tonne 4WD Trayback. 
Gotta Love technology... Keith, Is there any way of mapping when the gear changes are? Cheers |
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| Posted: Sat Dec 15, 2007 1:01 pm Post subject: |
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| I know someone who has the Max recorded speed on their Garmin at over 500mph.
They would have upset BA Baracus, because they switched it on 'on a plane, fool!!'' Not big or clever. John |
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| Posted: Sat Dec 15, 2007 12:29 pm Post subject: |
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On top speed runs on the bike I found that the final mark on the speedo (170mph and bang on the red line in top on stock gearing) was 154.5mph. Best I have managed is 181.8mph (through timing lights, unfaired 1200 Bandit but somewhat played with) and at that the speedo needle was pointing down towards where 200mph would be if the markings went that high. Suspect the speedo on my little RS125 is even further out. 33 speedo seems to be within 10%, unlike the 155 that is miles out at 30mph (but gets more accurate with speed).
You crazy? Eat a sandwich that quickly. I had to drop it while changing gear.
Err, first result would probably be a new clutch being required. You are not that far from me. Wander over some time (or I will wander over) and we can try it out.
They are £465, although they do a cheaper one called a Performance Box for about £300 that doesn't include the G meter that the Driftbox has. It is a 10hz GPS unit, and has various displays. I tend to leave it in performance mode so it is showing current speed, max speed since you last stopped and last acceleration figures (0-60 and standing quarter). http://www.driftbox.com/ All the best Keith |
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| Posted: Sat Dec 15, 2007 10:24 am Post subject: |
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| Reckon we all need one of these driftboxes to check our cars out. How much are they Keith? I wnt one for Christmas! | |
| Posted: Sat Dec 15, 2007 9:42 am Post subject: |
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| That's some cerrtainly "in depth" measurements there Keith!
What gets me going are those who say "my Japanese crock o' unstylish XXXX" gets to 60 in 7 seconds when they're looking at the speedo (usually 10ish% short). So that is probably 54mph... and actually most tests these days are to 100kph which is 62 so they're probably 8mph short. So - this is a nice scientific blast by contrast. The dip in the graph is where Keith quickly paused to have a rapid sandwich! 
8.9 seconds. What would be the expected result if chipped, intaked, exhausted (?!?!?!!) and mildly cammed? Anyone know? Bob |
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| Posted: Sat Dec 15, 2007 1:45 am Post subject: |
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| Hi
Graphs of the run playing silly buggers. Against distance. 
Against time. 
All the best Keith |
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| Posted: Thu Dec 06, 2007 8:53 pm Post subject: |
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| Hi
"Autocar & Motor" managed it in 8.6 seconds. But they don't have to pay for clutches. Think Alfa claimed about 8 seconds. All the best Keith |
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| Posted: Thu Dec 06, 2007 5:48 pm Post subject: |
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| Good going. What's the 'brochure' 0-60 of the P4? Can't be far off.
John |
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| Posted: Thu Dec 06, 2007 5:07 pm Post subject: Performance |
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| Hi
For a while I have had a Driftbox. Basically a high accuracy GPS unit (with a built in G meter as well), designed for performance testing and drift scoring. Had it in the P4 today and decided to play silly b's and let the clutch have a bit of abuse. It managed to hit 60 in 8.9 seconds, although how much I could improve on that I am not sure. About a second better than the 155 manages (although the 155 lands up with a lot more of a nasty smell from trying). All the best Keith |
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