03-02-2013, 03:05 PM
(03-02-2013, 02:42 PM)Ruan Wrote: Their RPM readings are TOTALLY out...Exactly what i was getting at but his is the only one where the final revs arent right, pretty much every other car is spot on for what youd expect. the problem is it all relies on them tying up your revs perfectly to the machine (and also your rev counter being perfect) the torque being 100rpm out could have a good few bhp difference on the final figure.
FAR AS IM CONCERNED - THROW YOUR RESULTS IN THE BIN
That's why the results are so f*cked...
A TD04 XUD9 producing 210lbft and 125hp? Are you shitting me!!! There's no way it's making 210lb.ft at peak without making more power - we know that TD04s don't spool that quickly, so will be producing the power at a higher RPM.
If you're paying £30 for a dyno run, they shouldn't be doing anything less than laser tachoing the crank pulley or the pump pulley and doubling the figure to do their measurements... You've literally got to insist they do it, otherwise the readings are totally to shit...
You can hear with Davids car that it's revving to a SIGNIFICANT amount more than 3850 - it hits the bloody governor for goodness sakes!! If that's the stock governor, that should be about 4850RPM - the popping and banging is due to retarded timing, but I rekon that's relatively little to do with the static pump timing, that won't have helped, but the real cause is elsewhere - that'll be because it's starving of fuel seriously and is losing case pressure, losing all the dynamic timing and going to full retard poistion...
At the end of the day, the torque give or take you can take as correct if you believe their transmission losses, judging by the fact it's a Dyno Dynamics Shootout - that'll be 15% for FWD.
I rekon that the final reading given where it stops is at 4950rpm... If we extrapolate from there back I rekon it's making 210lb.ft at 3850 (2850rpm on the graph) - that's (210*3850)/5252 which gives you a reading of 153.9hp - MUCH more like the figure I'd be expecting, now that's at peak TORQUE... So in actual fact, you'll find the horsepower carries on a bit further, even though the torque is dropping since the RPMs are increasing...
At 4300rpm (3300rpm) it's making about 195lb.ft torque... Again (195*4300)/5252 = 159.6HP... Sounding much more like it now?
This is the EXACT reason Chassis Dynos are TOTAL bullshit, people DO NOT understand the correlation between RPM and power...
Later when I can be bothered and I'm less hungry, I'll try and replot that graph in Excel as best as I can... Basically read everything 1000RPM up and then recalculate the power on top!!!
This is what you get on a dyno day its a quick slap dash job and why your always better going on your own at another time and paying twice the amount or if you want to try a few things actually paying for dyno time. £100/hour sounds like alot but you can get alot of things done.
(03-02-2013, 02:53 PM)puglove Wrote: Full refund for everyone is needed then. Im pretty sure my 6 should of been higher!
How does this look for a 6 then?
all the petrol graphs ive seen look pretty much spot on. GTi6s rarely make 167bh pas peugeot over quoted their power to make them look like a better buy above the XSi.