Dyno Day Sat 25th Oct
- Thread starter starboard147
- Start date
PS when fitting the piggyback its easier to see th pin numbers if you take the ecu plug apart - once it is off the ecu there is a small screw in one of the backshell, the rubber 'seal' has to be rolled off the other end and then it slides apart - cant remember if this was in the instructions or not. Also most UK cars wont have a narrow band sensor (mine does it is 1990 and had a cat) but I guess you can connect that wire to your widebands narrow band output - it is probably possible to connect it in wideband mode with some playing in the software. Tony
Neil Haughey
New member
Spot on Paul. Saying anything more then that is pointless. As a side note what where the raw figures at the wheels like? A chassis dyno should measure this very accurately as its simple physics, my personal take on this stuff is that I am only interested in the figures at the wheels because ultimately this is what will say how fast a particular car is. Sorry I couldn't come along guys.
Its not cos your a director now then and no longer mix with us peasants [ORIGINAL: John Sims Glad you had a good day guys. Sorry I couldn't make it but it seems someone has stolen several hours out of each day and weekends don't exist as such. So are these the "Rollers of Absolute Truth" or the "Rollers of Disappointment"? I kind of favour the first one 'cos we can then say " On the RAT Lil produced 330" []
][][] RAT or my car was beaten down by the ROD! I'm off to Jamsport next week for a pick me up [] They do not normally use the shootout mode so previous readings on the RAT ROD may also not have a direct comparison, without including the variations of different days. Tony
rcsalmons
New member
Well - thanks for organising this Paul I had a cracking day. Paul interesting to compare our cars, same year, same mods and 1hp different - must have been that 99 Ron petrol you were running...... It was also good of Triton to let me have a second run for free to compare the MAXHP chips to those of Jon Mitchel. I would love to be able to say the second run restored the lost 20hp from my last dyno run but alas not - the difference was 0.2hp. So I have a spare set of chips, if anyone wants a set they can have them for what I paid. Come to the conclusion I am going to standardise on a dyno near me to check power - as Paul says different Dyno's even the same make cannot be trusted to give the same results. Anyway good day Thanks Rich
sawood12
New member
Wow, 20bhp difference. I know you will get differences between rolling roads but 20bhp difference is a bit much. I'd expect the differences to be much closer than that. The thing about the road at Silverstone is that it was supposed to have been specifically calibrated for Porsches so was supposed to be pretty accurate correlation between measured wheel HP and calculated flywheel HP - i.e. the assumption used in the calcs about transmission inertia and losses are closer than the standard assumptions. Sounds like a good day nontheless. Wish I could have been there - I've been pushing a paint roller all day :-(
Did anyone run a totally standard Turbo? If so how were its figures? By the sounds of it the S2s posted about 10% lower than expected. I agree with you Neil, except that when all the cars are the same transmission losses are broadly equal so wheel power is less of a requirement. On that note though I think I'm right in saying the DynoDynamics learns from other cars of the same type to make its shootout mode more accurate, so perhaps if it was used in this mode a bit more to run 924/944/968 it might get better and that might see figures rise. I still tend to think the rollers of truth are not bad in terms of repeatability on different days and accuracy in absolute terms, based on many standard cars seeming to make their quoted power output. It's a shame if that isn't "out of the box" with any DD dyno though.
rcsalmons
New member
Agreed 20hp is a lot but if you look at Silverstone most of the S2's were 210-220hp yesterday if I remeber right the highest was 189? but the range was 180-189hp. My previous Dyno run was at Chris's new place in Wellingborough again a DD dyno which he said had be tested against his dyno at Silverstone for consistency. If I had a spare £50 I would take it over again to check. Rich
I'm not going to get into the whole 'true dyno power thing' (been going to dyno days like this for 20 years now, and the debate is both endless and futile..., like golf...), suffice to say that I got bang on what I thought I should get from a standard 18 year old / 80,000 mile S2 that had a 'claimed' 211BHP when shiny new.. ie. 191.8 BHP / 188 ft/lbs. If I had gotten 210+, I would be more suspicious of the dyno's accuracy..., after all, you have to expect some of the pony's to have escaped after all that time... Phil.
Indi9xx
New member
Initially on saturday afternoon I thought there could be something up with the dyno when I started to see the results comming in after the dyno time was over. However, after a weekend of reflection, I think the dyno has accurately done its job, especially being in shootout mode. The problem is, saturday was a really cold day, and I can hear you all saying "yeah that should give us more power", except nooo, the dyno will correct for temp and air pressure differences. But what a cold day will do is mean the gear oil in the cars would be thicker and causing more drag. So even though the rear wheel figures will be correct and accurate, the calculated flywheel figures will be lower as in shoot out mode the dyno will not know there is an abnormal amount of transmission loss and therefore will not be able to compensate for it to show the real flywheel figure... Remember transmission losses increase with rpm at idle it may be 1/4 bhp loss, but by the time its wound up to 6000 rpm that loss could be 20bhp. However, on a car thats been driven for long enough for the transmission to be hot with usual transmission fluid, it may not cause so much of a problem, rather than a car which has a stone cold transmission filled with swepco. With shootout mode, in effect you could over inflate your tyres, use Dextron 2 ATF istead of gear oil and get a better flywheel figure than a car with correct tyre pressures and swepco installed. Just a thought... I could be wrong A couple of the cars had abnormal print outs which I am going to look into with dyno dynamics to get to the bottom of.
Pleased you did [ORIGINAL: Diver944 The best thing though was that after 5 years, LIL finally managed to beat Tony F on an actual Dyno Day (there were a few comments when people noticed I'd been helping him set up his Vitesse Piggyback, but I have to declare my innocence
] would have been upset if you hadn't! and I am sure I would have been further behind if you hadn't given me the crash course in piggy back set up - thanks again. now get a bigger exhaust on there! Tony
starboard147
New member
Understand where you're coming from, Jon, however the losses were consistent throughout the day... that's from the S2 that was 3rd on (immediately after driving down from Bristol) through to Rich, who went on twice and had a test drive in between. Also, the guy at Triton made sure that the car (inc transmission) was reasonably warm on the RR before he caned it (very considerate!). Anyway, it's only numbers!! Thanks to everyone for coming, I thought it was a great day. I'll echo the thanks to Triton, Gordon, and Jon M - cooking a BBQ in Oct is a thankless task. If everyone fancies it, perhaps we can do it all again next year... And Rich, I'm already looking at how I can flatten out that boost curve [] Paul
] PaulBit off Topic here... The CS is a laugh, great for the badly surfaced 'B' roads in Gloucestershire - only has 50 BHP, but puts it all to good use. Also good round town (high up and narrow), returns 90+ mpg, or 60 if I ride it like it's stolen (which is most of the time). Belt drive means minimal maintenance, ABS plus BMW reliability make for a great package.
That's what I thought; might be fun for my 60 mile commute on occasion as a change from the train, reasonably cheap to run/reliable and not likely to tempt me into trying to kill myself. I think it would be something like 18 months before they'd let me have a license for one here though.
Copperman05
New member
I dont think the dyno results were out, seemed pretty spot on to me, the S2's mostly loosing 16-20hp after 18-20 years would seem very resonable, and surely more believable than one showing very near the original stated output. We all know engines lose power over time and especially mileage. But then I guess if I had spent a few 1000 £££ on upgrades I would be blaming the dyno for poor results too[]. Perhaps nextime Paul should find one (dyno) that provides more favouable readings. [:-] Edd
]. Perhaps nextime Paul should find one (dyno) that provides more favouable readings. [:-] Edd
pauljmcnulty
Active member
Not sure what you mean, Edd? Are you saying that people should be shot down in flames because they've spent money on their cars? I don't get it. The point is, the guys who've been to these dyno days year after year, and developed their cars in between, want to see a real-world comparison. Sure, headline figures are great, but it's critical that the year-on-year readings are accurate for comparison purposes. It's nothing to do with jealousy, but people wanting to improve their cars. Think about it? [8|]ORIGINAL: Copperman05 I dont think the dyno results were out, seemed pretty spot on to me, the S2's mostly loosing 16-20hp after 18-20 years would seem very resonable, and surely more believable than one showing very near the original stated output. We all know engines lose power over time and especially mileage. But then I guess if I had spent a few 1000 £££ on upgrades I would be blaming the dyno for poor results too[
Copperman05
New member
Hold on there...who's shooting who here...I think your taking my post a little toooo seriously...what I said is said in jest hence the little smily faces?[]? I was just showing my amusement at some peoples view on the dyno results. And who said anything about jealousy? Edd
]? I was just showing my amusement at some peoples view on the dyno results. And who said anything about jealousy? Edd
Posts made and opinions expressed are those of the individual forum members
Use of the Forum is subject to the Terms and Conditions
