For those getting a dyno reading on their zed there are a few things that can affect the power reading. Even comparing the most common in the world Dyno Dynamics, even in Shootout mode, variations occur if weather station inputs are put into the dyno computer incorrectly, accidently or on purpose. Also other factors such as where the intake temp sensor is placed effects the correction factor as per this interesting link. http://stmtune.wordpress.com/2012/06/13/how-to-gain-49-kw-for-free/#more-3804 Also be very sceptical of Dyno readings that do not show the data at the bottom of the read out as per below. The recent thread was somewhat interesting and informative, but unfortunately went downhill. Seriously keep this clean and no personal attacks.
I was waiting for this JP! ;p lol And this is a valid point I'd be interested to see a competitive dyno with the ambient controls being changed on the same car with same mods
DO NOT LET THIS THREAD BECOME THE SAME AS SOME RECENT THREADS Mods WILL be giving out infractions will be given out as needed if it goes downhill. You cant say we didnt warn you lol. On topic, I have had my old TT dynoed a few times on different days but at the same dyno, with no mods in between. Same dyno operator as well. Had a variance of about 15rwkw between best and worst runs....
I watched the last threads with interest, it was really disappointing to see good info overshadowed by crap. That said in response to the quote above, how much of these discrepancies is fuel brand/quality, ambient temps, and tyre pressures etc. Or is it all operator data input discrepancy.
Some manufacturers do not provide atmospheric information on the bottom of the dyno graphs, this does not go to say that the operator has tampered with the machine in any way. John have you spoken with anyone at Dynapack about some of the suggestions you are putting forward - I will forward them through myself if you like. Would you like to explain to us what these setting are on the Dynapack and how you assume people are manipulating them? Location of temp sensor for the hub dyno in question: Weather conditions on the day: Correction method SAE, TCF: 1 Would you like a non corrected print out for the day then you can apply what ever formula you like to the figures. If this is what it all boils down to - people claiming we have manipulated readings by falsifying the atmospheric conditions then I will submit an uncorrected graph, no problem at all. EDIT: Tuner emailed for uncorrected graphs, next email to Dynapack making them aware of some of the things being said here so they might have their input on the subject. EDIT #2: It should also be noted that the Dynapack does not require manual inputs of weather conditions and constantly updates the atmospheric conditions while the machine is in operation automatically - unlike some of the older more unreliable machines that rely on operator inputs etc. We can actually provide a graph or the temperatures during the day and relate it to each individual power run and tell you all the atmospheric inputs 100% accurately at any time we were running the machine.
Right so just for those interested in what some have said about the hub dyno and some lies - sorry some things that have been said that are not true: http://www.dynapackusa.com/vehicle.htm Of particular interest: Wheel Dia - for entering wheel diameter so equivalent ground speed can be calculated for display - not used or necessary for power and torque measurements. TC Factor - allows user to enter a driveline loss factor (Transmission Correction) to add a percentage of power to the flywheel power graphs. A factor of 1.0 adds no correction factor, a factor of 1.15 would add a 15% correction factor to the flywheel numbers. Axle (rear wheel) numbers are not effected by the TC Factor box. http://www.dynapackusa.com/temp.htm Air intake temp is constantly monitored automatically.
Mungyz I understand and even agree with what you have said in a lot of your posts on this, can I ask - and I am not meaning this for you alone but everyone who is thinking of making comments about personal intentions when it comes to the dynos - to not carry it on in this thread. I have a lot of respect for the people who have contributed to these threads and I personally only want to see the actual results, not peoples interpretations on the intentions of the people posting them. lets take the results as they have been offered - in good faith - and see if we can identify things of help not try and discredit the operators or the equipment because we dissagree with the numbers
dyno dynamics always marketed themselves well and speaking with ppl and alot of research prior to getting mine tuned I understand they do read higher and can be fudged. I got my car tuned on a mainline.... hard to fudge, no shootout bullshit and far more accurate, but for the dyno tuner... lower reading dynos are not really what they want to buy as they have to keep up with the rest of the pack and the power their tuner can perceive to produce against the next tuner out there. Its business. The quarter mile will tell the story though. I want to go and get a dyno done this weekend on a dyno dynamics for camparison between the two will be very interesting.
Moral of the story is a dyno is a tool to tune the engine under load safely so it performs on the road. Comparing different machines readings accurately and competitively displays accute personality characteristics.
why is it so big an issue, these machines are designed to create a controlled repeateable situation to maximise a tune on any given engine. and the reality is most read within 10~15% of each other which has already been shown can be seen in multiple runs even on the same dyno. but how about we get back on topic and post the sheets the facts and try and sort the factors contributing to issues. not argue about our perceived perception on how accurate the machine is.
Very informative Mungyz and I thank you for being professional and on point. I have been playing phone tag with the Aussie Dynopac rep, as I had some questions, some of which you have answered. It still doesn't explain how the zed you have over there makes around 80rwkw more than most, if not all rolling dyno's, certainly ours, with similar features on the same boost and 98 octane?? Even if this engine was built to perfection, with the ideal cams and heads porting and valves etc the GTRS turbo's won't flow this power and 98 octane fuel would struggle. We may never know. Mungy what is the name of the workshop who has the dyno? Do they have dyno readings for other zeds or Skylines to compare? Are you sure they didn't have the dyno set on engine power not wheel or hub power?
I have been told that in NZ we have different formulas for diesel depending on location and season, this is to do with the effect the cold has on diesel, I was also told that the diesel for colder climates also produced more power - I stress this is what I was told when I was growing up in NZ - I wonder if something similar can hold true for our petrol formulas - I have often been told that leaded fuel had a higher effective octane then the equivalent grade unleaded, is it possible that we have differing fuel formulas giving the effect of a higher octane. Only a suggestion guys feel free to tell me I am wrong.
Interesting, although it is more then a small amount of power difference we are talking about. Even with alot more octane and allowing more timing it is still a big difference in power readings. There are some inputs required on the Dynopac which is different to the Dyno Dynamics.http://autospeed.com.au/cms/title_The-Dynapack-Dyno/A_111343/article.html
John TCF (Transmission correction factor) is set at one, this gives zero increase to the power as explained on the Dynapack site, if the TCF is set to say 1.15 then that is assuming you have a loss of power of 15% through the gearbox and diff so the power shown on the graph would be 15% higher to indicate assumed engine power. Seeing as we don't know exactly how much power is lost through the gearbox etc power at the hubs is the safest bet when using a hub dyno. When I have finished my testing on pipe kits etc I should be able to explain exactly what is going on and give as much proof as is possible to back up what I will say. I have a very strong theory at present but I'm not prepared to throw it out there on a public forum for people to bash it all to death with poorly educated/misguided opinions. It's all simple enough but not quite what people will expect so absolutely certain to create a shitstorm of opposing opinion from those who haven't done the testing as fully as we are. How ironic I am being accused of not testing properly when I actually intend to go FAR further than anyone I know of has.
The simple solution would be to put the car on a Dyno Dynamics dyno. One of the biggest variables in drive train power loss is the tyres. The main benefit of the hub dynos is eliminating this variable. However this makes comparing a hub dyno with a chassis roller dyno just about as difficult as comparing a chassis roller dyno with a engine dyno. A hub chassis dyno will always read higher than a chassis roller dyno just as an engine dyno will read higher than any chassis dyno. Rototest has an interesting database of stock dyno figures. http://www.rri.se/
Airtemp that the engine sees or outside air temp? Because the air temp that the engine intake sees, which is actual intake temp, makes a hell of a difference to power output. Measuring the outside air temp largely has no relevance to actual intake temp, particularly on an intercooled engine.
Something I am interested is the volume of air going through the system (taken from the actual air intake not at the manifold) when comparing the new pipes to the old ones at any given pressure. I am not sure there is any reasonable way to measure this but I am wondering if this is the reason why we are getting such an increase in the power outputs. (by this I am referring to the differeances of 2 - 2.5 inch systems). Put simply if you have 1 litre of tube capacity at 1 atmosphere above normal air pressure (app 14 psi boost) has a volume at normal atmospheric pressure of 2 litres. As such by increasing the diameter of our intake tract but keeping maximum boost pressure at the same level we are putting more air into the engine than before which in turn will (like a bigger cam on a NA engine) put out better power. This aside I thought that the system was running a MAP sensor over the stock system and this measures manifold pressure and unless the fuel maps have been altered to suit could cause leaning out and opens up a whole new basket of eggs. The result I can see several things that would help (leaning an engine out may even be part of it) and plenty that hinder. so I am lost, but just trying to put new lines of thought to get a proper discussion going
The air temp sensor is mounted as per the picture provided, air flow through the dyno room is significant and sufficient enough to rule out any large temperature differences between what the sensor reads and what the engine breaths. Having said that lets be fair and remember if you are tuning in NZ chances are air temp will be below 20 degrees C even over summer and during winter you could easily be working in 8 degrees C air temp. No doubt you Aussies get a raw deal and have to deal with far warmer temps, I don't believe for one moment that any of the correction factors actually work accurately enough to compare running in NZ to running in Aus. We actually noted the engine lost around 20 - 30Kw with an air temp rise of around 1 - 2 degrees C, other factors were at play such as fuel temp getting fairly high, the tune actually pulls timing back when air charge temp gets to high etc but in short air temp plays a big part for certain (but we all know this).
Contrary to popular belief I do not believe there is actually any more air flow with the bigger pipes than what there is with the stock sized pipes. If there was then we would have seen mixtures lean out as you suggest, seeing as we didn't .......... Anyway with the Dynapack we can run two airflow meters and have them logging and plot graphs etc, these airflow meters will serve no purpose other than giving readings to the dyno, the engine will still run off its own MAP sensors. We can run exh manifold pressure sensors, lambda sensors, inlet pressure sensors, inlet temp sensors, the Link ECU can log a whole crap load of info itself - put it this way: those that have complained of not enough things tested etc will soon have to eat their words. Might even stuff a couple of EGT probes in the oxy sensor bosses on the down pipes - cars going to go fricken slow with all this crap hanging off it :rofl:
