yeah great info - thanks!
yeah great info - thanks!
Ferrodo DS2500 is a great upgrade to the standard pad and as it provides a constant friction coefficent from cold to max temp there is no scary lack of brakes from cold as with many track orientated friction materials.
Id like to add to the rolling road part that a SAE correction factor is needed.
This the standardises the results against a base temperature and humidty and pressure, allowing a base BHP/Torque to be seen.
Then when you add a modification you can go back to the rolling road on a different day with different temperature and humidity and pressure and compare the results to the 1st base rolling road.
If you do not add this correction factor then rolling road graphs from different days are a waste of time as the humidty and pressure make a large difference on the power the car will produce.
This is also how certain tuning companies can fiddle the results by adjusting the correction factor to give different power values.
Very true, hence my recomendation for DD (Dyno Dynamics) rolling roads which will not produce a none SAE corrected result without printing as much on the graph, along with temperature, humidity, barometric pressure etc. etc. Add to this if power testing any DD operator should be running the road in the correct shootout mode which locks down most of the roads settings so manipulation of the end result is not possible. On SAE correction only you will still get varying results becaues of ambient tempetaure etc. as every car does not produce the same drop in power for the same rise in ambient temperature, drop in barometric pressure etc. etc.
DD stuff has really made DynoJet, Maha, Sun etc. rolling roads obsolete IMHO, not only are they fantastic to map on and bullet proof but they are about as accurate as a rolling road will get!
There are times when you want absolutely no correction factor though, especialy if you need to know the ftlbs the road records under specific humidity, pressure etc. You really need a climate controlled cell then so the results are repeatable.
Icarus i have a question,
I currently have fitted on my car 205/50/17 contact sport 2 tyres fitted all round. I will be changing them shortly and was wondering if i could change the wall height and drop it slightly to make them look more ''low profile'' ive been told that i could drop it to 45 or maybe 40 but adz on here also said he thinks that if i drop the wall height i would be able to fit slightly wider tyres aswell something on the lines of a 215/45/17 is this correct.
Any help appreciated.
Google for tyre size calculator which will show you various combinations of tyre that match the current rolling radius. It is very important to maintain the standard rolling radius or you speedo calibration and a few other things that rely on calibrated wheel speed will read low. As such you can't just fit a skinnier tyre.
Can I just add some details to this regarding Dyno Dynamics graphs and how to read them, in terms of correction.
Modern DD Dyno's (say, the last 2-3 years) use Windows-based software, the graphs are much larger, clearer, easier to read and more versatile. Older systems are DOS based, the graphs are noticeably different. I've not seen a DOS graph on here yet, most I have seen are Windows.
On the tell-tale Shootout data (little square box in the corner), you'll see two values, AT and IT. If there isn't a box containing Shootout data, the run wasn't produced in Shootout mode and should, for reference purposes, be disregarded.
AT - Ambient Temp - This is measured using a weather station connected directly to the Dyno.
IT - Intake Temp - This is a probe that is supposed to be placed in the intake airflow stream.
We, along with many other DD operators, have realised that by doing this in the way DD originally suggested can produce some unfeasible results. We tend to place the Intake Temp sensor in the 'vicinity' of the intake, but outside the engine bay. In all honesty, as long as it is in the Dyno cell, thats good enough. The engine consumes air fast enough to make the heat-soaked air in the open engine bay mostly irrelevant. Rule of thumb is that there should be less than 10°c differential between IT and AT. If there is more than this, then it is likely that the figures were exaggerated.
I've actually seen one well-known tuner post graphs suggesting a 30bhp improvement over book BHP on a high-end car, but the graph had almost 70° differential between Ambient and Intake temps! That alone would make 30bhp difference, so their mods were useless. In all honesty, the IT probe must have been either in the radiator fins, close to the exhaust manifold or in a cup of coffee!!
Also, if you see an (R) after the legend on the RPM axis, this means that RPM was calculated from Roller Speed. This is, in my opinion, a lazy way. The operator doesn't need to connect a probe to the engine to detect RPM, he can simply use the cars tacho versus measured roller-speed to effectively tell the Dyno what RPM the engine is doing. We all know the car tacho's aren't always that accurate and its only really on Diesels and very few Petrol cars that RPM can't be probed in the correct way.
It is also possible to plot RPM vs Road Speed, providing the RPM was picked up in the correct way. By doing so, you can clearly see if there was any 'slip'. This would tell you if the car had wheelspin or clutch slip. This would result in grossly inaccurate figures.
Shootout modes pertain to number of cylinders and induction type. By rights, our Meg's should be run in Shoot4F, but we tend to use Shoot4 for Turbo'd cars, it provides a slower ramp-rate and thereby a better chance for the car to produce boost.
My reasons for pointing these things out is not so much to expose tuners not doing their job properly, but to show you that comparing DD graphs isn't always quite so straight-forward.
I am looking forward to getting my R26 on our Dyno, so I can how they behave. I'll be sure to share my thoughts.
Hope this helps.
^^^^ that is an excellent post my friend - thanks for sharing.
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