Re: Dyno in Singapore
The main chassis dynos in Singapore are hub-type and rolling-road (inertia or eddy current). There are other variations of the rolling-road like water-brake but AFAIK none are in Singapore so will omit them from the discussion.
The most common hub-type is the Dynapack. As pointed out the wheels have to be removed and thus there are no frictional losses due to tie-down pressure, tire deformation etc. So assuming that there is no correction factor applied the figures you get should be rightly considered as "power/torque at the hubs". It may very well be the case that Car A with 350 PS at hubs will lose out to Car B with 350 PS at wheels, because tire and rolling losses were not accounted for, ceteris paribus (same car model/transmission, similar shifting speed and pattern etc). Then there are certain places where correction factors are not only applied, but used liberally and indiscriminately. :screwedu:
As for rolling road, the inertia types are the Dynojets, Hyper Dynos, DIMTech etc. Fundamentally these dynos calculate the force required to move a fixed mass (the rollers) at a measured rate of acceleration. This makes them pretty much useless for dyno tuning because the tuner will not be able to hold a steady load/RPM site and thus alter that particular site and see the effects in realtime. They also usually lack sensitivity and thus require smoothing functions to present a nice curve. Another major problem is that since they are measuring inertia a "tuner" could cheat by just changing the wheels to something less heavy and you get "free" horsepower. About the only thing they're good for is a full power sweep. To address some of these issues a lot of these inertia dyno makers have a "retarder" option to allow actual tuning to be carried out. How good these are, the sensitivity, hysteresis, overloading, all vary.
The best I've seen to date and seriously recommend are the Dyno Dynamics dynos. There is one at Subaru in Toa Payoh and I only use that. The dyno operator there is competent and knowledgeable. The dyno is calibrated on a regular basis and produces realistic figures, which are further reinforced by my own GPS test data. I have done repeated back-to-back runs and the power is almost always within 1 PS of one another. The only trouble I had was dynoing an automatic MINI which was always kicking down whenever full throttle was applied.
There's also Mainline Dyno which is receiving good reviews worldwide unfortunately I do not know of any in Singapore.