Dyno / rolling road

[TKM]

Hello,

Would like to confirm horsepower on my 356 , after putting PMO carbs on, I live very near to Ascot/Bracknell

Any known rolling road facilities nearby ?

Many thanks....

[edc]

Charlie's place Surrey Rolling Road now in Farnborough. If he reads this before I manage to make a call then I am hoping to arrange a Porsche dyno day in November.

[edc]

I'll be hosting a Porsche day here thanks to Charlie on Saturday 6th December if you want to wait and join in.

[Ian_UK1]

TKM said:

Hello,

Would like to confirm horsepower on my 356 , after putting PMO carbs on, I live very near to Ascot/Bracknell

Any known rolling road facilities nearby ?

Many thanks....

I know it's been said before on here, but a rolling road isn't really the ideal tool to measure absolute HP - there are simply too many variables. They're much better for doing comparison - before and after - runs as long as the operators know which variables to measure and to keep constant (as far as possible) from run to run. For this you'll need to have some 'before' figures taken with known parameters, then use the same dyno with the same control of parameters to get an 'after' figure and a meaningful percentage improvement.

Depending on the car, items typically needing to be monitored and controlled are water temp, oil temp, intake air temp and exhaust gas temp. Additionally both A/F ratio (lambda) and ignition timing would need to be monitored throughout the run (especially on current cars where ECUs will pull timing and enrichen mixtures to prevent detonation). For a non-ECU-controlled, carburetted engine all you can really do is make sure there is a proper supply of fresh ambient air to the carb intakes (and good flow to the radiator and under the car to keep the water and exhaust temps sensible) then monitor water temp, ignition and fuelling during the run.

Even with excellent dyno methodology and as many parameters as carefully controlled as possible, you'll still get a big spread of results from one dyno to the next, so it will be difficult to say exactly what the real output of your car's engine might be. The correct tool for absolute power measurement is an engine test cell, where every parameter can be kept under strict control, but the cost would undoubtedly be prohibitive.