30th September 2006 Rolling Road Day

[Kevin]

Where's the six speed graph which shows how the 6 speed delivers torque to the road better than a 5 speed?

What we can do now is get the formulae from Bob Butler off NSXPrime. Given the torque curve and gearing, and weight of a car, it should be possible to then calculate the velocity of a car over a given distance. The velocity would have to be worked out by integrating the acceleration or something like that.

Then, some more meaningful figures will be produced. 0-60 times don't mean much. What does mean something is over a 1/2 mile, if two cars started at the same time, at 0mph who would cover the distance the fastest and by how much or how far.

Spreadsheet racing is much cheaper than the real thing.

[NoelWatson]

Where's the six speed graph which shows how the 6 speed delivers torque to the road better than a 5 speed?

What we can do now is get the formulae from Bob Butler off NSXPrime. Given the torque curve and gearing, and weight of a car, it should be possible to then calculate the velocity of a car over a given distance. The velocity would have to be worked out by integrating the acceleration or something like that.

Then, some more meaningful figures will be produced. 0-60 times don't mean much. What does mean something is over a 1/2 mile, if two cars started at the same time, at 0mph who would cover the distance the fastest and by how much or how far.

Spreadsheet racing is much cheaper than the real thing.

I think it would be useful to get our cars on a weighbridge. If anyone fancies doing this in the Surrey area let me know. We also need to think about aerodynamics. Honda claim the 2002 NSX was 0.1 second quicker to 125 thanks to improved aerodynamics. Not sure how the 97 changes affected drag

[markc]

Sorry the zipped spreadsheet file didn't upload, I've edited my previous post and uploaded it there.

The 3.0ltr with 6spd plot is there as is a stock 1996 (shorter gears) and NSX-R.

Noel the rev limiter is definately 8,300rpm, for all model years. I don't know why most rolling road NSX pulls only read to 8,000rpm?

I'm Lightwater in Surrey based. Very happy to stick my car on a weighbridge, but being primarily for 10ton+ lorries are they accurate enough at lower weights? What about proper race scales, anyone got a set or know someone who has?

Spreadsheet racing is the best

Mark

[NoelWatson]

Sorry the zipped spreadsheet file didn't upload, I've edited my previous post and uploaded it there.

The 3.0ltr with 6spd plot is there as is a stock 1996 (shorter gears) and NSX-R.

Noel the rev limiter is definately 8,300rpm, for all model years. I don't know why most rolling road NSX pulls only read to 8,000rpm?

I'm Lightwater in Surrey based. Very happy to stick my car on a weighbridge, but being primarily for 10ton+ lorries are they accurate enough at lower weights? What about proper race scales, anyone got a set or know someone who has?

Spreadsheet racing is the best

Mark

Mark, the 8000 is entered by the machine operator. If 8300 is correct, my torque peak is near around 6600 and power around 7500 - does this sound a bit high? It also means the figures are wrong on the NSXPrime site so we will have to take that into account for our calculations.

[markc]

Noel, I think you're saying that your measurements could be scewed by the machine thinking that 8,300revs is actually 8,000revs? I don't think this is the case.

The dyno should use a clip/clamp of sensor which connects to one of the cars ignition leads so that it can measure the number of ignition pulses and therefore (because you tell the machine how many cylinders the car has) the revs. It therefore knows the engine revs and measures the power/torque generated athose revs.

I'm guessing that the operator enters the maximum revs that the run will be made to and then does the run. The machine stops measuring at whatever the maximum entered revs was, even if the car actually continues on to a higher number, before measuring the drivetrain losses during coastdown?

Mark

[NoelWatson]

Noel, I think you're saying that your measurements could be scewed by the machine thinking that 8,300revs is actually 8,000revs? I don't think this is the case.

The dyno should use a clip/clamp of sensor which connects to one of the cars ignition leads so that it can measure the number of ignition pulses and therefore (because you tell the machine how many cylinders the car has) the revs. It therefore knows the engine revs and measures the power/torque generated athose revs.

I'm guessing that the operator enters the maximum revs that the run will be made to and then does the run. The machine stops measuring at whatever the maximum entered revs was, even if the car actually continues on to a higher number, before measuring the drivetrain losses during coastdown?

Mark

Mark,

Can't comment on what Power Engineering do, but Surrey Rolling Road don't attach any form of rev measuring equipment to the car. They run the car up to the limiter and then type into the dyno what they think the limiter is - for my run 8000 was entered.
The type of rolling road at SRR uses a lookup table to calculate drivetrain losses rather than the coastdown method.
If you fancy going for a dyno one weekday evening let me know - I will put my car on Optimax and reset ECU to see if I can beat 285!!

Regards

Noel

[Kevin]

It sounds like a lot of assumptions and calculations and reading the rev counter being used there.

[simonprelude]

Dyno's usually only go to 90 - 95% of the rev limiter to avoid engine damage.
Max power and max torque come in before there anyway so in the eyes of the rolling road operator there is no need.

[NoelWatson]

Dyno's usually only go to 90 - 95% of the rev limiter to avoid engine damage.
Max power and max torque come in before there anyway so in the eyes of the rolling road operator there is no need.

Not sure why it would damage the engine any more than on the open road?

[NoelWatson]

It sounds like a lot of assumptions and calculations and reading the rev counter being used there.

Maybe, but I think the methodology of using the lookup method for loss is common for that type of rolling road. I mentioned previously that SRR reckoned it gave a lower flywheel reading for Scoobies than Power Engineering.