List of Participants, 2007 Solosprint Nationals

[pigeon]

Re: List of Participants, 2007 Solosprint Nationals

Don't trust the car's speedometer. Speedometers usually display 2% to 8% faster speed then reality on EOM tires. Add to that error the fact many people use R-compound tires that have a smaller diameter then the stock tirse.

When I was in Chris's T3 Protege in the rain the G2X GSP data showed the maximum speed was 131 km/hr (i'm not sure you can go 20 km/hr faster on that straight just because it's dry).

When I was in a another car that shall remain nameless, the speedometer showed about 175 km/hr at the end of the back straight. But G2X data of that session showed the maximum speed was 149 km/hr. (Sorry to break the news to you Chris, this car has at least 50% more WHP then yours).

Not sure what Steve D's STI speedomer was displaying but G2X data in the dry showed he was reaching a maximum speed of 207 km/hr.

Well that means I was faster along the back straight at Shannonville! The radar gun got me at 141km/hr during event 9 at the end of that straight.

I think its that uphill area, my car doesn't do much accelerating up that... it just kinda sticks at 110 - 115 until it gets to the top, then it sloooooooowly picks up.

On sunday, the only factors that would have made me faster along the back straight was that I was braking later in the dry, as opposed to the rain, and I was alone in the car. I don't know if that would equate 20 km/hr but im hoping that it was something faster than 131 :P

[Slowpoke]

Re: List of Participants, 2007 Solosprint Nationals

I've never tested the Hoosiers to see how far off the speedometer is, and Hoosier doesn't publish the rolling diameter of the 245/40/17. However, I was hitting the rev limiter in 5th just before the crest ... the speedo was indicating just over 220. The time required to shift to 6th and the fuel economy gearing actually made me slower at the crest, so I just held the engine at 7000 RPM in 5th as I went over the crest. So off by ~13 km/h (6.5%) would not surprise me since it's off that much on the stock 225/45/17 tire.

To the car's credit, I've hit 230km/h on the speedo in previous years with 255/40/17's, so the car is capable of 220... just that until I get a turbo sized for the engine rebuild, I'm making less power than in the past.

[Guillermo]

Re: List of Participants, 2007 Solosprint Nationals

also, i'm assuming that the GPS is not measuring elevation changes!

since technicaly going uphill, the cars cover a larger distance than the GPS think they are covering in the same amount of time....

Serge,
GPS measures velocity as a change in displacement over time in 3 dimensional space, it includes change in altitude. The specs of my 4 year old basic hiking GPS lists velocity data is accurate to +/- 0.1 km/hr. GPS is significantly more accurate at calculating velocity then position.