Originally Posted by Martin@AMS (Post 3289383)

I really don't think it pulled 2.4 g's of acceleration, I don't think that's feasible on the street, especially with R888's (which are designed more for lateral acceleration, not longitudinal) which I've driven on a road course. For reference a Top fuel dragster pulls 4.5 G's

P-box uses GPS to calculate everything. There are no accelerometers. Any math majors or fellow engineers out there? Change in position over time = speed. Change in velocity over time = acceleration

The sampling rate of the GPS is in the P-box and all the other consumer grade devices from Race logic is 10hz, so 10 samples per second. This is taken right from the P-box specifications in the manual. Absolute positioning is 5m diameter (16.4 feet) 95% circle of error probability. Meaning that 95% of the positioning will be in a 16.4 foot diameter circle. They do say that distance measurement is accurate to within .05% But I just calculated the data from our V-box and P-box that were in our car on the exact same run, and the error is more than that.

The p-box and v-box is a great tool but the closer I look at our #'s and the discrepancies we showed when we ran both units in our car the same time, the more I see that if you're trying to get accuracy to the .1 of second or less, there could be some accuracy issues.

I've used a lot of different dataloging systems that use either GPS and/or accelerometers (Motec dash, AIM, Race Pack, p-box/v-box, Chase cam, Race keeper, etc) and that data is never 100% accurate or perfect, especially when compared to dedicated track timing equipment (road course or drag strip).

-Martin

Originally Posted by houstonT (Post 3290820)

Martin, I appreciate your expertise and our relationship as it's grown through the years via the TX2K GTR Nationals. I'm not interested in arguing with someone I consider a friend so I will just state facts. UGR has a proprietary shifting system that they install on the e-gear SL's, as you know, the e-gear is ARCHAIC as compared to the tranny in the GTR. If you've never ridden in an e-gear G, the feeling is similar to a 6-speed car in that you can feel full dis-engagement and subsequently full engagement of the clutch. When that thing re-engages, it's like a sledgehammer hitting the back of the car. That spike is a single point spike representative of the gear engaging and if you look at g's throughout the pull, they are in the 1.3-1.0 decreasing range as you'd expect. Additionally, these cars FIGHT for traction and the clutch is at the edge as well so movements in the longitudinal g's are to be expected IMO.

At TX2K12 I'll get you a ride in an e-gear g and you'll see what I mean, those things shift VIOLENTLY.

For what its worth, they ran a 3.21 60-130 in my 6-speed car today. Being that both cars were at similar power, but have diff gearing, my car is heavier than the SL (Kevin drove and KC was passenger) and it was more hot and humid today than a few days ago...the numbers jive. I will post the graph once I get the data.

See ya soon bud,
Peter

Originally Posted by Divexxtreme (Post 3298956)

997John ran a 5.48 with 1-shift in his Protomotive built 997 GT2 at 800 rwhp. Great job, John!

Originally Posted by TwinTurboM3 (Post 3298960)

Scott,

for 800 whp, isnt this a little slow?

5,48 s cause of wheel spin or due to gear change?

Originally Posted by TwinTurboM3 (Post 3298960)

Scott,

for 800 whp, isnt this a little slow?

5,48 s cause of wheel spin or due to gear change?

Originally Posted by 997John (Post 3298975)

Scott, thanx for posting the result.
It show me in the program i did it in 5.43 not 5.48.
Any way it doesnt matter for me, both are good # for this weather.