Such a big deal about the slope still, Sak, so… I did a quick back of the napkin calculation for Thompson, for that 11.7 sec run the slope would have helped to the tune of an average 10.9 hp. It’s not nothing, but not as much as you’re making it sound.
That’s an odd comment. If it’s not a big deal, why do you want to drive all the way there?
If your napkin tells you that -1.3% slope won’t add up to anything more than 10 hp (a.k.a. about 1/100th of a second, or 0.1 MPH in trap speed) I will have to politely disagree with said napkin. I know you’re an engineer, so your napkin math trumps other people’s real world testing, but needless to say, real world testing disagrees with your napkin.
http://forums.rennlist.com/rennforums/997-turbo-forum/510590-6speedonline-60-130-a-joke.html
[quote=TB993TT]the slope below is 4.2m in 307m so 1.35% and the difference it makes to a 60-130mph run (compared to flat) is about 0.5s…
On the flat I was doing 7.45s 60-130s and on the 1.35% slope as above you can see on the graph it took 7s flat…
[/quote]
That’s a 1.3% decline too ironically…shaving almost half of a second off a 60-130 run for a VERY fast car. That’s pretty big…certainly not possibly written off as ‘10.9 hp’…especially when a B8 S4 should be an even bigger gap. Of course the bigger speeds take ages, however I’m quite comfortable saying that over a quarter mile (0-115 MPH), you’re still going to see considerable delta on an S4. For perspective, APEXIT saw about 1.1 seconds difference running flat vs. running -2.9%.
If you’d like to put it to rest, we could easily test this with a flat run vs. a -1.3% run for your car for say 0-110 MPH. Do a couple of runs of each and see what the data says.
Interesting data from the pbox. I have found that the pbox is almost universally wrong vs. dragstrip clocks when it comes to ET and the charted data. The live display data is just about bang on. It is not that the charted data is inaccurate all the way down the track. Rather it is off 2 tenths of a second in the first 60 feet (it can’t replicate a nicely staged run’s rollout very well). From the 60 foot marker on the timeslip, to the end of the track, it is bang on the money. I have data from Cayuga that shows this. I have data from Milan dragway that shows this. I have data from Atco that shows this. Pretty much bang on 2 tenths off on the 60 foot, then accurate the rest of the way. Those are all flat tracks. I have some other track data too if you want to see it.
The trap speeds show a little high on the pbox high because pbox reads velocity at the 1320 foot marker…while dragstrips read an average of your last 66 feet of track. The difference between your 1320 foot MPH and your 66 foot trap speed is usually 1 to 1.5 MPH on modest powered cars like these.
I think we’ll end up doing Cayuga as well in Oct. I won’t know which weekends I’m free til later this month. Which may determine which one I go to.
Sak, all I used was power = force * velocity = (car mass * g * sin(slope)) * (average velocity). I’d have to integrate to do it properly, and I failed my math courses many times over, so no thank you.
I have a better idea, I’ll use cartest, which applies pure physics to solve a car’s acceleration. It can correct for slope. Don’t forget engineers excel by being lazy. But first I’ll put the kids to bed…
Sweet. FWIW, if we can get some fast cars up here and us GTA folk, that would totally be worth it.
And yes, if Thompson is really a magical track where fast times are made, I have no problems going there to set a fast time, I’d love that. I went to ATCO in the freezing cold of February because of it’s 33 feet of elevation and everybody said it’s fast (if they didn’t force us to go through the water box, it would be, I’d say). Nobody else really seems to call Thompson a fast track though.
[quote=“Jspazz,post:42,topic:3695”]
You think a better idea than actually testing the car would be to plug numbers in a web site?
[quote=“Jspazz,post:42,topic:3695”]
have you ever heard of ubly drag way? Me neither before this thread.
Nor have I ever heard of Thompson. Its a small empty track on the middle of rural Ohio lol.
lol sak. True true.
Well simulators are good enough for F1, so cartest is good enough for me. Don’t knock it until you’ve tried it, you can completely model your car, from minute gearing changes to the CG even, and the physics and numerical analysis it uses is solid. It’s like a 15 year-old program and stands the test of time, which is why you don’t really see new programs coming out.
I used my S4 model based on my car to keep it relevant. Consider all the car dimensions, tire size, Cd, frontal area, weight balance, gearing, dyno, launch RPM and launch behaviour, shift time, clutch slip time, wheel and tire weight, rolling resistance, tire expansion factor at speed, rollout, air temp, air pressure, humidity, etc etc all inputted in. So I had already ended up modeling at my goal of 11.99@116.5, which is maybe optimistic but hey it’s my goal, and still pretty close to my actual 12.08@115.1.
So…without further ado…here are the results.
1/4 mile:
0%: 11.99@116.5
1%: 11.92@117.5
2%: 11.84@118.5
3%: 11.76@119.6
60-130:
0%: 11.72 sec, 1732 feet
1%: 11.32 sec, 1656 feet
2%: 10.92 sec, 1606 feet
3%: 10.57 sec, 1552 feet
I think this also proves what you are saying, Sak, as to why the debate on 60-130 and slope is so important. But it seems to apply less to the drag strip, where we are measuring the time to distance as opposed to time to speed - time to speed is clearly a bit irrelevant of a measurement in racing - speed needs to be integrated mathematically to get the distance, and time-to-distance is always the ultimate goal.
It also indicates to me that going to Thompson would shave the 0.1 seconds I need to get my 11.99, hoping that the DA is good though - however, if DA is plus 1000 compared to here, I think it’s a wash.
Ok now I’m solving for tailwinds. Looks really interesting so far.
Well if you guys want to come up I have our cottage just down the road about 30 minutes and it will hold us there. We just clean the bedding and leave 200 for the cleaning lady done! So there u have it. I chose Ubly because it is going I be fun, semi central location, and they also have the track open the next day as well!
I was speaking to MhP today and they are probably going to come up and bring some Mercedes as well, e63 and sl 65. Dad will bring some of his toys and a few other people.
Just an FYI…
Ps MHP is in Columbus I think.
Tailwinds:
1/4 mile:
0 mph: 11.99@116.5
10 mph: 11.96@117.2
20 mph: 11.92@118.0
30 mph: 11.90@118.6
60-130 mph:
0 mph: 11.72 sec, 1732 feet
10 mph: 11.37 sec, 1675 feet
20 mph: 11.07 sec, 1627 feet
30 mph: 10.81, 1587 feet
Again, the 1/4 mile seems to be less affected. This is interesting for Bear, since his time was only aided about 0.08 sec compared to no tailwind, or 0.05 sec compared to 10 mph tailwind - and I think a lot of other people’s fast times are set in “some” tailwind, to be fair.
Going back to the program to see what a supposed Stage III setup would do at the strip, if it had some decent power…
Snap! October 5 may be difficult for me to swing. Usually can’t get off work on a weekday. I was thinking this would be a weekend thing. In any event, it’ll probably be a game time decision for me, so I’ll have to let you guys know without much notice . . .
Saturday they are running too and may try to rent both days
so did you guys decide on a location? It is in Ohio I’d possibly swing by to hang out.
Cool
What is MHP?
inky freshest. Worst possible location for you…north of Detroit a bit.
P.s. Inky freshest = Ubly dragway in the mind of the Samsung Note lol
is it Modern Horsepower, the guys who do the nasty heads/cam/headers C63s?
lol, inky freshest didnt know we were going to compton. But yeah North of Detroit is a trek
You have a place to stay
I am excited…where is Primetime???