Extrapolating this weekend's numbers to 1320' numbers (1 Viewer)

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How could I extrapolate this weekend's stellar numbers to 1320' numbers? (Assuming no rev limiter and the car holds together and all goes well)

Namely, the 3.70 and the 3.9x's as well as the 6.40's in pro stock.

Ant's incrementals for the 3.70
60ft-0.832 sec., 330ft-2.100, 660ft-2.967/290.44 mph

 

[Crew Chief Pro]

With the Rev Limiter the speed wouldn't change much if any.

The ET would be 4.35 at the quarter, give or take a few hundredths. Hard to know exactly since they run the engines different, not sure they are set to run the entire quarter mile in their current configuration.

Either way, a 3.700 run from Brown, and 334 mph from Langdon is simply amazing.

More amazing is V. Gaines Pro Stock win and runs 6.48 ET.

When mother nature will allow us the opportunity the sport can be exciting.

 

[FC138fan]

How could I extrapolate this weekend's stellar numbers to 1320' numbers?

Namely, the 3.70 and the 3.9x's.
Thanx

Good question -

I believe the answer is an explosion just before the quarter as the engine loses it's load just after 1000'.

But seriously, mathematically you could extrapolate using the good ole fashioned kinematic equations.

For simplicity and for the formulas to work, we would have to assume constant acceleration, and neglect wind resistance, rolling resistance etc.. In reality, this is not true, so the numbers I get are fantasy numbers.

A 3.70s time at 1000' gets an acceleration of 146.09 ft/s/s

With that acceleration rate, from a dead start over 1320 would take 4.25 seconds.

For speed, from a dead start that acceleration extrapolates to 423 mi/hr. This number hints at the inherent error of assuming constant acceleration, as in reality I'm sure there is a much higher acceleration rate early in the run, and it tails off later. Thinking of what the graph's would look like for constant vs varying acceleration vs time (especially later in the run), it makes sense that that last bit of time can throw off the mph by that much.

Great question as I've just been reviewing and thinking about different techniques as to how to approach this question without the assumptions.

The best way I can figure is to get the racepak data. Then you can have a graph of say the G load vs time. With that you can get graphs of the same data displayed differently, such as velocity vs time, or position vs time - all of which can be generated from the G load vs time.

You could curve fit some sort of polynomial trend line or whatever to extrapolate what the quarter could be - in fact, just the last couple points leading up to 1000' would be the most useful - but this method would have limitations based on the physical capabilities of the engine, but it would be better then what I assumed.

Even getting the incremental times I could use the basic kinematic formula to get better extrapolated data.

Also note, that even if there were no acceleration between 1000' and 1320', it takes 0.65 seconds to travel 320' at 334 mph... so add 0.65 to 3.70 and you get 4.35 - I don't remember what the record was for the quarter when they were running, but I think it was like 4.40 or something, so I guess even if it blew up at 1000' it would be a new quarter mile record.

With all that said, I think my first assumption (engine explosion) is likely what the result would have been considering the rules regarding gearing ratios and RPMs.

 

[Just Paul]

When Shoe made "the run", (4.42) his 1000' was 3.759. His 1/8 mile speed was 283.

Antron's 1/8 mile speed was 290, so 7 mph faster on his 3.70 pass.

It's my estimation he could have run 4.34-4.36 probably close to 340.


For FC, the quickest 1/4 time is Robert Hight, he went 4.63. His 1/8 mile was 3.95 @ 273 which is just a tick quicker then Capps 3.96 at about the same speed. That would tell me Capps 3.96 would have been about a 4.64.

 

[Rat]

How could I extrapolate this weekend's stellar numbers to 1320' numbers? (Assuming no rev limiter and the car holds together and all goes well)

Namely, the 3.70 and the 3.9x's as well as the 6.40's in pro stock.

Ant's incrementals for the 3.70
60ft-0.832 sec., 330ft-2.100, 660ft-2.967/290.44 mph

I would say the run was about a 4.371. I have always added 7 tenths to any run to give me a rough idea of what it would have been and I worked a long time on this 100% unrealistic equation. (it just can't be proved)

After much study of Shoe's 4.428 as well as his slew of other low 4.4's in the AJR era and Spencer's 3.728, as well as Kalitta's 4.4's. I have noticed that it would not be absurd to add 0.67 to any run a dragster ever makes and have darn good idea of what it was. Out of all the runs I looked at the window was always about 0.66-0.69. So I feel safe saying 4.371.

For FC: We have yet to hit the old national record 4.636 and his 1000 ft 3.955. I studied many runs there. Again, add 7 tenths to any run for a rough idea and 0.68 for a closer one. (smaller window for this class)

Keep in mind: It's been said to me by many top crew chief's that most runs from this era's racing would not even hold together for the extra 320 feet.

 

[FC138fan]

I see your incrementals, this should be more accurate.

I used your 660' time & speed and used 3.701 at 328.78 at the 1000

Over that segment the average acceleration was 56.006 ft/s/s (1.74G)

Assume that acceleration continues beyond the 1000' and he's already going 328.78 at the finish, it would take an additional 0.640s to go an additonal 320'.

Or a 1320' ET of 4.34s

Applying 1.74G over another 0.640s from 328.78 would push it up to 353.22 mi/h

If you know the gearing and whatnot you could figure out the engine RPM and probably see it in an impossible range.

That would be a great physics 101 question, and a classic example of extrapolation.

 

[Bullet]

How could I extrapolate this weekend's stellar numbers to 1320' numbers? (Assuming no rev limiter and the car holds together and all goes well)

Namely, the 3.70 and the 3.9x's as well as the 6.40's in pro stock.

Ant's incrementals for the 3.70
60ft-0.832 sec., 330ft-2.100, 660ft-2.967/290.44 mph

I think the 6.4's in Pro Stock would still be 6.4's...

 

[Nitrohelper]

......Applying 1.74G over another 0.640s from 328.78 would push it up to 353.22 mi/h........

The "Gs" normally reduce that last part of the track, however it's a mute point because Goodyear maintains that the sidewall design is only safe under 340 mph...
The "G" force would be reduced dramatically when the rear tires come apart...

 

[FC138fan]

The "Gs" normally reduce that last part of the track, however it's a mute point because Goodyear maintains that the sidewall design is only safe under 340 mph...
The "G" force would be reduced dramatically when the rear tires come apart...

You are right, sir.

I think it's become obvious that they have hit the wall at the end of the race. Unless there is a leap in technology (tires) they're going to start seeing top end tire failures as they continue to increase speeds at 1000'.

I'm not sure when the clutches are getting 1:1 with the rear end. When that happens, speed is governed by engine RPM, and I'd guess that there's a limit to how high the RPM can go until it bombs. I'd guess that as time moves on, they are getting 1:1 quicker and quicker, and top end RPM's are getting higher and higher. Even if they did come up with a tire that can handle 350 and beyond, unless they change the rules governing gear ratios the engines will be failing.

Wonder if the next step is 1/8 mile racing? Not sure what Goodyear want's to invest more money to re-invent the tire. And if they do, would the NHRA change the rules to save engines?

 

[vegasnitro]

You are right, sir.

I think it's become obvious that they have hit the wall at the end of the race. Unless there is a leap in technology (tires) they're going to start seeing top end tire failures as they continue to increase speeds at 1000'.

I'm not sure when the clutches are getting 1:1 with the rear end. When that happens, speed is governed by engine RPM, and I'd guess that there's a limit to how high the RPM can go until it bombs. I'd guess that as time moves on, they are getting 1:1 quicker and quicker, and top end RPM's are getting higher and higher. Even if they did come up with a tire that can handle 350 and beyond, unless they change the rules governing gear ratios the engines will be failing.

Wonder if the next step is 1/8 mile racing? Not sure what Goodyear want's to invest more money to re-invent the tire. And if they do, would the NHRA change the rules to save engines?

Engine RPM is limited by rule by NHRA. They mandate all teams run a rev limiter.

 

[FC138fan]

Engine RPM is limited by rule by NHRA. They mandate all teams run a rev limiter.

I thought that previously.

However, I heard (on here) that the rev limiter doesn't kick in until after a certain time period, meaning that you could beat the rev limiter if you could get to the finish before it kicked in.

I don't know the official rule or how the mechanism works, just what I've read on here.

Here's the post:

For starters it's not a rev-limiter. It is a timing retard. When you hear a Pro Stock car on the line waiting for the tree he (or she) is on the limiter which will not allow the engine to rev any higher than a certain RPM. In the nitro ramks, the retarder comes in and backs timing out of the engine effectively reducing power, but it does not limit the RPM.

Also if I remember correctly the retard doesn't come in until 3.8 seconds, therefore in this case it would have no effect at all. Now that may have been adjusted and I'm not aware of it, but I believe that was the setting.

Alan

I guess it depends on if they adjusted the 3.8 seconds to kick in earlier, but even if they did, if they could maintain higher G's earlier in the run they could theoretically go 350 at 1/8 mile.

 

[twostep]

I believe Brown and Langdon would have run 4.36 and 4.37, assuming no failures. I understand the math but the reality is that from 1000 feet on, the ET varies little from pass to pass, if at all, if you're talking the same car and barring any complications such as a dropped hole, etc. Speed? Can't really say. My hunch is in the 347-348 range.

As for the rev limiters, or more accurately timing retarders, you can 'sling' the car past them up to a point. Schumacher had one in place when he ran 337 years ago. And the crew chiefs have already had it out with NHRA over these things, which can play hell with the engines, so I don't look for a tightening in this area.

If anything, I'm thinking 3.40 gears to control the speeds, if things continue to escalate. But everybody's gotta remember, Reading was a once-in-a-blue-moon event. It could be years before we see another 334.

 

[Toejam]

Does anybody think they run the same tune-up at 1000' that they would at 1320? I bet they would dial it back a tad....

 

[Gordon]

I think the 6.4's in Pro Stock would still be 6.4's...

Now that's funny right there...

 

[FC138fan]

Does anybody think they run the same tune-up at 1000' that they would at 1320? I bet they would dial it back a tad....

I think all serious contenders such as the top 8 cars push their parts as far as rules allow. If they don't, they're not going to win. It's all about getting from A to B as quickly as possible. If they can get to 1000' in 3.70, they will continue to do so whether the finish is at 1000' or 1320' otherwise they put themselves at a disadvantage, don't you agree?

 

[Gordon]

I think all serious contenders such as the top 8 cars push their parts as far as rules allow. If they don't, they're not going to win. It's all about getting from A to B as quickly as possible. If they can get to 1000' in 3.70, they will continue to do so whether the finish is at 1000' or 1320' otherwise they put themselves at a disadvantage, don't you agree?

I agree wholeheartedly, but what I think Joe was trying to say is he believes Crew Chiefs have figured out how to tune the cars to run as hard as physically possible to the 1,000' stripe and no further. Any attempt to run the current tune-up to 1,320' would likely lead to a big fire ball. Meaning, they would make ever-so-slight tuning adjustments that would allow the car to make it to the 1,320. I've never tuned a fuel car, so I don't pretned to know the answer, but it wouldn't surprise me to learn he is correct in this assumption.

 

[FC138fan]

Meaning, they would make ever-so-slight tuning adjustments that would allow the car to make it to the 1,320.

OK I gotcha, I guess I agree. However I think the tune up to the 1000' would be identical because it is the absolute quickest way to get to 1000'.

I don't think they would back it down over that 1000' just so it can make it to 1320'.

I will add your caveat I've never tuned a fuel car, so I don't pretned to know the answer.