This conversation is way beyond me... But I do know form KPG(kevin) that he ran 11.5 1/4 mile at 128 mph one day and 11.5 at 122 mph another day... Temps, atmospheric changes, etc???

On the other hand, I would trap 123 mph most of the time but my ET was sometimes .5 seconds of a difference... 11.5 to 12.0 for example. And this was always due to the 60ft. time.
just sharing my experience.

 

The formula is accurate. It shows what the car is capable of.

I've used it on quite a few cars. Mine included. It puts me at 580 rwhp...which is almost exacty what I make at 1.3 BAR (which is what BAR I was at when I trapped 136). I made 563 on a Dyno-Dynamics dyno at 1.3 BAR...known for reading low, and 600 at 1.3 BAR on a Dynojet...known for reading high).

I believe that discrepancies you see are due to either a miss-shift, the driver letting off too soon before the traps, or the claimed HP not being incorrect. As I've said all along; Trap Speed doesn't lie.

The car you are talking about trapped 129+ on that run (that run had his best E.T., but NOT his best Trap)...but if you scroll down to the list "in order of Trap Speed"...you'll see that the same car had a best Trap Speed of 134, ewith a slower E.T. Right where it should be. That's why I have a seperate list ranked in order of Trap Speed. It shows the car's capability regardless of driver/launch. It also shows how the car will do from a roll.

For my Stage 2 car to have trapped 126 with AWD at full-weight...I needed to make 475 AWHP on that particular day.

 

Scott, do you agree that the variances in play are just beyond reasonable? RWD to FWHP conversions, dyno errors etc. we are talking easily a 10% variance. If a 60ft impacts your trap speed by a couple of mph it will certainly go unnoticed here.

 

Jean, I've always respected you for not resorting to insults. Good luck with your theoretical drag racing.

 

Quote:

Originally Posted by Jean

Finally, just two questions to end this from my side to prove again that there is a correlation whatever it is...

Yes. Very easily. I could drive my car just past the first beam to start the clock…and then accelerate through the entire run. I would trap 135-136 just like always, but have an E.T. of 2 minutes or :20 minutes if I so chose.

Quote:

2- Will you be able to achieve 136mph in your car if you cross the 60ft mark at 30 mph and then accelerate?

No doubt about it.

 

Mr. Blonde I did not mean to insult you, I was a bit rough, I too respect your posts, and sincerely apologize for that, no hard feelings I hope.
I don't have an agenda in this obviously, trying to understand why the physics would be wrong. There can be 20 different posters telling 20 different sotries of their runs, it does not help answering the question.

I am not doing any thoretical drag racing though, it is only about relationship between 60ft and trap speed. I have raced my first rallye 21 years ago, so I am not new to this nor a bench racer. I do like to understand the dynamics at work.

Scott, that would be an interesting test an ET of 20 with the same trap speed, obviously I am not saying park the car after the beam, wait for 10 seconds and then start. I will do some testing with my car over a certain distance to check it out. So you can have a 60ft of 3-4 seconds and still get 136mph. Interesting.

 

I appreciate that Jean, no hard feelings here!

 

Okay...group hug time.

 

Hehe .. happy to hug any 6speedonliner .. the most civilised forum I've ever been part of.

 

No hugs for you Scott, don't feel like breaking a rib if you get a little out of control!

Cheers Kenny.

 

Here's some random thinking as to why 60' time has little bearing on trap speed... bear in mind I've never run at a drag strip.

I read an interesting article on Top Fuel Dragsters a year or 2 ago. The relavent part of the article was this - T.F.D. reached top speed at 1/8 track (300MPH) and essentially coasted down the back 1/2. If this is in fact true, perhaps it can help explain why 60' time has little to due to ET and why HP is related to trap speed.

Jean, you've done a lot of data logging on the AX22. What does the chart of "g-force" look like for a full acceleration run over 1/4 mile. It appears your argument is assuming a constant G load over the run ( and hence the direct relationship between 60' and trap speed) where as I'm guessing G load rapidally deteriorates, as with the top fuel dragster, and this negates the importance of 60' time in relation to trap speed.

 

Kevin, weather is cool out now and took my car out and all i have to say is DAMM!! Let me know when you get the racelogix box back, i would love to try it out and post up some numbers!

Martin

 

Damn, thought I'd log on and get to be a part of a good food fight......
Instead, everyone is being civil and levelheaded........
First off, I'm Andrew, the guy who was working with Scott on the formulas.
My education and background is in mechanical engineering, working in the past for Borg-Warner as an ME and currently write financial market algorithms for index mapping software on the side in addition to my day job.
Scott and I were talking about why so many of the calculators out there are wrong. After looking at the data and the formulas, I came to the conclusion that it was an issue of the formulas being written too closely to theory and without adjusting the assumptions by taking enough real world data into account. A simple way to see this is through a graphical analysis of data points.
If you look at the Hale formulas along with the graphical points shown below, you can see that a) the formula is close, but needs slope and curvature adjustments to be more accurate, and b) there aren't enough points from a variety of vehicles to represent the outcome within a reasonable statistical confidence window for most cars.
What I did was include many more data points from multiple vehicles and graph the results next to the Hale equation lines. I then rewrote the algorithms to more closely represent the real world graphical results. These formulas now work well for street vehicles in the 50-1000bhp range. Adjustments to the algorithms would have to be made for pro drag vehicles that can transfer launch energy at a statistically abnormal rate.

Regarding the trap speed vs. e.t. discussion, there are multiple ways to visualize what is happening to make it more clear. And to be fair, both sides are correct for their given questions. The problem is that the specific question in each case is not clearly defined.
Think of the difference as transferred energy to the ground in time (e.t.) and transferred energy over distance (trap speed), which are two very different ideas, as we’ll see. If it weren’t for launch energy transfer and tire capabilities ie. all of the power/energy could be transferred on the launch immediately with consistent accuracy, we wouldn’t be having this discussion as e.t. would be as representative as trap speed. But that’s not the real world.

The force available to accelerate a vehicle from a stop to the first 30-90ft. is mostly based on traction or g-force capability. That’s why a mid-hp car can have similar 60ft. times to a very high-hp car. It’s not a good indicator of hp since the max g loading of street tires is around .5-.6g/tire no matter what you do. In first gear along with a revved engine (significant stored flywheel/crank/piston/rod/pressure plate energy) most cars have the ability to generate .5-.6+ g/tire or break the tires loose for some distance. That’s why as one car may hook better than another, they’re still limited to approx. .5-.6g/tire on the launch….this enables a car that has spun its tires or bogged off the line to essentially re-match the other car’s acceleration and speed, at a given distance within the .5-.6g/tire exceedance zone, very quickly since in the lower gears it’s a traction issue and not a power issue. Notice I said speed at a distance and not speed at a time. The time already left the station, so to speak, the distance didn’t.

And here is where people get the disagreement. The time measurement is a constantly moving reference which is unaffected by the car’s performance. But distance is not ie. as you are slower than another car, you have more relative distance left but not more time left. So if you make a mistake on the launch ie. excessive spin or bog, that time measurement will be permanently changed because time marched on unaffected by your mistake. But your rate of distance coverage was changed and reduced giving you some distance to make up the mistake. And in addition, the distance where the loss took place is approx. 3% of the distance of the race, and a distance where max power could not be transferred due to the .5-.6g/tire limit….as a result, speed at a snapshot time , with time continuing at the same rate, was affected but speed at a distance past the spin/slip zone, with distance traveled reduced during the slip/spin/bog, along with the ability to rematch .6g/tire quickly, had little to no change. If the tire spinning/bog continued much beyond the zone where the car could exceed .5-.6g/tire acceleration, then you would start to see the reduction in trap speed in addition to the increase in e.t. as overall avg. power over distance would start being affected. But since it takes place in this “.5-.6g/tire max zone”, the speed at time is changed but not the speed at distance. This is why e.t. is significantly affected by launch and trap speed isn’t.

Now here is where it all comes together. Both cars weigh the same. Car A runs a 1.7 60ft. and turns a 12.2 @ 120mph. Car B runs a 2.0 60ft. and 12.6 @ 120mph…..what happened? Car A got a better launch enabling a .3sec better 60ft., but car B had an extra .3sec at .6g/tire to accelerate up to car A’s speed at approx. the 60 ft. They were both going approx. the same speed at some fixed distance after the 60ft., although car A reached that speed in less time, but the same distance, and both have the same whp because they accelerated together after that point of slip/skid/bog. Car A was able to transfer more avg. power to the ground over time ie. in 12.2 sec it had traveled farther and reached 120mph quicker but at the same distance as car B (the difference in time being in the launch energy transfer) although car B was still able to reach 120mph in the ¼ mi. distance ie. the same total power transfer with respect to distance showing whp and not transferred whp over time.
So as has been stated before, if you take the .5-.6g/tire launch window out of the equation, and compare cars from say a 3rd. gear roll, you might as well throw away the e.t. too and go by trap speed because the e.t.'s variables are no longer in play.

 

Outstanding, outstanding, outstanding post, Andrew! You never cease to amaze me.

 

Well, I gues that settles it!

Cool Carver. It's good to hear a guy get into it who knows what he's talking about.

Bonus points for you!