60-130 Vbox and 1/4 Timeslip Database

[Sportsguy83]

Originally Posted by CoupedUpSubie

If you run identical cars with different rear ends the trap speed will be different. I can see where there is just as much room to manipulate numbers with this system as with a dyno.

I see where you are coming from, I understand your point. But you mean to tell me swapping inputs in a computer program is as easy as replacing the rear end? There will always be a way to manipulate data, the point is making it harder to manipulate it and its the only thing that can be done.. make it harder.

[mrk1]

As much as I am pro finding an even playing field I don't think it can happen.

[spdbydesignchris]

Originally Posted by CoupedUpSubie

Trap speed is NOT an indicator of horsepower. If you run identical cars with different rear ends the trap speed will be different. I can see where there is just as much room to manipulate numbers with this system as with a dyno.

Trap speed is 100% an indicator of horsepower......


You're confusing ET with Trap speed.


Ex. 10.8 @121.....10.8 is ET, 121 MPH is the trap speed.


If I have two cars at the drag strip, and one goes 11.4@144 (2.4 60 ft) due to bad tires, granny shifting out the hole, poor suspension setup, gearing mismatch....and the other goes 10.8 @128 (1.5 60 ft)....which car is making more power to weight?


It's the car that traps 144 MPH.


If you put both of these cars on the street, from a roll, the 144 MPH car is going to absolutely destroy the 128 MPH car.


This is the reason why many forums have 60-130 metrics, as it's a gauge of brute horsepower....and it's the reason I'm suggesting we setup a metric on this forum, to judge true HP performance.

[Boss Paco]

30-100? 30-90?

[evo4g63]

Originally Posted by spdbydesignchris

Trap speed is 100% an indicator of horsepower......


You're confusing ET with Trap speed.


Ex. 10.8 @121.....10.8 is ET, 121 MPH is the trap speed.


If I have two cars at the drag strip, and one goes 11.4@144 (2.4 60 ft) due to bad tires, granny shifting out the hole, poor suspension setup, gearing mismatch....and the other goes 10.8 @128 (1.5 60 ft)....which car is making more power to weight?


It's the car that traps 144 MPH.


If you put both of these cars on the street, from a roll, the 144 MPH car is going to absolutely destroy the 128 MPH car.


This is the reason why many forums have 60-130 metrics, as it's a gauge of brute horsepower....and it's the reason I'm suggesting we setup a metric on this forum, to judge true HP performance.

Agreed with 100%.

[CoupedUpSubie]

Gearing does make a difference in trap speed, and yes I mean in mph not seconds. Thus the reason I said identical vehicle's. With these cars a rear end can be swapped fairly quickly and without side effects. A common factor in racing is what the final gearing is as it is the easiest to change next to tire size. A 2700 lb car with 350 whp and a final gear ratio of 3.9 will end up with a different trap speed in 1/4 mile then a car with 4.44 final gear with the same power provided it doesn't run the engine to its extreme limit. It is simple physics. And will effect 60-120 times as well, as seen in Nascar with teams selecting different rear end gears from their given choices at each track.

While more data is good I am just saying it still won't be a absolute gauge of actual performance, like the idea is being sold as.

[spdbydesignchris]

Originally Posted by CoupedUpSubie

Gearing does make a difference in trap speed, and yes I mean in mph not seconds. Thus the reason I said identical vehicle's. With these cars a rear end can be swapped fairly quickly and without side effects. A common factor in racing is what the final gearing is as it is the easiest to change next to tire size. A 2700 lb car with 350 whp and a final gear ratio of 3.9 will end up with a different trap speed in 1/4 mile then a car with 4.44 final gear with the same power provided it doesn't run the engine to its extreme limit. It is simple physics. And will effect 60-120 times as well, as seen in Nascar with teams selecting different rear end gears from their given choices at each track.

While more data is good I am just saying it still won't be a absolute gauge of actual performance, like the idea is being sold as.

Trap speed is trap speed....no matter how you slice it.


In the example above 144 MPH is 144 MPH, doesn't matter what gearing is in the car, as your crossed the 1/4 mark at xxx MPH.

[spdbydesignchris]

Now, not having to shift into 5th gear, because your new gearing allows you to go through the traps in the top of 4th would effect ET....but our focus here is trap speed, and that's why I'm proposing determining a metric that would allow for fair comparisons among setups....

[jamesm]

couldn't people just use normal logs rather than buying a vbox? is the vbox more accurate than your wheel speed sensors?

[spdbydesignchris]

It's GPS guided, so yes, more accurate.


And if selling a several thousand dollar FI kit is your goal, $400 spent on a Vbox should be an after thought to promote your product.


At the consumer level, I can understand....but at the vendor level, $400 is a tiny investment compared to the cost of designing and fabricating a kit for mass sale.

[jamesm]

true... i guess as a consumer it's a heavy ask for something my iphone can do reasonably well. but for a manufacturer it'd be a great way to compare things on a level playing field. now let's see how many of them actually want a level playing field

[JuniorAWD]

Originally Posted by spdbydesignchris

Trap speed is trap speed....no matter how you slice it.


In the example above 144 MPH is 144 MPH, doesn't matter what gearing is in the car, as your crossed the 1/4 mark at xxx MPH.

Originally Posted by spdbydesignchris

Now, not having to shift into 5th gear, because your new gearing allows you to go through the traps in the top of 4th would effect ET....but our focus here is trap speed, and that's why I'm proposing determining a metric that would allow for fair comparisons among setups....

Wrong.. You must not race much

I can go 10.8@136mph shifting into 5th at the top of the track and 10.7@140 holding out 4th. The shift to 5th hurts mph on the top side of the track, but the et doesn't suffer much. Kinda like lifting right before the traps. Just like I can change my 1/8th mph if my gear is almost done close to it.. hold it gain MPH, shift right before loose mph.

Ive made 10 passes on the same day with my GTR, I could get a 4-5mph variance just by cutting a 2.0ft bog versus a 1.8 that just rolled and didn't bog.

Ive made a bunch of passes on our P&L stg1 kit on pumpgas and saw a drop of 2-3mph when I shifted to 5th and barely any loss in ET. The drop in acceleration kills mph.

So trap speeds can be deceiving, a good driver can pick up mph with faster shifts on the same car vs a guy that shifts slow and doesn't keep the car in boost.

Its way easier to compare these things on auto/dual clutch stuff. On a MT car driver variables just way too heavily on results.


Make the list, but I wouldn't base much off of it. As for vbox results, the subie guys use 50-100 due to gearing, maybe use that here.


Jr

[JuniorAWD]

Originally Posted by jamesm

couldn't people just use normal logs rather than buying a vbox? is the vbox more accurate than your wheel speed sensors?

Its not the wheel speed sensor, its more the sample speeds and time stamps on logs can be misleading.


Vbox is way more accurate

[Ironsquid]

Originally Posted by tendogy

The flip side is that a 60-130mph run is only going to show performance above ~5300rpm. It's a great indicator of true high-end horsepower, but it will mask the deficiencies of a slow-spooling turbo or an overly-parasitic supercharger which will kill low-RPM performance.

This statement is not accurate. 99.9% of all serious drag tests are above 5300 even from 0-130mph (assuming FRS/BRZ only). Unless you're launching like a granny, or on street tires. Either way you're above 5300 after the 60ft.

I would be more inclined to say that a 60-130mph run lessens the traction variable. Even then it's probably not the answer.

The reality of it is, you can fudge, argue, theorycraft, edyno, desktopdyno, until you're blue in the face there's always going to be a discrepancy.

We should just educate the population that reading a number on a forum and thinking it's 100% accurate is bad.