Understanding the Racetrack

[farmtruc]

Hey guys, I just wanted to discuss the racetrack. Feel free to chime in. I hear a lot of guys not really understanding how time, hp, launching, etc plays a part at the track.
When a car runs a 9sec 1/4 mile, we all know it's haulin ass, or a truck runs a 12sec, it's moving very well.
But there's more to it.

I'm not trying to be the know it all about racing, but I wanted to explain how HP, MPH, and ET relate when running down the track.

Imagine three points down the 1/4 mile. A: starting line, B: mid way (1/8mile), and C: finish line.

Start at point A and walk to B, then run as fast as you can to C. Let's say it took you 5mins to finish the 1/4 mile.
Now, start at point A and run to B, then continue running to C. Say it took 2.5mins to finish.
Understand how running from point A to B dropped your time, you're not running any faster through the 1/4 mile, but you got there quicker.
Also, see how you ran your ass off through the 1/4 mile, but you didn't run any faster than you did at the 1/8 when compared to the finish line?
This is a good comparison on how a higher stall converter works. It allows your truck to launch off the line hard and get to the finish line quicker, not necessarily at a faster mph.

For example, my Avalanche ran the 1/4 mile at 14.7 at 97mph with the stock stall converter, after the 2600 stall was installed, it now runs 13.9 @ 98mph. See how it got off the line quicker and got to the finish line quicker.

As far as HP, this is what moves you faster through the traps. MPH is a good indication of how fast a truck is and how much HP it has.

Reaction time, this doesn't mean anything during test and tune. Going back to the example above. When the light turns green, stand at point A for 1 min, then start, it took you longer to get started, but you still made it through the 1/4 mile in 2.5mins when using the second example.
I just had to say that because I hear guys at the fence sayin, "man did you see that, 2 sec reaction time and he ran a 15, that truck is good for a 13sec pass" that's not true. Even if it had a perfect reaction time, it would still run the 1/4 mile in 15secs.

So to sum it up, if you want to lower your ET, get off the line a lot harder!!

I didn't mean to try to sound rude or all knowing, lol, I just know a lot guys don't go to the track and I'm sure they all have questions but don't want to ask. I get these questions all the time, hope it helps clear up some questions.

Anyone have anything to add or debate?

thanks,
allen

[DamnYankee]

Good analogies - I guess one of my questions would be how would you go about actually matching a stall to a cam? Are there any proven methods or "formulas"?

Obviously the cam mainly gives the hp and the stall gets you there quicker, so with all of the different stalls, I would assume you would want the one that gets you there the quickest for your best 1/4 mile times.

[farmtruc]

<div class='quotetop'>QUOTE(Moze &#064; May 18 2006, 11&#58;00 PM) [snapback]53540[/snapback]</div>

Good analogies - I guess one of my questions would be how would you go about actually matching a stall to a cam? Are there any proven methods or "formulas"?

Obviously the cam mainly gives the hp and the stall gets you there quicker, so with all of the different stalls, I would assume you would want the one that gets you there the quickest for your best 1/4 mile times.
[/b]

An easy, general way would be to pick a converter that stalls just below or right at the trucks torque curve. Say your torque shoots up to 350tq at 3200rpms, I&#39;d get a 3000rpm stall converter in there.
Just one way.

allen

[chrisj6]

<div class='quotetop'>QUOTE(Moze &#064; May 19 2006, 12&#58;00 AM) [snapback]53540[/snapback]</div>

Good analogies - I guess one of my questions would be how would you go about actually matching a stall to a cam? Are there any proven methods or "formulas"?

Obviously the cam mainly gives the hp and the stall gets you there quicker, so with all of the different stalls, I would assume you would want the one that gets you there the quickest for your best 1/4 mile times.
[/b]

A good way to choose a stall is see where your powerband really kicks in, you will want your stall speed 2-300 rpms below this. As for me, I SHOULD have gotten a 26-2800 stall converter, as my powerband starts around 3k. I got a 2500 stall and it lowered my 1000&#39; time by .45 seconds, but my mph was 4 mph better also.

Chris

[Tim Z]

that was a great way to clear things up allen, sometimes laymans terms help out a lot. I ts great to learn all you can so your confident when going to the track, Drag racing is a lot more than just mashing the pedal and going.You can have the same horsepower but can use different parts or techniques to get better starts or traction to yield different times.

[bud8fan]

yep...i dropped a 1/2 second off my time with a restalled stock verter...
allen there is more in yours if you can hot lap it...you will see a gain of 2 tenths or better for a couple since the turbo gets hotter every run and spools up better giving you a better et....that goes to anybody with a sts turbo system....

[custom 68]

that is a neat way to look at the analogy,
I am planning on going to the test and tune tonight...I have not raced in years so I am not sure what to expect. I have not ran my 68 down the track especially with the new motor. My problem on the street anyway is traction. I havent figured out a launching technique that really impresses me. Now my tires are old since I have had them on this truck for a long time during my build up and I dont have posi. The gearing is 3.73:1 so I am ok there. Once I save some more money I will get the limited slip.
I am a stock (nelson tuned) 5.3 with a TB converter my truck weighs an estimated 3900 pounds.
should be fun
Dave

[TXsilverado]

just had to say that because I hear guys at the fence sayin, "man did you see that, 2 sec reaction time and he ran a 15, that truck is good for a 13sec pass" that&#39;s not true. Even if it had a perfect reaction time, it would still run the 1/4 mile in 15secs.[/b]

ive seen frame of thought in the forums way too many times. its heartbreaking to tell someone thir truck wouldnt have made a 14 or 13 second pass if their reaction time was better.

[RedHeartbeat]

Most people don&#39;t realize that your ET isn&#39;t what&#39;s on the board but an addition of what&#39;s on the board plus your reaction time.

[farmtruc]

<div class='quotetop'>QUOTE(RedHeartbeat &#064; May 19 2006, 08&#58;46 AM) [snapback]53559[/snapback]</div>

Most people don&#39;t realize that your ET isn&#39;t what&#39;s on the board but an addition of what&#39;s on the board plus your reaction time.
[/b]

I&#39;m a bit confused, just to clear things up for me and others (unless I&#39;m the only one, lol). But your time on the board is what you ran, not a combination of your 1/4 mile time and your reaction time.
Down here, the reaction time isn&#39;t added to the board time, it&#39;s just what your truck ran in the 1/4 mile.
If your truck runs a 13.0sec in the 1/4 and your reaction time is 2secs, the board will still show 13.0secs.
Now the total time if took to get through the 1/4 mile once the light turned green would be 15secs, but the actual 1/4 mile time is still 13.0sec.

Just making sure I&#39;m reading your post right,
thanks,
allen