But,
basically if you are running at the max potential of your setup (i.e. you are running 13.0's on a car with 350hp), most of the time if you go a 0.1 slower you will have a little more mph....why is this, because you are spending more time accelerating (althoug its a very small time difference).

You cannot use a situation like mine to make comparisons of ET to mph of course.(well not yet anyway, once I get a tire lol).
Basically you have to look at scenarios where your ET's are consistent and look at those mph's.

fyi....et calculators say for weight of my car (with me) and my pump gas rwhp I should run 11.1@122 and on race gas (25psi) 10.1@134 and (30psi) 9.78@139 lol so as you can see there are a lot more variables lol

 

Yes your past run is not a good barometer. If your Power is constant (at least very close) which in this case it is, then your ET will be dependent on your 60'. If ET is consistent then 60's will be consistent hence Trap will be consistent as long shifting is also consistent..lol That gave me a headache...

In the end what I'm trying to find out is that as you improve your 60', your ET will also improve, now does your trap suffer? Hopefully you get a good range of 60' tomorrow and post up some result.

Does your EMS can do logs? It will be nice if you can log your runs so we can confirm your shift point is also the same...

 

The theory is true: if you decrease 60 foot time or 1/8 mile time you increase 1/4 mile trap.

The impossible task is “Holding everyhing else constant.” I posted several time slips showing the difference between theory and the real world.

 

Why do people keep saying this? That's not how it works. The rate of acceleration is what determines your trap speed at the end of the 1/4 mile (or any set distance). Not the time spent accelerating. That makes no sense. By your logic, if you went and ran 14s in your car, you would trap higher than if you ran 11s in the same car because "you are spending more time accelerating." That is absolutely false. The fact that people keep saying otherwise is mind-boggling. Didn't you guys ever take a physics class? lol

 

So real world experience defy the theory? Assuming my car is Automatic, then I'm pretty sure shifting point and shift time can be replicated (to a point). If the race is done on the same day then DA will be constant and so does gearing. So the only thing will vary is the launch or the 60'. So we go back to square one...lol The only thing I can see happening is that people switching to a different wheels and running Slick/DR and running the tire pressure to 17psi affecting over all diameter, hence different gearing. Most of the variable can be replicated to some degree so the theory should hold

 

I've done 8.6 @ 82.75

and I've done 8.78 @ 83.45 with a .154 difference in the 60'

e/t and trap speed don't always go hand in hand.

There's the shift factor to consider

 

Many people say with lower 60' your trap will be lower... I know about the shifting/gearing/DA (I've beens saying this all along..) plays a role but let us assume they are consistent then I still dont see why Trap will suffer as your 60'/ET improves. I only have a few 1/4 mile run (11 total) with my G35 and so far I dont see a strong evidence that as I improve my 60' and ET my trapped suffered. I have logs of my every runs from time/rpm/boost/knock/timing being run/AF..etc so I have an idea on all my runs. I wish I can always take a day off just to go the track but I couldn't.. else I will be there every week.

 

I believe that we agree. When members ask to evaluate time slips, my evaluation follows a formula based on experience:

First 1/8 mile. This is driver determined. Variability can be extreme.

Second 1/8 mile. This is vehicle and density altitude determined. The driver has little to do. The last 660 feet is about the vehicle not the driver.

 

Here's 3 slips from racing last thursday night that show different scenarios for the same car.

3 runs

60': 2.16
330:5.78
1/8:8.73
mph:82.40

60':2.02
330:5.64
1/8:8.60
mph:82.66

60':2.19
330:5.86
1/8:8.80
mph:83.49
(used triptronic on the 2-3rd shift @ peak hp. I believe that increased the trap)

 

/\ 1/8 mile is to short to make an assumption.. 1/8 mile is all about the driver so if you improve your launch that you got a good 1/8 mile trap and ET then the million dollar question is does your 1/4 trap suffer? This is the point of this discussion, if you get a good 60' and 1/8 mile ET and Trap, what happen to the last half?




Ok so let say you got an ET = 12.9, 60' = 2.3 and Trap = 114mph. Base on your experience, let say next run you manage to bring the 60' to 1.97 and assuming your ET improved to 12.2.. Now do you believe that your Trap will be lower or higher? My argument is that I believe the Trap should be the same if not a little higher coz you accelerated much faster the first half.

 

1/8 mile is 1/2 of the race, but it's safe to assume, that unless you do something lame the last half of the 1/4... like a granny shift or something, a good 1st 1/8 will result in a good 1/4.

 

The only way a faster ET will give you a higher trap than a slower ET is when you bog the car, or if you miss one of the gear shifts.

Sometimes spinning can be more beneficial than bogging because when you bog that means you are not launching in your powerband. When you spin you are losing power, but often you are putting more "average power" to the ground than when you bog.
But here's the simple true: The quickest ET and highest MPH are achieved when you can launch in your powerband and with minimal or no wheelspin at all.

Example: If you put some slicks on an otherwise entirely stock 350z and launch it at 5000rpms, it is going to trap higher and ET lower than if you had stock street tires, provided the slicks diameter and weight does not change too much from stock specs. The reason is that it's awfully difficult to hook with street tires while launching at 5000rpms.

A lot of things affect your MPH, but it really comes down to how much "average power" you're actually putting down from start to finish.

 

I totally agree with this!!! There are even some people here or other board that will say running slick/DR will lower your trap Like I posted before the only way I see that happening is if the diameter of the tire get chanted which change the over all gearing of the car. So in the end it is safe to summarized better 60' equate to better traction, better traction yield better ET and in a race with a fix distance better trap...

 

Excellent point that people never really think about...

 

Those who favor wheel spin than wheel hop say Aye.

aye

 

Three more time slips after some runs yesterday by a buddy of mine in his Z32. You can't argue actual data. Power settings kept constant, no nitrous...

1.46 60'
10.47 ET
134 trap



1.51 60'
10.57 ET
135 trap




1.84 60'
10.87 ET
136 trap

 

how do you know everything is constant? Do you have logs on RPM shift point? Since I always log my runs I will keep adding to this thread coz in my case there is no strong evidence that lowering your 60' and ET actually hurt Trap... I can also post some of my runs with lower ET and 60' didn't do much..

 

Here are my first track day in October. You can see my highest trap was done on my lowest ET and 60' but the temp was 2 deg colder compare to my second run. My first one was my lowest trap but it was also my slowest 60' and ET. Most of the shifting was done between 6000rpm-6100rpm on this run. If you compare my first run to my second run there was only 2 deg difference on the temp but the barometer was pretty close. By your logic, I should have trapped higher on my first even if the run was 2 deg warmer.

 

Good ET. Post the 13.58 time slip here: https://my350z.com/forum/drag/233840...ons-stock.html

 

Nah, that is a bad time... I only shifted to 6100rpm and that is why my trap/ET was very low. Last track day I had I was trapping 111mph... Once I get a lighter wheel (all my runs was with my Work VSXX 19's) and better 60' then I'll post my time there. I have a G35 and a ST so that is a horrible time... lol