Help me figure out these ET's and MPH's...

[rustang1]

I went to the track tonight and last Wed (8 days ago) for T&T.
I averaged my runs from last week and tonight to make it easier. Last week was a different track than tonight. Both are 1/8th mile.
Last week:
60ft-1.94
594ft-7.50
1/8th-7.99
MPH-90.96
DA was 1500 Temp low 80's

Tonight:
60ft-1.87
594ft-7.41
1/8th-7.91
MPH-88.38
DA was 900 temp was low 60's

difference:
60ft-.07 quicker
594ft-.09 quicker
1/8th-.08 quicker
MPH-2.58 slower

It's a given quicker 60ft makes a quicker ET but the 2.5 Slower MPH with 600ft better DA is what I can't figure out.

 

[NC85]

Look at each of your runs individually. Your "averaging" of your runs clouds the information.

Just quickly looking though, I'd venture to say either you ran the car too much without a good cool down OR missed your shift points.

How many runs and at what times were each one?

 

[kona 199]

what mods does car have to see the 7-90s

 

[Scott8583]

It could be a couple of things... When I spin my MPH usually picks up a little, even though my ET slows. Not sure if it's from the added wheel speed from spinning or what. Second, you might have done something different at the trap. MPH scrubs off faster then ET. Either you were shifting just before the 1/8th or maybe letting off before the stripe...

I'm surprised your track has a timer at 594' instead of 330'. 594' seems worthless. You can run identical 60' times with slower/faster 330' times...

 

[nate-roth]

It could be a couple of things... When I spin my MPH usually picks up a little, even though my ET slows. Not sure if it's from the added wheel speed from spinning or what. Second, you might have done something different at the trap. MPH scrubs off faster then ET. Either you were shifting just before the 1/8th or maybe letting off before the stripe...

I'm surprised your track has a timer at 594' instead of 330'. 594' seems worthless. You can run identical 60' times with slower/faster 330' times...

This has been my experience too. A long time ago an experienced racer told me that the mph is higher when you spin because the mph is calculated between the last two timers, thus when you spin initially you are usually accelerating at a faster rate between the last two timers than if you hook and the car is accelerating at a more even pace through the whole run. Seems to make sense. I've done a ton of drag racing, but my cars always hooked up and if they did spin I'd just abort the pass so I never tested the theory.

 

[rustang1]

Car is 2011 Premium GT 401A A6
All stock except for:
Tune
catless xpipe
removed front swaybar
555r tires on 10inch factory replica wheels

Both of these 1/8th only tracks used to have 330ft time but I guess they changed timing systems or something. I don't know the reasoning for the 564ft vs 330 ft. timers.

Car was very consistent both nights. last nights 5 runs were 1.87-1.88 60ft with 2 7.91's, 2 7.92's and 1 7.93 et. MPH was 88.04-89.46

Both nights were run with same psi. same burnout, 20-30 minutes between runs.

I can understand dead hooking with .07 average better 60ft bringing down the mph a little but 2.5 mph seems like a lot for the 1/8th. I figured the 600 DA better air would run a better mph even with the better 60ft dead hooking.

All I can think of is it was breezy with 15-20 gusts last night but they were mostly from the NW instead of head-on, but died down after the sun went down.
The track is also located in a valley with a creek and swamp area nearby. It is known from experience that there is a lot of moisture in the air and it rolls in after dark.
The DA apps data is probably not very accurate.

That's all I can think of to explain the lower mph.
I guess it's most likely a combo of all of the above.

I'll try to go to the other track Sat and see what I can learn.