Drag/Acceleration The Official 1/4 mile track thread.

[Whiteybird]

Smaller rim = larger sidewall = more tire flex = more grip

This.

I’m still torn on doing a rear brake swap to run an even smaller rim. Dunno how it would interfere with any of the electronics.

 

[Kamauxx]

Looks like the BMS brake snip is dominating the list.

Nah, it's only 8 of the top 10. Pure coincidencesesesesss.

 

[Doel]

daannggg if anyone is wondering that Florida Angel run was at 1933 ft (DA). Very impressive.

 

[brancky3]

This.

I’m still torn on doing a rear brake swap to run an even smaller rim. Dunno how it would interfere with any of the electronics.

Base model brakes should work without issue I'd imagine. They still have the e-parking brake, right?

 

[Whiteybird]

Base model brakes should work without issue I'd imagine. They still have the e-parking brake, right?

That’s what I have to look in to. And see if the brackets are available for purchase as well to perform the swap.

 

[STINGER]

Amazing result. Is he a GT or GT2?

Also what tire size exactly?

More info on the custom front mount?

 

[Tonkabob]

His prior run was high 11.7s so he found some hookup magic!

 

[Tonkabob]

Ran my best non brake switch time today, second fastest non brake snip time after tork. Just a little better et and trap than my 11.86 back in May, but the temp was 20 degrees hotter today.
This run was the finals of IFO, so made $200 for runner up! Not bad for a bench racer.
Only one other LC times as i was letting off bracket racing. Started off doing my limited brake snip 11.81 12.02. Car wasn't happy on the second snip run so switched to LC for the first round of racing.
With full snip deep into the 11.5s!

Second pic is comparing my two 11.86 LC runs today vs May.

 

[GRich]

Picked up a 12.333 this past weekend, which is my best time so far. Not good enough to place in the top 15, but getting closer! After I do the BMS Brake Snip, get better tires, and have some cooler temps (92 degree outside temp on this run), should be hitting sub 12's

 

[Tonkabob]

Picked up a 12.333 this past weekend, which is my best time so far. Not good enough to place in the top 15, but getting closer! After I do the BMS Brake Snip, get better tires, and have some cooler temps (92 degree outside temp on this run), should be hitting sub 12's

What were your IATs like at 92 degrees and using WMI?

 

[GRich]

So when I got to the line after waiting 20 minutes, they were at ~145. After my run, they went down to ~120. But by the time I got back to the line to do my second run (another 20+ minutes), they were back at ~140. This was my first time running with WMI.

 

[GRich]

So when I got to the line after waiting 20 minutes, they were at ~145. After my run, they went down to ~120. But by the time I got back to the line to do my second run (another 20+ minutes), they were back at ~140. This was my first time running with WMI.

@Terry@BMS - I meant to ask you this after my run this weekend... Does WMI only kick in when the car is in drive? I tried to rev up my engine while I was waiting in order to lower my IATs before I got to the line, but the IATs didn't drop. In the future, should I hit the prime button to get the IATs down before my run?

 

[Tonkabob]

@Terry@BMS - I meant to ask you this after my run this weekend... Does WMI only kick in when the car is in drive? I tried to rev up my engine while I was waiting in order to lower my IATs before I got to the line, but the IATs didn't drop. In the future, should I hit the prime button to get the IATs down before my run?

You have to be at a certain boost level - about 10, configurable, before WMI kicks in and with a rev in park you don't get enough load to make boost.

 

[Tonkabob]

I'm curious about the impact of ambient temp on times vs IATs. I guess IATs are the only thing that matter but lower ambient help drop IATs faster.
Spring at 55 degrees I ran 11.86 with 132 starting IAT and 118 final IAT.
Summer at 75 degrees I ran 11.86 with 118 starting IAT and 108 final IAT
Tunes where different but using just the ambient for the DA probably isn't that accurate vs looking at the IATs?

 

[Hyperjetta]

I'm curious about the impact of ambient temp on times vs IATs. I guess IATs are the only thing that matter but lower ambient help drop IATs faster.
Spring at 55 degrees I ran 11.86 with 132 starting IAT and 118 final IAT.
Summer at 75 degrees I ran 11.86 with 118 starting IAT and 108 final IAT
Tunes where different but using just the ambient for the DA probably isn't that accurate vs looking at the IATs?

I'm not an expert, but my understandable is that a low DA will result in higher HP/TQ than a high DA for any given engine.

DA is calculated based on ambient temperature, elevation, barometric pressure and relative humidity. Lower ambient temps generally means lower IAT, so there is correlation, but it's not the only factor.

Do you recall the DAs for those two runs? I'm guessing the summer run was more humid than the spring run?

 

[Revvdmedia]

DA is something I was wondering when making runs. If ambient was the only consideration, DA was 2995 on the day run with about 68F ambient temp. With intake starting temps at 164F, if plugged into the DA calculator in the same otherwise conditions (IAT replacing ambient), DA rises to over 5000. Is IAT more relevant for "relative HP" when used in that consideration, or is ambient the main driver in the calculation?

 

[Terry@BMS]

The ECU will attempt to compensate for DA differences (combination of base baro and IAT) by raising or lowering its load target. The compensations used may vary on flash maps. Some flash tuners zero them out or otherwise adjust them. But one of the reasons we spoof IAT up sometimes is to get the ECU to raise its boost set point and add in more WGDC off its internal mapping. The trade off being less timing via the IAT reduction. Which in many cases also meets our needs.

 

[Tonkabob]

I'm not an expert, but my understandable is that a low DA will result in higher HP/TQ than a high DA for any given engine.

DA is calculated based on ambient temperature, elevation, barometric pressure and relative humidity. Lower ambient temps generally means lower IAT, so there is correlation, but it's not the only factor.

Do you recall the DAs for those two runs? I'm guessing the summer run was more humid than the spring run?

Temp and elevation are the largest factors of DA by a long shot. So roughly the 55 degrees was around 200 DA and the 75 degrees was around 1200-1500 by memory. Would be good to have DA calc that also took in IAT for us super geeks.

 

[19GT-AWD]

Second pic is comparing my two 11.86 LC runs today vs May.

DA 05/5/19: -185 ft
DA 8/25/10: +1,421 ft

 

[Hyperjetta]

Temp and elevation are the largest factors of DA by a long shot. So roughly the 55 degrees was around 200 DA and the 75 degrees was around 1200-1500 by memory. Would be good to have DA calc that also took in IAT for us super geeks.

In order to calculate a true DA based off IAT you'd need to also account for the other properties of the air at that point (charge pipe). The elevation doesn't change, but the air pressure and the relative humidity will. The air pressure is obviously much higher thanks to the turbos, but the relative humidity I would think changes as well. Now you have me thinking...hmm. Time to read up on thermodynamics haha