05VENOM

Just got back from E-town and these numbers don't make sense. What do you guys think.

The following numbers were randomly picked from over the summer. All on different days.

Temperature 47 --- 68 --- 66---- 70
60' Time 2.166 -- 2.049 -- 2.024 -- 2.154
1/8 sec 8.499 -- 8.431 -- 8.347 -- 8.320
1/8 MPH 87.69 -- 87.83 -- 88.42 -- 90.30
1/4 sec. 12.905-- 12.879 -- 12.765 -- 12.619
1/4 MPH 112.55 -- 114.08-- 114.88 -- 114.61

These numbers were from tonight:

Temp -- 78 ------ 78 ------ 77
60' sec -- 2.058 -- 2.038 -- 2.043
1/8 sec. -- 8.392 -- 8.421 -- 8.425
1/8 mph -- 87.60 -- 86.93 -- 86.96
1/4 sec. -- 12.839 -- 12.900 -- 12.898
1/4 Mph -- 108.55 -- 107.60 -- 108.12

What is going on with these MPH's. The 60' times are some of my best. The car is definitely shifting a bit lazy. I had the tranny/engine software update in late June where it would start in 1st. But a 6.0mph difference, could the temp matter that much? Now even though the temp's were 77/78 it was pretty humid out. Still am shocked with these MPH's...are my 3 lowest yet in this car. I never trap below 110mph.

rflow306

Venom could you post your 1/8 mile traps also.

Iron Sheik

I suggest you check your IC pump!!! just kidding...
Something is iffy... your trap is basically on par with a 550, no???

Iron Sheik

05VENOM

Sure, will add/edit them to the above post.

05VENOM

If you compare my run on 6/13 compared to tonight you could see my confusion.

....... 6/13..... 8/31
60' .... 2.049... 2.043
1/8 sec .... 8.431... 8.425
1/8 mph .... 87.83 .... 86.96
1/4 sec..... 12.879.... 12.898
1/4 mph .... 114.08.... 108.12

These runs are practically identical except for the mph

rflow306

Unless the barometric pressure was way lower this last time out, something is causing the car to slow down the last 300 or so feet. I think it should have ran at least 110-111 mph with just the temp change mentioned.

Maybe Juice can compare the da from the previous runs to your most recent, to see if there is a huge difference.

jason427

It did look warmer out for the new runs.

Jason

blackbenzz

I just got back from the track and same crap. I was at the track exactly one week les than a year ago. Cut almost identical crappy 60's and yet I trapped 5mph lower and ran .3s slower It must be the dense humid warm air. I add more mods and I go slower! Did embarass a Shelby GT500 to the point where he just coasted after the 1/8th. As if he wasnt racing lol

enzom

Very strange. I think you swapped the 114 and 108, btw.

Doesn't make sense to me. You gained 26.25 mph in the last 1/8th in June. But only gained 21.16 mph last night. To lose 5 mph in the last 1/8 is a huge drop.

Even where my traps may differ by 4 mph (118 vs. 114), those runs were in much different weather conditions. More importantly, if I took the delta between the highest and lowest traps, there is only about a 2mph difference in gains in the last 1/8th (24 mph vs. 26 mph). When my car is slower, it is slower for the whole run, not just the last 1/8th. Lat night, your car was much slower in the last 1/8th compared to your June run.

What happened last night could be a combination of things - (1) bad air, (2) strong headwind, (3) bad fuel (less likely) or (4) a mechanical issue.

Headwinds can kill your traps. If the air was so bad, I would think you would have seen a bigger performance decline in the first 1/8th. Same with fuel. Unless you think that the headwind was very strong last night, I think you have a mechanical problem.

If you know anyone with a datalogger, you should see if you can borrow it and figure out why the car is falling on its face in the last 1/8th. If I had one, I'd offer it up. Good luck.

05VENOM

You're right, I did switch the mph & time above(just corrected it)
I did mention on the phone there was a cross-wind, the flags atop the bleachers were going crazy but to make that much a difference. I need to get back to E-town fast to see if it was just last night. If I get a repeat guess i will have to make a service call to my dealer.

Happy2th

hmmmm

enzom

You did mention that. Cross-winds can hurt, too. Let's try (as we keep trying) to meet up there. Hopefully, next Friday will be slow in the office and I can take off early.

In fact, we should try to have a bigger meet down there soon as the weather starts to cool off.

05VENOM

Absolutely, you know I am always down for that.

juicee63

Run on 8/31

The closest weather results for 08/31/2007 at 06:01 pm

Time recorded 5:55 PM
Temperature °F 78.8
Dew Point °F 60.8
Altimeter Setting 29.94 in Mercury
Density Altitude: 1595.9 feet
Track Elelvation: 86 feet

UnCorrected ET:
12.8 (sec) @ 108.5 (MPH)


Corrected ET to Sea Level:
12.573 (sec) @ 110.501 (MPH)

Run on 6/13

The closest weather results for 06/13/2007 at 06:01 pm

Time recorded 5:55 PM
Temperature °F 62.6
Dew Point °F 48.2
Altimeter Setting 30.08 in Mercury
Density Altitude: 314.7 feet
Track Elelvation: 86 feet

UnCorrected ET:
12.87 (sec) @ 114.0 (MPH)


Corrected ET to Sea Level:
12.827 (sec) @ 114.386 (MPH)


so we have a 20 degree difference, HUGE and you did fairly well at a 1600 DA.

On 6/13 looks like the car made more power and it is likely TEMPERATURE effected.

juicee63

You should call your SA, and check on the latest campaign, your car was fine through the 1/8th then BOOOOOOM looks like you hit a WALL. AIR was worse but 2 mph worse not 6

car should of hit 112, ET was improved so IMO wind was not the problema. Its gotta be the ECFU, computer bs..

DarrenCT

1 word.... humidity-- damn Northeast summers are soooooo muggy

juicee63

Yeah the more I ponder this the more this seems like a weather related slowing of an AMG.

Blackbenzz also was 5 mph slower, wonder if he was slower through the 1/8th mile as well

blackbenzz

Here is my data (I am comparing my worst pass on 9/9/06 because 60' is comparable):
9/9/06 -- 8/31/07 Pass#1 -- 8/31/07 Pass#2
60' time -- 1.979 -- 2.059 -- 1.919
1/8 sec -- 7.950 -- 8.470 -- 8.095
1/8 mph -- 92.13 -- 87.01 -- 88.61
1/4 sec -- 12.126 -- 12.891 -- 12.451
1/4 mph -- 118.19 -- 112.75 -- 113.86

juicee63

If we want to do this right I need appx time of the runs. Lets see how much better the air was on 9/9/06 or if it was better.

blackbenzz

Who needs approximate times when the times are on the slips? I dont know if they are correct though. 9/9/06 3:41PM. Pass #1 on 8/31/07 8:39PM and Pass #2 9:25 PM

juicee63

Here is Pass #2 on 8/31/2007

The closest weather results for 08/31/2007 at 09:30 pm

Time recorded 9:52 PM
Temperature °F 78.1
Dew Point °F 66.0
Altimeter Setting 29.99 in Mercury
Density Altitude: 1534.1 feet
Track Elelvation: 80 feet

UnCorrected ET:
12.45 (sec) @ 113.86 (MPH)


Corrected ET to Sea Level:
12.239 (sec) @ 115.861 (MPH)

And pass #1 9/9/06



The closest weather results for 09/09/2006 at 03:45 pm

Time recorded 3:52 PM
Temperature °F 79.0
Dew Point °F 66.0
Altimeter Setting 30.04 in Mercury
Density Altitude: 1533.8 feet
Track Elelvation: 80 feet

UnCorrected ET:
12.13 (sec) @ 118.19 (MPH)


Corrected ET to Sea Level:
11.925 (sec) @ 120.267 (MPH)


your car is 5 mph slower as the DA is nearly identical for the times listed.

weird. For your runs weather is not a factor as the days you ran had nearly identical "air"

In Venoms case, the DA was 1200 ft higher so his run was likely hurt by the higher DA, but I think the 5 mph trap speed is indicating something more than weather in Venoms case and definately in your case. What does your car run on average throwing out best and worst?

blackbenzz

After seeing that corrected time I HAD to go back and check my time slips because I had also run a 11.7 @118.9 with a 1.7 60' which would have corrected to something crazy! Needless to say, at the top of the time slip it says 9/9/06 but down below it says Jan. 7 2007. I'm guessing it was january because that would make more sense. Cooler, less dense air = higher trap and lower et. Ughhh, I dunno. I just cant wait til the weather gets colder! Here is the 11.7 pass last year http://s143.photobucket.com/albums/r...current=11.flv

JAYCL600

The closest weather results for 01/07/2007 at 11:01 am

Time recorded 10:52 AM
Temperature °F 50.0
Dew Point °F 35.1
Altimeter Setting 30.36 in Mercury
Density Altitude: -905.1 feet
Track Elelvation: 80 feet

UnCorrected ET:
11.80 (sec) @ 118.9 (MPH)


Corrected ET to Sea Level:
11.912 (sec) @ 117.743 (MPH)

blackbenzz

So it was actually slower than the time I ran! Not cool

juicee63

LOL

I have never seen a NEGATIVE DA -900 ft WOW!!!

That actually makes this a WEATHER issue vs. Mechanical.

That should be good news and just further demonstrates how AIR can impact your times in a very significant manner.

So you and Venom at two different tracks with similar DA both had 5 mph slower traps....