I am a little stumped on this one

[HJ's Garage]

Last week end I went out to the Strip here in Vegas for the Street Car Super Nationals. On Friday night I had to wait for 7 hours to make a run and when I did the car was pretty cold. I ran a 13.13 at 106.35 with a DA of 3600 feet. That would correct to around a 12.6 or so. I was pretty Jazzed as that was my best run here ever.

The next day I drove to the track at 7am and made my first run by 9am. It was a dissapointing 13.46 with a DA of 2600 feet, so it should have improved, not gotten worse, based on the DA anyway. We got rained out and I only had the one round that day.

On Sunday morning I again drove to the Track and made my first run by around 9am and again a dissipointing 13.39 with a DA of 2300 feet?

The only thing that I can come up with is the fact that I drove to the track on both Sat and Sun (about 45 min to an hour) and only had around an hour or so before my runs to cool off.

I have a L99 with JBA LT's, Hi Flow Cats and 3" Exhaust, K&N CIA, Hotchkis Maxi Brace, 370's with Jannetty Posi mod's and end caps and a tune by Wicked HP.

I would appreciate any insight that you guy's might have to offer. I assume the 160 degree Thermostat will come up in this thread for discussion.

thx

[Roger Ramjet]

Using DA to correct performance introduces some error unless the temperatures are nearly the same. If you have the raw weather numbers for temp, baro, and RH, recalculate performance using the SAE HP Correction Method. Comparing performance vs. SAE HP Correction factor will show that you have a weather related change or just an inconsistancy.

[HJ's Garage]

Irrespective of weather, why was my time off by 2.5 tenths on Sat and Sun, compared to Frid night? That is my real question.

[JANNETTYRACING]

Originally Posted by HJ's Garage

Irrespective of weather, why was my time off by 2.5 tenths on Sat and Sun, compared to Frid night? That is my real question.

Take a Look At your 60 ft times this will tell the story.

Spinning even just a little can hurt your et quite a bit.

Ted.

[Orange Krate]

Originally Posted by Roger Ramjet

Using DA to correct performance introduces some error unless the temperatures are nearly the same. If you have the raw weather numbers for temp, baro, and RH, recalculate performance using the SAE HP Correction Method. Comparing performance vs. SAE HP Correction factor will show that you have a weather related change or just an inconsistancy.

+1 I have seen numbers fluctuate like that with a significant change in RH. Temps could be stable but have the fog/clouds roll in and wheel spin increases proportionately.

[Roger Ramjet]

When the dew point is within 10* of the ambient temp tire spin is more likely because of moisture on the track.

[HJ's Garage]

Originally Posted by JANNETTYRACING

Take a Look At your 60 ft times this will tell the story.

Spinning even just a little can hurt your et quite a bit.

Ted.

Friday night 60' = 2.008 (best ever)
Sat morning 60' = 2.202
Sun morning 60' = 2.036
No spin according to those watching.

Is there a reasonable correleation between engine temp at the time of the run? It was cold Friday night, but I drove both days to the track on Saturday and Sunday for the morning runs. I have heard that when cold, the engine might run in an open loop, with less control by the computer?

[Slowhawk]

I'd say heat soak.Just idling up the staging lanes can affect times.

[SGOS252382]

My car runs faster on a rested engine. I drive 2 hours to get to the track. So I like to get there about 1 hour before racing starts to let my engine cool down. I also like to get up in the front of the line so I don't have to stop/start a bunch of times while staging (sometimes you just can't afford it though)

But many things can affect your times.
1. Air pressure - cars like a high pressure (rainy weather is low pressure)
2. wind speed and direction - tail wind will aways help
3. humidity - higher humidity slows you down, especially if its warm outside.
4. Temperature - temperature has the greatest affect on track times. Just a few degree change in temperature will affect your track times.
The colder and drier the air is, the more HP your engine will make.


Some guys say their cars get faster when they are hot lappped. But my cars have always run better after sitting for a while.

[JANNETTYRACING]

Originally Posted by HJ's Garage

Friday night 60' = 2.008 (best ever)
Sat morning 60' = 2.202
Sun morning 60' = 2.036
No spin according to those watching.

Is there a reasonable correleation between engine temp at the time of the run? It was cold Friday night, but I drove both days to the track on Saturday and Sunday for the morning runs. I have heard that when cold, the engine might run in an open loop, with less control by the computer?

0.1 in the 60 ft can be .2 -.3 in the Quarter mile.

That is why we can run low 12s with our street package with 1.66 60 Ft times.

One of our Torque converters would really help you out up to 1/2 second with no other changes.

Ted.