ET/MPH vs. Temp./Humidity

**96LT1355Z28** · 09-11-2011, 02:03 PM

How much does everyone's car's ET and MPH vary with temperature and humidity? Last night I was racing in my local series going 11.35-40 at 120. As the night went on the temp dropped and humidity went up eventually past the dew point. My car kept getting slower ending the night with two 11.70's at 116. No other cars including another LT1 and several LS's didn't seem to be affected and some even improved. Is there something I should be looking at, mine actually seems to run better when it's hot out! WTF

**LSWHO** · 09-11-2011, 02:41 PM

I've seen 4mph and 4 tenths in better AVERAGE weather. Meaning from normal summer weather to normal winter weather. I think it was from septemberish to decemberish. And yes, september is summer here. March-Octobter is summer here. Nov-Feb is "winter."

This can give you an idea: http://www.dragtimes.com/da-density-altitude-calculator.php

also your car may not have as effective of a cooling system as the others you paid attention to. Time in between runs has a huge effect on times as well. My car is VERY consistent. But if I don't run for a couple hours in between runs I can gain 1.5mph and a tenth or two. 4mph is a lot though. I'd look at your cooling system.

**96LT1355Z28** · 09-11-2011, 03:17 PM

My temp gauge barely moved all day, it's never gotten over 180 even at the shootout in 100 degree temps. This "day" was from about 1PM to 9PM my car has usually always been within 1 or 2 tenths I just can't figure out where the power is going. It felt fine in 1st and 2nd but I could tell I was staying in 3rd and 4th longer before getting to the stripe. I know weather affects performance but I would think the other cars would have the same problem.

*after talking to AChotrod on LS1tech I'm wondering if it's possible for the clutch to grab hard enough to pick up the front end in 1st but slip in 3rd and 4th?

**96LT1355Z28** · 09-11-2011, 08:24 PM

Just got back from a drive and the clutch is holding strong in 4th and 6th going WOT.

**LSWHO** · 09-11-2011, 08:36 PM

Who tuned your car? If it's getting worse when cold it's possible (though unlikely) that it's richening up in the cold too much and causing you to lose power. Other than that, maybe your tranny is heating up too much after so many runs?

**96LT1355Z28** · 09-11-2011, 08:47 PM

Tuned by Ed Wright, it's been super consistent since he tuned it in July of 2010. Somethings gotta be going on causing a power loss that I just haven't found yet. The only code is a PO132 for signal high B1S1. Watching the lave data B2S1 actually reads low as in below .100 MV. I've re-soldered the extensions, put in new connectors in case I had a bad pin, replaced O2's with Ac's from dealer and switched sides the problem stays the same. Thing is at the shootout and yesterday the code never came up, it came back today during street driving.