The last two times I've gone to the track with my 94 Z28 Vert A4 2.73's I have ran my best ET's on the very first runs. I would think that I would get a better feel for traction as the night goes on, but my car's ET's and mph drop as the night seems to go on. I usually allow at least 30min between runs. I'm thinking I should do the throttle body bypass mod to help this. Is there something I'm totally overlooking here, that should cause this to happen?

 

The only thing I can think of is your car is not running as cool as it could be. The colder your engine the more horsepower. After your car makes its first run, if it doesn't cool down properly there is more heat and a lack of power. I would try a 160* Thermostat and a manual cooling fan switch so you can run your fan when you are waiting for your next pass. Anybody else have any ideas please chime in. Just my .02

 

in two words...Heat soak. Get some ice on the manifold and do the fan switch mod and your times will drop.

 

Could just be the driver, and I don't mean in a bad way. The past few times I've been out, I ended up making my best passes on the first run. After that, adrenalin took over, and I'd start making a mistake here, launching too hard there. I know my car doesn't drop off because I hot lapped it 34 times in one night without a drop off.

It's a thought.

 

Could just be the weather too.

 

Well I live in Hawaii, so the weather is a little bit warmer than on the mainland, but the nights are still cool. I doubt I made many mistakes when driving the 1/4. Next time I'll check the temp gauge after I make my first run I guess. Is it better to leave the engine off just before I make a run, or should I leave the engine running with the fans on (manual fan switch, I haven't done this mod yet)?

 

Until you do the manual fan switch, you can just turn on the A/C for a bit while waiting. That will turn the fan on and help cool the engine in between runs.

 

But be careful that water doesn't drip from it.. they'll toss you off the track for that..

 

I know we're not allowed to run our AC's on while running our cars, but is it permissable at most tracks to run my AC while in the staging lanes? I've never thought about that....my fan doesn't run when the AC is off...duh I think this is my problem!