SleeperX

How much can too much gas slow you down? I had 3/4 of a tank of gas and the best time that I coudl run was a 12.1 at 115mph. A few weeks back I ran a 12.1 at 120 mph. My 60 ft was better this time at 1.799 vs. a 1.956 when I ran a 12.1mph at 120mph. Could it be due to too much fuel? I am thinking that the extra gas helped me get off the line better, but slowed me down at the top end. Any thoughts?

newton22

If that extra bit of gas, which I somewhat doubt, gave you extra traction, then yes, that probably was a major factor in getting your better 60' time. If you don't have traction problems even with a near empty tank, then the gas wasn't a factor.

It shouldn't affect top end too much though. If any, extra weight should lower your 60' time.

velvet fog

F=ma - so yes, gas can affect your times. at roughly 7 lbs per gallon, an extra 10 gallons = 70 lbs to get moving down the track.

Would 70 lbs have enough effect to change your 60 ft times by that much? probably not.

Were the weather conditions the same? Track temperature, air temperature (density) etc probably have more to do with it.

Torquey55

I ran a best time of 12.57 with around a 1/4 tank of gas. I have just over 200 Lbs of stereo equipment in my trunk which I thought it might help with traction on launch, but it definitely slowed me down. It's like going down the track with a passenger. Has anyone run the 1/4 with a passenger along for the ride if the track allowed? If so, what kind of time did you get?

SleeperX

Good point. It was probably about 20 degrees warmer. 70 degrees vs. 50 degrees..

Grumpy666

It's hard to make comparisons based on elapsed time, since so many variables at launch affect it. You were making more horsepower a few weeks ago (assuming that you didn't let off the gas until you were through the third timing light). A 4300 pound mass with a trap speed of 120 mph is making about 580 HP. A 4370 pound mass at 115 mph is making about 520 HP. Were environmental conditions different? Have you been driving like a sissy boy recently, which will affect ECU parameters?

Fikse

extra fuel wouldn't account for a 120 to 115 trap speed drop... that's about 50HP..... extra gas/weight, and the warmer weather could account for a good part of that though.... how many times did you run? could also be a timing error....

t-boy

Are you saying that 10hp would equal 1 more mph in trap? My trap in my w210 went up 2mph after ECU upgrade. Does that mean it got lme 20hp?
BTW does octane additive help or hurt?

SleeperX

[QUOTE=Fikse]extra fuel wouldn't account for a 120 to 115 trap speed drop... that's about 50HP..... extra gas/weight, and the warmer weather could account for a good part of that though.... how many times did you run? could also be a timing error....[/QUOTE

My first time to the track (ever) I ran a 12.6 1/4 mile. Wheels spun off the line badly. But my trap speed was 116 mph. The same day, my next run was a 12.1 with a 120 mph trap speed. So if I was able to run a 12.6 with a 116 mph trap speed, how could I run a 12.1 with 115 mph trap speed. Seems to me like my car is slower at the bottom end. Off the line it was quicker this time around, but my trap speed was much lower. Next time I will run with much less gas to see what happens. Either that or my car has slowed down tremendously.

Fikse

not sure what your mods are, so I'm not sure what your car should be running... if you pulled 120MPH, I would guess you have a pulley and ecu...

trap speeds will stay pretty consistant if you get a good or bad launch....

I ran 12.07 @ 116 stock... so 12.1 @ 115 is right in line....

SleeperX

I have a Renntech stage 2 (ECU, pulley, & headers). I would think that I should be running mid 11s with stock tires and a little launching experience...Last time I ran my car was my first time. 60 foot was very weak (because I couldn't launch it). This time I launched much better, but my 1/4 mile was only 12.1 and my trap speed was only 115mph. Thus I thought that the extra gas might have given me a better launch, but slowed me down at the bottom end. If not, something is wrong with my car....

e55 baller

adding 100 lbs is like shaving off about 10-12 rwhp and will ADD on average about 0.1 to your ET and drop your mph by 1 mph