Finally... real Test and Tune

driller

driller

El Presidente
Staff member
I spent the day at the track at a private rental I was invited to. These events are really cool, as you can get quite a few runs in the allotted time compared to the open for the public T&T where it seems 3 runs in 5 hours is the norm anymore.

The only downside was it was quite warm which meant no new best ETs, but the focus was feeling out the car with the new mods and trying different tactics for the best ET.

I conclusively determined a couple things, one of them being the cutouts seem to hurt the sixty foot times but help in the 1/4 mile - ET and mph. :D

Another oddity, the tune from Lonnie at Blue Oval Chips outperforms the last dynotune I recently had. :rolleyes:

And of curious note... when the low fuel warning comes on, I have about 2 good runs left in the car - after that it will start sputtering at the top end of the track. I wasn't sure what it was 'til I was back in the pits. With the car sitting at a slight incline, it started sputtering like mad. A quick look under the hood enlightened me to the low and fluctuating fuel pressure showing on the fuel pressure guage. :eek:

Anyways, the best of the day was a 13.66 @ 99.74. Out of a dozen runs, the car ran mostly 13.7s at 100 mph +/-, despite the density altitude starting at 1900 feet and climbing to over 2900 feet before the end of the day.

I'm still analyzing the numbers, but overall it was a successful test and tune session.
 
Last edited:
JP,
I used to run as "near empty" as I could for weight savings...

But after my fuel pump died I decided that I would run with a full tank instead.

Now my best ETs are all with a FULL fuel tank.

You want to try something?
Try 10-12 gallons instead of 2-5 gallons.
The marginal weight difference will be offset by the "dependable fuel pressure", and not chancing leaning out the motor on the "big end"

See if you can get the same results as I did..

nearly empty didn't net me much if any ET change, but running with a near full tank has gotten my best 60's to date.

...just a thought from the far side gallery
 
XLRVIII said:
nearly empty didn't net me much if any ET change, but running with a near full tank has gotten my best 60's to date.

...just a thought from the far side gallery
Click to expand...

Always good to hear from the "far side".

I generally try to have 5+ gallons of fuel in the tank for the track. I have become quite adept at guessing how much to fill up en route so as to hit the track with the target fuel on board. What I neglected to accomodate for this trip was the more than typical number of runs(4X the typical).

With a full tank at 18 gallons and the traditional 5 gallons to race with leaves a difference of 13 gallons. With gasoline at 6.13 pounds per gallon, that equates to a nominal 80 pounds. Enough to care about? Most would tell you that equates to 0.08 in the ET.

But... the placement of the additional weight may lend credence to your theory, along with the fact that is a liquid and will surge in the tank to the rear upon launching. With the additional weight on the rear wheels, less weight on the front and the associated momentum of the fuel at launch, it is quite likely to improve traction.

It is usually accepted that for every tenth off the sixty foot is 1.5 to 2 tenths off the quarter mile ET. Your sixty foot times would only need to improve by 0.04 to 0.05 seconds to eliminate the negative issues of the additional weight of the fuel. Any improvement above that would be seen as a quicker ET despite the additional weight.

You're a genius! :wink2-green
 
I might try 5 gallons at my next trip to see if it makes much difference nowadays..and I'll danged sure post the results.

If when tiff ran the 14.06 in my car will full tank.. .08 would have netted the first 13 second pass for "grandmas car".

Definatley enough to "worry about" IMHO..when shooting for "low et".

over the years we have drifted from the "low ET quest" to "consistancy".
We altered our launch rpm, staging technique and fuel load in order to get the most consistancy out of the car.

For Low ET, we used to launch off idle.. which helped with the stock converter.

We also use to stage as shallow as possible to get the "best hit off the tree".. and would run with hardly ANY fuel in the car.

For consistancy we might "bump in" after we turn on the staged lights to improve RT at the cost of ET.

again for consistancy we launch at 1000RPM rather than off idle.. which again gives up some ET for consistancy's sake.

Tiff went back to all the "low et" techniques when she ran Glenns car friday night and dropped .44 off his best time of the night.

.2 was due to drivers weight difference, but the other .24 is probably the difference in "low et" technique..
So roughly .25 difference between our LOW ET and Consistancy techniques.


Now I'm trying to "unlearn" some of those habits and am having a hard time "cleaning the slate".. and going back to "low et" techiques.
 
I will drive Grandma's Car to a 13 sec. pass. Taking the Bracket Racer out of me is a little harder than I thought it would be. haha
 
You must log in or register to reply here.
Back
Top