Performance measurement

[Brooks]

I was looking thorugh some old Direct Scan runs comparing my improvement in mid-range peformance. I picked an arbitrary speed range and measured the time between the two points. In this case the time between 30MPH and 80MPH.

My best time so far has been 6.8 seconds. This was recorded on an 8.4@83 run in the 1/8 on pump gas and the mods in my sig.

I zero the run on the first frame that indicates 30mph and move to the first frame showing 80mph to get the time.

I have DS set at 18.2 frames per second but I don't think it would make much difference if the frame rate were different.

I was curious how that compares to others. What kind of 30-80 times are you guys getting on Direct Scan?

Come on whip out your laptops and post some times!

Charles Brooks

 

[salvageV6]

Ran the GN last night with Direct Scan. New (used) Reds 100 chip and alky. Not exactly sure of the boost wasn't watching.

34mph where I started to 84mph.

8.53 seconds per direct scan 18.2 fps.

That's the slow car.

 

[bruce]

Originally posted by Brooks

I have DS set at 18.2 frames per second but I don't think it would make much difference if the frame rate were different.

If I'm not mistaken the VSS update is on the 50 msec loop, so you have a possible .1 sec error before you even hit the space bar.

And I do think the sampling rate would play into this.

 

[TurboDave]

Just checked one of mine, it was 4.94
That was on an 11.74 run at only 116.31

On a slightly quicker and faster run of 11.67@117.5
it ended up being 4.88

 

[Brooks]

Salvage, try making a run from a dead stop up past 80MPH then zeroing at 30 and making the measurement. I should have mentioned that in the first place, sorry.

Bruce, yes there's a timing delay however it applies throughout the recorded data. As long as the person is aware it's there it's a non issue. DS itself only updates at 18.2Hz or approx 55ms. Not exactly a speed demon but it gets the job done.

The 30-80MPH metric has turned out to be a pretty decent yardstick for me in evaluating my chip changes along with a few others. What metrics do you like to use and apply to Direct Scan data to measure performance changes?

 

[Brooks]

Nobody else?

 

[TurboSy]

Mine was 4.05, I've never used this as a performance guide before now, but it makes good sense, especially on the street.

Mark L
Syclone
11.3 @ 119

 

[TRDirks]

OK, I have a couple times for you Chuck.

11.67@117mph w/Art Carr TC too loose for my tastes = 4.61sec.

11.74@115mph w/Deltrans 2800 12" TC = 4.66

Both runs were at 20psi w/Hoosier QTP's The only differences would be torque converter, air temps (much cooler on the faster run), and I was spinning through mid 2nd gear on the faster one aswell

If all goes well I will have some better ones this weekend at Cecil

 

[ijames]

I got 5.60 on a 12.50 107.9 run and 5.38 on a 12.46 107.6 run with my new ~3200 stall 10" Yank converter, and 4.94 on a 12.53 107.3 and 4.72 on a 12.18 110.5 run with my 2800 stall DelTrans modified D5 converter. The Yank definitely feels "softer" in the midrange and the times bear that out. It wins on the 60' and is as efficient over 5000 rpm so it nets out about the same et.

 

[ijames]

Just for grins I went through the files uploaded to bmcomputersource.com in their ds directory:

File ET MPH 30-80
cat1-1 14.90 93 8.95
cat1-2 14.30 96 10.16 looks like wheelspin
cat1-3 13.55 102 6.75 looks like wheelspin
cat2-1 12.5 110 4.83
cat2-2 12.80 103 6.26
cat3-1 12.28 110.67 4.72
cat3-2 11.76 115 4.72
cat3-3 12.16 109 4.83
cat3-4 12.04 114 5.60 run doesn't start at zero mph
cat3-5 11.67 117.52 4.88
cat3-6 11.88 116.2 4.61
cat4-1 10.57 126.97 3.35
cat5-3 ? ? 6.64

Looks like cat 1-2 and 1-3 have wheelspin that gets the vss over 30 mph (which makes these 30-80's too big), from the hump in the speed scope plot, so maybe 30 mph is too low a starting point. I know you wanted to cover the widest span possible, so maybe dropping 2 runs out of about 10 isn't too bad. 3-4 is confusing because it doesn't start from zero mph, so how can there be an et/mph (besides, it's a tta which will skew the data relative to tr's)? I included 5-3 out of curiousity since Bruce doen't have any timeslip data and lots of people are curious about his car. Okay, Chuck, your job is to plot all of the posted 30-80 times vs. the mph and see if you can fit some function to that to predict mph from the 30-80 time . From looking at other data in the past, the mph is much more reliable since it doesn't depend much on the 60' time, so I like to use the formula et=1356/mph to get an average et for a mph.
[I'm going out of town for a few days so don't get upset if I don't post .]

 

[Brooks]

Thanks guys,

Carl, I had to drop a couple runs myself due to wheelspin. I definitely need better tires.

Bruce, I went and recorded a few runs at 9 frames per second and there is some spread in the results but averaging 6 runs got me to 6.83 seconds. Pretty close to the single 18 frame per second run that netted a 6.8. I think if I averaged several runs at each update rate that they would come fairly close.

Charles Brooks

 

[ijames]

Chuck, any progress doing curve fitting? Just having a tuning metric is nice but I'd love to be able to do a <30 to >80 pass and predict a mph and et.

 

[Eric Stage I]

There's limited data, but "184.3*(time^-.3157)=mph" will get mph in the ballpark.

Examples:

30-80 time of 3.4
3.4 to the power of -.3157=.6795
184.3 * .6795 = 125.2mph

30-80 time of 4.8
4.8 to the power of -.3157=.6094
184.3 * .6094 = 112.3 mph

30-80 time of 6.3
6.3 to the power of -.3157=.5593
184.3 * .5593 = 103.1 mph

 

[Brooks]

No, I didn't play with the numbers until lunch today.

Looks like Eric got a little beter results than I did. I used it as a programming exercise and wrote a small app but came up with some funky numbers. I worked with 10 of the sets from the posts here and my own numbers to come up with a curve but when I ran some test numbers through it they were a little awry.

I'll play with it more next week.

Charles Brooks