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Old 10-31-2004, 09:50 PM   #1
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Default Bad Day - Car slower?

Went to the track today and had an awful day. My times were crap and I don't know why. I was pulling 2.2x 60 foots for starters, so that pissed me off right off the bat. However I've run high 13'* with crappy 2.2x 60 foots before and today I was mainly get 14.1xx'*. I tried with a 3.3" pulley, then 3.3" pulley with race fuel, then 3.2" pulley with race fuel, and the best I could pull was 13.9xx at 97.xxmph with a 2.17 60 foot. I only changed one thing and my car last time and I fear it is the problem -- tires.

I had my old Nitto NT450'* put on my car last week and the size is: 245/50/16. I brought the tire pressure down to 26psi like I did with stock tires. Now this is my guess as to why I was slower:
1.) The car was spinning the wheels faster than before because these Nitto'* have a smaller diameter than stock 225/60/16'*, hence the car had to work harder.
2.) 26psi was too low for such a wide tire and the car had to work harder at higher speeds.

Other than that I'm stumped. Besides my crappy 60 foots, which I can work on, she had much better traction than before these tires due to the extreme v-tread pattern.

Was it my tires? Should I look at getting some stock sized 225/60/16s? Could I get away with 235/55/16'*? Or was my psi just too darn low.
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Old 10-31-2004, 10:02 PM   #2
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Slightly smaller tires will give you more gear actually. You may remember jeffrey with those silly 15" steelies and small tires, just for the track.

How was the weather different, what else have you changed? You were messing around with the EGR and other components, maybe one of them is hurting you? Times between runs different?

Could just be a bad day...
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Old 10-31-2004, 10:04 PM   #3
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EGR was hooked back up, times were pretty darn consistant, it was cool out.

Maybe my psi was too low for these tires.
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Old 11-01-2004, 12:05 AM   #4
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Don't Know Kyle, I had the same problem went to the track last 2 sundays, first week bot my best 13.824 run and all in the 13.8/9s and that was all with a 3.4 next week ran a 3.2 and 110 octane and barley could hit a 13.9 to save my life I threw the 3.4 back on a was 14.2 ohh well somedays it'* like that I guess.

Anyone dressed up at the track today? We should try to meet up once more before winter. meet you at Byron in 2 weeks.
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Old 11-01-2004, 12:36 AM   #5
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Byron is only open for 2 more weeks this season. Last weekend they will be opened is Nov 13/14th. Maybe we can meet up there, anyone is welcome.

As for these wacky times, Taylor did you throw on the slicks when your times started to suffer? Just seeing if there is a relation to the whole tire size idea. Otherwise it might be the level of moisture in the air and barometric pressure which could have caused poor times in both our cases.
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Old 11-01-2004, 12:48 AM   #6
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Both time were with the slicks and a base of 100 ocatane, 2nd week tried a splah of 110 to it. only change for me was gas a 3.2 2nd week and car was slower. although firs t week track temp was 35-45 and 2nd week was 55-70
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Old 11-01-2004, 01:02 AM   #7
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1) Don't run 110 octane as its probably leaded and will destroy your 02 sensor
2) smaller rims = less rotational mass so your 60'* would probably suffer more
3) Slicks will lower your trap speeds 1-2mph


Kyle, did you scan your runs?
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Old 11-01-2004, 07:42 PM   #8
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Quote:
Originally Posted by Rogue
1) Don't run 110 octane as its probably leaded and will destroy your 02 sensor
2) smaller rims = less rotational mass so your 60'* would probably suffer more
3) Slicks will lower your trap speeds 1-2mph


Kyle, did you scan your runs?
1.) I run 104 octane and verified that it is NOT leaded.
2.) Stock rims, but tires are slightly smaller diameter.
3.) Not slicks, just Nitto NT450 Extreme Performance tires (wicked V-tread )

I scanned but couldn't get the logs to save. Something quirky with the palm, plus I was rushing everytime I staged to click "Start Logging" with my finger nail.
KR on 3.3" pulley the way home was a dead 0.0 all the time (left over 104 octane).
KR with 3.2" pulley was 0.0 until 4500+rpms, which then jumped up as high as 4.9. However, this eyescan was 10 minutes after dumping 2 gallons of 104 in. I did not glance at KR after this point, was angry and distracted by getting good 60 foots.

Todd, think the tire change would be the issue? Maybe psi too low? Or was it human error?
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Old 11-01-2004, 07:55 PM   #9
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Have you dyno'd you're car yet? Just curious.
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Old 11-01-2004, 09:00 PM   #10
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Quote:
Originally Posted by Allmachtige
Todd, think the tire change would be the issue? Maybe psi too low? Or was it human error?
Hard to say without looking at the scan. I know it takes a bit for the car to recognize the race gas and advance your timing (sometimes 20 miles or so). I'm really curious as to what your 02 readings were, especially with the ltrim problems youve been having.
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