Back again in the new car, still slow :(

Speedboosted

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After owning this new to me 2006 GT for almost two months and fixing some fuck ups the previous owners had done, I was excited to hit the track. Motor is a mild build with Manley rods and coated pistons, Clevite bearings, stock crank, teflon valve seals, and ARP bolts throughout. Stock heads/cams/ blah blah. Still even has factory exhaust manifolds and cats lol.

Anyways, the car also has a Shelby American edition of the Paxton 1200 (air to water setup) on the standard pulley and I saw a peak boost of 11 psi at 6500. Automatic with 3.31 gears and for drag racing I was on 275/60/15 NT555r.

Made 4 passes, first one was really soft and the car shifted at 6300, ran 12.6 @ 110. Loaded another tune from Lito (love that guy) that allowed it to shift higher and made 3 nearly identical passes, all at 12.1 @ 113. I'm reasonably happy with the time, but real disappointed with the trap speed. My N/A car trapped 109...

Thoughts?
 

Turbotungsten

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What was the air like and was there any serious head wind? Really 113s not too bad, but I agree you should see a little higher.
 

Speedboosted

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Air was pretty good, no real headwind that I could tell. There was a light breeze but it was cross the track. My phone shows a DA of 600 ft when I was making the 12.1 passes.

1/8th mile was 7.8 @ 94 which seems good, but man it laid down up top to only pick up 19 mph.
 

slackinoff

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I am still learning on dadalogging so excuse my ignorance. But, what about logging an entire run and having Lito look at it and maybe sAy.....oh yea, lossing valtrain controll here or boost or it's pulling timing arfter th 8th...just a ignorant guess.
 

Speedboosted

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I am still learning on dadalogging so excuse my ignorance. But, what about logging an entire run and having Lito look at it and maybe sAy.....oh yea, lossing valtrain controll here or boost or it's pulling timing arfter th 8th...just a ignorant guess.

I did log every run, car didn't pull timing. That was my first thought though as it felt exactly like it
 
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bunits19714

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you lost 5-6 mph on the back half- fuel trims on the logs all look good- is the belt slipping? are you getting a boost leak? what was your trap rpm?
 

Speedboosted

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What gear and what rpms did it trap at?

you lost 5-6 mph on the back half- fuel trims on the logs all look good- is the belt slipping? are you getting a boost leak? what was your trap rpm?

4th gear, only crossing around 4600-4700 rpm. Could very well be some belt slip and I already checked for possible boost leaks and couldn't find any areas that stuck out
 

stkjock

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needs more gear IMHO, 3.31s and a 28" tire w/ a centri blower? you didn't get that advice here
 

Speedboosted

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Lol I know, gearing is no good. I guess I'm just surprised it's that bad. More boost, fuel, suspension, and gears coming soon. I think I'm going to go with 3.73 so it doesn't totally suck going down the highway unless it needs more? Not looking to break records, just a mid-low 11 second car
 

stkjock

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4.10s if you stay with a 28" tire - centri needs the RPM

I ran 4.10s and a 26.4" tire and it was fine on the highway 70 mph = 2500 rpm
 

46addict

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Lol I know, gearing is no good. I guess I'm just surprised it's that bad. More boost, fuel, suspension, and gears coming soon. I think I'm going to go with 3.73 so it doesn't totally suck going down the highway unless it needs more? Not looking to break records, just a mid-low 11 second car

I wondered why you're only running 11# on a built motor. So more boost/fuel, suspension and a stall/gears will help. Once you swap to 3.73s you may wish you had gone steeper. I know I did. But I understand you're building a street car. With 4.30s you can still be under 6500rpm in 4th crossing the line at 120mph on 28" tires. In 5th at 70mph on 27" tires (stock street tire size) you are still only at 2500rpm.

edit: I just realized 5th in a 5r55 is a hair steeper than 5th in a 3650. So add 200 rpm to highway cruise speed. 4th is still 1:1 for both transmissions.
 
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bunits19714

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94mph in the 1/8 doesn't = falling off 5-6 miles per hour because of wrong gearing????? I agree he could use more gearing but has nothing to do with falling mph by a large sum.
 

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