LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Need help, diagnosing performance issue!

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Old Nov 12, 2007 | 05:35 PM
  #1  
Ironxcross's Avatar
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Need help, diagnosing performance issue!

I am losing performance somewhere, its not drastic but the car definately has more in it. Preheader runs were 13.9 at 102 mph with a 2.28 60'. Post header runs were 13.8 at 103 mph with a 2.24 60'. Considering the 60' is similiar, one would think that the car should run better times with the headers.

There is an exhaust leak that can be heard but it cannot be located, I have checked all gaskets, and collectors and still I cannot find an exhaust leak. The easiest way to hear it is to kneel down on the drivers side by the front tire and you can hear a "tick tick tick tick". Are there any other parts of the header that could leak?

If anyone has any hints or suggestions, that would be great.
Old Nov 12, 2007 | 05:39 PM
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It seems the area in which the header mates with the y-pipe is vulnerable to leaks, I would check that out as well. If there is a leak that is occuring before the front 02 sensors, then that can degrade the performance. Is the car running any differently or popping a SES light?
Old Nov 12, 2007 | 05:41 PM
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Originally Posted by 2000GTP
It seems the area in which the header mates with the y-pipe is vulnerable to leaks, I would check that out as well. If there is a leak that is occuring before the front 02 sensors, then that can degrade the performance. Is the car running any differently or popping a SES light?
I checked that area before, I have it wrapped with a bandclamp and heat resistant tape. Theres no SES light (but the car is tuned for the headers). The car runs perfectly smooth, and pulls hard. The only thing that makes me suspcious are the 1/4 times and the small exhaust leak.
Old Nov 12, 2007 | 05:48 PM
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what were you expecting to run? if you straightened out that 60 foot you would be in the mid 13's.. an exhaust leak that is past the o2 sensor isn't going to make a difference in your 1/4 mile time.
Old Nov 12, 2007 | 05:53 PM
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Originally Posted by red94chicken
what were you expecting to run? if you straightened out that 60 foot you would be in the mid 13's.. an exhaust leak that is past the o2 sensor isn't going to make a difference in your 1/4 mile time.
well, the thing that makes me wonder is that both 60' foots were the same for my header and non-header runs but the runs were only .1 apart. I was thinking that the headers would have made more of a difference
Old Nov 12, 2007 | 05:54 PM
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I agree, your times are being a little hindered by your sixty foot times. Otherwise, they are not off par for your mods. Even with the band clamps, my headers still have slight leaks on the drivers side where it mates to the y-pipe.
Old Nov 12, 2007 | 05:55 PM
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you did go up in mph so that is a sign that its making more power.. but for the 10-20hp the time is not going to drop much.
Old Nov 12, 2007 | 05:59 PM
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Originally Posted by 2000GTP
I agree, your times are being a little hindered by your sixty foot times. Otherwise, they are not off par for your mods. Even with the band clamps, my headers still have slight leaks on the drivers side where it mates to the y-pipe.
Originally Posted by red94chicken
you did go up in mph so that is a sign that its making more power.. but for the 10-20hp the time is not going to drop much.
so do you think with better suspension and tires, that i'd see more out of my exhaust modifications?

oh and when i did the runs, i was granny shifting. i dont speed shift
Old Nov 12, 2007 | 06:01 PM
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Originally Posted by Ironxcross
so do you think with better suspension and tires, that i'd see more out of my exhaust modifications?
Sticky tires will make a huge difference, some suspension work will play a bit of a role as well. Some practice with your launches will also make a difference.
Old Nov 12, 2007 | 06:05 PM
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Originally Posted by 2000GTP
Sticky tires will make a huge difference, some suspension work will play a bit of a role as well. Some practice with your launches will also make a difference.
so you think with a 2.0 or lower 60' i could be in the mid 13s? alright
Old Nov 12, 2007 | 06:14 PM
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Originally Posted by Ironxcross
so you think with a 2.0 or lower 60' i could be in the mid 13s? alright
Yes.
Old Nov 12, 2007 | 06:17 PM
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Originally Posted by 2000GTP
Yes.
Well, makes me feel better that my car is normal.
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