loss of power after header install.........
12-12-2007, 02:40 AM
#1
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loss of power after header install......... so i have the headers in i fixed a missfire it had.......runs fine no codes.......but i feel it slower......i heard a tune will fix that up.....is that true cuz im starting to think i fucked my car up........anybody have that problem? N running lean or rich would cause me to lose that much power? anybody please help.....very confused........ oh and one more thing anybody know what to do cuz i think my y pipe is banging around down there..... will a muffler shop be able to fix that? sorry so much questions pretty new at this.........
12-12-2007, 07:58 AM
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confirm you have no leaks
clear the computer and allow the car to re-learn the a/f curve after the headers
sometimes the car will feel slower at lower speeds, but the headers should unleash good power up top. it may be all in your head.
if the ypipe is hitting, you could be getting false knock and the computer is pulling timing...which will REALLY hurt power.
what you needed to do was install poly motor mounts when the manifolds were off, before putting the headers on.
Thunder racing sells a mufflex piece that keeps your ypipe from banging. or you could have a shop clearance the pipe a little. heat up the spot and pound it in for some more clearance. it won't be enough to affect power, but 1/2" of denting can make all the difference on clearance with the frame.
something like this, on my old flowtech ypipe:
clear the computer and allow the car to re-learn the a/f curve after the headers
sometimes the car will feel slower at lower speeds, but the headers should unleash good power up top. it may be all in your head.
if the ypipe is hitting, you could be getting false knock and the computer is pulling timing...which will REALLY hurt power.
what you needed to do was install poly motor mounts when the manifolds were off, before putting the headers on.
Thunder racing sells a mufflex piece that keeps your ypipe from banging. or you could have a shop clearance the pipe a little. heat up the spot and pound it in for some more clearance. it won't be enough to affect power, but 1/2" of denting can make all the difference on clearance with the frame.
something like this, on my old flowtech ypipe:
12-12-2007, 08:11 AM
#3
Get it tuned. When I first put mine on I went from 332 to 333. After some tuning it jumped to 354, but it was running too lean. They gave it more fuel and I ended up with 342.
12-13-2007, 11:22 PM
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its going to have to be the mounts cuz the muffler shop bend that **** and its still banging.......and i lost power.......i know i did.......it doesnt kick like it used to.........why??????? i thought headers were supposed to help......all it did was make me super loud.......which is cool.......but i lost power..........
12-14-2007, 06:47 AM
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if you lost power...something is wrong.
either you have a leak, or you're A/F was out of wack to begin with and the headers messed it up more.
do you have track times to prove you lost power? dyno numbers?
very possible the callibration on your SOTP meter are off too.
either you have a leak, or you're A/F was out of wack to begin with and the headers messed it up more.
do you have track times to prove you lost power? dyno numbers?
very possible the callibration on your SOTP meter are off too.
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12-14-2007, 07:44 AM
#8
Yeah... whens the last time your *** was checked for accuracy?
Might not be a loss in power, it is probably just a shift in the torque curve. Your peak TQ numbers might have moved into the higher RPM's, much as they do when you open a cut-out.
But really, you probably did something wrong.
FYI headers you will feel more at WOT than when just goin 1/2 throttle on it to speed up. All though I can honestly say after my header install I felt it all the time.
Might not be a loss in power, it is probably just a shift in the torque curve. Your peak TQ numbers might have moved into the higher RPM's, much as they do when you open a cut-out.
But really, you probably did something wrong.
FYI headers you will feel more at WOT than when just goin 1/2 throttle on it to speed up. All though I can honestly say after my header install I felt it all the time.
12-14-2007, 06:54 PM
#9
it is common for an LS1 to loose power after header install. Your computer has no idea what the hell is going on with the AFR and will not adjust appropriatley. A tune will help tremendously!
12-14-2007, 06:59 PM
#10
It's not uncommon for people to think that a header install caused them to "loose" power. First, a tune will certainly help. Second, headers usually move the power band. You may have lost a little power down low, but you picked up a boat load of power in the mid and upper ranges.
12-14-2007, 07:01 PM
#11
It's not uncommon for people to think that a header install caused them to "loose" power. First, a tune will certainly help. Second, headers usually move the power band. You may have lost a little power down low, but you picked up a boat load of power in the mid and upper ranges.
12-14-2007, 09:20 PM
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well dont know if it helps but with the misfire on the dyno i put down 260 hp with headers..... if it moved the power to the top and mid range then how come i stop moving like at 50 mph the push stops......i know i lost power cuz on the freeway a shitty 5.0 took off on me at about 60 and i couldnt make it up.......it used to be before id still have some kick left up top........ somethings wrong...... i heard backpressure might be an issue anyone? oh and anyone know about that smog pump thing its supposed to be hooked up right? anyone help!!!!!!!!!!!!!!
12-14-2007, 10:24 PM
#18
well dont know if it helps but with the misfire on the dyno i put down 260 hp with headers..... if it moved the power to the top and mid range then how come i stop moving like at 50 mph the push stops......i know i lost power cuz on the freeway a shitty 5.0 took off on me at about 60 and i couldnt make it up.......it used to be before id still have some kick left up top........ somethings wrong...... i heard backpressure might be an issue anyone? oh and anyone know about that smog pump thing its supposed to be hooked up right? anyone help!!!!!!!!!!!!!!
Something is wrong with your car. Stop driving it, take it to a shop.
12-15-2007, 12:36 AM
#19
you didn't lose power down low, you gained power up in the mid to top range.
I dynoed my car after headers and true duals and found I went from 306HP to 344HP and from 325ft/lb to 352ft/lb.
After the tune I went up to 349HP and 359ft/lb.
The only reason the "down low" felt weaker is because it didn't change much if at all but the upper goes up. It's one of those perspective things. The torque curve jumps up quite a bit and will gain a true peak. Before my headers, I had a dead flat torque curve ~15ft/lb difference between 4k rpm and 2500rpm... After headers, I had a new torque spike of 359ft/lb from 4000-5000rpm. It became my sweet spot (below and above was in the 340ft/lb range, but you could FEEL that 4k spike...
If you have a 6 speed think of it this way, if you lost power down low, you'd have a hard time accelerating in 6th under 2krpm, or at least it'd be significant enough to make it lug around. In fact, I found that I could accelerate a bit better in 6th under 2krpm (if you can still overtake a car at highway speeds using cruise control in 6th then you can be sure you didn't lose any power).
I dynoed my car after headers and true duals and found I went from 306HP to 344HP and from 325ft/lb to 352ft/lb.
After the tune I went up to 349HP and 359ft/lb.
The only reason the "down low" felt weaker is because it didn't change much if at all but the upper goes up. It's one of those perspective things. The torque curve jumps up quite a bit and will gain a true peak. Before my headers, I had a dead flat torque curve ~15ft/lb difference between 4k rpm and 2500rpm... After headers, I had a new torque spike of 359ft/lb from 4000-5000rpm. It became my sweet spot (below and above was in the 340ft/lb range, but you could FEEL that 4k spike...
If you have a 6 speed think of it this way, if you lost power down low, you'd have a hard time accelerating in 6th under 2krpm, or at least it'd be significant enough to make it lug around. In fact, I found that I could accelerate a bit better in 6th under 2krpm (if you can still overtake a car at highway speeds using cruise control in 6th then you can be sure you didn't lose any power).
