Low end power is gone
11-11-2008, 08:20 PM
#41
ive never heard anything like that on this board...you have to have a muffler for low end...i run with my cutout open all the time and there isnt much of a difference with it closed...i would suggest running it at the track and checking the times or find a buddy and gauge off where his car is at or something to see if its all in your head before you go changing exhaust setups again...
11-11-2008, 09:25 PM
#42
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velocity. Back pressure is a good thing as long as it is not over restricting. Search around and see where people have said that they gained low end power by getting rid of true duals. Its all about finding a balance.
11-13-2008, 12:09 AM
#43
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I noticed you ported the throttle body. Did you grind the bumpstop as well? Go too far and you're going to throw codes. Well, maybe not since your light isn't coming on.
After my header swap my car started running rich as hell and my times never picked up until my last track outing. Perfect prep and weather had more to do with it than anything. I'm only 3 tenths and 1 mph better than when I was stock. Was it tuned before or after the header swap? Your numbers seem fine, so maybe it's all in your head. Take it to the track!
After my header swap my car started running rich as hell and my times never picked up until my last track outing. Perfect prep and weather had more to do with it than anything. I'm only 3 tenths and 1 mph better than when I was stock. Was it tuned before or after the header swap? Your numbers seem fine, so maybe it's all in your head. Take it to the track!
Last edited by RaggedRides; 11-13-2008 at 12:14 AM.
11-14-2008, 07:39 AM
#46
I've got a few dyno sheets that prove otherwise that you loose low end torque.
When I did full exhaust I shot up in torque from 325ft/lb to 359ft/lb. That gain wasn't just at peak, it was across the whole torque curve. dyno started at just above 2000rpm. Now I'd be hard pressed to believe that considering the whole torque curve shifted up 20 ft/lb + that below 2000 there could have been more torque before the headers.
What you are feeling is that dramatic change in the torque curve, prior to the headers, my torque curve was FLAT, like 2500 and 4000 were separated <10ft/lb of torque. You don't feel that. With headers in, you now have a sweet spot for torque which if you can keep your eye on the tach will represent itself as a part in the throttle where its climbing, climbing then SPIKING, or at the very least shows itself more than normal. With that in mind, your low end feels like ***.
When I did full exhaust I shot up in torque from 325ft/lb to 359ft/lb. That gain wasn't just at peak, it was across the whole torque curve. dyno started at just above 2000rpm. Now I'd be hard pressed to believe that considering the whole torque curve shifted up 20 ft/lb + that below 2000 there could have been more torque before the headers.
What you are feeling is that dramatic change in the torque curve, prior to the headers, my torque curve was FLAT, like 2500 and 4000 were separated <10ft/lb of torque. You don't feel that. With headers in, you now have a sweet spot for torque which if you can keep your eye on the tach will represent itself as a part in the throttle where its climbing, climbing then SPIKING, or at the very least shows itself more than normal. With that in mind, your low end feels like ***.
11-14-2008, 02:57 PM
#47
I've got a few dyno sheets that prove otherwise that you loose low end torque.
When I did full exhaust I shot up in torque from 325ft/lb to 359ft/lb. That gain wasn't just at peak, it was across the whole torque curve. dyno started at just above 2000rpm. Now I'd be hard pressed to believe that considering the whole torque curve shifted up 20 ft/lb + that below 2000 there could have been more torque before the headers.
What you are feeling is that dramatic change in the torque curve, prior to the headers, my torque curve was FLAT, like 2500 and 4000 were separated <10ft/lb of torque. You don't feel that. With headers in, you now have a sweet spot for torque which if you can keep your eye on the tach will represent itself as a part in the throttle where its climbing, climbing then SPIKING, or at the very least shows itself more than normal. With that in mind, your low end feels like ***.
When I did full exhaust I shot up in torque from 325ft/lb to 359ft/lb. That gain wasn't just at peak, it was across the whole torque curve. dyno started at just above 2000rpm. Now I'd be hard pressed to believe that considering the whole torque curve shifted up 20 ft/lb + that below 2000 there could have been more torque before the headers.
What you are feeling is that dramatic change in the torque curve, prior to the headers, my torque curve was FLAT, like 2500 and 4000 were separated <10ft/lb of torque. You don't feel that. With headers in, you now have a sweet spot for torque which if you can keep your eye on the tach will represent itself as a part in the throttle where its climbing, climbing then SPIKING, or at the very least shows itself more than normal. With that in mind, your low end feels like ***.
Right
In oversimplified terms:
Backpressure = negative cylinder pressure = loss of intake scavenging charge = less cylinder fill = less power everywhere.
11-14-2008, 03:22 PM
#48
I've got a few dyno sheets that prove otherwise that you loose low end torque.
When I did full exhaust I shot up in torque from 325ft/lb to 359ft/lb. That gain wasn't just at peak, it was across the whole torque curve. dyno started at just above 2000rpm. Now I'd be hard pressed to believe that considering the whole torque curve shifted up 20 ft/lb + that below 2000 there could have been more torque before the headers.
What you are feeling is that dramatic change in the torque curve, prior to the headers, my torque curve was FLAT, like 2500 and 4000 were separated <10ft/lb of torque. You don't feel that. With headers in, you now have a sweet spot for torque which if you can keep your eye on the tach will represent itself as a part in the throttle where its climbing, climbing then SPIKING, or at the very least shows itself more than normal. With that in mind, your low end feels like ***.
When I did full exhaust I shot up in torque from 325ft/lb to 359ft/lb. That gain wasn't just at peak, it was across the whole torque curve. dyno started at just above 2000rpm. Now I'd be hard pressed to believe that considering the whole torque curve shifted up 20 ft/lb + that below 2000 there could have been more torque before the headers.
What you are feeling is that dramatic change in the torque curve, prior to the headers, my torque curve was FLAT, like 2500 and 4000 were separated <10ft/lb of torque. You don't feel that. With headers in, you now have a sweet spot for torque which if you can keep your eye on the tach will represent itself as a part in the throttle where its climbing, climbing then SPIKING, or at the very least shows itself more than normal. With that in mind, your low end feels like ***.
