Interesting findings on throttle body spacers
05-18-2012, 08:40 AM
#1
Interesting findings on throttle body spacers CLIFFS AT BOTTOM
My truck came with a 1" Helix aluminum TB on it. It is a 99 5.3 Silverado and is otherwise stock. I have wanted to remove it since I bought the truck almost a year ago but was unmotivated.
It has internal threads which protrude into the intake flow path in hopes of spinning the air or some hoopla.
Upon removing it I was shocked to notice the truck had a noticeable increase in off idle response. You can imagine my shock. I drove through town towards the highway in disbelief.
But once I reached the highway and began accelerating I was able to determine what was up. The transmission didn't respond to throttle the way I am used to. Downshifts required more effort and input. I concluded that the 1" spacer was taking up slack in the throttle cable. I confirmed with a scanner reading TPS % and visually inspecting to see the pedal now had to be buried into the carpet to get WOT (and the TB wasn't even reaching the bumpstop).
To confirm I rigged up a small spacer to take up slack on the pedal. By running the cable through a barrel spacer and washer then crimping the washer so it would prevent the ball retainer on the cable from slipping through, the pedal was raised back towards the driver and the slack was again removed. WOT occurs before the pedal contacts the carpet and the blade reaches the bumpstop fully.
During driving, the off idle response was back and the transmission downshifts were back where I had grown accustomed to them being. During acceleration there was no loss or gain of power on the butt dyno. I can update the thread with highway mileage comparisons after the next long trip I take.
Conclusion: IMO gains of low end associated with TB spacers should be credited to removal of slack from the 1" further spacing of the throttle cable from it's mounting point on the intake. HP gains on a dyno could be due to the vehicle not reaching true WOT without the spacer.
CLIFF NOTES: Removed a tb spacer from a 5.3 truck and throttle response seemed to be hurt, further inspection revealed this was due to the pedal having extra slack in travel and not reaching WOT as easily (if at all). Once the slack was removed from the cable, throttle response was back with no noticeable loss of power anywhere in the curve.
My truck came with a 1" Helix aluminum TB on it. It is a 99 5.3 Silverado and is otherwise stock. I have wanted to remove it since I bought the truck almost a year ago but was unmotivated.
It has internal threads which protrude into the intake flow path in hopes of spinning the air or some hoopla.
Upon removing it I was shocked to notice the truck had a noticeable increase in off idle response. You can imagine my shock. I drove through town towards the highway in disbelief.
But once I reached the highway and began accelerating I was able to determine what was up. The transmission didn't respond to throttle the way I am used to. Downshifts required more effort and input. I concluded that the 1" spacer was taking up slack in the throttle cable. I confirmed with a scanner reading TPS % and visually inspecting to see the pedal now had to be buried into the carpet to get WOT (and the TB wasn't even reaching the bumpstop).
To confirm I rigged up a small spacer to take up slack on the pedal. By running the cable through a barrel spacer and washer then crimping the washer so it would prevent the ball retainer on the cable from slipping through, the pedal was raised back towards the driver and the slack was again removed. WOT occurs before the pedal contacts the carpet and the blade reaches the bumpstop fully.
During driving, the off idle response was back and the transmission downshifts were back where I had grown accustomed to them being. During acceleration there was no loss or gain of power on the butt dyno. I can update the thread with highway mileage comparisons after the next long trip I take.
Conclusion: IMO gains of low end associated with TB spacers should be credited to removal of slack from the 1" further spacing of the throttle cable from it's mounting point on the intake. HP gains on a dyno could be due to the vehicle not reaching true WOT without the spacer.
CLIFF NOTES: Removed a tb spacer from a 5.3 truck and throttle response seemed to be hurt, further inspection revealed this was due to the pedal having extra slack in travel and not reaching WOT as easily (if at all). Once the slack was removed from the cable, throttle response was back with no noticeable loss of power anywhere in the curve.
