C7 A8 Dyno power output difference 4th vs 5th gear

[turabo87]

Finalized a C7 A8 with bolt ons (H / C / I), flex fuel, Stage 2 Comp Cam and a Circle D high stall. Was wondering if anyone that has dynoed C7's A8 before has experienced different power output between 4th and 5th gear pulls on dyno. Fueling, timing delivered, throttle %, was consistent between pulls (no timing pulled, no KR, no TQ management advance, full throttle 91%open....on either gear), yet for whatever (apparently mechanical) reason 5th gear made about 25 less WHP than 4th gear. Made 528WHP in 4th consistently, yet on 5th gear pulls made around 503WHP. TCC was also commanded to stay on 4th and 5th gear. Don't know if it's a common thing on A8's.

[1scls1z]

Finalized a C7 A8 with bolt ons (H / C / I), flex fuel, Stage 2 Comp Cam and a Circle D high stall. Was wondering if anyone that has dynoed C7's A8 before has experienced different power output between 4th and 5th gear pulls on dyno. Fueling, timing delivered, throttle %, was consistent between pulls (no timing pulled, no KR, no TQ management advance, full throttle 91%open....on either gear), yet for whatever (apparently mechanical) reason 5th gear made about 25 less WHP than 4th gear. Made 528WHP in 4th consistently, yet on 5th gear pulls made around 503WHP. TCC was also commanded to stay on 4th and 5th gear. Don't know if it's a common thing on A8's.

That seems backwards...cars usually make the most power on a dyno the closer you get to the 1:1 gear. 1:1 on a A8 is 6th gear. So you should of made more power in 5th gear.

[Alvin]

This is normal. The car isn't making more or less power.. The dyno will read differently when the car is pulled in different gears. Every car is like this.

[sevinn]

What kind of tire?

[turabo87]

Toyo Proxes R888. Tires ran at different PSI and read same in dyno. We actually found a slight problem during street testing and fixed a slight power dip: I saw some TCC slip at higher load and RPM. I increased TCC pressure further and fixed issue, which was perceived as a small RPM dip during a 5th gear pull up top around 6700RPM. Now it makes sense why I saw a slight power dip on dyno graph too on 4th.

[sevinn]

Toyo Proxes R888. Tires ran at different PSI and read same in dyno. We actually found a slight problem during street testing and fixed a slight power dip: I saw some TCC slip at higher load and RPM. I increased TCC pressure further and fixed issue, which was perceived as a small RPM dip during a 5th gear pull up top around 6700RPM. Now it makes sense why I saw a slight power dip on dyno graph too on 4th.

Only reason I ask is because a drag radial can start eating power on the dyno when it's trying to grow. Your results do seem a little opposite of what i'm used to seeing but happy to hear you found that little issue as well.