Confused on 1/4 mile speed loss

[gtstangrunner]

Hey I installed a BBK twin 65mm throttle body on my 03 Cobra and the throttle response was alot better and the sotp feels like I made power but I went to the tack and ran a 12.6 at 109mph . Last time out before the throttle I went 12.5 at 115mph. How could I loose 6mph in the 1/4 mile. That seems like alot. The best the car has ever done was a 12.2 at 114mph. I'm realy confused, could I have lost power, do i need a tune or what.

 

[Uncle Meat]

What made you think there would be a performance increase with the BBK over the stock TB? Unless you are running a ported blower and an insane amount of boost I doubt you had even come close to exceeding the stock TB's flow rate.

For the cost of the BBK unit you could have had your stock TB & inlet ported for less money and the flow would have been almost equal.

Was there a substantial difference in the ambient temperature between this run and your previous trip to the track? Temperature has a huge impact on these supercharged cars.

U.M.

 

[SVT98Snake]

what were the track conditions?

What tire pressure were you running?

 

[gtstangrunner]

Its not so much that I was looking for a performance increase my concern is that when you hit a ET thats .1 off and loose 6mph in trap speed tells me I might have lost some horsepower but my reaction time and 60 foot still cut a close ET. Like I said I've run a 12.5 at 115 mph so a 12.6 at 109 doesnt seem right. The conditions were 70 degrees and partly cloudy and the tire pressure was the same as the last time I raced it, its not a daily driver. Do you think my tune is off?????? Also I plan on getting ported and running 14psi soon so th eTB will be better used. By the way anyone want to buy a 75-125 ZEX dry kit with window switches included?? Let me know and make an offer. THanks for the input guys

 

[SVT98Snake]

109 is a 12.6 mph....115 is more of a 12.1-12.4.

A TB will probably require a new tune because the increased airflow will alter your a/f. I don't think that 6 mph though...but anything can happen. I had to get a new tune with my CAI.

Get it retuned and then let us know how it is.