i went to atco about a month ago when it was 85 outside, i trapped a 119.7mph.. i go back tonight and trap a 113-115mph

same boost level, same 60ft, same everything? just colder out

i noticed after my 2nd run. i was in 4th gear at 7,800rpm @ 115mph hitting fuel cut threw the line. im on stock gears and exedy twin any know why that might happen. and the cluch is not slipping. last time i went i was at 7200-7300 at 115mph i belive help

found the problem! My spark plugs were bad

 

Differnt size tires and/or wheels case closed. lol.

Thats the only thing that will make the speed vs rpm change in the same gear besides actualy changing the gears in the tranny.

 

tires n wheels are the exact same

 

Did you do a boost leak test, just to verify your all set there?

With cooler air, your car *should* make more power. Did you log the runs at all?


-Bink

 

....There HAS to be something different...you don't lose mph for no reason. Look at all the Data you have...what was you MPH through the 1/8th? were on the track did you car start to slow down?

 

yes i did logs are fine

 

nope it felt strong the whole way

 

Clutch might be slipping at high Rpm.

 

ehh lets hope not. doesnt seem like it but that could be.. clutch was broken in correctly, and only has 5k on it with 14 launches about

 

If you havent changed anything, your rpms are higher through the traps, & your trap speeds are down, the only thing is could possibly be is your clutch is slipping in 4th gear.

 

This is the only 2 things that will make the speed vs rpm & gear change. If the clutch is working properly. So time for a new clutch.

side note: if the tires were new the first time and now are worn out it might change the speed vs gear & rpm change slightly but were talking maybe 1-2mph differnce and lots of lost rubber.

 

MPH before in the 1/8th was 92.3 MPH 1/4 119.7 MPH
MPH last night in the 1/8th was 89.1 MPH 1/4 115.2 MPH

 

Ok so you lost over 3 mph on the 1/8... It could be driving or the power is def down...

 

Was it a back to back run?If so the clutch might be getting too hot.

 

i really dont think it was the cluch