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turbov6joe

Signal 1 J-12
Joined
May 22, 2002
Messages
2,220
Switched from a Nitto DR (245/50/16) to a MT Street ET (26/11.5/16) and dropped 3 MPH in the 1/8, and 3-5 MPH in the 1/4.....does this seem normal? The state of tune of the car was the same as two weeks ago when it ran 118 MPH compared to last night's best 113 MPH. Any thoughts???
 
Was the weather about the same? Temperature? head wind?

what was the difference in short times? If you hook better at the line, mph may drop but ET will be better
 
Temp was about 22º warmer, humidity was lower, short times were 1.86 versus 1.98...nothing significant there, no headwinds, all other variables as close to the previous weeks as possible. What I think it boils down to now that I've had time to talk to folks and mull upon it, is that the car was running fat due to the heat (86º) and I couldn't get the EGT over 1450º to 1600º where it likes to sit, I couldn't get a launch much over 5 psi due to an overly rich A/F mixture down low, and a few other things. I'm having Eric Marshall change some programming for me, namely pulling fuel out from down low through the midrange, and also having a few more clicks of adjustment of "leaner" fuel curves programmed into the thumbwheel chip I'm using. I was able to get the EGT up to almost 1600º on some backroads highways passes I made Saturday by cranking the alky speed up a few notches and running 40 psi static FP. I also noticed that by dumping the exhaust, the boost was much more stable...gotta be a restrictive OE exhaust system causing that; soon to be addressed!
 
Operator Error ;) Just kiddin Joe. Fat down low will kill it, and 1450 EGT (Im assuming in 3rd gear) is rich, lean her out some. But of course you know that.
 
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