1/4 Mile Performance Question
08-31-2007, 08:19 PM
#1
MBWorld Fanatic!
Thread Starter
1/4 Mile Performance Question
I'm interested in forum's take on this.
2003 SL55. Stock except for: SLR cams, VRP 80 mm TB, VRP airbox, VRP Extreme Belt Wrap, EvoSport headers, Quaife LSD, Nitto NT555R2 track tires (not drag radials). No overdrive pulley. The intercooler pump was replaced under warranty two weeks ago.
On a nice day in Michigan (77 F, humidity about 50%) I just ran a 12.38 with a 110 MPH trap speed.
Drag slip and partial Autoenginuity log attached here: https://mbworld.org/forums/showpost....2&postcount=20.
12.38 is the best I've ever run, by 0.20 seconds. But I've been trapping 109 MPH to 111 MPH all summer long, so no change there. I was hoping that the new intercooler pump and the EBW would lift the trap speed up to 116 MPH, give or take a little.
To me it looks like the IATs are running high in spite of the new intercooler pump (peaking at 172 F) causing the ECU to pull timing (from -16 degrees to -13 degrees).
But what do you guys think?
2003 SL55. Stock except for: SLR cams, VRP 80 mm TB, VRP airbox, VRP Extreme Belt Wrap, EvoSport headers, Quaife LSD, Nitto NT555R2 track tires (not drag radials). No overdrive pulley. The intercooler pump was replaced under warranty two weeks ago.
On a nice day in Michigan (77 F, humidity about 50%) I just ran a 12.38 with a 110 MPH trap speed.
Drag slip and partial Autoenginuity log attached here: https://mbworld.org/forums/showpost....2&postcount=20.
12.38 is the best I've ever run, by 0.20 seconds. But I've been trapping 109 MPH to 111 MPH all summer long, so no change there. I was hoping that the new intercooler pump and the EBW would lift the trap speed up to 116 MPH, give or take a little.
To me it looks like the IATs are running high in spite of the new intercooler pump (peaking at 172 F) causing the ECU to pull timing (from -16 degrees to -13 degrees).
But what do you guys think?
08-31-2007, 10:27 PM
#2
MBWorld Fanatic!
Was the car idle-ling along time in the staging lanes?, where you aggressive in the burn-out box?. Your starting iat's indicate heat soak before the run, a 30+ degree change in iat's through the 1/4 mile under boost is not bad for a stock ic system. The initial iat of 130 + is to high to start off with, unless the car is being hot lapped. imho.
BTW: Nice track they give you 1000ft trap speeds.
BTW: Nice track they give you 1000ft trap speeds.
08-31-2007, 10:36 PM
#3
MBWorld Fanatic!
that's funny..."stock except for all this cool sh*t!!" 
it's not uncommon for a slight decrease in et to net a slight decrease in mph so i wouldn't be too concerned with that particular mph.
with that said, i do believe you have some power still left on the table. iat's are the problem and either your i/c circuit still isn't operating efficiently or that it's not specifically the larger pulley's that are causing the problem as everyone has suspected for so long.
it's not uncommon for a slight decrease in et to net a slight decrease in mph so i wouldn't be too concerned with that particular mph.
with that said, i do believe you have some power still left on the table. iat's are the problem and either your i/c circuit still isn't operating efficiently or that it's not specifically the larger pulley's that are causing the problem as everyone has suspected for so long.
09-01-2007, 01:56 PM
#5
MBWorld Fanatic!
