I didn't want to post anything until I had a chance to go back to the same track on a day with a similar DA for accuracy.

Back in May I ran a 12.30 at 111 (most traps for me were 110 that day). In order to achieve that I had to short shift due to having an A/F of 14.* at WOT at around 5k RPM's.

Anyway, a month or so after that I installed the SL55 AMG fuel pump and noticed a substantially different A/F. I didn't want to jump the gun and announce anything at the time, as I wanted to be sure the richer condition wasn't a result of a boost leak.

After switching back to the stock manifold gaskets and finally see full boost (20+, my gauge maxes out at 20) I went to the track today to see what it could do. Traction was a bit of a challenge, so my ET's aren't much different that before. However, 12.3's and 12.4's today were obtained with a significantly slower 60' of 2-2.1's instead of the 1.8's I was seeing last time.

The real indicator to me is the change in my trap speed and A/F ratio. Today I was trapping 115-116 with a head-wind and 10.* A/F ratio. I was running pig rich fighting the wind and still trapped 5-6 MPH faster than when I was running lean.

In summary, adding the SL55 AMG fuel pump increased my trap speed and lowered my A/F from 14's to 10's. I think it's pretty clear it works.

 

Which pulley do you have now? A 181?

 

Yes, I'm running a 181.

 

you will need more than a set of Hoosiers...been there done that...my 12.2 was with the summer tires on the roadster...my Hoosiers netted a 12.3... Got to be able to launch those big Hoosiers...good luck man chasing those 11's...we all want to get there..

 

Thats great! Im glad it worked!!

 

Clear your long term fuel trims and run it again!

 

Doc, 255/50/16 Hoosier tires along with my 13lb CLK wheels would be much lighter than the stock 19" combo.


Thanks Jimmy.


Tuna, I don't follow what you're getting at.

 

this is an interesting alternative pump. might just try it and see if its as good as the 55 pump
Racetronix - WSP330 - In-line Screw Pump 330LPH, High-Pressure

 

What I meant was you should clear your LTFTs and run your car WOT to see how much they are changing your tune. You are already running very rich so I would bet you're adding a bunch fuel in closed loop. That is applied on top of your tune.

 

That will make a difference. I have 18", but rims are just as light...good luck...

 

doc your 18's weigh 13lbs? what are they?

 

Very nice! You should be 11.7, 11.8 just like what my car has done with that 116 mph. Glad you got her running the way she ought to. Can't wait to see sticky tires on her. Congrats! Cooler weather finally coming my way this coming weekend. My best this past weekend was only a 12.0 @ 114.

 

Actually, I expect the trap speed to drop by 1-2 MPH once I get traction, since I will be accelerating for less time (lower ET). Hopefully leaning out the A/F and running without a headwind will make up for getting traction and keep my trap speed up.

I plan on running with Steve down in Alabama in a few weeks, so hopefully a bit of negative DA will get me a little closer to 11's.

Good luck this weekend if you run.

 

Essentially the same pump

 

One question, okay there may be additional questions but one to start .

Is your A/F ratio 10.* throughout the RPM range, to redline I should say?

 

I don't have a Dashdaq or Scanxl pro, so I can't dagalog RPM and A/F together. As a result, I can't really say for certain since I don't have hard data to back it up.

The A/F seems to range from very low 11's (lower RPM's) to low 10's at redline. I'm going to lean it out 1 point across the board and call it a day. That will have the A/F in the 12's down low and 11's at redline, which is exactly what I want.

 

Something I noticed from looking at your timeslip was that you hit 93MPH in the 1/8th when you also hit 116 in the 1/4.

On my first two runs I hit 115 and 116 in the 1/4 with and 1/8th of 90mph. However, on the next run I turned on the TC and hit 93 mph in the 1/8th also, as well as 116 in the 1/4.

Strange, but the TC got me 3mph more in the 1/8th if that's even possible.

 

You need to look at your fuel trims bro....................

 

I'll take a look this weekend.

 

tunaglove edumacate me! i have a dashdaq and zt-2 setup for datalogging. how do i log the fuel trims and what shuld i be looking for?