I’ve mentioned this in several threads recently, but since going to APR stage 2 and making two trips to the drag strip, I was pretty disappointed in my times. I made another trip tonight, and did some additional testing/logging. It’s not really apples to apples, but I have some ideas as to what is going on. A big thanks to Ron (Primetime) for getting me sorted out on the logging.
This will be a long post, but here are the cliff notes:
- My car is not the fastest car…
- The heat here in DFW is definitely effecting my times. Temp have been over 80 degrees, and DA has pretty consistently been between 2400-3200 on all my passes.
- The stock intake sucks balls. On most of my cars in the past, I have found the stock box to work pretty well, but I don’t think that is the case here.
- I am probably not the best drag racer as this is only my third trip all in the last 6 weeks or so.
The long version…
The last two times at the track, my car pretty consistently ran in the low 13 range at 105-106 MPH. My best time was a 13.06@106. Most times were more like 13.3@105. The times were about the same with or without launch control (1.9 60’). All runs were on 93 from two different stations. DA was 2400-3200 (interestingly, my fastest time was at 3200). Unfortunately, I did not log any of these runs.
After the above disappointing times, I did a lot of logging. Our findings were:
-The Air Mass was pretty low, IAT’s were not great, and boost was pretty low (14 PSI in most cases). I think Ron thought a lot of this had to do with the stock intake box. I am running the APR tube, and AWE filter.
-The car was also showing misfires on cylinders 2 and 4 in some cases, but not usually during high RPM runs. It seemed pretty random. The general consensus is that this is not a huge problem, but we’ll see…
-Max timing was in the 16 degree range, but we were seeing timing pulled up to 7+ degrees in some cases. This got a little better with different gas. I think the high temps here probably have something to do with it. Most logging took place at around 80 degree with a DA over 2000.
-No faults or other obvious issues.
I went to the track again tonight and made 10 passes. I had a mix of 93 and some Torco Accelerator for what should have been around 101 octane. I had mixed results when I logged with this mix last night, but I as down to 25 miles left when I got to the track and decided to make a pass with it. The results were awful. 13.5@103 (on my 100 map). I then filled up with 104 octane race gas. First 3 passes were not much better. 13.3-13.4 @ 104. Very disappointing. The car was also hanging on the 2-3 shift every time (without LC).
At this point I was going to try some other things. I pulled the stock intake funnels (leaving the box obviously), and interestingly my times dramatically improved (and I was hot lapping at this point with only a few minutes between runs). First run I went to 13.0 @109 without LC and had the 2-3 hang up. My next runs got better and better all the way down to 12.69 @111.58 MPH with launch control. I could have been the car adapting to the 104 race gas better, but air mass went up dramatically with only a slight increase in IAT’s. The only way I could get the car not to bog on the 2-3 shift was with launch control. The 3 runs I used LC were the only sub 13 second runs. Not sure what is going on as the last two times out my car only did this once on 15 or so passes (were I used LC half the time, and smash and go the other half).
So what to think at this point?
-The stock intake is a out. I have the CTS intake (Roc-Euro clone), but they have not been able to provide the right hardware to mount the heat shield. They sent me stuff that showed up today, but it’s still not right. I really want to send it back, but I am going to retap the mounting holes to make it work this weekend (they are going to refund me $100 for the trouble). I just ran out of time today before I had to leave for the track.
-I need to figure out what is going on with my AWE downpipes. The resonators were blown once before, and the car felt a tad slower. I have only had them back on for a few months, and it sounds like one is blown again. This could be effecting my power slightly.
-I am going to keep running the gas from this latest Texaco I am using. The timing pull is lower than what I have seen for the Chevron and Shell I had been using.
-Hope for some cooler temps, and keep logging to figure out why I am seeing the lower boost and higher than normal timing pull. Hopefully the intake helps here…
-Hope this 2-3 hang up goes away. I really had only seen this a few times before tonight. If it does not go away, I’ll try the APR DSG tune when it comes out. I tried my other maps to see if it was something with the 100 map, but it still hung up when I did not use launch control, and my times were obviously slightly slower.
-The car got faster and faster as the DA went down. I hot lapped 6 passes between 11pm and midnight when the track cleared out, and got faster on each one when I used LC. This tells me that having a CPS is not killing me at the strip (that was APR’s only suggestion when I talked to them).
-Overall, my car may be a tad slow, but the APR tune/maps seem to be doing what they are supposed to. I have never seen any bypass, and requested boost is where it should be- the car is just not making it. When I tested 93–>91–>stock maps tonight, the car got slower MPH each time. The only tall tell sign in the logs is lower timing on each, and then obviously some bypass on the stock map.