I have owned my GN since 87. I am still amazed at what these engines will do. I had raced my car this year after leaving it sit for 6 years. First time out, after spring cleaning, I ran in the low 15's. Not good enough for me, of course.
I added a XP pump, adj reg. GNX o2 sensor, got a couple of chips from Armstrong and Thrasher and added some 100 octane gas. Best time now is low 14's. Still not good enough because I am only acheiving about 14 pounds of boost and running on BFG TA's. The 60 foot times never changed. Always 2.2.
I reasoned that perhaps my 160K never been rebuilt engine might be in need of new springs. So I took the car into my trusted mechanic for a set of compcam 980's. He pulled the springs and confirmed the old ones were mush. I had him check the injectors. Sure enough, three were shot. I had him check the header for cracks. Yes, one huge one all the way around. And yet with all of these problems I was still turning 13.9 to 14.1. Amazing, I think.
I am anxious to see what my new set up; springs, new injectors, and welded header will do. Perhaps I will arrive at the end of the 1.4 mile in the 13's range yet?
Norm
These repairs had their impacts. I mad3 4 runs on Friday. 14.09, 13.68, 13.99, and 13.83. All of this improvement comes after 60'. I am still 2.2 which means traction, I think? I am running BFG T/A. I cannot build any boost at the line because the tires slip at about 1 PSI and higher. I am encouraged by the improvement in acceleration after 60'. the MPH as gone from 96 to 101 and I picked up .5 in ET. I need to up the boost a bit. I am getting about 12 PSI out of the turbo using 101 octane and Thrasher 100 chip.
Norm
You definetely can up the boost a bit if you're running 101 octane with a 100 chip.
What PSI are you running in your tires? They may be to low. Are you staying away from the water box? You don't want them wet.
Shawn, I am running 35psi on the tires and no water box. Since day 1 my 60' times have been 2.2. All of the ET that I have gained, 15.1 improved to 13.6 comes after the 60' point. I'd like to get to 1.9 60' which should put me at 13.0 in the 1/4. Norm
Norm
I think the tires are going to be the limiting factor in the 60 ft (and track preparation...)
Sounds like you are definitely going the right direction, and as previously mentioned, you should be able to start working the boost up and continue to gain E.T. (and it'll pretty much be after the 60 foot).