Converter locked gained me almost .2 at that power level.

never got to lock the converter with the bigger turbo, the gains would have been immense imo

 

I'm not sure how much more gains I could get out of my truck. My goal was 10's and I did it the 1st time out with any real track time. I was extremely happy to do it in as few of passes as I did. I got to give a big thanks to Mario over a CPR for helping me out with my burnouts and getting me going in the right direction. Things that probably could have been better are:

Right now the truck has some sort of leak and makes a awful screeching sound under full boost.

I didn't do any adjustments on the the traction bars or front coilovers to get it to do a 1.577 60' on one pass. All that I messed with was my 2 step but once I started getting my burnouts right I never did over power the tires so I'm sure there is room for improvement there

There was a pretty good head wind that day.

My ethanol content could have been higher in my gas but I didn't know there was going to be a track rental until the day before and I had tank full of 91. I did what I could to get the ethanol up but it could have been better.

Also I can't explain why my truck was having a better mph with my cutout closed compared to open. My last 5 passes were all in the 10's but the 1st was at 128mph with the cutout closed. The next 3 I did with the cutout open and my mph kept getting slower 125, 123, and then 119. Last pass I closed the cutout and jumped back up to 127mph.

 

Probably making more power down low with cut out closed. You more than likely were spinning your tires in the first 60' and got your wheel speed up which will equal higher mph. Id bet you loose just enough down low with the cutout open to keep wheel spin down, thus hooking up better and making up for loss of mph.

 

Those slips are very peculiar. I really wouldn't expect that much difference in trap speed based on the 60'

How are your AFRs with the cutout open? I'm wondering if it's just going quite lean due to the extra flow and getting any knock retard?

 

It was hooking really well, I don't think that's it.

I looked at the AFRs a few times and the times I looked it was between 10.5-11:1 so I don't think it went lean but I wasn't watching that closely. My wideband display is supposed to be able to pull logs, I should probably start to take advantage of that feature.

I was wondering if the sound of the exhaust dumping under the truck bouncing off the ground could set off the knock sensors. When the cutout is open I can really feel it in the whole cab of the truck and it seems to run rougher under all conditions with the cutout open. I used to think it was all in my head but after seeing the timeslips I beginning to think it doesn't like the cutout open for some reason.

 

Great run!

 

The timing getting pulled from knock sensors from vibration or something tapping frame with cutouts open plausble but with headers and cam wouldnt those be desensitzed already, kr in your logs would be an easy way to tell.

Or my guess probably making more power (or should be i guess is the issue) with cutouts open and you need more fuel, which should net more hp/mph, and you are running lean,


Or maybe your combination is past the limit of resolution by ecu or calibration. Your truck has; 2bar boost, 3 diff fuels, unkown alcohol content, decent hp, fuel setup maxed, slicks (wheel speed), cam, and finally with cutouts open/closed can be just enough that pushes you over the edge. Thats probably a long shot but you do have a lot going on and not in heavily charted waters with these di motors

either way this is a problem datalogging could help identify, would be curious to look at them if you had them from your runs. Cpi pretty well known, worked on a tbss snail recently on tbssowner actually, and is probably already looked at your logs and adjusted.

 

Nice runs! Truck is definitely making some power! Just for reference, my truck might be a little heavier but at 16psi on my 408 I am managing a high 10 with some wheel spin off the line. So your setup is definitely working well!

^^ This! Something is going on. How restrictive is your exhaust? I tried unhooking my exhaust at my downpipe with really no changes in my track times. I am running a 4" exhaust with a straight through muffler. Really need to start doing some extra logging at these power levels.

Not a DI motor unless I missed something?