Hitting a wall...


Jul 9, 2002

Trying to figure out why I can't go any faster and/or Increase Boost or Timing, my Combo is in my sig., now the Problem that I'm having is that ANYTHING After 22-23#'s of boost and 23/21 timing I get Knock. My O2's are at 790-800 at the TOP of Third, and I've VERIFIED Fuel Delivery at 68-70PSI during my passes. All passes are Smooth, and pull decent, and I always Gain ~22.5 - 23mph from 1/8th to 1/4. My Initial is set at the 12:00 position, and my Controller is on 8. I use ONLY 93 Octane, and My fuel is at 142 overall(+10.9%), if I Increase the fuel my o2 numbers go Up and I SLOW DOWN, if I increase the Initial and up the Alc., it floods it with Alc., and I slow down. I HAVE tried backing OFF the Alc., and UPPING the Fuel, but that just seems to get me More Knock, so I am Apparently STUCK at this 22-23# and 23/21 timing Threshold. This is with a Turbotweak chip for a Stock Turbo, but the Turbo is the One and Only change I've made to my Combo, still have the Bone Stock Downpipe and Intercooler so I thinking I can still use the same chip(just increasing fuel)....I've attached the PL files if anyone wants to take a GANDER, on the PL Files where you see the KNOCK is where I TRIED to Increase the Boost! All the Temps during these passes were in the Low 50's, and the track is at Sea level, Ethanol is Fresh VP...
Arrrgg Aparantly you can't attach PL Files!! Anyhow, here are my Timeslips..
the ones on the bottom..
what about backing off the fuel and adding alky? It the o2 sensor fresh? My o2's drop to 750's but 0 knock. Just guessing....
still have the Bone Stock Downpipe and Intercooler so I thinking I can still use the same chip(just increasing fuel)....

maybe the downpipe and exhuast are your limiting factors. You need to un-cork the motor and reduce any chance of back pressure.

Its like this, if you substituted race gas in place of pump gas.. you could further play with the alky and reduce its amount. Typically for 22 PSI, you shouldnt need position 8 unless there is something else going on. Could even be something simple like weak valve springs.

Hope this helps. I'd do valve springs first.. then I would un-cork the downpipe by un-hooking the cat.. try those.
Razor, thanks, we talked last week (I called), and you had mentioned that I was most likely getting to a point where I was just flooding it with Alk, and turning the Initial back down helped a little,...oh, and yes, I finally did valve springs back in January...I'm putting a 3" DP on later in the weak too, and I'll do some more testing then...the Right way too..Sooo much easier just doing the Rolling 3rd gear Test:)

btw, still would be nice if I was able to post PL files....the board here won't let you attach a .DAT file...

This week I put on a New 3" DP and TP, to replace the Stock DP and 2.5" TP, what a Difference! and I was able to turn the Alch DOWN, and the Boost UP...Previously I had the Controller up at 8.2, and as I said previously could only go as high as 23Lbs before getting knock..so NOW I'm down to 6.9 on the Controller and up to 24-25Lbs...tried even going Lower but then the Knock starts creeping in.......Also spoke to Eric at Turbotweak, and he's going to make me a New Chip for the Bigger Turbo, DP, and Upcoming Cotton's FM...Then Hopefully I can Bump up the Timing as well..currently at 23/21.....
Rock on! Your 12.30/12.40 runs look spot on, just a hint of knock as if it's false... Can't wait to review your upgrades!

Rock on! Your 12.30/12.40 runs look spot on, just a hint of knock as if it's false... Can't wait to review your upgrades! Thanks,

Thanks, but thats For Sure not false, as when I turned the boost Down slightly ALL knock was gone...but now, but Eliminating the exhaust Bottleneck, it's MUCH better, we'll know next Saturday on the next Track outing....
Update Update

Guy's, went Back to the Track last night got my Four Runs in, ...Went from a Previous best (above) of 111.2mph, to Todays 113.24 MPH, the ONLY difference being a 3.5 inch DP replacing the Stocker(thanks for your Help Pauly), and a TT Chip modded for my New Turbo..Here's the Skinny:

Basically left at idle to chk my boost, which was a Rock Steady 24PSI

Next Pass(round robin):






VERY little knock, just @1.5 at the 95mph lock up point..still have my Bone Stock intercooler on there, and the Weather was Hot & Soupy, so Needless to say I was More than happy with That, so Apparantly the DP was worth ~2.5 - 3mph, especially Considering the Much warmer & More Humid Air!!

So it looks like the Key here was the TT Chip-Number 1, and the DP surely helped too..Next Up - A Precision Stock location.....then well see how I do at the July 31st Ohio Event...:smile:
Get some slicks, it will run high 11's first passout. All you need is to leave with a little boost 4-6 PSI.