Power log -- getting some knock, need help

[TurboCajun]

after recently putting a new cartridge on turbo and fixing the exhaust leaks I have gone from 24psi to 29 psi of boost. the car is running good but after data logging I noticed so knock, on the log I made two hits the first one the boost stayed at about 24-25 psi and no knock, I was not at full throttle, second hit at full throttle the boost was at 28-29psi and showed some knock, to me everything looks OK on the fuel readings etc. I was wondering could it be that I am loosing spark.
1) should I back off on timing
2) should I back off on boost
3) should I change gap on plugs


Any help appreciated
Thanks

[TurboCajun]

After looking at the log again I may just need to add more fuel

[Scoobum]

02's are at 760 at the end of that run at 26 PSI. Add high gear fuel or throw alky at it and the KR should go away over 25 PSI.

Don't add high gear timing. Eric knows what he's doing...and you're gain will be minimal. Boost trumps high gear timing. The heavy hitters aren't using much (timing).

If you're running 5.7 you'll have to be on your game in regards to fuel/temp/humidity. Scoob makes it look easy.

[TurboCajun]

my plan was not to add timing but take some away and get it closer to 18 degrees, I really like the feel of the 29 psi just kinda scared of the KR, but I am still at 128 setting on fuel (70 percent) duty cycle on that log. so I have room to add which makes me think that I can add enough to go the 1/4 mile at around 125mph.
Thanks for the help Scoob

[Steve Wood]

sounds right to me

[Scoobum]

my plan was not to add timing but take some away and get it closer to 18 degrees, I really like the feel of the 29 psi just kinda scared of the KR, but I am still at 128 setting on fuel (70 percent) duty cycle on that log. so I have room to add which makes me think that I can add enough to go the 1/4 mile at around 125mph.
Thanks for the help Scoob

Keith...when you hit the track...run it out to the 1/8th mile...and get out of it. Save the file and go back and look at it. Make your fueling adjustment...a nd go back out and run it out to the 1000 foot mark...and get out of it...and save the file. Make your fuel adjustment...a nd go back out and run it out the full 1/4. Try and keep the high gear 02's at 780 for each run. If you feel it's a tad rich on the 1/4 mile blast then pull a little fuel or alky. Scoobs tip of the day. Sneak up on the tune.

Go out and buy yourself a cheapass digital thermometer/barometer...and jot down the temp/humidity for each run. If the temp or humidity drops, I promise you the 02's will lean out. Throw fuel or alky at it.


On a side note, I've seen my car pick up as much as 2.5 tenths on a 15 percent humidity drop. Watch your head gaskets boys and girls.

[wmsonta]

"Make your fueling adjustment...a nd go"
http://airdensityonline.com/tracks/

We have used a cell phone to get air density, grains, etc, for 3 seasons. I recommend it. Scoob is correct, however everything I post is NA.

I help an ET racer who runs 6.53 in 1000' air, but 6.75 in 3200'. Quarter mile changes would be dramatic.

HTH.

[TexasT]

watch the temperature and humidity for you boosted fellows. HG changes or worse ain't no fun.

[wmsonta]

watch the temperature and humidity for you boosted fellows. HG changes or worse ain't no fun.

All that and more is available from the website I posted above. In real time, including right now w/closed track. At your individual track, if listed. Most are listed.

An incredible tool for ET racers, where a lot of races come down to hundreds of a second and conditions can change in minutes.

[Scoobum]

watch the temperature and humidity for you boosted fellows. HG changes or worse ain't no fun.

All that and more is available from the website I posted above. In real time, including right now w/closed track. At your individual track, if listed. Most are listed.

An incredible tool for ET racers, where a lot of races come down to hundreds of a second and conditions can change in minutes.

I bracket race my GN. Keeping it on a dial is a handful with temp/humidity changes. The NA guys have an easier time of it as their ET's don't fluctuate anywhere near as my boosted application. I'm constantly having to change the dial from round to round...or add or subtract high gear fuel to keep it on its dial. I park beside two Superpro teams...and they keep me posted with their weather stations. Thanks for the link.

[wmsonta]

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[TurboCajun]

Thanks Guys
I am not a comp racer I just go to the track to get times for myself. I do a lot of testing on a good road near home, most of it is 3rd gear hits that way when I get to the track all I have to worry about is the beginning of the run and the end. most of the time I am just making adjustments to 1st and 2nd gear fueling, the rest is usually safe at 760 @ 18 degrees with no Knock. My concern here was because of the higher boost psi would I have to worry about spark blowout, but I will add some fuel at WOT and see if that gets rid of the knock and if it does I should be OK.

[Steve Wood]

I think you will need a A/F ratio around 10.8 which is probably what you will have when the O2s are around 780-790

We are all bored so we like to make it complicated some days LOL