Knocking now that I have traction

[Black Box]

I finally got around to trying out my Hoosier QTP's this weekend, and tried a few street launches. I never had any serious knock before (less than 2º before the alky kicked in), but I had severe traction problems on Hoosier 275/50D15 QT's). Not anymore. These tires are bad ass.

I can now hold 12 psi on the footbrake without a burnout, on the street. As soon as I let off the brake and nail the throttle, the tires barely even squawk. But as soon as they hook, the car takes off like a shot, but the thing starts knocking audibly. I let off a little until the knock subsided, then got back in it. The Scanmaster shows 5º, at 37 mph. The lowest O2's it recorded are 800mv at 78 mph, so I'm a little confused as to why it's knocking. I didn't hear any knock at 78 mph, and it didn't show anything on the SM during the run at that speed, or any other time except the launch.

I've got SMC single nozzle alky, set to turn on at 11 psi, pump speed at 7. The car only has bolt on mods (009's, TurboTweak chip, Big Mouth CAI, stock MAF, PP, 62/65 JJ TB, 160º stat, Autolite 23's at .032"), stock turbo & IC. Max boost is 22psi, FP is 43psi line off.

The traction is awesome, and I bet at the track with a good burnout I'll be holding 15psi at the line, but it won't do any good if I can't keep the head gaskets in place.

I want to make some adjustments next weekend, but would like to hear any ideas you guys have....too much load on the engine causing knock? I'm thinking that now that I have 28x11.5x15 QTP's on the car (which are actually closer to 28.5" tall), it numerically reduced the gear ratio, thus increasing the load on the engine at low RPM's. Or it could be rich or lean? Sorry I don't have any other data, I'm in a primitive mode right now until I can get my laptop hooked into the car and run WinALDL.

Thanks in advance,
Steve

 

[rob86gn]

that's a respectable 1/4mi time. I'm taking my car to the track possible this weekend for the first time. Set up almost the same only no alcohol inj and no drag tires. I'm hoping for low 13's on 20lbs.

I don't know why your car is knocking though. Unless fuel is bad or it's hot. That's the only thing I could think of. What is the timing programmed in the chip? Mine is only 20 deg adv on 93 octane.

 

[Black Box]

Rob,
Thanks, I was happy with the time, but it definitely has more in it. I'm shooting for 12.50's or better. Got a different converter in it now (2800 stall) and a rebuilt trans. With these tires, I should get a good launch. I was surprised that I could hold 12lbs, since I only have the big brake shoes on the rear (stock wheel cylinders), and could barely hold 5psi with the old tires.

I can rule out the heat, since it was around 75º when I was running it, and probably the gas too since my friend's '68 Camaro was running strong, and we filled up at the same station, same 93 octane gas. Thanks for the suggestions though.

I've got a TurboTweak chip, variable timing (alky chip).

Good luck at the track!

Steve

 

[Chris Schneider]

my car does the same knock at the track when the car hooks up for the first 60-100 ft,the gauge is red,but the scanmaster recalls 0.0 knock retard(turbotweak chip),I'm thinking its false knock through the drivetrain.

 

[JDSfastGN]

i would agree that its false knock from the hard launch. you can get Eric to put an ignore on knock under a certain speed.. something i meant to ask for but forgot. Its hard to put the car under a big enough load in 1st gear to create actual dangerous knock espcially with your 02s imo. Does it knock at all in a good 3rd gear pull?

 

[Black Box]

Nope, no knock once it's rolling. 2nd and 3rd gear are knock-free. It's just off the line when I got the pingpapingpingping (which led me to think it wasn't false knock).

I wonder what's causing the false knock through the drivetrain? I have an engine tie-down (poly mount coming this winter). Maybe I'll check the trans mount to see if it's shot.

Thanks for the help guys. Much appreciated.

Steve

 

[QUIP'6']

my car does the samething going up a hill in first and nailing it it will knock to where you can hear it then it quits i dont know if it has something to do with fuel enhancement my o2's are 800 in all gears

 

[JDSfastGN]

Nope, no knock once it's rolling. 2nd and 3rd gear are knock-free. It's just off the line when I got the pingpapingpingping (which led me to think it wasn't false knock).

I wonder what's causing the false knock through the drivetrain? I have an engine tie-down (poly mount coming this winter). Maybe I'll check the trans mount to see if it's shot.

Thanks for the help guys. Much appreciated.

Steve

hmm i must have missed the part where you said you could hear the knock.... that changes things a bit. Don't want to give out bad advice. It may or may not be real.... could be something in the engine compartment that sounds like ping. I really don't know.

 

[QUIP'6']

hmm i must have missed the part where you said you could hear the knock.... that changes things a bit. Don't want to give out bad advice. It may or may not be real.... could be something in the engine compartment that sounds like ping. I really don't know.

it shows 10 degrees them dissapears after the car gets rolling

 

[Quick6'n'-K.C.]

OK-
Read my sig before reading the rest of this...Black Box My daily should be the same chip you have.

Dial the fuel pressure down below 40 psi depending upon how much timing you have in first gear. mine is 28° and 25° Mine is still rich at 20psi of boost and 34 of line pressure stock injectors basically, they are 30#ers. Just newer injectors.
Your 02 800 volts dont mean squat, what is the EGT reading right at the end of the track BEFORE you lift? Well, you are living in the stone age... NO BIGGIE!

quote from you "The lowest O2's it recorded are 800mv at 78 mph"
GUESS WHAT, its 850 at 110, lower the fuel pressure and dial the scan master back, the car is rich.

Do you purge you meth kit, are you running meth or alky? what smc kit?
How old is your SMC kit? is it progressive, i guess not, and you dont purge your pump,.....I love my SMC kit, works fine, made the power in my sig, but its 4 years old.

There is so much i forgot to post, email me

Let me know your timing
wanner@kc.rr.com
BW

I owe all this power to ED BREWER, thank you EB