I'm getting 9* of knock when I spray and 0* NA. I plan on getting an Accel timing computer to go with the 300+ I have, but How much timing do I need to pull. I don't want to run nitrous again till I can get a handle on this. Someone please HELP!!!

 

Do you have any O2 sensor values, or better yet, a pull w/nitrous on a wideband-equipped dyno? If you're running lean, that would cause detonation....causing a timing retard. If the detonation gets any worse, you might be picking up parts off the dragstrip! I'd probably make sure the A/F ratio was on the money before I worried about timing.

 

Nothing form a wideband. But here is the info from a N2O run:

RPM: 4000RPM
MAP: 4.76 volts
Left Oxy: 946
Right Oxy: 963
Spark Adv: 35*
Knock retard: 9*

and the NA run:

RPM: 3073RPM
MAP: 4.76 volts
Left Oxy: 888
Right Oxy: 910
Spark Adv: 44*
Knock retard: 0*

 

44* is way too much advance.....stock is about 39*. You need to run no more than the stock advance in the 95+ kpa v rpm (you spray at). You must be running a different than stock program in your pcm.....

 

Yes the programing has been changed a bit. I have a Accel timing computer on the way. So if I'm spraying a 100 shot how much do I need to retard the timing? If you look at the N2O run spark advance was only at 35*...so how much should I retard the timing when I spray?

 

Take Greg's advice and shoot for 39* NA. I'd then knock off 2* during nitrous usage for 37* total.

 

Hey you may not want to hear it but i would try knocking it back to around 30 degrees on spray. 44 is fine but its aalot of sweep for the rotor when the retard hits. Try putting base back at 36 or so. You will give up a little power but you pick up consistancy.

Vince

 

30 seems like overkill given he's only running a 100 shot, doesn't it?

 

Yes the pcm pulled timing due to detonation....after the fact...not what you want. Like Josh said , I would run 37* .....so pull 7* @ wot.

 

So you guys think I need to have the PCM re-programed to 39* NA and them pull 2* more with the Accel unit when I get it to run N2O. I've got the file to put the stock spark table back in, just have to wait till I get to Vegas to have someone hook me up. After that I'll have the Accel to retard 2* more which will put me at 37*, does that sound right?

 

You can just pull it with the Accel.....I used tunercat to set my timing to stock 39* at 95+kpa v. 3000+ rpm. I can pull more with my mallory ing. for the 150 shot when I need to.

You dont need to use the whole stock spark table. .....just the area you spray at (95+kpa v. rpm you spray at)

 

OK, I see. So you don't think 44* of spark NA is to much?

 

30 sounds like overkill but if I were tuning the motor I would run it at about 34 degress total at an AFR of 13.3-13.5. That would make good power and strong torque. Then slight kick back to 30 degrees on spray would make sense. JMHO 37 degrees is way to much timing. Timing doesn't make power AFR does with a moderate curve. JMHO.

Vince

 

I agree, that's a bit high for a 100 shot. I ran around 40-41 for awhile with no knock on 93 octane.

Check your plugs. When I replaced mine, my knock went away.

 

44 NA is not a problem if you have no knock....