Nitrous and ST knock Retrad

Dodgetony · Post by **Dodgetony** » Sat Mar 21, 2009 2:43 pm

I ran my 09 RT Auto today logging data using a ZEX 100 horse shot. I am getting 2 ~ 6 degrees ST spark knck. Without the nitrous I dont get any.

For the nitrous runs I pulled 3 degrees timing all across the board, and added +4,+7,and +9 on the fuel. My A/F ratio is 12.7.

What should I do?

Quick · Post by **Quick** » Sat Mar 21, 2009 3:11 pm

A/F is 12.7 with or without the nitrous?
You might want to get plugs a step or two colder as well (copper is preferable).

Most guys I know running nitrous have 2 tunes. Track and street (nitrous and no nitrous).

Dodgetony · Post by **Dodgetony** » Sat Mar 21, 2009 3:46 pm

My AF is 12.7 with the nitrous.

I plan on running separate tunes for the nitrous. My main question is, is the amount of knock retard I am seeing on nirtrous a problem?

I am running one step colder plug (NGK 4306) which is a copper plug.

Quick · Post by **Quick** » Sat Mar 21, 2009 4:02 pm

Dodgetony wrote:My main question is, is the amount of knock retard I am seeing on nirtrous a problem?

I don't know. I think 2* is ok if it's just a couple of bumps and not constant.

SRT8Tech · Post by **SRT8Tech** » Sat Mar 21, 2009 6:21 pm

Might wanna add more fuel. I think 12.7 is still a bit lean for N2O.

Dodgetony · Post by **Dodgetony** » Sat Mar 21, 2009 7:22 pm

SRT8Tech wrote:Might wanna add more fuel. I think 12.7 is still a bit lean for N2O.

I was wondering about that. I will add more and see if that helps with the knock. I dont want to keep pulling timing if I can correct it with adding fuel.

Quick · Post by **Quick** » Sat Mar 21, 2009 10:21 pm

I'd go all the way down to 11.8/11.9 before I pulled any more timing but I don't know much of anything about running nitrous

Dodgetony · Post by **Dodgetony** » Sun Mar 22, 2009 4:01 pm

So...I spent the morning tuning and data logging. I got my AF down to around 11.9~12.0 at WOT. I pulled 3 degrees and still get anywhere from 2 ~ 6 degrees ST spark retard. I get absolutely none with the AF at 12.7 and no timing pulled when running NA.

I am ready to pull my hair out.

Quick · Post by **Quick** » Sun Mar 22, 2009 6:18 pm

Ummm.... just checking. You're NOT running a dry system are you? And you ARE using a wideband and not just looking at the commanded A/F right?

Dodgetony · Post by **Dodgetony** » Thu Mar 26, 2009 3:58 pm

I am running a ZEX wet system. And I have a wideband installed in the car.

Quick · Post by **Quick** » Thu Mar 26, 2009 7:38 pm

So what does the "anywhere from 2 ~ 6 degrees ST spark retard" look like in a log? Can you post a log?

Is it continuous? a lot of bumps? a few bumps? where? random? particular rpm ranges? right after/around shifts? etc. log would be best.

Dodgetony · Post by **Dodgetony** » Thu Mar 26, 2009 8:10 pm

I am sure this has been asked before, but how do I post a log?

johan · Post by **johan** » Fri Mar 27, 2009 8:39 am

From what i have seen on nitrous cars, the st knock is very hard to tune out without raising the knock thresholds, something you really dont want to do when running nitrous.
It must be the higher cylinder pressure caused by the nos creating more "noise" that the sensors pick up.
I doubt you will be able to tune it out.
What is the actual spark you see during the run?

Dodgetony · Post by **Dodgetony** » Fri Mar 27, 2009 9:23 am

johan wrote:From what i have seen on nitrous cars, the st knock is very hard to tune out without raising the knock thresholds, something you really dont want to do when running nitrous.
It must be the higher cylinder pressure caused by the nos creating more "noise" that the sensors pick up.
I doubt you will be able to tune it out.
What is the actual spark you see during the run?

The spark goes from 40's down to 10. The 10 occurs when the ST retard is around 5.5 at 5570 rpm's.
This is with 4 degrees timing pulled on the 93cai tune using 94 sunoco gas. (100 shot of nitrous).

ElectricBlueHemi · Post by **ElectricBlueHemi** » Sat Mar 28, 2009 1:33 am

You might try the 87 octane tune and see how it does. That works for many people.

Nitrous and ST knock Retrad

Nitrous and ST knock Retrad

RE: Nitrous and ST knock Retrad