Tuning questions about KR

[Greyling]

So,...a couple quick questions.

Once the snow melts here in a couple days and I can get the car out to try tuning it with a Scanmaster I want tomake sure I have a coupel things straight.

Knock Retard. I want to tune for zero obviously,...But I'm seeing several folks though who mention 2* or 4* of KR like it's no big deal.

Is there an acceptable area I just need to be in? Say 6* and below? Or just straight tune for 0*?

It seems from searching/reading that on the shift it's common to have a couple degrees of KR. Can I consider this acceptable and ignore it?

Another quickie,... O2 sensor. What are my limits as far lean/rich?

I Just don't want to end up with 8 Lbs of boost.
New to the tuning of the thing like I said.

Car is an 87 GN with 35K miles.
Have the following upgrades:
Bosch 237
Green stripes
FP (yes,... dunno what kind though)
Custom cat back (Cool guys at the local muffler shop liked the car and instaled a 3" cat back into duels for 400 bucks)
Thrasher 92

All the spring cleaning was done and the car runs great.

Have to wait 2 more days for the Tin Man intake and hard MAF pipe.


Thanks for the help!

A-

 

[bruce]

Let's say you settle for 4d of KR.
And your chip is set for a max limit of 12d of timing retard.
And you get a tank of bad gas, that generates 10d of K/R. Well you've used 4 just from the error in the tune, and now need 10d more allowable K/R, but the chip cuts you off at 12.
(Not exactly the best discription but just trying to illustrate a point)

So now you have 2d of too much timing.
The engine will now detonate.

One other point is that the code takes out more timing the absolutely necessary once it sees knock to keep the motor out of knock, so while 2d less timing might have kept the motor out of knock the ecm is pulling 3d or so.

 

[turbot2496]

I'd tune it for 0 knock period if you can. If you get a little on the shifts I guess thats ok but on my car, you get to the end of the quarter and hit recall on the SM and it shows 0 the way its tuned so I don't know, I guess there all different and some may false knock on the shifts. If you can get it tuned for zero knock though thats some good piece of mind when you get on it.

 

[Greyling]

OK,... now I'm really confused now that I've read Bruces reply,...
=\

I'll stick with trying to keep it as low as possible. It just seems from reading al these posts that like 2-4 degrees is acceptable and folks aren't too worried about it.

 

[bruce]

Originally posted by Greyling
OK,... now I'm really confused now that I've read Bruces reply,...
I'll stick with trying to keep it as low as possible. It just seems from reading al these posts that like 2-4 degrees is acceptable and folks aren't too worried about it.

Now I'm confused, why ask guestions if you not going to try and understand the answers?.
Whatever.

 

[Greyling]

Errr,... well,...I am trying to understand.
The way you put it though there is a KR budget based on some things that I have no idea how to get ahold of. (How many degrees a bad tank of gas will give for example)


Having a hard time with the way you explain it is all,....


Nevermind,.... I'll tune for 0

From the sounds of it I shouldn't settle for any KR.

 

[turbot2496]

Well basically what Bruce is saying is that every degree of KR you accept as normal in your tuning is a degree of safty you are giving away if the car does get lean or detonate for some reason like bad gas or sudden vaccuum leak etc. Thought that was clear from what he typed but I hope this helps. I would shoot for 0 KR if possible. Good Luck.

 

[Greyling]

Ahhh,... that makes a bit more sense.

Thnx!

Will shoot for zero.

 

[XLR8]

Good luck with the snow leaving. I would tune for 0 KR. That way, in case something happens, you are probably safe. Although I tune for 0 KR, my car seems to run the fastest at the track when I get 0.7 KR at the 2-3 shift??? There is one guy in the local club that says anything under 10* is no big deal - of course he is on his third motor.

 

[dennisL]

You didn't say how you plan to tune for let's say, 0 knock.

Will you be making chip changes and if so, which chip will be used as the "baseline" or starting point.

Oh, and don't worry about not understanding Bruce. I'm told that sometimes Bruce doesn't understand Bruce.