Thread: Knock Retard

When people here are talking about "too much KR" are they talking about a perceivable loss in power/predetonation e.g. knocking or are they talking about KR done, transparent to the driver, by the ECM and knock sensor?

second sticky from the top. posted by reptile. lots of good stuff there

That's not really what I'm talking about.

The ECM can retard the timing of the engine to prevent detonation. When people here talk about a smaller pulley causing too much KR, it seems to me that this could be referring to two different things:

1) The additional boost by a smaller pulley is causing perceptable knocking and hestiation as detonation occurs.

2) The additional boost by a smaller pulley is forcing KR by the ECM without the knowledge of the driver

Let me put this another way: I have a '98GTP with a smaller pulley. I have done no performance modifications other than basic ignition (new coil packs and new wires). I have NEVER once had anything I would call a knock, I've never thrown a code, and I've never had anything that I would describe as perceivable KR.

My question: could I still be having "too much KR" as a result of the pulley swap but not know it because my ECM is doing the work for me?

I've had the new pulley for at least a year and my car has never ran better (or faster). What's more: I run crap gas (85 octane at 5500ft elevation) without any problem whatsoever.

Or - let me put it another way: do you need a scanner to know if you're getting too much KR?

Some people just say knock when referring to KR (knock retard). You can't physically hear KR, but you can hear knock. Knocking is a mechanical problem that is most likely a bad rod bearing or main bearing, or something else actually hitting another part. KR blows and it is noticeable if you have enough, especially if you know what it's like running KR free. How small of an s/c pulley do you have on?

You wont hearing the typical pinging because these cars pull timing the instant it detects it.

But for real, your engine is being pushed WAY too hard for the amount its flowing.

Keep in mind - the altitude here means that the octane available is not as high. The three grades are 85, 87 and 91.

I know a tremendous amount about octane - hell I even had several classes on it in college (Thermo 1, 2 and heat transfer).

What I don't know is how the GTP handles knock; or, more specifically, how perceptable it is without a scanner.

As I said, I've never had any issues with hesitation, pinging, or anything performance related. With my altitude, I get 20% less O2, so it's possible that whatever KR problems the rest of the country has is just not noticeable here.

I used to run nothing but 91 octane since I bought the car new way back when. When I bought my new GTO, I was hemmorhaging $ for gas, and decided to get gas on the cheap for my GTP. Ever since then even with the new pulley (3.2 if memory serves me correct), I've been running the cheapest thing possible without any performance issues whatsoever (same mileage, same performance, no issues at all). I have put about 20k miles on it since my pulley swap.

So, it's certainly possible I'm seeing KR, but the question I must ask is "should I care"?

Originally Posted by matt5112

You wont hearing the typical pinging because these cars pull timing the instant it detects it.

But for real, your engine is being pushed WAY too hard for the amount its flowing.

not true. i heard my first motor to knock, then it blew up. 3.5 pulley on an L36 with manifolds and a clogged cat. the best way i can describe the sound is like a rattle. it sounds like ball in a penut can actually.

LOL at "should I care"

If you're tight for gas money then yes.

If you dont give a **** if you destroy your engine then no.

Thats the short and simple version.

Get a scan gauge already and be on what we call "the safe side".

But thats the rare case.

Most people have the engine run normally then its flashing CEL due to bent plug(s).

I just checked - it's a 3.2. I've had it in the car for over a year with nothing but 85octane pump gas (and a lead foot).

At altitude, I get 20% less o2 than the rest of you. With operating o2 sensors, I should get 20% less gas than you too.

I've not run the CFM or stoichiometry calculations on it, but I always figured that a smaller pulley put me closer to stock at sea level.

I figure that the rotational speed of the pulley is close to linear to its output (this is not really the case as air is compressible, but it's close).

The rotation speed os RPM*pi*d. Since the first two variables are the same regardless of pulley size, I can also say that the speed is linear too. In short, a 3.2 pulley is less than 20% smaller than the stock 3.8 so its rotational speed would be less than 20% faster.

If the rotational speed is somewhat linearly representative to the CFM, then I'm getting back to sea level (or so).

The bottom line - I would like to scan it just to make sure.

One question along those lines: do you monitor KR real-time (my assumption) or is it stored in the ECM?