Knock Prevention!?

[Sydneykid]

Hi Busky2k, every time I add it up, I end up with the Power FC being cheaper than ..................

^SAFC for the fuel

^ITC for igntion

^Boost cut defeater for running over 12 psi consistently

^180 kph speedo cut override

Then there is the resolution issue, a PFC has 20 X 20 (400) load points both fuel and igntion. An SAFC and an ITC have nowhere near that. What if the engine is running too rich at one load point and too lean at the next load point. Nothing you can about it with an SAFC but the PFC has 50 points in between to get it exactly right. Ditto igntion timing (but worse) with an ITC.

As well, the Commander has saved me a heap on extra gauges, and the diagnostic screens are great for finding that elusive problem.

Sell the bits and buy a Power FC, that's what I always suggest. You will get a far better result for not much more. And when you sell it, you will just about get your money back as PFC's don't seem to depreciate much.

My 20 cents worth

[Busky2k]

Sydneykid, I wouldnt mind a PFC if I had the money of course

I picked up the stuff for cheap, both the SAFC II (new) and SITC (2nd hand) for $800. I dont have to worry about a speed cut defender because my car is Aus spec or boost cut defender since the SAFC does that (ie leans out the AFM signal).

If I want a PFC and Handset, Im looking at at least 1500 2nd hand, and 400-500 for the tune. I know it'll be better, but I dont think im gonna gain much in terms of power as the Ign Timing and AFRs are almost perfect at WOT as is!! Hell I dont even have a FMIC yet... LOL

I understand where your coming from, because I would have got a PFC + tune If i had 2k to outlay. But I dont, and probably wouldnt anytime soon. I went the piggy back route beacuse its alot easier on my pocket. Btw the SAFC has 12 RPM points and automatically interpolates between the low and high THR map aswell.

I would completely agree with you if I had a JSpec Skyline tho! And, if i had more mods. So far, my piggy backs are just fine Bigger turbo tho, and hell yeah, goodbye piggybacks, hello PFC

[JimX]

Sheesh, you spent $800 for ITC and S-AFC? If you were going to spend that much I would have definitely gotten the PowerFC. You can get them for around or under $1000 second hand. I assume that was $800 pre-tune, so add in a couple of hundred to tune them. Unlike the PowerFC, the S-AFC and ITC don't have their own (superior) base map and you need to tune them to get any use from them.

You don't need the hand controller for the PowerFC, and the tune can be had for around $350-450. If you're lucky you don't even need the tune. I bought mine with hand controller for $1275, it would have been around $1000 if I didn't get the Commander. I still haven't tuned it yet, and it's running far better on the base map than it did with the tuned S-AFC. I'm getting it tuned as soon as my Z32 AFM arrives and I put it and my 550cc injectors in.

The only reason I got the S-AFC to begin with was because it was a cheapass upgrade. Once you start adding things to it like the ITC and boost cut defenders etc, it quickly becomes poor value for money.

[Busky2k]

Yeah yeah I acknowledge the PFC is far superior! But I didnt buy them both at the same time. Initally I had the SAFC for $600, tune was $50, and that was great. Then 12 months later I grabbed the SITC for $200, to save me always screwing with the CAS...

I couldnt afford at the time the outlay for the PFC + Tuning for ~2k at the time all in one go. I havent seen an S14 PFC with commander for less than $1400, and Ive been shoppin. I would want the commander, as its the live adjustability to timing etc that I like. Eg when I put toluene in the tank, when its a hot day etc etc... It all comes down to how much you wanna spend really. And I dont see the point upgrading, as I probaly wouldnt get more than $500 for the gear. So I still need another $1000 easily... not exactly BYFB with a car thats still fairly stock, and I dont plan on a Z32/Bigger Injectors/etc...

Looking back on it, i shoulda just saved more when before I bought the SAFC, but yeah, too late huh? Im still quite happy as it is now anyways...

Im still a student, so you can consider me a bean counter *sob*

[JimX]

Well if you're happy with the results, that's all that matters. I'm not suggesting you upgrade now, since you've already spent the money and you're happy with the tune. It's just that $800 is a lot of dosh just for 2 interceptor units, but with the way you did it, I probably would have done the same in the same situation.

But anyone else out there with $800 to spend on an ECU upgrade, don't do the same thing!

[lukits01]

Hey guys got a noobish question

what's the relationship between engine knocking (detonation) and engine pinging?

In fact, what is engine pinging?

[edgasket]

Hey guys got a noobish question

what's the relationship between engine knocking (detonation) and engine pinging?

In fact, what is engine pinging?

It's the same thing isn't it? pinging, detonation, knocking, pinking, pre-ignition...

[JimX]

Pinging is another term for knocking, which is caused by pre-ignition. They all mean the same thing pretty much. Pre-ignition can also cause the car to run-on or diesel after it is shut off. Not really common in our cars because I think if they had pre-ignited enough to cause them to run-on, it would have melted a piston by that stage.

[Busky2k]

Preignition and detonation are different things.

Preignition is just when the complete fuel mixture starts to burn before the spark plug ignites, usually caused by glowing sparkplugs, valves and whatnot.

Detonation is when a portion of the mixture autoignites away from the spark plug, then the rest is ignited later on by the spark plug. Then you have two flame fronts, which eventually collide, causing massive cylinder pressure spikes and shockwaves. Then this hits the pistons/cylinderwall/etc and this is the pinging noise that you hear. Its the shockwave that kills the parts.

[JimX]

Busky2k, I'm not an expert on this, but you seem to have described the exact same thing twice and called it 2 different things. I have been told by mechanics in the past that pre-ignition (due to whatever reason - hot spots, too lean a mixture, too much ignition advance, etc) causes detonation (the shockwave/noise you can hear if it's loud enough).

[Steve]

JimX, I am no expert, but what busky describes appears a little different - detonation being the ignition of the air/fuel mix BEFORE the flame front that is caused by the spark - it actually explodes rather than burns.

From what busky is saying, preignition is started by a hot plug, before the spark, but burns with the same characteristics as if the fuel was ignited, not spontaneously combusts as in detonation.

Does that make sense, or am I missing the point? Busky?

[Busky2k]

Im not an expert either, but the 2 situations are very similar, but then again, very different aswell.

People can use the word 'preiginition' for 'detonation' since it covers the same principle; the mixture is ignited other than from the spark plug, but there are differences which separate the two.

Preignition; eg, switching a carby car off and the thing still runs for a few more seconds, because the fuel is still being ignited by a glowing hot valve or spark plug. Sorta like dieseling itself so to speak, and there is only 1 flame frount coming from the hot source and burns evenly. It doesnt cause damage usually, unless preignition is occuring during normal operation and its the same as running way too much ignition advance like described below.

Detonation; This is where the pressures in the cylinders spike to extremely dangerous levels. As i described before, its cause by autoignition of 1 part of the mixture near the cylinder wall or piston and the flame front begins to travel upwards in the same direction as the piston. Then the spark plug fires the other unused portion of the mixture and now you have 2 flame fronts. One going up, the other travelling down. When they collide.. Its a big bang and cylinder pressures go through the roof. This is whats damaging. Detonation is caused by unstable fuel mixtures (ie too lean, too high boost) at WOT and this causes _parts_ of it to autoignite on its own, not by a spark, or glowing valves/spark plugs. (Also to note, preignition can lead to detonation, but usually we boys dont usually have problems with glowing spark plugs etc so we can discount this factor.)

Also too much ignition advance is quite similar, but this is also coined detonation since your igniting the mixture too early and it can hit the piston before it reaches TDC. Piston going up, flame front going down.. u get the picture. Also too much ignition advance can cause it to burn unevenly when the cylinder VE is high. (ie more boost).

I dont claim what i say is 100% correct, but this is what Ive read on a few times and what I understand...

For futher reading, check out this nice little summary I found (after I wrote this, doh! now I cbb fixing what i wrote)

http://www.turboice.net/documents/turbowhi...paper/knock.htm