I know its very difficult to determine whats going on by looking at the plug tips. what some say, is that you need to look deep inside the plug insulation center to see what is really going on (there is a magnifying tool for this) . with additives in the fuel, its very common to see a white or orange tip plug (lean looking) when the plug is still seeing rich conditions, as was the case with the holbert engine which spent a good deal of its life, right at 12.5:1.

If it pings, like a buddy of mine did (6 liter Devek motor) I dont know what we will do. of course, we can use the usual techniques of running higher octane gas, but if pulling timing out of the ignition helps this, then its shark tuner-ville, sooner than later. if its pinging under WOT and lower rpms (say 3200 to 4500) then i will pull the flappy and see what happens. of course, we are going to try and get the mixture pretty fat to start to make sure were are not in the danger zone.

as far as plugs go, i forgot which number is the hotter or colder plug, but we can get a set of one or two numbers colder. dont we run 8s now. so the 7s of the stock 84s are colder, or do i have it reversed. I dont recall. (WR8DS vs WR7D....). I took a picture of the plugs as it came off the race track earlier in this thread.

Mk

 

so, in general, the 85 cams are 8 degrees retarded vs the GT cams , so maybe it will work in this situations favor. I certainly dont want any low end "grunt" , as i have a transmission to protect, which is almost as amazing as the engine has been! (knock knock).

mk

 

Mark on my 86 engine I run 1 deg retard on both cams (measured when engine at full temp).

I noticed a good top end increase when I did this.

 

It should not pink under any conditions, the knock control system will take care of that. It can retard the igntion a long way :-) But you don't want to invoke the knock control syste, because it takes a long time for the ignition to recover back to stock advance once the signs of detonation have stopped (the system will take control at levels of detonation you cannot hear).

If you have access to a SharkTuner, do as Louie advised earlier in his thread on EZK retard steps and recovery times.

Tune the LH with ST for the desired A/F ratios at cruise and WOT. The car will be smoother and quicker.

 

If you know a good engine tuner (hopefully with a brake dyno) there is a known method of finding out the knock threshold for a motor.

This is why we only use shops with brake equipped dyno's if possible. Yes you can go through the same process on a non brake equipped dyno, but IMO it's not as precise and no, it does not involve watching the knock count. In fact, the experienced tuners I know disable the knock sensors when tuning.

The big question is how accurate the stock compuer / knock sensor system will be with a different bore and stroke.

 

John that being said , Why then do many GTS cars have issues with audible pinging ?? at least in California.

 

That is there way of complaining about being driven in such a restrictive environment.

Its like walking a race horse, they dont like it.

 

With Bosch the lower number is cooler, with NGK the higher number is cooler.

A cooler plug will be less likely to ping and less likely to preignite.

I saw the plugs earlier. It looked to me like the car could use more advanced ignition, but take that with a grain of salt because if the engine was running when the car was brought into the pits it will throw off any reading of them (and it looks like this was the case, unless the car was running way rich).

That's true about having to look deep into the plug with a bore light to get a really good mixture reading, but you can get a pretty good read just by looking at the jetting on the unthreaded releif at the bottom of the threads if you do enough runs (no less than three). Just find an empty stretch of road where you can do 3 full throttle runs (something like 3 back to back 1/4 mile runs). I think the magnifying glass is only helpful to look for signs of detonation.

So, you look to the ground strap for heat range and timing and you look either deep down on the insulator or on the non-threaded relief of the spark plug threads for mixture. Looking deep down on the insulator has the benefit of letting you just do one run.

 

I agree that tuning for maximum torque on such a dyno is the ideal may to go...

On the 928 you would have a hard job disabling the knock sensors without the EZK retarding the igntion 6deg.

IIRC it is bore size that is the determining factor for knock frequency. But I've never had the time to investigate the compatablity with stock EZK.

 

We must put on the wideband O2. The dyno will have its own, but you need one. We need to know what's happening on the road. I was hoping you have an extra bung so we can still run the LH off your narrowband. The LC-1 has narrowband output, but I prefer not to use it. We'll use its narrowband if we have to, but if you are going to keep it installed, which would be a good idea, have a second bung put on the exhaust.

Anyway, with that and the Spanner, we can do some WOT runs, logging AFR and knocks, and see if there are any danger zones. I believe idle and cruise will be fine (stoich). And because your WOT switch works well, we should have some protection with WOT ignition retard as well as the new knock sensors. However, I expect WOT will be leaner than ideal and you will have knocks. If the mixture is not 12-13 on WOT and there are more than just a couple of knocks on a run, it needs to be tuned right away. WOT is going to be no better than stoich with your stock LH. I have a Sharktuned chip set for 30 lb injectors and about 425HP. We can try that. If WOT is still stoich and there are knocks, no racing until its Sharktuned.

 

I don't know Jim, I assume they have reached the normal linit of 9 deg max retard, but need more retard to suppress their oily detonation ? I assume this is with 93 fuel ?

 

my friends devek 6 liter pings like some of the GTS's ive heard about. believe me, it has nothing to do with how its being driven. He now lives in az and it pings even more when its hot, and that most all the time vs LA or norcal where the car has been.

mk

QUOTE=Lizard931;5696972]That is there way of complaining about being driven in such a restrictive environment.

Its like walking a race horse, they dont like it.[/QUOTE]

 

California only has up to 91 octane, which is like 96 in the non-US octane scale.

 

The second picture on this website is a good example of a good looking spark plug, thogh it could use slightly more ignition timing advanced and a slightly richer mixture.
http://www.hoigto.com/tech/sparkplugreading.htm (even though I disagree with some of the stuff it says about how to read the plugs).

 

I was wondering about that. The tunes we have on the boosted cars are on the conservative side so it's not an issue.

This is why Todd modified his engine to run without a thermostat with two huge fans behind the radiator. He wants his head temperature to be as low as possible to avoid detonation.

I'm assuming you are running a colder thermostat than stock. Might not be a bad idea to flush out the radiator quick before dropping in the motor. Every little bit helps.