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928S4 Stroker Race Car - Read Plugs after 2 seasons
I pulled a plug #2 just to see what they look like i was going to pull them all and do a compression test, but i did that a year ago when i though something was wrong with the car. did a compression test, cold, on the engine, and it still registers 195psi. (usualy 200 to 210) when warm. what does the plus say? it has about 50 street miles on it since the last race last month at laguna.
Those spots on the ground are usually vaporized aluminum melted off the piston from hot spots. Could be lean or detonating. When the vaporized alu hits the cooler plug it solidifies into a dot. Carefully scrape off one of those dots and see if its ferrous.
Kibort did the final assembly and the tune. So.....in a sense he's talking to himself?
Oh.....I get it.....you're trying to take another snide jab at Twin Turbo Todd, I get it. One thing is for sure, if and when this motor lets go, Todd won't blame the driver or the fuel he used.
Todd does have major concerns about the tuning of this motor and such concerns have been expressed to Kibort many, many, many times. But, this engine was built so well, it just keeps going like the Energizer Bunny.
From what I've seen, ideology prevents sharktuning.
Given the LH works, sorting out which 14 pins are the diagnostic port, on a used plug, should be the matter of a couple of hours on a weekend afternoon, at which point PEM's and WBO2 and tuning can happen.
EDIT: Looks like it got somewhat too hot. What are your AFRs? Change all 8.
the AFR's are very rich...but, you can see clearly the AFR are in the 11s to near 12:1. Ill pull the others, but i did a compression test and everything was great , i think last year.
one of the things to consider, is that when you drive non, WOT, you run closed loop. there is little tuning you can do when its running closed loop.. its trying to keep things at near 14.7:1 for fuel economy and additives in the street gas can make plugs look funny, but there is a lot more white than ive seen before, so, ill pull the others to see what they look like.
by the way, who do we buy spark plugs from now? I've used a plug one step colder based on Todd's recommendation . The way to really read the plug would to be after a session at the track.. Ill do that too and report back.
is this pug now bad? the car still runs great? dont you replace plugs when you see noticeable wear on the electrode?
Kibort did the final assembly and the tune. So.....in a sense he's talking to himself?
Oh.....I get it.....you're trying to take another snide jab at Twin Turbo Todd, I get it. One thing is for sure, if and when this motor lets go, Todd won't blame the driver or the fuel he used.
Todd does have major concerns about the tuning of this motor and such concerns have been expressed to Kibort many, many, many times. But, this engine was built so well, it just keeps going like the Energizer Bunny.
How many hours does this engine have on it again?
120 hours on the engine now... racing since 2008, not missing many events over 9 years and HP hasnt change much at all as i usually dyno at least twice per season.
Originally Posted by icsamerica
Those spots on the ground are usually vaporized aluminum melted off the piston from hot spots. Could be lean or detonating. When the vaporized alu hits the cooler plug it solidifies into a dot. Carefully scrape off one of those dots and see if its ferrous.
are you talking about the rough area on the side of the ground strap?? ill pull it an see. what if it is just deposits, it wont be magnetic.
I think the tune is pretty safe, especially since I've gone to the dyno with it, dozens of times. all of the tests have been under 12:1, finally when i backed off the fuel pressure a little lower, i was able to run close loop and have the plugs not be black with soot after even highway driving. now,its still mostly below 12:1, but closer than its been before..... ill be doing some WOT testing when i bed the brakes before Sonoma and ill pull and change them, then.
most recent dyno from Dec 2018 with air fuel
Here are the recent dyno numbers... a plug pulled 2 years ago and one right after the engine was installed in 2008
taken in 2016 same set as today.
dyno numbers.. same fuel air ration as measured a few months ago taken after engine built in 2008
i was worried about that one plug so i pulled a few more, half the engine to get an idea what is going on. without bright sunlight, they all look very grey and under high magnification, even the previous #2 plug show by the picture earlier. the part that looks like , as someone said, "***** of aluminum" , is only white soot. comes off like chalk. The plug in question , was #2 (the original shot in the sun) and its below with out the sun and looks close to the others. and the others are #5 and #1 (#6 looked the same as #5 )
compression of the 4 cylinders i checked was:
1. 195
2. 195
5 200
6 195
When did you last have your injectors flow checked/cleaned?
why do you think there is an issue?..... if you look at the dark pictures above, all the plugs look like that. pretty normal in my experience. actually a little on the rich side if you notice all the carbon on the edges. Ill take a picture of the plug in question after a day at the track, or bedding the brakes this weekend. im sure it will look fine. keep in mind , these are two season old plugs, but the "stuff" on the ground strap and electrode insulation, is very soft and comes off like a powder almost. mixtures show 12:1. the motor is healthy and running in a safe tune i would say. the lighting of the close ups are making it look like its "white" but its not. the two pictures above showing the rich looking plug, that are grey and black, are the same plugs in the close ups.
06-21-2018, 08:45 PM
928S4 Stroker Race Car - Read Plugs after 2 seasons
