Hey guys went over a buddy of mines house yesterday to work on this rich *****es car. Namely he's 19 and is on pace to make 120,000 this year due to our recent intrest rate drop (he sells morgages).

So he complained that he had a dead cylinder. I went over and little did he know it was because of zero compression. He runs 10 pounds of boost with a paxton and has a bunch of other bolt ons. Now apparently he informed me that he went to change the plugs before i got there and the one in that cylinder was completely blown apart. What could cause such a massive failure of spark plugs? He said the plugs were colder then stock, but not cold enough. I don't think that was the problem tho i was thinking more of detonation.

I'm intrested in finding out htat answer. He's going to have to have the head pulled due to the valve train problem that has ensued. I'm sure combustion chamber looks like chernobyl. Thanks guys

Matt

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89 Camaro IROC
350" GM Crate Motor
278/290 .476/.494,
3000 Lockup Converter,
..plenty more
Harwood 2" Cowl

UNITED WE STAND

 

I would pull a head & see what is going on in it. My buddie just pulled the heads on his vette (350 with a 144 blower) & he snapped the head off of one of his Exh valves & it was bouncing around in the Cly for as long as it took him to get to the side of the road.

When he pulled the plug it looked the same, completely mangled.

BW

 

Detonation is probably (99.99999%) the cause.
Allthough plugs that are too hot will cause detonation chances are that the fuel mixture was lean when under boost. That is a common problem when someone bolts a blower on and does not address engine tune/calibration and/or fuel supply issues.


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Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro
"Cogito ergo zoom"

• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

EFI Performance Club on Yahoo

 

Well its a 2001 mustang by the way. He did address motor tuning and fuel becuase I asked him and he has a AFPR and a custom burnt chip put in when he got the supercharger. I don't know the specifics of the chip but apparently he paid alot of money for it. It was all done right and boy that car was fast but well now he's down to 7 cylinders so i'm not worried!

What else could cause detonation like that?

Matt

 

Too much air, too little fuel, or too much timing. some are easier to check than others. too much air (check boost gauge), too little fuel (check FP gauge), too much timing (????? this is the hard one, maybe a scan tool?) I take it that this was a kit, just bolt it in & go? if so that means that most likely the general Eng issues have been addressed. if this the case then this sounds like tuning or freak failure, hard to say. what do the rest of the plugs look like?

BW

 

BW, i know that that wasn't the only plug that broke apart. Aparently he was running on 6 cylinders until they put new plugs in. Then they did a compression test when it still wasn't running right and the one cylinder has as 0 reading. OUCH! One guys theory is that the plugs weren't cold enough making the combustion chamber too hot which then melted the electrode and smoked the valve. Those plugs looked horrible.

I thought it was timing as well but the chip was supposed to of resolved that issue being its ALL computer controlled. Pretty scary if you ask me.

Matt

 

I am sure that you cant tell by the mangled plug but what did the others look like?

Were they black & drippy (on the porceline, not the threads) or were they white & have spots on them? if they were white & had spots on them (my guess), were the spots black or metalic? you are going to have to get upclose & personal with the plugs for them to tell you a story, it might be an interesting one.

Sounds like it is time to pull a head. I find it very interesting to know how motors fail. I have blown up my share of motors & have checked out the carnage, but have not been paying close enough attn to them before they blow up to know what was going on inside them. This is my new quest. if you push a motor & pay attn to what they are telling you (check plugs, temps etc) then you can know what is going on in the motor.

BW

 

why dont you do some worrying about your own car matt

later man

 

Just because he has an AFPR and chip doesn't necessarily mean the air fuel ratio or timing is tuned correctly.
If the combo hasn't been tuned by someone that knows how to read plugs, or used exhaust temp probes, or a wide band O2 sensor (or any mix of these) then the air/fuel mix is likely off.

Almost always being too lean is what causes this type of detonation to occur.

Plugs being too hot will not directly heat up the combustion chamber or valves. They can have a hot spot on them (the plugs) that causes preignition and/or detonation though and detonation causes the extreme heat that cooks parts. I doubt a burned valve is the cause of the compression leak. It is likely a blown head gasket (if he is lucky) or a hole burned in the top of the piston (if he's not so lucky)

Too much timing advance can cause detonation.
Too much cylinder pressure can cause detonation (ie too much boost + too much compression).
Too much heat can cause detonation.
Too much load can cause detonation.
Another hot spot in the combustion chamber other than a hot plug (like a burr or sharp edge) can cause detonation.
An air/fuel charge that is not homogenized can cause detonation.

Any of these can cause detonation, but leanness is the most common cause.



[This message has been edited by IROCKZ4me (edited November 22, 2001).]

 

Just an observation...... 99' - up 4.6L mustangs have return-less fuel systems. Nitrous systems for them are dry kits. There is a guy w/ a 2001 in this area that had a new custom fuel rail built for when he installs his Procharger.

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1986 IROC, fully loaded, Mini Ram'd 383, Art Carr 700R4, Accel DFI, 12 bolt rear, etc, etc......

 

What was the gap in the plugs? When I use nitrous, I gap the plugs at 35, without nitrous they are gapped at 45 or higher. This is with AFR heads.

Pete

 

what exactly does afpr stand for?

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1987 LG4 Camaro z28
Modifications- Flowmaster 80 series, KN airfilter, edelbrock open air element, high flow cat, 180* stat, edelbrock performer intake manifold, msd blaster coil, ascd big block hood, panasonic cd player, rockford everything else. http://members.aol.com/tru69cugar/images/twink.jpg

 

AFPR = Adjustable Fuel Pressure Reglator.

 

when you pull the head on that driver side cylinder you will find a very badly blown head gasket blown between #6 and #7 (ford numbers them 1-2-3-4 pass, 5-6-7-8 driver) because of the firing order of "rustangs" as you call them he-he, the adjacent cylinder fires as the other is on its way compressing the fuel air charge the result is a violent out of control cylinder pressure spike that we can even hear on out dyno that is like powerful detonation as well as we usually see a piece of the head gasket poke into the cylinder and assault the spark plug angrily shredding it. I suggest especially if he's gettin aftermarket heads to switch to wire-loc head gaskets from fel pro. fords do not have the clamping power of GM's on thier head gaskets. -Tom www.outlawperformance.com management