Comp 918 failure caused #6 piston to disenegrate :(

Well I took off work yesterday to tear my motor apart and found the #6 exhaust valve spring broken, then once i got the head off I looked doen in the block and where a piston is supposed to be i found one chunk about the size of a chicken nugget the rest were so small they fell into the oil pan im assuming. When it happened it completely chewed up the head and ate the spark plug. looking down in the cylinder hole u can see that it chewed up the crank and the cylinder wall was demolished.

Well my dad said take this negative and turn it into a positive..
Hello reman longblock LQ9!!lol

Looks like I might need to expedite my order to replace my 918s.. lol. what color was the stripe on the side of the comp spring?

Yea dude i would def get something else! And these were supposed to be the new revamped ones wit no problems. Man I dont remember, but now there isnt one on them, for some reason i think maybe pink or purple but i could be completely wrong Luke(408luke) may remember i got them from him

i think the old color was blue, but these were the new ones because i remember sending the old ones to comp and as soon as i got the new ones i sent them to you. Oh well i guess lq9 time :D have you thought about a 370? or at least going with forged rods and pistons? be careful who you get that reman from, i would be worried about bearing clearances and such especially since you spray. Is my cam still good? :lol: if not you can go even bigger now :devil:

Well right now $ is pretty tight (thanks to college.lol) so for now i think im just gonna put the motor in and drive it. I image a full bolt on lq9 will embarese the ol cammed out 4.8 any day of the week, just cuz of the amount of torque. i havent torn it down that far yet but idk if i will use anything out of this motor. Im thinkin bout turnin the cam or crank into a lamp stand for my living room.lol

Same thing happened to me, except mine were the "new and improved" 918s...sucks, but creates a new oppurtunity! good luck

Post some pics dude. BTW, your package should arrive today :)

How many miles were on them? I still stand by my belief that any performance valve spring (especially duals) are only good for 15000-20000 miles.

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Originally Posted by Frenchy

How many miles were on them? I still stand by my belief that any performance valve spring (especially duals) are only good for 15000-20000 miles.

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That's it? That means you should change them on a yearly basis, atleast.

How long do you let truck idle before driving it?

Well ive never heard the 20,000 mile thing before, i may def think bout when i eventually cam the 6.0.. Andrew i start it and drive it.
Thanks bryan!

I'd bet that's the reason it broke. Aftermarket valve springs are more brittle cold, it's a downside to having performance springs, the reason better springs aren't used from the factory. You're supposed to let them warm up before putting any kind of extra load on them to avoid stuff from breaking. Not saying they'll always break, but in this case, it did.

The reasoning behind the 20000 mile deal is that they are a stiffer spring. This extra stiffness creates more heat. Excessive heat takes the spring out of spring steel. So basically you're left with coiled brittle steel. Duals are worse for it because they are stiffer as an assembly but the springs themselves are actually weaker. Now I seen a company (I wanna say PAC) advertising their springs guaranteed for 100000 miles, so maybe the companies are finally figuring out there's guys running monster cammed DD's now and need the durability.

them comp 918s suck...that happened to my buddy,he caught it early though while idling 1 spring broke and they were the new batch as well lol

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Originally Posted by Frenchy

The reasoning behind the 20000 mile deal is that they are a stiffer spring. This extra stiffness creates more heat. Excessive heat takes the spring out of spring steel. So basically you're left with coiled brittle steel. Duals are worse for it because they are stiffer as an assembly but the springs themselves are actually weaker. Now I seen a company (I wanna say PAC) advertising their springs guaranteed for 100000 miles, so maybe the companies are finally figuring out there's guys running monster cammed DD's now and need the durability.

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One of the guys at TR told me that he had patriot golds I'm his car with a fairly large lift cam...~.600" lift...and that he has pit around 50,000 miles on the springs. And not just 50k of conservative driving.

Glad I went with the PAC 1518s when I got my springs for the 243s. Threads like this seem to pop up often, that's why I made the choice to stay away from the 918s.

Ya im really leanin towards leavin the LQ9 just boltons for now and then maybe in the future doin alot of investigatin and findin a company that guarentees there springs like ur talkin bout devon.. But for now im really wonderin how a full bolt on 6.0 is gonna act with my 3400 stall and maybe some spray.lol

I will never install another set of single behive springs. If you loose one you more than likely loose a motor. The last set of the Patriots dual 650's only lasted me about 10k miles before i started seeing valve float. Good thing is with the duals if one breaks you usually don't drop a valve and you can catch it. And theres really no such thing as too much spring pressure. We will see how long the new 675's last..

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Originally Posted by DBRODS

I will never install another set of single behive springs. If you loose one you more than likely loose a motor. The last set of the Patriots dual 650's only lasted me about 10k miles before i started seeing valve float. Good thing is with the duals if one breaks you usually don't drop a valve and you can catch it. And theres really no such thing as too much spring pressure. We will see how long the new 675's last..

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Which springs did you go with Jon?
I went with the patriot extremes. .660 lift should be good for a while.

OP,
How much lift on your cam?

581/588 the springs r supposed to be good to 600...

Damn dude! Sorry to hear the bad news! Makes me want to change out my springs, (PAC) but they have about 20k on them!

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Originally Posted by 06 4.8

Well my dad said take this negative and turn it into a positive..
l

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Wise old man!!!

difficulty is opportunity in disguise!

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Originally Posted by 06 4.8

Well I took off work yesterday to tear my motor apart and found the #6 exhaust valve spring broken, then once i got the head off I looked doen in the block and where a piston is supposed to be i found one chunk about the size of a chicken nugget the rest were so small they fell into the oil pan im assuming. When it happened it completely chewed up the head and ate the spark plug. looking down in the cylinder hole u can see that it chewed up the crank and the cylinder wall was demolished.

Well my dad said take this negative and turn it into a positive..
Hello reman longblock LQ9!!lol

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Were these the original design 26918s, or the recent, higher-rate 26918s?

All the chevrolet geared performance websites need stickies on comp 918s. After reading about the first ones I said no way am I gonna risk my motor. Patriot dual golds for me.

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Originally Posted by zeake

All the chevrolet geared performance websites need stickies on comp 918s. After reading about the first ones I said no way am I gonna risk my motor. Patriot dual golds for me.

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They've killed a few Hemi's too

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Originally Posted by Frenchy

They've killed a few Hemi's too

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so have i. lol

I've got comp duals on my heads.... I'm almost positive that I read that comp/pac are made by same company?