JamesB

What happens when your LS1 loses a valve spring

13 posts in this topic

I thought you guys might like to see this.

A dyno specialist I know from an Australian performance forum posted this. It's the LS1 in one of his co worker's cars.

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valve spring broke, valve fell in and head broke off

block has a hole in it from where half the piston went out the side, the motor is a throw away.

there were lots of bits all through the motor, although the back cylinders were not to bad

His co worker is not happy at the moment.
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OUCH!

I've never seen anything like that.

It ain't pretty.

For interest, the spring was a "comp cams 918" The dyno shop has made a decision not to use them again in any engine they build.

The piston shattered when the valve dropped in, there was half a valve in the exhaust pipe!! LOL the ls1 has a windage tray which half a piston fell onto then the crank pushed it out the block.

The same dyno shop runs a street/strip turboed LS1 in a VY Ute. It's putting out 574.2 rwhp @ 15 psi boost (dyno estimated 707.9 hp @ flywheel). Now they've got to work on getting the power to the track (the strip in Sydney has an absolutely crap surface, and is poorly maintained). video.

11.3 first pass, turned the tyres that hard in the 1st 3 gears it was a peddle show,

pulled 50hp out and still fryed them through the first 3 gears with a 11.2

pulled another 30 out and missed a damn gear for a 12.0 with a big moment across the line, its fun pointing at walls at 200km/h!

They stretched the head studs on one bank during the last run due to the missed gear and the over rev. Even though they have an available LS2 engine, the decision has been made to fit a cast iron 6.0 litre in place of the LS1 in the Ute. The LS1 is going into a ski boat.
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Further update.

After making enquiries amongst the other engine builders, the dyno specialist has heard of at least 4 other failures of the same series of springs in the past few months. One report indicates that the spring manufacturer went to a new supplier of the spring material some time before the springs started breaking.

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This is the first ls1 i have seen do that. I have seen a 302 ford do this though. A friend of mine had more valvetrain issues than anyone i have ever known. I have actually used those springs before in an ls1 build. There is usually nothing wrong with them, provided you are not running a cam with lots of lift and duration. They only last about 12-15K before you start to see real bad valve float. You get much less miles if you hit the rev limiter a couple of times.

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HOw much NOS was involved? :AH-HA_wink:

All joking aside that sucks. The LS1 is still a GREAT motor.

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This is the first ls1 i have seen do that. I have seen a 302 ford do this though. A friend of mine had more valvetrain issues than anyone i have ever known. I have actually used those springs before in an ls1 build. There is usually nothing wrong with them, provided you are not running a cam with lots of lift and duration. They only last about 12-15K before you start to see real bad valve float. You get much less miles if you hit the rev limiter a couple of times.

That brand of springs were pretty much the standard for LS1s over here, but since the "rumored" change of spring material supplier, and the rash of broken springs, people are now steering clear of them.

That particular engine hasn't been revved over 6500, and the cam they are running is a 222/224/112 grind with .560 lift. Those springs are supposedly good for .600 lift. The brand of springs they are now running are good for .610 lift with aggressive ramp rates.

Another guy on the forum is a service mechanic at one of the Holden dealers, and he says that there has been a spate of broken valve springs on the factory 300kW engine. Here's the post he made (with slight edits for profanity)

I've had $h!loads of the factory 300kW cars with broken valve springs, usually they drive in with a misfire, we replace the spring (generally warranty won't pay for a full set but will pay for a motor if it goes bang...go figure) and off they go until the next one breaks.

In my experience they are amazingly hard to kill - I had a 300kW Coupe in a while back that had a big TB, exhaust, Mafless etc and a missfire, but the exhaust still sounded tough. (even with the broken spring)

So the f***head service advisor thought he would do a lap of the block at 11tybillion rpm to see how it went, then parked it in the workshop.

The workshop manager heard the car and came over for a stickybeak, before starting it and free-revving the jeesus out of it "to hear how it sounded".

I stood there with my jaw on the floor in disbelief, hoping the motor would let go just to see the look on the c***heads face while he tried to explain to the customer and the boss why a very expensive motor was now in pieces.

By some miracle it didn't drop a valve, I pulled the spring out in 4 pieces and we managed to get a full set for the customer under warranty.

This was another 300 car that wore a lobe off the cam, and pumped bits of hardened steel around with the oil until all the bores were cactus.

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That's just freaky, talk about a bad day....although that doesn't surprise me to hear about the valve springs breaking, everything has a limit....

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