Comp 918 failures?
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From: Spring Lake, MI
Comp 918 failures? How many have had them? Freind of mine broke one on his HD the other night racing a Lexus, I think.
Well you know what happened then right? valve hit the piston with authority, then ended up spitting peices of rod, wristpin and piston right through the oil pan.
Wrecked his night....its his daily driver...good thing we have the motors laying around at the shop though. Makes me doubt the ol' 918's with such a mild cam. His was a custom grind but it was very small. 220/224 572/578 114+4.
Now he is putting one that is at the shop. lol. It happens to be a 6.0l iron block with 2e heads and a 233/239 TSP cam. lol gonna be one mean HD to mess with.
Well you know what happened then right? valve hit the piston with authority, then ended up spitting peices of rod, wristpin and piston right through the oil pan.
Wrecked his night....its his daily driver...good thing we have the motors laying around at the shop though. Makes me doubt the ol' 918's with such a mild cam. His was a custom grind but it was very small. 220/224 572/578 114+4.
Now he is putting one that is at the shop. lol. It happens to be a 6.0l iron block with 2e heads and a 233/239 TSP cam. lol gonna be one mean HD to mess with.
Thread Starter
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From: Spring Lake, MI
Yes they were blue stripe, they had about 20k on them. He was spinnig to 6450 on the 1-2 shift and 6300 on the 2-3 shift. The 2e's he got are indeed MTI heads and they have their dual springs that are good for .650. I have done my share of cam swaps and this was a first for me on a 918 so I was just looking to see if there was other failures like this.
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.570+ lift on both the intake and exhaust on a 220 and 224 lobe, those springs didn't owe him anything. That's fairly agressive lobe. It's generally accepted that you change or check springs at 10-15k mile intervals with that type of lobe profile.
TECH Senior Member
Joined: Mar 2004
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From: BFE
Guys, I've taken 918's to 18k with .610 lifts. All were still within specs.
You do not have to change them every 10k.
THAT IS A MYTH
All you have to do is do spring maintenance, which is measure seat pressures and install heights. If within specs, they will be good for another 10K.
Please do not start this 918 PHOBIA again.
You do not have to change them every 10k.
THAT IS A MYTH
All you have to do is do spring maintenance, which is measure seat pressures and install heights. If within specs, they will be good for another 10K.
Please do not start this 918 PHOBIA again.
Originally Posted by PREDATOR-Z
Guys, I've taken 918's to 18k with .610 lifts. All were still within specs.
You do not have to change them every 10k.
THAT IS A MYTH
All you have to do is do spring maintenance, which is measure seat pressures and install heights. If within specs, they will be good for another 10K.
Please do not start this 918 PHOBIA again.
You do not have to change them every 10k.
THAT IS A MYTH
All you have to do is do spring maintenance, which is measure seat pressures and install heights. If within specs, they will be good for another 10K.
Please do not start this 918 PHOBIA again.
I personally don't think measure load will help, these springs are pretty hard material and any failure will be quick and catastrophic. I plan to go by miles (# of cycles in fatigue terms).
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Originally Posted by vettenuts
I personally don't think measure load will help, these springs are pretty hard material and any failure will be quick and catastrophic. I plan to go by miles (# of cycles in fatigue terms).
#1 reason of their failure is improper warming to operating ops,
# 2 is improper install as per cam requirement.