what the hell is going on with Comp 918s????
05-19-2007, 05:37 PM
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what the hell is going on with Comp 918s???? All of a sudden, I'm hearing about comp blue stripe 918s failing left and right.....
Can anyone give me a straight answer as to what the hell is going on here?
I bought my cam and 918s last July and had them installed around October...They seem to be ok so far through a few thousand miles, though i'm honestly not sure if maybe the valvetrain is making any new noises or not (it always sounded loud and kinda ugly after the cam swap).
Should I be worried about this? for what it's worth, i'm running a .567 lift cam on an XE lobe which seems like it SHOULD be WELL under the limit for these springs....
anyone with some input?
Can anyone give me a straight answer as to what the hell is going on here?
I bought my cam and 918s last July and had them installed around October...They seem to be ok so far through a few thousand miles, though i'm honestly not sure if maybe the valvetrain is making any new noises or not (it always sounded loud and kinda ugly after the cam swap).
Should I be worried about this? for what it's worth, i'm running a .567 lift cam on an XE lobe which seems like it SHOULD be WELL under the limit for these springs....
anyone with some input?
05-20-2007, 07:11 PM
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everyone will have a different answer...i had 27,000 miles on my old comp 918's. The first half of the miles were witha TR227 cam, the 2nd half was with a TSP233/239 with .605 lift. I never had a problem with mine... I bought duals just to be safe this time though.
bye bye LE2 383 Trending Topics
05-22-2007, 08:16 AM
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Originally Posted by DeepBlueZ
All of a sudden, I'm hearing about comp blue stripe 918s failing left and right.....
05-22-2007, 08:48 AM
#10
Mine have been on for about 6k miles with T2 cam and no problems. I've only read a couple failures and its typically propagated into a major thing, when its not. There are alot of factors to consider when hearing these failures and a very big variable is the installer.
This being said, when I get heads later this year, I will be getting a dual spring.
James
This being said, when I get heads later this year, I will be getting a dual spring.
James
05-22-2007, 09:58 AM
#11
Maybe I should have mentioned I did have one broken blue stripe 918, but that was several years ago when they were initially installed. The engine was running just fine with the broken spring. I didn't even know the spring was broken until I pulled the heads to ship them to Richard at WCCH to be CNCed. As I was removing the valves and springs to get the heads ready for shippment I found the broken one. The bottom coil of one spring stuck to the cylinder head deck. The spring hadn't rotated or moved in any way so I got very lucky and no damage was done. Comp replaced the spring for me. That was several years and many thousands of miles ago. I just removed those springs for the second time recently and this time around none were broken. You have to be confident about the parts you install on your engine. If you don't feel right about it swap them for something different, but I wouldn't lose any sleep over having 918s in my engine. The likelyhood of a failure is very slim.
Last edited by eallanboggs; 05-22-2007 at 05:45 PM.
05-22-2007, 06:42 PM
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Originally Posted by HushH
Where have you heard about all of these??? I've seen a few posts on here, but I think most of those have been pre-bluestripe.
They're ALL recent, post blue-stripe.
I'm NOT saying ALL Comp 918s are defective....far from it. I just don't like the timing of these particular cases relative to the time my own cam and valvetrain went in.
05-22-2007, 08:16 PM
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I've had the 918 springs for about two years on a daily driven vehicle and I had the 915's before that. Never had any trouble with either! I feel like Comp has some extremely stringent quality control/assurance processes in place on all of their products.
I'm an engineer in another field and I've investigated warranty trends and field failures on a number of occasions to try to determine root cause. When something happens to you or someone you know, it's easy to jump to conclusions. However, when you try to take a careful, rational look into things you might not jump to those conclusions so quickly.
One thing that I will mention is that valve springs, especially with high spring rates and used with relatively large valve lifts and at high RPM must be brought up to operating temperature before they are pushed hard (especially at or near their design limit). This is true of any manufacturer's springs (single or dual) even with careful attention to metallurgy/quality control, etc.
Steve
I'm an engineer in another field and I've investigated warranty trends and field failures on a number of occasions to try to determine root cause. When something happens to you or someone you know, it's easy to jump to conclusions. However, when you try to take a careful, rational look into things you might not jump to those conclusions so quickly.
One thing that I will mention is that valve springs, especially with high spring rates and used with relatively large valve lifts and at high RPM must be brought up to operating temperature before they are pushed hard (especially at or near their design limit). This is true of any manufacturer's springs (single or dual) even with careful attention to metallurgy/quality control, etc.
Steve
Last edited by Steve Bryant; 05-22-2007 at 09:24 PM.
05-22-2007, 10:00 PM
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Originally Posted by Steve Bryant
One thing that I will mention is that valve springs, especially with high spring rates and used with relatively large valve lifts and at high RPM must be brought up to operating temperature before they are pushed hard (especially at or near their design limit). This is true of any manufacturer's springs (single or dual) even with careful attention to metallurgy/quality control, etc.
Steve
Steve
I agree..I ALWAYS warm up my car for at least a minute before I drive it and I wait till it hits full operating temperature to push it anywhere north of 3000 RPM.
Obviously, I don't know all the specifics of all the cases of breakage lately, but a lot of the people sounded like they were mechanically knowledgeable enough not to push a cold valvetrain.....
05-22-2007, 11:30 PM
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Originally Posted by Steve Bryant
I've had the 918 springs for about two years on a daily driven vehicle and I had the 915's before that. Never had any trouble with either! I feel like Comp has some extremely stringent quality control/assurance processes in place on all of their products.
I'm an engineer in another field and I've investigated warranty trends and field failures on a number of occasions to try to determine root cause. When something happens to you or someone you know, it's easy to jump to conclusions. However, when you try to take a careful, rational look into things you might not jump to those conclusions so quickly.
One thing that I will mention is that valve springs, especially with high spring rates and used with relatively large valve lifts and at high RPM must be brought up to operating temperature before they are pushed hard (especially at or near their design limit). This is true of any manufacturer's springs (single or dual) even with careful attention to metallurgy/quality control, etc.
Steve
I'm an engineer in another field and I've investigated warranty trends and field failures on a number of occasions to try to determine root cause. When something happens to you or someone you know, it's easy to jump to conclusions. However, when you try to take a careful, rational look into things you might not jump to those conclusions so quickly.
One thing that I will mention is that valve springs, especially with high spring rates and used with relatively large valve lifts and at high RPM must be brought up to operating temperature before they are pushed hard (especially at or near their design limit). This is true of any manufacturer's springs (single or dual) even with careful attention to metallurgy/quality control, etc.
Steve
Very well said indeed. FWIW, I have about 6000 miles on my comp 918 springs installed about 1.5 years ago and ALWAYS bring my blown C5 Z06 (with stock LS6) up to full operating temps. anytime she sees in excess of 3000 rpm!
05-26-2007, 09:31 AM
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Originally Posted by SS Enforcer
So it looks like the new comp 918's may be crap after all. So now what do I do with the new ones I just bought.
cheers
cheers
As with any product, proper installation is key. How many people that use 918s actually check the install height? How many actually shim the springs so that they are at the proper install height. All of these things are important factors not only in the performance of a spring but also in its life. How many of these springs are being used with these ridiculously aggressive cam profiles that punish the valvetrain? So many variables....yet everyone wants simple answers....typical...
Andrew
05-27-2007, 02:00 AM
#18
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Agreed with Projects' theory. I ran a set 2000 road miles and three SCCA race weekends last year with .600 lift, swaped for a new set when I changed guide seals this year. No problems yet. Yes, they are shimmed to recommended height.
Steve B good call on temp. I always wait until oil is at 180 before WOT runs. Saw this proven on Dyno several years ago, several dyno runs at 150 oil temp, spit out bearings. 180 never a problem.
Steve B good call on temp. I always wait until oil is at 180 before WOT runs. Saw this proven on Dyno several years ago, several dyno runs at 150 oil temp, spit out bearings. 180 never a problem.
05-27-2007, 11:08 AM
#19
