Why am I breaking valves???
08-28-2007, 05:11 PM
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Why am I breaking valves??? I tried posting this in the Gen III internal page and haven't recieved much input I thought maybe some of you advanced guys would have a better idea. In the last year I have broken 2 valves on 2 different motors and I can't help but wonder why.
The car is a 2002 Z06 that I run road racing track events with, I'm not hard on the motor, I shift right at or a little after 6k, 6200 at the most. I haven't mis-shifted/overreved either motor. (Rarley I'll hit the gate instead of the gear but I never aimed for 4th and hit 2nd) I heel toe downshift and blip the throttle to match revs coming into corners but not anything out of the ordinary at the track.
Tunes are conservative running less than 13 to 1 AF usually between 12.5 to 12.7 on the WOT pulls.
The car has full bolt ons, 1 3/4 Melrose Motorsports headers, Random cats, stock Ti mufflers, DeWitt's radiator with internal engine oil cooler, Blackwing, ported throttle body (by LPE), ported LS6 intake (by LPE).
1st motor stock LS6 bottom end with LPE heads, LPE GT1-1 cam (229in/242ex .631"in/.631"ex 114 lsa) stock LS6 valves, Comp 921 valve springs, Comp push rods, and Harland Sharp rebuilt stock rockers. I put about 2k miles on the motor and the way I figure the head of the number 8 exhaust valve broke off and blew the motor, broke the timing chain and cracked the block. I've also entertained other ideas, such as valve float, but I don't think the lightweight valve floated with a 921 spring, if anything I think we had too much spring for that valve. So there I am with a blown LS6, I figure this time I will have LPE build me a motor from top to bottom so it's done right.
2nd motor LS6 stoker Callies Racemaster crank, Manley H beam rods, JE pistons, LPE heads, LPE GT11 cam (215in/231ex .631in/.644ex 118 lsa), (I think the valves were Manley but I do know that they were Titainium intake and exhaust, Ferrea 99100 valve springs (150#@ 1.800" 475#@ 1.250" CB 1.050"), Comp pushrods, and T&D shaft mount rocker arms. This time the number 3 exhaust valve head broke off and took out the head and the block.
So WHAT THE HELL!!!!! Both times I tried to keep the valve train lightweight to minimize the chance of valve float etc, I keep the revs down and both times a valve head breaks off. Do I just have the worlds worst luck or am I missing something here?
The car is a 2002 Z06 that I run road racing track events with, I'm not hard on the motor, I shift right at or a little after 6k, 6200 at the most. I haven't mis-shifted/overreved either motor. (Rarley I'll hit the gate instead of the gear but I never aimed for 4th and hit 2nd) I heel toe downshift and blip the throttle to match revs coming into corners but not anything out of the ordinary at the track.
Tunes are conservative running less than 13 to 1 AF usually between 12.5 to 12.7 on the WOT pulls.
The car has full bolt ons, 1 3/4 Melrose Motorsports headers, Random cats, stock Ti mufflers, DeWitt's radiator with internal engine oil cooler, Blackwing, ported throttle body (by LPE), ported LS6 intake (by LPE).
1st motor stock LS6 bottom end with LPE heads, LPE GT1-1 cam (229in/242ex .631"in/.631"ex 114 lsa) stock LS6 valves, Comp 921 valve springs, Comp push rods, and Harland Sharp rebuilt stock rockers. I put about 2k miles on the motor and the way I figure the head of the number 8 exhaust valve broke off and blew the motor, broke the timing chain and cracked the block. I've also entertained other ideas, such as valve float, but I don't think the lightweight valve floated with a 921 spring, if anything I think we had too much spring for that valve. So there I am with a blown LS6, I figure this time I will have LPE build me a motor from top to bottom so it's done right.
2nd motor LS6 stoker Callies Racemaster crank, Manley H beam rods, JE pistons, LPE heads, LPE GT11 cam (215in/231ex .631in/.644ex 118 lsa), (I think the valves were Manley but I do know that they were Titainium intake and exhaust, Ferrea 99100 valve springs (150#@ 1.800" 475#@ 1.250" CB 1.050"), Comp pushrods, and T&D shaft mount rocker arms. This time the number 3 exhaust valve head broke off and took out the head and the block.
So WHAT THE HELL!!!!! Both times I tried to keep the valve train lightweight to minimize the chance of valve float etc, I keep the revs down and both times a valve head breaks off. Do I just have the worlds worst luck or am I missing something here?
08-28-2007, 08:20 PM
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If the exhaust down-ramp is really extreme and you are turning
big RPM, is there a chance that the cam "outruns the spring" and
the valve smacks the seat uncontrolled? Is the valvetrain noisier
than "normal"?
If the lifter squishes or was set up with positive (?) lash you may
add to this problem. You would like a soft landing of sorts and no
slop. Impact makes for fractures.
big RPM, is there a chance that the cam "outruns the spring" and
the valve smacks the seat uncontrolled? Is the valvetrain noisier
than "normal"?
If the lifter squishes or was set up with positive (?) lash you may
add to this problem. You would like a soft landing of sorts and no
slop. Impact makes for fractures.
08-28-2007, 10:35 PM
#4
Look out for any black cats crossing your path.
I dont think there is any reason other than valve failures. They dont make different valves based on spring pressures. Bounce could be an issue, but I doubt it. Never been crazy about the 2 piece design of standard valves. Seen a few take out perfectly good motors.
I would think this is a good question for one of the guys that run a spintron.
The RPMs you're running, combined with a dual spring designed for a hyd roller, shouldnt be pounding the heads off.
I dont think there is any reason other than valve failures. They dont make different valves based on spring pressures. Bounce could be an issue, but I doubt it. Never been crazy about the 2 piece design of standard valves. Seen a few take out perfectly good motors.
I would think this is a good question for one of the guys that run a spintron.
The RPMs you're running, combined with a dual spring designed for a hyd roller, shouldnt be pounding the heads off.
08-28-2007, 10:39 PM
#5
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Originally Posted by LT-4Play
I tried posting this in the Gen III internal page and haven't recieved much input I thought maybe some of you advanced guys would have a better idea. In the last year I have broken 2 valves on 2 different motors and I can't help but wonder why.
The car is a 2002 Z06 that I run road racing track events with, I'm not hard on the motor, I shift right at or a little after 6k, 6200 at the most. I haven't mis-shifted/overreved either motor. (Rarley I'll hit the gate instead of the gear but I never aimed for 4th and hit 2nd) I heel toe downshift and blip the throttle to match revs coming into corners but not anything out of the ordinary at the track.
Tunes are conservative running less than 13 to 1 AF usually between 12.5 to 12.7 on the WOT pulls.
The car has full bolt ons, 1 3/4 Melrose Motorsports headers, Random cats, stock Ti mufflers, DeWitt's radiator with internal engine oil cooler, Blackwing, ported throttle body (by LPE), ported LS6 intake (by LPE).
1st motor stock LS6 bottom end with LPE heads, LPE GT1-1 cam (229in/242ex .631"in/.631"ex 114 lsa) stock LS6 valves, Comp 921 valve springs, Comp push rods, and Harland Sharp rebuilt stock rockers. I put about 2k miles on the motor and the way I figure the head of the number 8 exhaust valve broke off and blew the motor, broke the timing chain and cracked the block. I've also entertained other ideas, such as valve float, but I don't think the lightweight valve floated with a 921 spring, if anything I think we had too much spring for that valve. So there I am with a blown LS6, I figure this time I will have LPE build me a motor from top to bottom so it's done right.
2nd motor LS6 stoker Callies Racemaster crank, Manley H beam rods, JE pistons, LPE heads, LPE GT11 cam (215in/231ex .631in/.644ex 118 lsa), (I think the valves were Manley but I do know that they were Titainium intake and exhaust, Ferrea 99100 valve springs (150#@ 1.800" 475#@ 1.250" CB 1.050"), Comp pushrods, and T&D shaft mount rocker arms. This time the number 3 exhaust valve head broke off and took out the head and the block.
So WHAT THE HELL!!!!! Both times I tried to keep the valve train lightweight to minimize the chance of valve float etc, I keep the revs down and both times a valve head breaks off. Do I just have the worlds worst luck or am I missing something here?
The car is a 2002 Z06 that I run road racing track events with, I'm not hard on the motor, I shift right at or a little after 6k, 6200 at the most. I haven't mis-shifted/overreved either motor. (Rarley I'll hit the gate instead of the gear but I never aimed for 4th and hit 2nd) I heel toe downshift and blip the throttle to match revs coming into corners but not anything out of the ordinary at the track.
Tunes are conservative running less than 13 to 1 AF usually between 12.5 to 12.7 on the WOT pulls.
The car has full bolt ons, 1 3/4 Melrose Motorsports headers, Random cats, stock Ti mufflers, DeWitt's radiator with internal engine oil cooler, Blackwing, ported throttle body (by LPE), ported LS6 intake (by LPE).
1st motor stock LS6 bottom end with LPE heads, LPE GT1-1 cam (229in/242ex .631"in/.631"ex 114 lsa) stock LS6 valves, Comp 921 valve springs, Comp push rods, and Harland Sharp rebuilt stock rockers. I put about 2k miles on the motor and the way I figure the head of the number 8 exhaust valve broke off and blew the motor, broke the timing chain and cracked the block. I've also entertained other ideas, such as valve float, but I don't think the lightweight valve floated with a 921 spring, if anything I think we had too much spring for that valve. So there I am with a blown LS6, I figure this time I will have LPE build me a motor from top to bottom so it's done right.
2nd motor LS6 stoker Callies Racemaster crank, Manley H beam rods, JE pistons, LPE heads, LPE GT11 cam (215in/231ex .631in/.644ex 118 lsa), (I think the valves were Manley but I do know that they were Titainium intake and exhaust, Ferrea 99100 valve springs (150#@ 1.800" 475#@ 1.250" CB 1.050"), Comp pushrods, and T&D shaft mount rocker arms. This time the number 3 exhaust valve head broke off and took out the head and the block.
So WHAT THE HELL!!!!! Both times I tried to keep the valve train lightweight to minimize the chance of valve float etc, I keep the revs down and both times a valve head breaks off. Do I just have the worlds worst luck or am I missing something here?
The things I noticed:
Ti intake and exhaust valves on a 6200 rpm engine? Why Ti exhaust? I believe the Daytona Prototype (DP) engines use stock LS6 valve sizes, spin to 7100 for up to 24 hours and only use Ti on the 2.00 intakes [edit: oops, I think they use Ti exhausts also on the GM DP engines, come to think of it] with very aggressive lobes. IMO, IF you need Ti intakes, buy good ones, or have your builder buy good ones. Xceldyne and DelWest come to mind, but, IMO, Ti is overkill for your engine. There are some really nice SS valves from folks like Ferrea.
Running valve springs over .100 from coil bind? Isn't .040 or so more like it? I'd probably use other springs. Nitrided PAC beehives which handle .650 might be a choice.
I don't know whose lobes LPE uses, but maybe bouncing on the seat is screwing the exhaust. Your problems seem to be valvetrain related, so perhaps you might go to a valvetrain specialist for help.
My $.02
Last edited by Old SStroker; 09-17-2007 at 09:58 PM. Reason: More info.
08-29-2007, 07:03 AM
#7
Originally Posted by Old SStroker
No offense intended to LPE, but perhaps it's the choice of components.
The things I noticed:
Ti intake and exhaust valves on a 6200 rpm engine? Why Ti exhaust? I believe the Daytona Prototype (DP) engines use stock LS6 valve sizes, spin to 7100 for up to 24 hours and only use Ti on the 2.00 intakes with very aggressive lobes. IMO, IF you need Ti intakes, buy good ones, or have your builder buy good ones. Xceldyne comes to mind, but, IMO, Ti is overkill for your engine. There are some really nice SS valves from folks like Ferrea.
Running valve springs over .100 from coil bind? Isn't .040 or so more like it? I'd probably use other springs. Nitrided PAC beehives which handle .650 might be a choice.
I don't know whose lobes LPE uses, but maybe bouncing on the seat is screwing the exhaust. Your problems seem to be valvetrain related, so perhaps you might go to a valvetrain specialist for help.
My $.02
The things I noticed:
Ti intake and exhaust valves on a 6200 rpm engine? Why Ti exhaust? I believe the Daytona Prototype (DP) engines use stock LS6 valve sizes, spin to 7100 for up to 24 hours and only use Ti on the 2.00 intakes with very aggressive lobes. IMO, IF you need Ti intakes, buy good ones, or have your builder buy good ones. Xceldyne comes to mind, but, IMO, Ti is overkill for your engine. There are some really nice SS valves from folks like Ferrea.
Running valve springs over .100 from coil bind? Isn't .040 or so more like it? I'd probably use other springs. Nitrided PAC beehives which handle .650 might be a choice.
I don't know whose lobes LPE uses, but maybe bouncing on the seat is screwing the exhaust. Your problems seem to be valvetrain related, so perhaps you might go to a valvetrain specialist for help.
My $.02
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08-29-2007, 09:31 AM
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Wow thanks for the responses!
I do all of the work on my car, I have a full shop that does work on vettes. I've worked on plenty of C5's and this is the first car to have such problems.
The reason that LPE and I went with Ti on this motor was because it was going to be used for roadracing events and most of it's life was going to be spent at 3k to 6k rpm we would keep the valvetrain as light as possible to save valvesprings etc. Also Ti, I thought was stronger and displaced heat better than stainless.
Now when LPE did the break in they said that there was valve float at 6500 rpm so that is when we switched from 921's (135#@1.770 400#@1.120 1.040" CB) to the Ferrea valve springs (150#@ 1.800" 475#@ 1.250" CB 1.050"). This allowed the engine to rev past 6800 with no float. Now when we intially built the motor and talked about the Ti valves we figured that this motor would rev to 7k no problem, so it did seem odd to me that there would be float at 6500 with the 921's.
Comp grinds LPE's cams but they use some pretty easy lobes I thought they were similar the the lobes that GM uses.
Also the reason that I didn't rev the motor past 6200 was because it wasn't making any more power. The motor made 525 fwhp from 6000 all the way to 6500, if it would have made more power I would have let it spin a little more. Also I was planning on going to more new tracks and it's hard to know where you could use a couple more revs.
The first motor I figure the valve failed first because there was a double roller chain on the car and the valve was wedged into the head.
I do all of the work on my car, I have a full shop that does work on vettes. I've worked on plenty of C5's and this is the first car to have such problems.
The reason that LPE and I went with Ti on this motor was because it was going to be used for roadracing events and most of it's life was going to be spent at 3k to 6k rpm we would keep the valvetrain as light as possible to save valvesprings etc. Also Ti, I thought was stronger and displaced heat better than stainless.
Now when LPE did the break in they said that there was valve float at 6500 rpm so that is when we switched from 921's (135#@1.770 400#@1.120 1.040" CB) to the Ferrea valve springs (150#@ 1.800" 475#@ 1.250" CB 1.050"). This allowed the engine to rev past 6800 with no float. Now when we intially built the motor and talked about the Ti valves we figured that this motor would rev to 7k no problem, so it did seem odd to me that there would be float at 6500 with the 921's.
Comp grinds LPE's cams but they use some pretty easy lobes I thought they were similar the the lobes that GM uses.
Also the reason that I didn't rev the motor past 6200 was because it wasn't making any more power. The motor made 525 fwhp from 6000 all the way to 6500, if it would have made more power I would have let it spin a little more. Also I was planning on going to more new tracks and it's hard to know where you could use a couple more revs.
The first motor I figure the valve failed first because there was a double roller chain on the car and the valve was wedged into the head.
08-29-2007, 10:05 AM
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Ferrea LS1 springs are aweful and very breakage prone.
Piston Top pictures please !
Piston Top pictures please !
Originally Posted by LT-4Play
Wow thanks for the responses!
I do all of the work on my car, I have a full shop that does work on vettes. I've worked on plenty of C5's and this is the first car to have such problems.
The reason that LPE and I went with Ti on this motor was because it was going to be used for roadracing events and most of it's life was going to be spent at 3k to 6k rpm we would keep the valvetrain as light as possible to save valvesprings etc. Also Ti, I thought was stronger and displaced heat better than stainless.
Now when LPE did the break in they said that there was valve float at 6500 rpm so that is when we switched from 921's (135#@1.770 400#@1.120 1.040" CB) to the Ferrea valve springs (150#@ 1.800" 475#@ 1.250" CB 1.050"). This allowed the engine to rev past 6800 with no float. Now when we intially built the motor and talked about the Ti valves we figured that this motor would rev to 7k no problem, so it did seem odd to me that there would be float at 6500 with the 921's.
Comp grinds LPE's cams but they use some pretty easy lobes I thought they were similar the the lobes that GM uses.
Also the reason that I didn't rev the motor past 6200 was because it wasn't making any more power. The motor made 525 fwhp from 6000 all the way to 6500, if it would have made more power I would have let it spin a little more. Also I was planning on going to more new tracks and it's hard to know where you could use a couple more revs.
The first motor I figure the valve failed first because there was a double roller chain on the car and the valve was wedged into the head.
I do all of the work on my car, I have a full shop that does work on vettes. I've worked on plenty of C5's and this is the first car to have such problems.
The reason that LPE and I went with Ti on this motor was because it was going to be used for roadracing events and most of it's life was going to be spent at 3k to 6k rpm we would keep the valvetrain as light as possible to save valvesprings etc. Also Ti, I thought was stronger and displaced heat better than stainless.
Now when LPE did the break in they said that there was valve float at 6500 rpm so that is when we switched from 921's (135#@1.770 400#@1.120 1.040" CB) to the Ferrea valve springs (150#@ 1.800" 475#@ 1.250" CB 1.050"). This allowed the engine to rev past 6800 with no float. Now when we intially built the motor and talked about the Ti valves we figured that this motor would rev to 7k no problem, so it did seem odd to me that there would be float at 6500 with the 921's.
Comp grinds LPE's cams but they use some pretty easy lobes I thought they were similar the the lobes that GM uses.
Also the reason that I didn't rev the motor past 6200 was because it wasn't making any more power. The motor made 525 fwhp from 6000 all the way to 6500, if it would have made more power I would have let it spin a little more. Also I was planning on going to more new tracks and it's hard to know where you could use a couple more revs.
The first motor I figure the valve failed first because there was a double roller chain on the car and the valve was wedged into the head.
08-29-2007, 10:44 AM
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I just looked at the pictures that I have taken, and I only have a picture of the bad hole. I only took one head off anyway, so I wouldn't be able to get you all of the piston tops. I had the valve covers off and none of the springs were broken, visually. Plus there was just over 2k miles on the motor, probably 30 hours including break in time. I wouldn't think a spring would fail that quickly. JMO
08-29-2007, 10:50 AM
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0.630 ish camshaft with short lobes. Oh yeah ferrea spring is junk it could have broken faster. Get me pictures of the 4cylinder that are exsposed please.
Originally Posted by LT-4Play
I just looked at the pictures that I have taken, and I only have a picture of the bad hole. I only took one head off anyway, so I wouldn't be able to get you all of the piston tops. I had the valve covers off and none of the springs were broken, visually. Plus there was just over 2k miles on the motor, probably 30 hours including break in time. I wouldn't think a spring would fail that quickly. JMO
08-29-2007, 10:51 AM
#13
Originally Posted by LT-4Play
Wow thanks for the responses!
I do all of the work on my car, I have a full shop that does work on vettes. I've worked on plenty of C5's and this is the first car to have such problems.
The reason that LPE and I went with Ti on this motor was because it was going to be used for roadracing events and most of it's life was going to be spent at 3k to 6k rpm we would keep the valvetrain as light as possible to save valvesprings etc. Also Ti, I thought was stronger and displaced heat better than stainless.
Now when LPE did the break in they said that there was valve float at 6500 rpm so that is when we switched from 921's (135#@1.770 400#@1.120 1.040" CB) to the Ferrea valve springs (150#@ 1.800" 475#@ 1.250" CB 1.050"). This allowed the engine to rev past 6800 with no float. Now when we intially built the motor and talked about the Ti valves we figured that this motor would rev to 7k no problem, so it did seem odd to me that there would be float at 6500 with the 921's.
Comp grinds LPE's cams but they use some pretty easy lobes I thought they were similar the the lobes that GM uses.
Also the reason that I didn't rev the motor past 6200 was because it wasn't making any more power. The motor made 525 fwhp from 6000 all the way to 6500, if it would have made more power I would have let it spin a little more. Also I was planning on going to more new tracks and it's hard to know where you could use a couple more revs.
The first motor I figure the valve failed first because there was a double roller chain on the car and the valve was wedged into the head.
I do all of the work on my car, I have a full shop that does work on vettes. I've worked on plenty of C5's and this is the first car to have such problems.
The reason that LPE and I went with Ti on this motor was because it was going to be used for roadracing events and most of it's life was going to be spent at 3k to 6k rpm we would keep the valvetrain as light as possible to save valvesprings etc. Also Ti, I thought was stronger and displaced heat better than stainless.
Now when LPE did the break in they said that there was valve float at 6500 rpm so that is when we switched from 921's (135#@1.770 400#@1.120 1.040" CB) to the Ferrea valve springs (150#@ 1.800" 475#@ 1.250" CB 1.050"). This allowed the engine to rev past 6800 with no float. Now when we intially built the motor and talked about the Ti valves we figured that this motor would rev to 7k no problem, so it did seem odd to me that there would be float at 6500 with the 921's.
Comp grinds LPE's cams but they use some pretty easy lobes I thought they were similar the the lobes that GM uses.
Also the reason that I didn't rev the motor past 6200 was because it wasn't making any more power. The motor made 525 fwhp from 6000 all the way to 6500, if it would have made more power I would have let it spin a little more. Also I was planning on going to more new tracks and it's hard to know where you could use a couple more revs.
The first motor I figure the valve failed first because there was a double roller chain on the car and the valve was wedged into the head.
08-30-2007, 09:05 AM
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Sorry, I didn't take a good picture of the piston tops but I did take a pic of the head.
http://i236.photobucket.com/albums/f...g?t=1188482428
I did find out the valves were made by Victory Valves, and they were one piece forged Ti valves.
Victory Valves
Hope this helps
http://i236.photobucket.com/albums/f...g?t=1188482428
I did find out the valves were made by Victory Valves, and they were one piece forged Ti valves.
Victory Valves
Hope this helps
08-30-2007, 11:47 AM
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How do the valve seats look on the rest of the cylinders that didn't break valves ? Also did the intake or exhuast valve break ? Waned to see the pistons to look and see if they had valve reliefes. Looks good there.
Originally Posted by LT-4Play
Sorry, I didn't take a good picture of the piston tops but I did take a pic of the head.
http://i236.photobucket.com/albums/f...g?t=1188482428
I did find out the valves were made by Victory Valves, and they were one piece forged Ti valves.
Victory Valves
Hope this helps
http://i236.photobucket.com/albums/f...g?t=1188482428
I did find out the valves were made by Victory Valves, and they were one piece forged Ti valves.
Victory Valves
Hope this helps
08-30-2007, 05:00 PM
#17
Originally Posted by LS1curious
How do the valve seats look on the rest of the cylinders that didn't break valves ? Also did the intake or exhuast valve break ? Waned to see the pistons to look and see if they had valve reliefes. Looks good there.
08-30-2007, 06:22 PM
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This engine was consuming a tremendous amount of oil. My thought is that the valves have fatigued from excessive heating. Most likely looking at the valve itself the excessive combustion temps came from prolonged detonation due to oil contimination.
I suggest finding a new engine builder experienced with building road racing engines.
I suggest finding a new engine builder experienced with building road racing engines.
08-30-2007, 06:34 PM
#19
Originally Posted by LS1curious
This engine was consuming a tremendous amount of oil. My thought is that the valves have fatigued from excessive heating. Most likely looking at the valve itself the excessive combustion temps came from prolonged detonation due to oil contimination.
I suggest finding a new engine builder experienced with building road racing engines.
I suggest finding a new engine builder experienced with building road racing engines.
Yeah it was burnin oil, but ya think its gonna snap a one piece titanium valve due to elevated combustion temps due to detonation, before its going to burn an aluminum piston? OoooKaaayyy.......
Before I put it on something like that, I'd more say it was retarded timing, causing increased exhaust temps. That would more likely cook an exhaust valve stem. Detonation would more likely burn a piston, as its happening in the chamber. Increased exhaust temps occurring in the port would have more of an effect on the stem.
Besides, from the pics, no sign of severe detonation. It is going thru some oil though.
