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Heads - fix oem or go aftermarket?

 
Old 07-11-2019, 05:00 PM
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matt95
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Default Heads - fix oem or go aftermarket?

Bought an 08' Z, bone stock, 30k miles and want to remedy the head issue. I've read and read and not found a definitive answer, possibly because there isn't one?? Anyway my overall goals would be a somewhat mild cam and heads. May do exhaust and intake down the road. Certainly not going for max hp. It's a sunny day driver, probably hit the strip on occasion and possibly a track day or two. If I end up at 550 to the wheels or more i'll be happy.

The real question is fix the oem heads or just go aftermarket? With the different approaches to fixing, replace guides and polish valves or bronze and Katech TiMo valves, maybe it's better to just go with aftermarket?? I'd rather spend an extra grand now than do the heads again in 15k miles.

Input is appreciated, as I certainly am confused after reading for way too many hours...
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Old 07-11-2019, 05:38 PM
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Aftermarket offers no real advantage at those levels. You get 6 bolt, thick deck, but nothing special or good about guides/machining/etc. You start with an aftermarket casting and still have to send it somewhere to get machined, setup, pick out guides, valves, etc.

The 3 places I would choose from are AI, WCCH and SPS. Talk to them all, pick which is closest, or suites you best, and go for it.

Even aftermarket heads need to be redone often if you go aggressive on cam or don't pick a good combo. Plus most of them need expensive valves/etc that really add to the cost.
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Old 07-11-2019, 08:13 PM
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Thanks for the info, always more I can learn! I was thinking a person could order the prc 265’s or trick flows for just over 3k, sell the oem heads and be done for a bit over 2k vs 1.5k to fix the oem heads. That’s what got me thinking a bit more investment on the front side may be worth it.

Last edited by matt95; 07-12-2019 at 07:31 AM.
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Old 07-11-2019, 09:06 PM
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When you add in Ti valves, which you will want unless you are going to turn the redline down 500-800rpm, the cost becomes more than that. Same with springs, and other parts needed. PRC with decent valves/etc come out to $3400ish, so not much more, but still more.
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Old 07-12-2019, 10:13 AM
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If looking for 550 RWHP, intake & headers will be required.
Add $3-5K depending on what's used to whatever cam/tune/heads cost.

Just went through this last June w/ my '08 w/ 62K at the time.
Opted for 'baby cam', head rebuild w/ a few upgrades, tune & pre/post dyno runs, didn't do an intake or headers.
I & H would've put me somewhere over 500 RWH, plenty satisfied w/ 485 so passed.
What I got nicked me ~$6K as it is, easily be around $10K w/ those other 2 items.
Good headers aren't cheap and neither are decent intakes.
Unless DIY, labor's a sizable bite.

Consensus is LS7 heads should be inspected every ~15K unless willing to assume some risk.
I chalked it up to required maintenance w/ an amazing and quite unique powerplant.
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Old 07-12-2019, 10:29 AM
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I'm not looking to lower the redline, as it's part of what makes the LS7 so unique and great, at least in my opinion.

I hope to do heads and a cam now, with intake and exhaust as possibilities down the road.

Goal was to avoid the 15k head maintenance, fix it once and be done, maybe that's not possible though...
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Old 07-12-2019, 11:11 AM
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Why is there now a 15k maintenance? I havent seen that in the user manual...
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Old 07-12-2019, 02:16 PM
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Originally Posted by Apocolipse View Post
Why is there now a 15k maintenance? I havent seen that in the user manual...
Maybe he's referring to the general guideline of inspecting the heads every 15K miles or so to check on guide wear? Even with fixed heads, folks have had them go out of spec again. Not sure what all heads this has happened on, but I know I've seen threads on AHP and WCCH at least with out of spec guides after the initial fix. I'm at 10K on my AHP heads and will be having them inspected within the next couple thousand miles if I don't part ways with the car first. I've accepted that as long as I keep the car, wiggle tests or some other form of inspection will be part of the cost of ownership; I don't personally believe there is a fix and forget option.

Last edited by 99Hawk262; 07-12-2019 at 02:19 PM.
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Old 07-12-2019, 02:26 PM
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Moly coated valves and whatever guides or ms90 guides and stock valves is the fix.
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Old 07-12-2019, 02:43 PM
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Originally Posted by Unreal View Post
Aftermarket offers no real advantage at those levels. You get 6 bolt, thick deck, but nothing special or good about guides/machining/etc. You start with an aftermarket casting and still have to send it somewhere to get machined, setup, pick out guides, valves, etc.

The 3 places I would choose from are AI, WCCH and SPS. Talk to them all, pick which is closest, or suites you best, and go for it.

Even aftermarket heads need to be redone often if you go aggressive on cam or don't pick a good combo. Plus most of them need expensive valves/etc that really add to the cost.
SPS Did my heads and Iím super happy.
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Old 07-12-2019, 03:01 PM
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Originally Posted by 99Hawk262 View Post
Maybe he's referring to the general guideline of inspecting the heads every 15K miles or so to check on guide wear? Even with fixed heads, folks have had them go out of spec again. Not sure what all heads this has happened on, but I know I've seen threads on AHP and WCCH at least with out of spec guides after the initial fix. I'm at 10K on my AHP heads and will be having them inspected within the next couple thousand miles if I don't part ways with the car first. I've accepted that as long as I keep the car, wiggle tests or some other form of inspection will be part of the cost of ownership; I don't personally believe there is a fix and forget option.
Yes, inspecting every 15k is what I was referring to. Maybe that's just part of the cost to own one of these beasts.
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Old 07-13-2019, 08:41 AM
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Unfortunately, I don't think there is a permanent "fix". There are posts on here about problems occurring with aftermarket heads also
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Old 07-15-2019, 11:20 PM
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Originally Posted by 449er View Post
Unfortunately, I don't think there is a permanent "fix". There are posts on here about problems occurring with aftermarket heads also
As a "new" owner of a 2010 Z06 without the head fix, I don't understand there not being a more permanent solution. From my brief reading, the problem stems from poor machining on the part of the vendor/supplier of the factory heads with the main problem being the valve seats were not concentric to the valves. Every time the valve came into contact with the seat, it put the valve stem in a bind against the guide and would consequently enlarge the I.D. along with weakening the valve stem through continuous bending. So, I fail to see why properly machined heads would not be much more reliable. It's also been said that bronze guides hold lubrication better than other types of valve guide material.

Last edited by MPeters1961; 07-16-2019 at 11:20 PM.
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Old 07-15-2019, 11:23 PM
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Bronze and CrN dont mix.
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Old 07-15-2019, 11:40 PM
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Originally Posted by Apocolipse View Post
Bronze and CrN dont mix.
Fill me in. Where does Chromium Nitride come into play? Are you saying the valves are CrN coated?
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Old 07-16-2019, 12:13 AM
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Originally Posted by MPeters1961 View Post
As a "new" owner of a 2010 Z06 without the head fix, I don't understand there not being a more permanent solution. From my brief reading, the problem stems from poor machining on the part of the vendor/supplier of the factory heads with the main problem being the valve seats were not concentric to the valve seats. Every time the valve seat came into contact with the seat, it put the valve stem in a bind against the guide and would consequently enlarge the I.D. along with weakening the valve stem through continuous bending. So, I fail to see why properly machined heads would not be much more reliable. It's also been said that bronze guides hold lubrication better than other types of valve guide material.
Just got done doing this run around with my ZR1, I talked to just about every shop in the country about what they suggest.

The consensus... The machining is fine, the reason I have got is as follows...

Exhaust:
The PM guides don't take heat away from the sodium exhaust fast enough and burned the thin layer of oil turning it into what is basically a rubbing compound slowly eating at the guide.

Intake:
The Ti valves are missing the moly coating they should have had for the PM guides. The fix is to get Ti/moly valves from Katech and use bronze/PM guides. Alternatively you can have the Ti valves polished and use a bronze guide.


The reason given for the exhaust valve breakage is that the guides wear and the exhaust valve starts to bang on the seat every time it closes. This slowly work hardens and cracks the valve. (the same can happen on the intake but it takes longer)
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Old 07-16-2019, 01:06 AM
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Originally Posted by Landru View Post
If looking for 550 RWHP, intake & headers will be required.
Add $3-5K depending on what's used to whatever cam/tune/heads cost.
maybe... I have 540 with a conservative tune (I did not care about numbers - I asked for something super safe for repeated track reliability) and have ported, fixed heads and 116 Cam. Slightly ported stock intake manifold and throttle body.

Thatís it. Stock air cleaner, stock exhaust. Tuner believes that there is a good chunk of power to be found with a good air filter assembly.
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Old 07-16-2019, 09:17 AM
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Originally Posted by Jfryjfry View Post
maybe... I have 540 with a conservative tune (I did not care about numbers - I asked for something super safe for repeated track reliability) and have ported, fixed heads and 116 Cam. Slightly ported stock intake manifold and throttle body. Thatís it. Stock air cleaner, stock exhaust.
I'm impressed, very respectable.
A 'slightly ported' I & TB make more than I'd have guessed.
Then again can't compare a 116 w/ the 'baby cam' custom ground cam I have.
Stressed to builder I wanted stock-like drivability, ergo 'baby cam'.

Tuner believes that there is a good chunk of power to be found with a good air filter assembly.
Basically told the same, although headers were in the equation.
Told HP was left on the table w/ conservative tune, am fine w/ it.
How far did your guy go w/ tune?
I was very concerned tune w/could be too lean causing potential & catastrophic issues.
Asked them to cool it w/ tune, probably thought I was nuts but I was the one paying.

FWIW: I'm very rural, nearest city 55-60 mi away.
Country builder I used is 30 mi from Road America, most of his jobs involve HP builds of all marques set-up for serious racing.
5 FT wrenches are kept plenty busy all season long, all committed high HP fanatics.
Given how rural they are, they make damned good $.

Plus after reading these threads for more than a decade, appears type of dyno can make a difference.
IIRC mine was done w/ a Mustang.
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Old 07-16-2019, 10:33 AM
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Originally Posted by Legionofone1 View Post
Just got done doing this run around with my ZR1, I talked to just about every shop in the country about what they suggest.

The consensus... The machining is fine, the reason I have got is as follows...

Exhaust:
The PM guides don't take heat away from the sodium exhaust fast enough and burned the thin layer of oil turning it into what is basically a rubbing compound slowly eating at the guide.

Intake:
The Ti valves are missing the moly coating they should have had for the PM guides. The fix is to get Ti/moly valves from Katech and use bronze/PM guides. Alternatively you can have the Ti valves polished and use a bronze guide.


The reason given for the exhaust valve breakage is that the guides wear and the exhaust valve starts to bang on the seat every time it closes. This slowly work hardens and cracks the valve. (the same can happen on the intake but it takes longer)
Interesting, thanks for sharing what you learned!
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