Words of truth!
No matter how 'great' the shop is, sh*t happens to us all.
How that situation is handled after the sh*t happens is the true test of quality.
Reference Hib's thread about his "Street Attack" oil consumption issues. Last I looked he was out of pocket for 2 (3?) of their Oh-So-Expensive engine builds, and getting the shaft on a refund.

 

At least the head builder repaired the bad head and installed all new valves and maybe even got us a new can, not for sure though. We had to buy a new short block, cost at least 8 grand for someone else’s screw up. All part of wanting to go faster.

 

They sent me a new head, wanted the ms90 guides but that didnt happen.I thought I was going to get 2 new heads, but they just did the bad one. Then I had to replace the piston and hone the sleeve.

 

So it sounds like you might've been able to save your block?

My engine was completely destroyed. I had AHP heads with ms90 guides as well. In my situation a rocker broke and an intake valve broke. No idea what broke first, and I don't know if one caused the other. However, other intake valves were definitely showing wear and look like they would've broken at some point anyway.

 

I do appreciate all the conversation on this topic. You never know on the internet what you are going to get. Seems like most people’s experience with Kohle was just like mine, perfect with a great product delivered. It is amazing how one person with a one off experience can turn a whole group sour to a product. One day I need to get around to putting their cam in.

 

Sounds like you were lucky, this is what happened to a friends motor after having heads redone.



The pieces are what was a piston.


And the block was junk.

 

The answer is not to make the CrN coating thinner by polishing it up...as clearly demonstrated by intake valve failures after the "fix"

 

There are six of us in this thread alone who posted about issues with their heads:

1. Post 3
2. Post 23
3. Post 31 explained out of a lot of heads, one set did have an issue
4. Post 39
5. Post 41
6. Post 47 (my post)

Count all the people on the social media page you were talking about, and there are more. It's clear now there's definitely a possibility of failures with their heads. Seems like they stood by the heads in some cases, but in others, it doesn't appear so. I would say they did not stand by them in my case. They quoted me ~$500 (something like that) to tear it down and figure out what's wrong, then quoted me like $15k for a new engine. Additionally, I would've had to pay someone to tow the car over 100 miles one way to them. After diagnosing, they wouldn't have been able to get to it for a few months if I were to have them install a new engine, so it also would've sat outside during that time (I will say it was generous to allow it to sit there). Then there's towing it back. I didn't want to possibly deal with paint or other issues from the elements on top of the cost of a new engine, and towing it there just for a tear down didn't seem like a good idea when someone more local could also tear it down. Therefore, I had someone local tear it down, and that's how I saw what's wrong.

My intake valves were polished. Actually, AHP still offers their "AHP Package 4 LS7 Cylinder Heads" with "Stock Titanium Intake Valves Treated and Polished" (quoted directly from their website). So if this really is an issue, then there are heads still being sold with it, which is one thing you all should worry about if you have these heads. This thread already had a few others with broken intake valves, so the risk is there.

Look at my original thread here about my engine failure, and you'll see what my intake valves looked like: https://www.corvetteforum.com/forums...-blown-up.html

Look at posts 47, 84, and 87. I actually remember you posting on that thread!
Post 47: https://www.corvetteforum.com/forums...post1598519143
Post 84: https://www.corvetteforum.com/forums...post1598590935
Post 87: https://www.corvetteforum.com/forums...post1598591393

Especially look at the #7 intake valve in post 87. When I emailed AHP the pic of my #7 intake valve, I never heard a response. They also mentioned in that thread I posted above that a real professional would never look at pics, but they complain about a guy in post 16 in this thread about not sending them pics. I would've definitely worked with them to send them my heads if they were at all curious about what happened (if they paid for the shipping, which is not unreasonable when you can clearly see the condition of the intake valves), but they never asked or insisted, and they never appeared to be concerned at all that their product may have a flaw. I was the one keeping the conversation going and reaching out. Post 38 asked for people to post experiences like mine, so I hope this info helps people when they decide to buy new heads.

 

So who did the install of your heads would be my first and most important question.

Also feel like there’s a lot being left out most likely, not saying quality control mistakes don’t happen and AHP isn’t immune to that, but I do find it hard to believe a reasonable solution wasn’t offered. Reasonable meaning a compromise on both sides. One can’t expect a shop to cover a $15k+ new engine when the customer only paid for say $3k in parts/heads...that’s barring gross negligence that can be proven beyond a reasonable doubt that the parts in question could be isolated to the specific cause of catastrophic engine failure. Now that’s gonna be extremely hard to do on a modified race car engine, regardless if you don’t give your Z hell, it’s still a race car with a race car engine.

Pointing out the few people with some sort of issue I’d say isn’t much to stand on or a valid reason to trash a shop, one sided story just isn’t gonna hold water especially when there’s cars like mine running these heads making double the power most of you have and it’s boosted...and I run the **** out of it when I do take it out...and spin 7200 RPMs. I’m not the only one by any means, some of these guys who road race these cars with AHP our way more abuse on them and have all the real world data one could ever want on these heads and how well they preform. It’s all over this forum if you take a look.

I do understand you have had a bad experience and probably some bad luck overall and nothing is gonna change your mind on your experience and most likely shouldn’t. Just as nothing will change my mind or the many others who’ve done business with Khole, he’d have to do a complete 180 with me personally for that to happen.

I’ve had my run in with a legit **** show shop that literally took $4k out of my pocket, I got zero to show from it but more work that they screwed up being found down the road...it was the gift that kept on giving. Had to triple pay on work to get everything sorted out in the end. Ultimately I paid the **** show shop $4k total, $2k was given up front because that’s how I do business. The backside $2k was paid just to get my car away from them even though it was incomplete, wrong and they cost me more money down the road. It’s was an expensive life lesson I wish I wouldn’t have had to learn, big difference from a situation like that and the “six” post on here with “issues” 🇺🇸

 

73DBG, I will break up your post #52 and answer each section.

I stated in my engine failure thread that AHP did the head install from start to finish. I called them up, they prepared the heads ahead of time, I drove to them and dropped my car off, stayed overnight so they could finish installing the new heads the next day, then picked up the car.

What exactly do you think is being left out? If you're going to make that claim, please be more concrete about what else you think you need to know. Both sides said their stories in my original thread about my engine failure. I was actually very nice in how I handled things, both in that thread, and in my calls and emails to them. Unfortunately I think that's probably why I was brushed aside. Yeah they offered to allow me to pay them a ton of money to work on the car again, but I don't consider that standing by the product. I also never asked them to replace the engine for free.

Of course things can break, no one can argue against that. But don't you want to know about the possibilities? And then once there is evidence of parts failing, wouldn't you want to see the shops do a root cause analysis to try to ensure it won't happen again? Otherwise, it will happen again. If it happened once, it can happen again given the same conditions. Do you agree?

Additionally, the Z is certainly not a race car, but that's not the point of our discussion, so I'm not going to get into it.

And that's why I originally went with AHP; almost no one having issues. And here I am now after my engine failing and selling the car as a roller.

When my engine first failed, I specifically stayed objective and stated facts. I tried to keep emotion 100% out of it, and that was probably a mistake. Therefore, might as well be more emotional next time like how I am now.
About trashing the shop; like I said, originally I only stated what happened. If the facts happen to make the shop look bad, then that's on them. I never went on yelp, any other forum, any social media sites, etc and posted a negative review.

I already lost out on my engine and sold the car as a roller, so I have nothing to gain here. If you don't want to look at clear evidence that these heads can fail, then that's your risk. That said, I don't wish this on anyone, but I think people should be informed, especially since posts like mine were requested in this thread. I understand I'm telling things that most people don't want to hear.

You're correct, losing $4k vs losing $15k+ like I did is a big difference between our stories. Please don't try to downplay what happened to me. Also, please look at post 87 in my orignal thread.
Here is the post again: https://www.corvetteforum.com/forums...post1598591393

Look at my #7 intake valve and answer the following question:
Does that look like normal wear for an intake valve? Just answer yes or no, and we can go from there.

 

Honestly you lost me at a C6z not being a purpose built race car by GM. That’s exactly what it is. There will always be potential issues with cars like this, stock, modified whatever. There is not “set and forget” in this game. Lots of wearables and consumable parts that will need addressing throughout the life span of the car.

My valve springs will be checked shortly I’d say around 6-7k miles any sign of issues and I’ll have new ones ordered and put on, part of the game.

I’m not even trying to dismiss your personal issues, that **** sucks regardless and hate to see it. If anyone on here thinks “fixing the heads” no matter who you use is a set and forget they are sadly mistaken. I damn sure don’t, should the engine grenade like yours...absolutely not, but lots of variables in play. My main point is my interaction and what my car has seen and how it performs with the same product. I believe that’s everyone else’s point who’s took the time to comment as well.

I’ve told Khole personally to have the mods keep these threads open, especially if they are like this one. Nothing has been said in my opinion that warrants a lock down or removing post. No place is gonna have 100% positive feedback and if they do...run. Now it’s not my business, so I can only offer an opinion with no financial skin in the game, and believe me I’ve got my own gripes and complaints about how the mods operate but that’s another thread...

 

I shouldn't have responded about the C6Z and race car thing, I didn't want to get off topic. I know they borrowed parts and information from their racing experience to put into this one, etc. But when things happen like the dry sump tank initially being too small for long turns, oil pan design not being ideal, etc., that's where I was going. But I get your point, I was being unnecessarily pedantic.

Good that you'll have your springs checked. Sounds like you get your fun out of it!

I've personally never seen a thread deleted/removed/etc (not saying it hasn't happened, only that I haven't seen it), so I'm glad I'm allowed to say my experience as well.

 

Regarding the GM LS7 Titanium intake valves. Its is no secret that they suffer from lack of QC and finish quality. This is evident by a microscopic examination of the surface finish on the factory valve stem as they come from GM. What you will find when doing that is two things. One inconsistent and thin (bordering on poor) CRN coating. Two Decent RA finish but very poor RZ finish.
These two things are issues that GM produced the factory valves with (not us). Even Del West the manufacture of these valves has openly admitted these two issues and say the GM ti intake valves are not an accurate representation of the valves they are capable of producing. In short GM forced the manufactures hand to make the valves to GMs spec (for budgetary reasons) and not to the recommended specs Del West advised GM to make them to.
As a result of this we treat and tumble polish all our GM factory ti intake valves to do two things. One help harden and even out the factory CRN coating on the valve and two correct any RA and RZ roughness issues that may be present on the valve stem from GM.

Over the 8 years we have been reworking LS7 heads we have had very few issues with the factory GM ti valves after they go through our process. In fact the process we use on the factory gm ti intake valves is a process we carried over from one of the F1 teams a few of our guys used to work for/with.
With that said the failure Corvette_D is referring to occurred on a set of heads that was reworked in mid 2016. We have since then tightened up quality control on the factory valves even further and in fact any time in the past where has been any sort of issue what so ever we make changes (both policy and process) in order to correct said issue moving forward.

We do all we can do to ensure the quality of the GM factory titanium valves we are reusing/reworking on our head reworks meet our stringent quality control standards. For those looking for even more security or piece of mind we do offer both new (vs reused) GM LS7 ti intake valves as well as our very own AHP Ti Moly LS7 intake valves as upgrade options. With that said the issue/failure rate on the stock treated/polished and reused GM LS7 ti intakes is so low (less than .03%-.04%) that most choose (for budgetary reasons) to stick with the stock GM LS7 titanium intake valves being reworked and reused.

Something else to note regarding factory GM ti intake valves is that GM did correct the valve stem issues on the C7z06 titanium valves and treated/tumble polished each and every one of the LT4 titanium valves before installing them into the heads.

We would like to note that we have reworked well over 2,000 sets of LS7 heads over the years and have had less than a .03% failure rate on those heads we have reworked. That is a 99.97% successes rate. We feel that this is important to take into considerations and put into perspective when reading things like what Corvette_D is posting about.

Regarding Corvette_D's situation above he is posting about I would also like to address that (Corvette_D) is not stating the entire situation.
In late Sept 2016 (Corvette_D) picked up his car at our shop after we completed the work.
On 6/1/18 "D" emailed us asking about welding an extension on his dry sump tank along with potentially installing an oil pan baffle.
Next time we heard from "D" was Early December 2018 telling us something to the effect of the dealer diagnosing the engine as having Connecting rod issues and being hydraulic locked. We were never sure on what actually occurred in "D"s situation because despite numerous offers to look at it and go from there (we need to be able to diagnosis or at least look at it before we can determine any degree of responsibility) he never took us up on these offers. For reference and perspective im going to post some of those email bellow so all can get a more accurate picture of the situation "D" (Corvette_D) is talking about. Always two sides to a story and we would like our side to be known.










https://americanheritageperformance.com/

 

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I would like to address all the points made by AHP.

It doesn't matter that GM produced the valves with issues. The issue is that you, knowing that, still use those valves. What sort of analysis have you done to prove that your "fix" makes the valves better? Who knows, maybe it does, but it doesn’t appear to have worked in my case or other's cases.

After seeing my pictures and hearing my story, what did you change?

How do you know you're using the same exact process, controls, scrutiny, etc that GM uses? Are you basing the .03% - .04% failure rate based on your heads failing?

Above you mentioned 0.03% – 0.04%, now you're stating only 0.03%, but I'll ignore that inconsistency for now. How did you come up with those numbers? That equates to less than one failed head. This thread alone shows 0.3% failing (maybe you did the math wrong). You also mentioned in my "engine failure" thread you’ve never had any issues with your heads (I shouldn't have let that one slide…I was just too nice…). Here is the post where you mention never having issues: https://www.corvetteforum.com/forums...post1598751661

Even if those low numbers are true, it’s how you act when there’s an issue that will reveal the type of person you’re dealing with.

I stated 100% of the situation. What did I not state? Please be concrete, you made the claim, the burden is on you to provide proof. You just added in a bunch of information that doesn't add any value to the debate. How does me wanting to enlarge my dry sump tank have anything to do with this situation? What was the reason for posting that? There was absolutely no need to even mention it at all. All it does is add confusion and can sidetrack the debate. Also, I never once mentioned connecting rod issues? Where did you get that information from?

I told you and everyone here multiple times now why I didn't bring the car to your shop, so please stop acting like you were doing me a favor. There was no point in spending money to tow it there, pay you a fee to diagnose it, and then pay to have it towed back when I can have one of the great shops down here diagnose it. I would've happily sent you the heads if you paid for the shipping and even asked me to begin with, but you went silent after I emailed you the picture of my worn #7 intake valve. It would've been in your best interest to just get the heads. I think my politeness and kindness was just taken advantage of, so I've learned a lesson. Honestly, besides making me very uncomfortable by leaking my personal information on the internet, all your emails did were show how nice I was while I was dealing with a completely broken car that your heads definitely, with a reasonable doubt, could have caused. If not then, then definitely later as is evidenced by my worn intake valves. They would've failed eventually even if the rocker is what caused the failure, but we'll never know what happened first.

So yes, there are two sides of the story, like the emails you left out of the conversation. Why didn't you post the emails where I got quoted all the prices? You already posted part of it in one of your screenshots, might as well show all of it. Why didn't you post the email (that you didn't answer) where I sent a picture of my worn #7 intake valve?

I'll post them then (and to not be hypocritical and invade anyone's privacy, I will blackline all personal information. If the fact of showing these emails is still deemed person information and against forum rules or terms of service, I will happily remove them and am only going this far as I have been provoked to do so and would normally never publicly display emails without the consent of all parties involved)

First email is for context, the second email shows the prices. Not sure how AHP was doing good by me for quoting me all this stuff.


Here I'm also showing the email I responded to as well for context. I never received an answer to the email showing the worn intake valve




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