Indepth

Unfortunately, it seems that a series of rather frustrating and disappointing events has caused me to have to make this post now that I’ve been able to see the results, and this entire situation, to the end.

As many have done in the past, I selected AHP for my LS7 head re-work when I began the process of building my C6Z, embarking on the stereotypical H/C/I/E path that most tend to. I removed my heads and had them sent in to Kohle and his team for a mill, valve job, guide replacement, etc. along with their “race port” package they offered. Due to my naivety at the time I simply received these heads, followed AHP’s instructions (can’t forget those pesky lash caps!) and continued on with my build. It wasn’t until I got to the dyno for tuning that I began to wonder if something was amiss. My tuner carefully went over my parts list with me and had tuned many other C6Z’s before. When our tuning was done he stressed that the numbers seemed a bit low but he felt it was a restriction in the intake tract that was causing some power loss in relation to peak numbers. His remarks were referencing the dropping kPa readout from the car’s MAP sensor in the upper RPM band (seeing a 99-100kPa drop to 90-92kPa). This tuner is well respected in the area, so I had no reason to doubt him. However, having HPTuners myself, and being curious, I data logged my car just to verify – sure enough, same numbers. His recommendation was to open up the intake tract because it seems my build would need more air to breathe right – my LS7R cam is far from small and I had a feeling that might be the case. I picked up a MAMO ported and shaved MSD for dirt cheap along with a NW102 throttle body and replaced my Halltech MF103 w/beehive for a Vararam intake. In data logging both my tuner and I were able to now see my kPa drop off to 96kPa instead of the miserable 92kPa we saw prior. However, this still indicated to both of us that there was a restriction. We knew the Vararam intakes didn’t dyno well, so we removed the intake entirely for a few pulls just to verify the loss wasn’t coming from the intake itself. The bad news was we saw the same power and same kPa overall, the good news was we isolated that it didn’t seem to be intake based. I had already replaced the intake manifold and throttle body so there was only one thing left that could be within the intake tract that leads to the cylinders that could restrict airflow – the heads.

I had put about 3,500 miles on the build at that point and wanted to check on my guide wear rather than wait until I was nearing the 10K mile mark that's recommended to inspect at. Turns out, it was a good thing I did, because I had 1 guide out of spec already and about 2 more opening up from the installed specs. I contacted Kohle, who responded in kind stating that the measurements I found were out of spec, but not dangerously so, and to drive the car until the season was over if I didn’t want my car down during the season and he’d take care of me in the fall/winter when I had the car down. Great! Fast forward to fall where I am ready to tear my heads off for guide replacements (AHP standing behind their work it seemed), I inspected the guide wear once more and found even more guides out of spec.






No problem, Kohle has me taken care of with my new guide replacements anyways. I contacted him to ask him what address he’d like me to ship my heads to and was greeted with an odd response in turn (see below).




Clearly this is not what was agreed upon. I’ve had to play this game before as well – let the company that provided you the product that blatantly isn’t performing right tell you whether or not it actually is falling short. Kohle’s stark response laying out a much different scenario than earlier in the year left me feeling uneasy and like I would ultimately be the one holding the bill in the end for something that I shouldn’t be paying for again.

This leads me to the bulk of this post. At this point we all know that LS7 valve guides wear out, it’s simply a maintenance item on these cars that has to be done every 10K miles or so depending on your build (at least, most of us realize this it seems). I received the response from Kohle and began examining the heads more closely, with such a flippant response was there anything else I missed in regards to AHP's work on my heads from my initial install? Then it dawned on me, my struggle to find the source of my kPa drop could be the heads, they’re part of the intake tract as well after all. Hmmmm, how is this “race porting” I paid for? Well, upon further inspection I found what looked to be a quick hand port job that didn’t even remove all of the stock casting CNC lines! It was at this point I chose to part ways with AHP and seek another method of obtaining the max effort port work I was originally after (and paid for). I located a porter I felt could do the job properly and specifically asked him to take before/after pictures of my heads as he worked them. Below are a series of pictures that show the differences.

AHP Port Work:








Mid Re-Work (Take note of the amount of material removed, and this isn't even complete!):



Total Amount of Material Removed:



After Re-Work:









50/50 Shot:



Before/After video of my set of heads:


So I’ve now found out that my guides were out of spec with less than 10K miles on the car and that the “race port” package I had ordered was certainly not a “race port” at all, let alone port work really… Fast forward to the completed heads being on the car and a dyno tune performed (on the same dyno as before with the original AHP heads, that being the ONLY change) and we were able to pick up significant power along with a good kPa increase. We’re now seeing 99kPa or so on the dyno and 101-103kPa on the street! See the before/after dyno chart below. It seems the newly ported heads picked up power everywhere in comparison to the AHP heads.




I post this information to share my experience with a forum vendor and also to further shed some light on the magical 600rwhp number we all often chase but have little appreciation for. When people speak of having all the parts work together to have the right combination work, they really do mean it. I’ve spent a year or so tweaking mine to finally make it there. The dyno was performed on a 84*+ day with 75% humidity and 3200DA along with the car on a 27.8” street tire. I’m sure if I came back on a cooler day and stock sized tires I might hit that magical number, but this is proof enough for me. Time to get out and enjoy the car

RamAir972003

Unfortunately I was in the same situation as you with my exhaust loosing power with the lg 13/4 headers asked if I could swap after they told me thet would take care of me and what do you know lg did not stand behind there product never again but I feel you...promises are never honored....only few companys are honest...

Dan_the_C5_Man

Honestly, AHP's response to you seems totally and completely reasonable - they were willing to replace any worn guides and eat the material and labor costs. You pay for shipping (and any valves with issues). Seems reasonable, and better than what 95% of other shops would do in this situation .

The porting, that is something else, a separate issue. I guess we'd need to understand exactly what was promised - I would guesstimate that the vast majority of AHP customers ask for mild clean-up. I wonder if the second port job you had done didn't remove so much material that replacing guides in the future wil be problematic.

Most people consider the intake ports on LS7 heads to be the "gold standard" (they flow very well when matched with the stock cam), and typically focus more on the exhaust side.

American Heritage

The customer Purchased Minimum port work/ Street porting. This is basic clean up work of the ports with some shaping and light bowl throat work to improve flow and raise the stall points on the intake side (stock Intakes stall out right around .600" lift).
The customer paid $550 for the port work and was provided that port work. I have been told by some that he is claiming he ordered Race Porting which he did not. Bellow is his invoice clearly showing Street poring. On top of that even the video and pictures he posted prove that he was provided with street porting not race porting. On our street porting we did not do any intake runner work, the intake runners are left stock to keep a tight runner and high intake air velocity. On the video posted by the customer you can clearly see the intake runner CNC lines still in tack as further prof the customer was provided with Street porting not race porting.


Regarding the customers comments about the port work. Minimum porting is just that. It clean up the areas of the head that cause issues with flow and turbulence. For example cleaning up and blending of he throats to seats does wonders... Slightly knocking down the CNC humps on the short turn also does wonders. The idea of port work looking good going hand in hand with flowing good and performing good is a fallacy. Just because its shinny does not mean its good. With that said you can have nice looking port work that is nice and shinny that kicks but. An example of this would be our CNC Ported LS7 heads:



Point is you cannot judge a port off of looks alone any anyone that says they can has not spent months and month and month on a flow bench testing and developing ports because anyone who has knows that there is so much more involved with proper flow and performance than how a port looks.

The other thing that needs to be stated is that the customer did not order our full port work so his thread is comparing our minimum port work to another porters full port work. This is in no way fair and is the same as comparing apples to oranges. A Good example of this would be Steak, (if we were a steak house as example) We sell Choice, Prime and Kobe Prime Steaks. This particular customer was offered all the options we offer. He selected Choice steak. He at the steak and was happy with it. Then some time later he goes to another Steak shop and orders Prime steak and eats it. He then goes public telling everyone how much better steak shop B's steak is than Steak shop A's steak. What he is not saying is that he purchased and ate choice steak at steak shop A and purchased and ate Prime steak at steak shop B. Apples to Oranges!!!
Like I was saying we also sell the 40day aged Kobe Prime if someone wants it and is willing to pay accordingly for it.
We want to be Crystal clear that we always ensure our customers get what they pay for. If you order it you will get it. If you send in your heads to be reworked you will get your same castings back. We are a stand up company that operates on the Golden Rule.

Also an important fact that the poster left out is that for a good while now we no longer offer hand porting except to our High end customers.
For our High end Race customers we will offer Hand porting but that is only to a select few. An example of this is that we hand ported the heads that are on the Fastest N/A LS7/C6z06 in the world... Thats right the world Record holder N/A z06 is running our port work!!!

We now offer and provide CNC port work to our customers. This CNC process ensures accuracy and that every head/port is the same as its speced to be. We do about 400 sets of LS7 heads per year and have done so for the last 7 years or so. Switching over to CNC porting was just an evolution of growth for us.



https://www.americanheritageperformance.com/

rpmextra

I'm a little confused myself. The head work I got from kohle was nothing short of stellar. On top of that, he took someone else's mess of a job and helped me finish with these all said and done. Took my 9s goals and achieved them with these bolted to the car. Now I want to push it one step further and had Kohle port a MSD Intake for me and the works looks great.
Currently sitting at 9.86@142.63 with my NA C6Z SBE.
Can't wait to get out there with the intake.
As stated by Kohle above, the number one spot on the NA Z06 fast here on the forum, my good friend Sebast19x is also a AHP customer. He's been a honest, stand up guy through multiple transactions and can't see why he'd bail on one.

CASEWORER

I knew there was more to this story than meets the eye. Thanks guys for being a stand up shop and replying with a solid responce

vettebuyer6369

I’ll find out why it was closed then combine the 2 threads.

NOTE: we have reviewed this and the 2 threads are merged and open.

LS1Steve

MY AHP experience...
Street ported and running absolutely perfectly for 6K miles and counting. Great value, excellent communication, fast turnaround, high quality workmanship and labor, and super passionate about performance and great customer experience. I drive 800mi round trip to them for anything my car needs, without hesitation.

American Heritage

Since OP of the original thread (intodeep) chose to post this in multiple threads on the CF I will copy and past bellow what I just put in the other thread after he accused us of changing the invoices...
Bellow is our Factual Prof:

My messing up your screen name is not what you should be offended by...
You sir are a Liar and I will not stand nor tolerate that.
Pulled your old hard file out of the box from 2016 (had to go up into the Attic to get it) and it States "high velocity street porting"! Also if you look at your video you posted in this other thread you made about us you will clearly see the CNC lines still on the intake runner walls. This is a clear sign of street porting.
Our race porting had the CNC lines removed as well as many many additional work items that the street ported did not have.
Here is a pic of your November 2016 Invoice:


Here is a pic of your file on my computer showing that it has not been modified since 11/14/2016 (The tape is to cover up your personal info):


Here is a picture of the email I sent you with that very same invoice attached to it (if you notice right above was your email confirming receipt of it. Also note that the Invoice in our computer has not been edited since before it was emailed to you):


Here is a picture of your 2016 Credit card receipt and your core return to your CC once you sent in your old heads (again notice how the date coincides with the last modified date of your file in our system):


Once you received the heads, opened them up and checked them out you had this to say:


Really Sucks that an Honest and Stand up business owner has to take time out of his busy day to fight off your Lies! I'm sure all the other LS7 owners out there really appreciate your muddying up of the LS7 feedback world.

Indepth

I see you posted that invoice up in this thread, but this is certainly not the invoice I received. (See below)




My emailed remarks held true - got the heads, took them to the shop, had them installed. I had a business trip to go on and had no time to personally inspect the heads, shame on me for trusting AHP? (In reality the answer is yes, I guess.) Up until the point of that email you had held up what your rave reviews on these forums claim about you. You really were a great guy to work worth and extremely cordial in our conversations. That is, until the time came for me to inspect my heads last winter I saw some unfortunate realities.



You spent a lot of time trying to claim that this is a street port (my invoice doesn’t read that) and completely glazed over the fact that we had agreed upon my guides that were out of spec in a significantly short amount of time and were to be replaced at the expense of my shipping costs to you this past winter. When I approached you about it I got a story of corporate business changes not allowing you to do this repair in the fashion you told me you would. Considering it seems that I was supposed to receive race ported heads and instead got your street ports (as you claim) I didn’t feel comfortable with the stipulation that only you could make the call on replacing them for free. They’d been measured twice at this point and proven to be out of spec, you even agreed. If customer service was truly the number one thing AHP was after you would’ve fought the business to allow this repair because it was promised prior to their re-structuring. Also, this kind of takes away all of the claims that your PM guides are a ‘fix’ to the guide issue at this point, at least in my case I’d argue. Guides should not be wearing out in less than 10K mile and should be checked in 10K mile intervals and replaced as wear is uncovered.



Furthermore, I was met with even more frustrating news when TEA went to do my valve job. I received indication that ALL of my intake valves were bad due to the coating being bead blasted off. I certainly didn’t remove the intake valves and bead blast them and I know TEA didn’t. So, in the process of re-working these heads I also had to obtain an entirely new set of OEM intake valves. (See below for TEA’s email.)




Finally, the head flow numbers you’ve posted in the other thread (see below) I think are using the wrong bore size – stock LS7 bore size is 4.125” and this result states a 4.155” bore size was used. If you want to brag about flow numbers that’s fine, but at least use the right bore adapter? I’m sure you can get some heads flowing quite well; I just didn’t feel mine were one of those sets.




To recap:

- Head porting was not what I have on my invoice. AHP is claiming this is not the invoice I received, not true, no idea what happened here.

- Guides worn in a significantly short period of time. AHP first said they’d replace them then started to back pedal saying they’d need to verify they were out of spec first even though they already agreed twice they were out of spec based on measurements provided to them.

- Intake valves had no CrN coating upon inspection by the machine shop for assembly (TEA). Shop said they were clearly bead blasted and contained no coating any longer.

- Got heads re-worked and paid for new intake valves, installed heads and made power I was looking for.



Now that we’ve gotten more information here I think I see what happened - I was sent the an invoice with race ports listed and a mix up happened somewhere (whether it be in their systems/personnel/etc), billed incorrectly and sent street ported heads by mistake. Since I didn’t install my heads originally I didn’t have the chance to review the ports myself, resulting in this scenario. At this point in time what’s done is done; I initiated a dispute through my card company last week and was notified this afternoon it was closed in my favor. I’ve said my piece, shared my invoice that I have on file, and documented the process I went through with my AHP heads. Others may have much better experiences than me, and that’s that way I hope it is for many. Sadly, I think this was a case of a mix up gone wrong. Shame AHP can’t just admit to it, mistakes do happen sometimes…

I’ve tried to keep my posts as respectful as possible; it seems AHP has difficulty doing the same. Mods, feel free to re-lock this thread, I’m afraid this will just derail further into name calling rather than admitting that a potential mistake may have been made by the vendor.

AHP - you have my contact info, please reach out to me if you'd like to continue discussions.

rpmextra

Well there you have it. Facts on top of facts.
Hopefully after all the effort, this clears up some BS. Not sure what was the motive here, as I completely fail to see one. Kohle has been nothing but a stand up guy to Seb and I and we put 2 sets of his heads in the top of the NA Z06 fast List. Nobody knows the ins and outs of the LS7 and how to extract everything out of one quite like Seb who is still the record holder and he has AHPs heads and trust them to get the job done. I think Kohle works about 25/hrs a day, much like myself and has pushed, and pushed to achieve where is at. It's truly unfair that I see many with ZER0 actual AHP experience bad mouth the company, or those with experience twist the story to appeal them. I know for a fact, that if you have an issue, and it's justified, Kohle will 100% take care of you.