AHP Package 4 or Lingenfelter Heads?
 

I understand the sensitivity of this post in light of recent (and ironic timing) events with the AHP heads. I would like any recommendations to NOT consider the AHP failure discussed herehttps://www.corvetteforum.com/forums...nds-fishy.html My car will not see similar usage.

Bought my 2008 Z06 last month, came with a 3 month warranty. I am looking to get the heads reworked to prevent the valve drop problem in April or May (before the car comes out of the aftermarket warranty).

The car is stock with 46K miles except for the Corsa Sport axleback. I will not be doing any track days with this car (have my S2000 setup for that). I may install a mild cam in a year or 2, but have not fully committed to it. Car will mainly be used for cruising, some occasional drag racing, and back road aggressive driving.

Couple options I have found: Lingenfelter & American Heritage Performance

Lingenfelter is slightly cheaper at $1250. Uses OEM type valve guides, and reuses the OEM 76g valves. Their shop is within an hour of me, so I can save on shipping by dropping them off myself.

AHP is about $1400 with shipping and uses a custom hardened PM valve guide with the Ferrea 85g valves. Can AHP reuse the OEM valves if they pass inspection and drop a little off the price of the Package 4? If not, what is limiting the reuse of the OEM valves?

What else is recommended to be replaced in the valvetrain or vehicle during this overhaul? Keep in mind I just dropped a chunk of change on this rocket and my wife is not thrilled that I immediately need to through more money on it.

Thanks CF members!

Of the 2, I'd go AHP but then I'd also send my heads to AI

What is AI?

Personally, I would not use the stock exhaust valves. I have seen pics of blown up motors showing the sidewall of the stem of the exhaust valve and it is paper thin in some cases! But, that is just me because I know that some shops use them in their rebuilds. I went with the AHP Stage 4 with the MoldStar guides and am happy with them. Valvetrain is very quiet and peace of mind knowing that the exhaust valve head won't snap off is invaluable.

My advice to you is read up on your options, and once you have narrowed them down to a few call them to go over your setup.

My heads are getting done this week at AHP. I narrowed it down to AI or AHP. Both places were great to talk to. The only difference between the two was AHP had core heads and AI didn't. I didn't want to wait so I just paid the core charge and I'll have my heads in a few weeks. AI was 4-5 weeks out and my heads were still on the car at the time.

Steve

Keep in mind that from the start of production to May 2008 there was one vendor making the OEM exhaust valves. They had poor quality control where the stem wall thickness would vary and the weight could vary by 4 grams. After May 2008 GM selected another vendor (Mahle)who had better quality control and who doubled the way thickness. http://www.corvetteactioncenter.com/...-engine14.html
You will have to assume that you have the old OEM exhaust valve and so you will want to get rid of them. Kohle at AHP does use the NEW OEM valve or the Ferrea valve. He will install either one, its customers choice and price stays the same. Why use the new OEM exhaust valve, it lighter. Some will still say the Ferrea is better.

All the Ti intake valves have a coating placed on them that is somewhat rough and can cause increased valve guide wear. Del West who manufactures the Ti intake valves for Chevrolet has an additional process to polish the valves and smooth them out. This polishing process was NOT done on the LS7 intake valves. But now Chevrolet has Del West include this polishing process on all LT4 (C7 Z06) Ti intake valves. Why does the LT4 Ti valves get the polishing and the LS7 Ti Intake valves do NOT? When AHP rebuilds heads all the Ti valves go back to Del West for the polishing process. WCCH, if you pay extra for it, will put a molybdenum coating on the stems to work with bronze guides. Most other vendors do nothing to the coating on the Ti valves.

What AHP failure are you talking about?


It was the owner of the car to make sure his build would operate as intended. It did not. The owner even stated he never even knew the specs of his own aggressive cam.


He floated a valve because of old springs. End of story.


Not one part of the failure can be attributed to the craftsmanship of AHP.

Advanced inductions. We have them in stock.

What made you go with the moldstar guides over PM? I'm having some work done in a couple weeks, including sending the stock heads for porting and their stage 4 package. My car will likely not see any real drag racing or track days.


Jesse

I looked at LPE when I redid mine in 2013 d/t them being close to Indy, I ended up going different route with WCCH considering GMs lack of QC on their heads, I did not want to retain any of GMs OEM since I had that choice. Also, not all aftermarket warranties have the same coverages, I'd check to see what your policy covers in regards to the valves, etc. You maybe good or not. Good luck and congrats on your Z!

AHP with moldstar guides and be worry free

Moldstar are the best guides out for mortals


There are different PM guides


Lingenfelter uses soft stock PM guides, where AHP uses their own harder PM guides that hold up very well.


High HP engines that see more abuse do well with moldstar and many use it for piece of mind.


Both of AHP's guides are harder then the bronze bushings used by competitors which are even harder then Lingenfelter/ stock guides.

Lingenfelter uses OE PM guides...which have been tested to be soft in comparison to other options. I chose AHP's MS90 guides as they are a far superior alloy to anything else out there...and they actually harden with use, whereas other alloys soften. Even AHP's PM guides are just about harder than anything out there...except of course the MS90 guides.

Less often mentioned, but also important, is that Moldstar90 is a copper alloy. Having a high copper content means it is very good at transferring heat from the valve to the head. For that same reason, many top builds in the GT-R world are using Moldstar valve seats.

Hmmm... tough decision. I'll have to think about it over the next two weeks to determine if it is worth it for me. Extra peace of mind can be a nice thing...

Truly is an up to you decision...but for me, it was worth every penny to know I used the absolute best guide material available. :cheers:

It will be the biggest mistake in your Vette owning career to use lingenfelter heads over AHP , and regarding the discrepancy with the AHP heads you mentioned AHP was no way at fault , here's the only issue in question , and it has nothing to do with the product , AHP said he told the guy he shouldn't run the valve springs that were on the heads the guy brought in . The guy says AHP never told him to NOT reuse the valvesprings where AHP says they DID recommend that new ones should be used . AHP did not have it documented that they recommended the old springs shouldn't be used because of the relationship with the customer and felt he didn't need to . But now AHP said he will document EVERYTHING so confusion like what is happening now won't happen again . Bottom line the valvesprings had been used for several thousand miles with a cam that owner of the car described as "big" and were reused on the heads and a valve spring failed PERIOD . Like I stated AHP will make recommendations and document them and if you choose to disregard his advice that will be on you , if you do what AHP recommends you will be a happy customer like many other AHP customers have testified to .

Ai is my number one followed by wcch. The two you listed would be towards the bottom of my list.