What’s up Corvette Fam’
My engine is fine at the moment, but I have around 80k miles and I am opting towards getting the heads upgraded, mostly for peace of mind in regard to all of the LS7 weak points, such as the valves dropping.
So I decided when I purchased the car to just get the valves fixed and I contacted the original owner and confirmed there has not been any work done to address the LS7 weak-points.

There are 2 other owners I believe but I doubt they did the heads since there was no paper work and they had the car for a very small amount of time, (I guess I should check in with them to see why they sold the car).

I am only doing this job because I want the Valves fixed (and any other broken stuff while they are in there) for peace of mind, since I plan to have the car for a long time.

Second order of business would be my wish-list, which is basically to make around 650 hp like the C7 Z06’s LT4. I live in CA and I would prefer to keep the car Smog-Legal because I drive this car daily at the moment (except for the Shelter-in-place order). I want this to be a N/A motor and to retain the 427 displacement.

I am interested in Katech, AHP, Lingenfelter

-I’d like a warranty
-I like Katech because they made the LS7R but they are in Michigan and I am in Nor Cal. This would make any subsequent work probably much more difficult than a closer shop
-What type of cash would I be looking at spending for this

So, my questions are:
(1) Will any performance upgrades be smog-legal in CA, or am I forced to just repair the valves to remain compliant?
(2) How is 650 hp/ 650 lb-ft tq on this car? Does it ruin the drivability and what does it do to the mileage?
(3) Which shops are recommended?

 

Hi, I can answer your questions pretty well, just not the level of a motor expert.

Any reputable shop can work the heads, or get you aftermarket ones. Tony Mamo out of SoCal is the go-to best head guy out there for a reason, but $$$. BTR in Texas is my next go-to, for knowledge, performance, and customer service. HPR is close as well, but $$$ even though they work on some very modern RR builds.

Lingenfelter has a '630' hp package, that would seem to fit your goals to a tee, however, requires/installs long tube headers, which are illegal [in CA]. More realistically, most importantly with your drivability goals, you are looking at a 600 bhp range, which can be done in any number of ways, keeping shorties and stock cats so CA legal. Any much more and you're in 'big cam' territory, which might not fit your decision for a reliable daily driver..

 

Do u have any information on Tony Mamo. I been hearing his name thrown around a lot when it comes to heads porting

 

OP give us a call
310-326-2399
or shoot us an email
HP@americanheritageperformance.com

We would be glad to go over your options with you. We have one of the best (if not the best) CNC porting program for stock GM LS7 castings and also have our Proprietary Moldstar90 valve guides (same material used in many F1 and Indy car Heads).


https://americanheritageperformance....cylinder-heads

 

https://www.mamomotorsports.com

 

West coast cylinder heads.

 

Thanks Hitman!
I am definitely going to keep posting my updates as they come.

I just talked with Katech and the only downside I see is if I go for more power then I will not be smog-compliant. The warranty would only be applicable if I have them do the work for me which is only a pitfall since they are only 2,420 miles away from me. Unless I ship them the heads. From my understanding this is my preferred choice.

I want to reach out to Lingenfelter next and WCCH after. I also emailed AHP & I am still waiting for a response.

It looks like Tony Mamo only sells ported throttlebodys on the website which was posted in the thread.

 

Yes, the website is lacking; you have to call to discuss your head goals/requirements.

 

MMS LS7 Heads have the Most Flow & Velocity from the Smallest port up to ~.725" lift.
The TFS castings Tony starts with have a carb# so ask to have no end plate designation to
appear as factory TFS.

The MMS MSD Intake (also with carb# although not with porting, but who would know lol)is the Best flowing Intake which will fit under your hood without cutting.

I would talk with Cam Motion about a stealthy cam to work with stock exhaust manifolds and
Cats if you can't/won't deal with the underground smog. The Cam Motion lobes are smoother
than most of the other profiles out there and spring life durability will be better than more
aggresive like Comp for instance Something LIKE ~ 228/242 115+3 .630"/.610" might be a
starting point.

Also if Nick Williams 102 TB is not carb approved have Tony Port the OE TB and use a
V-Max Velocity Ring to eliminate gap/step between 90 mm TP and 102 MM opening of the
MSD Intake.

These Mods could easily gain 100-120 RWHP to your stock baseline of ~440 RWHP.
Just my .02
Good Luck

 

Up grading your heads and ending up with a 650 hp NA engine are two entirely different matters for several reasons to include cost, driveability and emissions.

On the upgraded heads, you can visit or contact both Mamo and Heritage, they are both in California and appear to have great products. Ask them about a competent installer in Cal. Then you can talk to the installer about the above three issues. 650 hp NA in California will likely have driveability and emission issues.

 

Thanks Jim
To clarify when I said 650 HP i meant Engine HP and not Wheel HP.

I wasn't planning on 650RWHP and I think the costs would probably be higher than I would want to spend, at this point in time.

This is my first Vette' and I didn't want to go all out just yet. I was hoping that after I do the heads job-- I could still have more potential in the future to continue the build (still running stock suspension and brakes, etc.)

I thought about more realistic goals last night and I think I would be more than happy with 505 RWHP and having the fixed heads. I think this would be cool since the car claims to have 505 Engine HP and I think to bring it up to those numbers seems like a great starting point.

 

That's a wise way to look at it.

Alternatively, consider that you will have the top end all apart anyway, good time for free labor to install springs, pushrods, good trunions, lightweight retainers, ls7 or better lifters, melling high flow oil pump, and of course to top it off a Stage I or Stage II BTR cam (for instance). Also a very nice option. Regardless of the exhaust.

To get up to 650 bhp, with 7 liters, you would have to def go double springs, which last less, and put more stress on the valve train, plus then at least BTR Stage III cam, if not more! It won't drive anywhere near the same, and would be more of a strip setup than otherwise, relatively speaking. With a given exhaust.

These different scenarios indeed will be +-100 whp..

 

not many mention it but I've started to hear good things about Frankenstein engine dynamics....

I picked up some stock ahp heads that are pending install, they have great customer service!

drew

 

Forgot to mention, this assumes some nice ported heads...

For stock fixed heads expect some less hp tq.

 

All the names you talk are great to achieve yours goal.

Personnaly do business with Richard @ WCCH, very helpfull with all my question and great product (BR7 WCCH CNC Heads in my case)

 

I've only heard good things about him, he's been around these boards for a while, great stuff out on the West Coast!

 

This was my recent build and the heads I used. I have done two Z06s using the AHP heads. Super pleased on both cars.

https://www.corvetteforum.com/forums...dyno-tune.html

 

I went with AHP route and I will post more when I pick up the car. I should be getting it soon (hopefully). I was looking at renting a car when I pick up the car since I have a solid 5-6 hours of driving, maybe I'll rent a C7, if i can find one.

 

C6 Z06 REVIEW

I had the car for around a year, and I got a list of upgrades from AHP. The car was great before but I never really got on it to aggressively since the head issues with LS7 but I definitely like the new power and want more! But this is great, and I am just trying to get as much seat time.
I want the car to be a CA Smog-Legal (minus CAI) daily driver that is reliable and a track monster as well.
The guys at AHP were great and I drove from Northern California to Southern California to have them work on the Vette. I would not only confidently bring my car in for service again but I would also bring it to them for any modifications I want. I definitely like how AHP inspects all of the car to ensure that it will be ok, and I definitely appreciate him torqueing allot of the bolts in my engine bay. Particularly my steering rack since it got stiffer on me recently (Magnet? Or something else broke). I also like how AHP replaced some other items that were breaking/worn out in my engine.

As far as how the car drives now compared to before…. I definitely am switching gears to stay in the power band more often as the car at time will surge is moving at low speeds but this isn’t bad and I am practicing on the car since it is not the same as before. This is my first manual car and I used to be able to drive off with only removing my foot from clutch slowly until it engages and has enough speed. I think when it was stock, I would remove my foot from the clutch at 5 mph and I now do so at around 7mph. I’ve driven close to 2,000 miles since I got the car back for the last 2 months.

The car is making (insert HP/TQ) I feel a difference and I am enjoying the new power… the new noises the Z makes. Around 3k rpm I notice a crazy whistle sound that sounds like a lot of air flow “whooshing” (like boost!) the other thing I noticed is I now get a a lot more burbles/pops which sound great upon deceleration.

The ZO6 is driving much cooler than before I noticed the engine oil and coolant are both much lower than when I originally purchased it.

Another big difference is a major increase in the gas mileage I am receiving. The car even smells cleaner, like less rich (with gasoline) compared to when I first had received it. I am now filling up less often and since the valves issue got addressed, I confidently get on the gas pedal, as I wish.

A funny story… 1 of the previous owners had installed A Corsa exhaust and the seller told me it may be a worn bushing or something but Kohle told me the muffler damn-near fell off the car when they got it on the lift. I guess it never fell off because I was driving pretty lightly. Anyway, I did a 3rd gear pull by my work and one side of my exhaust popped off one day... So, I taped it it and had it reinstalled and spot welded but I guess that was all of the new airflow coming out of the exhaust. This happened like a week or 2 after I got the car back from AHP and I ThOuGhT I was good and just kept driving but luckily this was no big deal.

I have a list of mods I want next, but I want to wait until I’m ready/as needed:
Monster Clutch assembly
RPM Transmission
RPM Diff
Tow hook
Coilovers
Additional heat protection under center console.

 

Made 540rwhp / 506rwtq
btr dual springs with ti retainers
AHP Ti Moly intake valves
AHP 116 Cam
AHP Ported MSD LS7 intake manifold
AHP CNC Porting of LS7 Heads
2 Hinson 3/8 Lower Solid Engine/Motor