znewton1

I just bought some BRAND NEW GMPP CNC Ported LS6 heads off of ebay. They are 60.9CC and come with the stock LS6 valves. I am currently running a fairly big cam, 238/242 .605/.609 on a 112LSA. I am a bit worried that I am going to have to flycut the pistons.

My buddy ran this EXACT setup on his 02 z06 (I have an '04 GTO) for like 15,000 miles and had ZERO problems but it seems many people reccomend flycutting with such a big cam. If I don't have to do it I really would like to avoid it.

Any suggestions would be appreciated.

Zach

Skypilot797

I have a 03 Z06. My LS 6 heads are milled to 62 cc's. Everybody's eyes opened wide when I thought about going past .600 lift and not flycutting. Something like .600 lift and 240 duration on a 114 is about max with my heads milled.
Since your going to have the heads off, best thing is check ptv clearances, no matter what. Flycutting isn't that hard and you can rent the equipment, if you need to.

chriswtx

iTrader: (5)

Its not the max lift that kills PTV clearance, its the lobe design, ie. lift/duration at .200, and the LSA. The tighter the LSA the worse the PTV clearance..

Russ K

iTrader: (1)

I have .180 intake valve drop & .205 exhaust valve drop. This on my 2001 ZO6 with ported LPE LS6 heads. The heads have 2.02/1.55 valves, and are milled to 61 cc, using the .052 mls gaskets. I heard that LPE does the porting for GMPP. I'm going to install the LG G5X3 114 LSA camshaft. The intake PTV will be tight at .057, but I have good double springs/titanium retainers. I take all responsibility for missed downshift/over reving.

As for your cam, I'd measure the PTV. My guess is with your 238 intake duration & 112LSA, you will need to fly cut.

Russ Kemp

slonomo

iTrader: (8)

Originally Posted by Sigforty
Considering I ran the f14 with milled 30 darts and stock gaskets for a 58 cc chamber I would not think u have to flycut. As for springs I would prefer the added security of duals.
__________________________________________________ _____________

This thread is about what I've been thinking about lately. I have a Comp 224 / 228 112LSA with about 540 lift and I want to go larger. Problem is that I have the GMPP LS6 heads (part # 88958622). According to Scoggin-Dickey which carries them, they are 243 castings, milled .055" to give a chamber size of 60.9cc. I don't want to fly cut either.

I've been thinking about an F-11 or F-13 on a 112. Patrick G suggested one of his custom grinds: 230 / 232 111LSA +2 with .612 / .595. lift I/E. Gave him my specifications and he thinks it would work. In fact I'm thinking about buying it. My only reservation is clearance, will cams like these work for me?

I'd like to get more power, but my current set-up ain't too bad either (Mustang Dyno). Anybody else out there with a similar set-up and information as to clearance, power, and steet manners?

Since P/V seems to be a hot topic, I thought that I would throw this in here and see if I can get more responses. Will an F13 work without flycutting using these heads. With all the people on this board, hard to believe there hasn't been alot of people down this road before.

slonomo

iTrader: (8)

Let's try this again, anybody else care to weight in? Seems like everytime I post to a thread, it gets killed.

JPH

iTrader: (2)

It will clear, but I would say you will need to flycut atleast .050 on the intake side and be ok on the exhaust side. Just check it and make sure man, that's the only way. You can take other peoples word for it, but I never do and I always end up finding what someone else has never checked. Good luck.

slonomo

iTrader: (8)

Thanks for the reply, question though. If I didn't want to flycut, how big do you think my limit would be 228 / 230, 230 / 232. I take it your reference was to a F14 type of cam at 232 /234. Any input would be appreciated.

8a8mfh

iTrader: (3)

So you're going choose a cam so you don't have to flycut?
So if you could get 80 hp more with a cam and flycutting, you'd rather go 80 hp less just to avoid flycutting?
Thats not the smartest way to build an engine.

8a8mfh

iTrader: (3)

Check the PTV clearance, pretty simple.

JPH

iTrader: (2)

234/242 at the biggest and it still will be tight. It's the intake side you want to be concerned with. Anything bigger than 228 @.050 with 110-112LDA and 106-109ICL gets really close with milled LS6/#243 heads and PTV ALWAYS has to be verified.

slonomo

iTrader: (8)

Flycutting has just got me concerned in two ways: losing piston strenght (although I don't ever anticipate using power adders), and loss of compression (I spent extra money to up the compression by milling, don't want to go with a bigger cam for extra time and expense to find that I cancelled out my gains). Otherwise I guess I don't have anything against it.

Take a look at my current cam specs, I still want it to be streetable, but I think I can meet that goal by adding a bit more duration, and with 540 lift there should be something to be gained by going to a lift around 600.

8a8mfh

iTrader: (3)

Duration will more likely cause ptv contact then lift.

This is the worst mistake you can make, asking around to see if others have ptv contact with a similiar set up.
My best advice is to choose the parts that get you where you want to be, check ptv clearance and cut if you need to. You should gain 2cc MAX with a very deep cut.

AU N EGL

That sounds like the Speed World Challenge heads with the 60.9CC Check the GMPP part number. 88958622

If so these heads were designed to use the GMPP Cup cam. 239/251 570/570 106lsa

From the good folks at GM. The LS1 "Grand-Am Cup" hydraulic camshaft. Thats right folks, this is no solid roller cam either. RPM range is 4000-7000! 550+HP

slonomo

iTrader: (8)

Actually I thought they were designed to go with the ASA cam: 226 / 23x with 525 lift on a 110 LSA.

ssheets

iTrader: (1)

Not sure how close this is, but it will give you something to think about.
I just installed an F14-112 on set of 5.3 heads with 2.02" intakes. My 5.3 heads were milled 3-5 thousandths and I ended up with .100" PTV on the intakes and .180" on the exhaust. I may chonge out the .054" MLS gasket to something thinner when I feel like pulling the heads off for the fun of it.

PREDATOR-Z

Guys, keep in mind that when measuring PTV you HAVE to get the readings 10* BTDC and 10* ATDC (int/Exht) respectively. Getting readings ATDC doesn't give the whole story. ATDC valves are closed, it is before and after in the cycle that contact occurs.

less than .060 on street is crapshoot, I would run .060>.080 but you're not out of danger yet.

lilbuddy1587

iTrader: (1)

I ran GMPP CNC LS6 heads that were 60.7CC's (verified by a machine shop) with a 24x/24x cam on a 111lsa (AZPS03, EDC special) and the pistons had to be flycut. The shop that did my work didn't measure properly for the exhaust side (they didnt cut for the exhaust, which I found out AFTER the fact) and I wound up with spun rod bearings and major PtV (exhaust) on all 8 pistons. The only thing that survived without harm was the block and heads.

So please listen to these guys and measure your piston to valve clearance, valve drop, etc. Make sure and degree your cam if you can get ahold of a comp/crane etc degree kit.

Good luck