Swapping a 6.0 ls into a G body

[Northernregal]

Those heads work better on a 4.100" bore, will work on a 4" but better on a bigger bore.
Anything 4" or under the Cathedral Heads work great.

LS7 Heads require a minimum 4.100" if I remeber right, so yea still want to see how this person is building this setup.

MAST Heads are mentioned so it may be the small bore LS7 Heads they make, which will go on the 4" bore. They like RPM's tho so there's that.

You can unshroud LS3 heads for a 4.00" bore pretty easily, so thats not an issue. Same for LS7 on a 4.065 bore.

For the flow difference, LS3 is around 340CFM and LS7 around 360cfm. Its pretty much the slightly better valve angle and chamber on the LS7 heads that would be the benefit. To railroad yourself into LS7 manifolds for almost no real world benefit is kinda short sighted. Might as well put a 105mm throttle body and 2" headers on it with a 21x/21x 0.550" lift "Stage 1" cam.

 

[64nailhead]

LS7 anything is for all out NA go. Anything other than a max effort deal I view as a waste of money. Unless of course you have money to blow. A stroked 6.0(408) with cathedrals will outperform the LS7 stuff until 5500-6500 and above.

Cathedrals FTW imo.

And cornering yourself to be only able to use LS7 stuff can get expensive if you need replacement parts as compared to cathedral stuff.

 

[johnnunez29]

LS7 anything is for all out NA go. Anything other than a max effort deal I view as a waste of money. Unless of course you have money to blow. A stroked 6.0(408) with cathedrals will outperform the LS7 stuff until 5500-6500 and above.

Cathedrals FTW imo.

And cornering yourself to be only able to use LS7 stuff can get expensive if you need replacement parts as compared to cathedral stuff.

Im basically going off my engine builders recommendation. REason i went with mast heads was it was going to be almost the same price as purchasing the trick flow heads and sending them out. Unfortunately i tried to do my research but thats EVERYWHERE. Some people swear on cathedrals and others argue how bad they are. So i just went with what the builder recommended. (well he said go 4.000 bore, and i ultimately went with 3.900). Will be running the L8Tcrank, wiseco pistons and callies rods. Builder also recommended if i stroke to stay NA, and just put the money into the heads. Also mentioned that ls7 i can purchase someones manifold with injectors and it would work without having to buy a big aftermaret system. Again not an engine builder just getting an engine built. Thanks for the input ill ask all that.

 

[johnnunez29]

You have some things that aren’t adding up.

What are you goals? Asking because if you’re planning to run expensive heads, then either you plan to be racing or have a lot of money to burn. Not that there is anything wrong with burning a bunch of money, but for a street car you’ll be burning it.

Putting a stroker kit into the 6.0, getting the heads a fresh valve job, proper cam, springs and headers can yield 600 crank hp and still be driveable.

Dont necessarily have a "bunch of money to blow". Went mast over trick flow due to being close in price after shipping out. Also may want to build something better in the near future ill have the mast heads to work off of. Ill ask builder anything that makes sense for sure. Trying to get as much power out na as i can. i asked elsewhere and people were telling me to go boost even stroked, while others said not to do it.

 

[Built6spdMCSS]

So i just went with what the builder recommended. (well he said go 4.000 bore, and i ultimately went with 3.900).

Picked up a clean rolling shell 86' MCSS and am in the process of bldg an lq9 (pistons on back order since i went with 3.900 stroke).

Soo what one is it?

 

[johnnunez29]

Soo what one is it?

What do you mean? Not sure what you’re asking me about? The bore?

 

[64nailhead]

Usually an LS7 head for a 4" bore won't work on a 3.90" bore due to valve interference and issues with valve shrouding.

This was what I was referencing about a mismatch of parts (I believe that is what Built6spd was referencing also, but I don't want to speak for him.)

Either the Mast or TF heads are good pieces. For something is strictly street driven they are overkill and genuinely not going to be a noticeable improvement over 706/899/243 head. LS heads work very well in stock form, even the ones with smaller valves.

 

[dgmeadows]

What do you mean? Not sure what you’re asking me about? The bore?

I think he is pointing out that in one post you referenced 3.900 as the bore, and in another 3.900 as the stroke.

 

[Built6spdMCSS]

Exactly.

What do you mean? Not sure what you’re asking me about? The bore?

The post above another guy sees it as well. You say two different things.

Usually an LS7 head for a 4" bore won't work on a 3.90" bore due to valve interference and issues with valve shrouding.

This was what I was referencing about a mismatch of parts (I believe that is what Built6spd was referencing also, but I don't want to speak for him.)

Either the Mast or TF heads are good pieces. For something is strictly street driven they are overkill and genuinely not going to be a noticeable improvement over 706/899/243 head. LS heads work very well in stock form, even the ones with smaller valves.

Pretty sure even the small bore LS7 Heads from MAST need a 4" bore.

If this guy is building something with a 3.900 hole in it, cathedral head all day but we shall see..

 

[johnnunez29]

Exactly.


The post above another guy sees it as well. You say two different things.


Pretty sure even the small bore LS7 Heads from MAST need a 4" bore.

If this guy is building something with a 3.900 hole in it, cathedral head all day but we shall see..

sh*t. Hadn’t noticed I put bore on there. My bad. 3.900 stroke and 4.030 bore