02TransAm/Batmobile

iTrader: (32)

Trying to bump up compression in my LS1 with a 234/242 110+4. What are the pro's and con's of each? How much is it to mill heads?

Thanks

02SOMWS6

iTrader: (6)

cons would be having to flycut the pistons. Pro's would be a good power gain across the board. I had milled heads to begin with. I just went with a bigger cam and thinner gasgets and should be damn near the 500 mark once it's re-tuned

vettenuts

iTrader: (4)

I have been looking at this, to me the question is thinner gasket or not. Seems like a lot of guys have problems with Cometics leaking, so I plan to bump compression but stick with the stock GM MLS gaskets.

02TransAm/Batmobile

iTrader: (32)

I've heard of problems with the Cometics also. I haven't heard of many complaints about the Felpro though.

Anyone else?

NemeSS

iTrader: (127)

thinner gaskets will provide more scr and dcr,
stock oem ls gaskets are in the .050-.055 compressed thickness
range, with a .005-.010 out the bore pistons for stock bottom ends.
thinner gaskets will cost more than having heads milled, but ptv will need to be checked,
thinner head gaskets also affect quench and usual rate at machine shops to mill alum. heads is about 50$ pair for .010-.015

Thimble

iTrader: (2)

Ideally, do both.

Thinner gaskets reduce the quench, milling does not. Lowering quench is desirable for knock/detonation resistance. Ideal quench should be in the .030-.040" range. Gasket thickness minus the piston out of the hole dimension = quench.

That cam on a 110 lsa will likely require flycutting with stock heads/gasket anyways, so as long as you're making room, why not optimize compression and quench?

Cometics seal just fine if you take some time to insure the head and block deck surfaces are clean and smooth. There are also several other thinner-than-stock head gasket choices out there that aren't MLS....SCE (copper), Mr Gasket (graphite), etc.

02TransAm/Batmobile

iTrader: (32)

I want to. But right now I am strapped for cash. Milling, gaskets and flycutting might be over my budget.

How much would all that cost me?

gts500

i went with .040 cometic MLS ,instead of milling and pump up a desent amount of compression.but i had to flycut anyway
the .040 cost 150$

YankeeVert.

Thats what I did. Milled the heads .020" and used the stock GM MLS gaskets. Worked out great.Car runs great on 93 octane fuel. No pinging,great low end torque and instant throttle response.

fuseone

just mill the heads and thinner gasket lol

02SOMWS6

iTrader: (6)

dont forget your get a ARP head stud kit also. There should be no issues with cometic's with a head stud kit

KONG

iTrader: (4)

Why would he need a head stud kit??? As long as you ensure that all surfaces are flat and smooth you will have no problems. I run .040 cometics with a similar cam grind and I use all GM bolts and have never had any problems. Correct preparation is key.

RGKSR

iTrader: (9)

I've used FelPro's and have had no leaks. The 1041's are .041 and will raise the compression a little. I just went to them in an effort to get a little lost power.

Bob K.

PREDATOR-Z

Well I do hope you have piston reliefs because you allready need to flycut.
To answer your question, it depends how much you want to bump compression. But it is always better to reduce gasket thickness first depending on you piston deck height value.

It would be easier to answer this question if you gave your motor specs.

BIG_MIKE2005

iTrader: (116)

I'm running these also with my 5.3 heads milled .018". I can only get 91 octane here & it's running perfect.

02TransAm/Batmobile

iTrader: (32)

Stock LS1 with Stock LS6 Heads Predator. Trying to get DCR into the mid 11's and SCR into the mid 8's.

Will do valve reliefs if necessary. Trying to figure out how big of a valve relief also.

02SOMWS6

iTrader: (6)

true, but a head stud kit will have more clamping down force. I always seem to go for over kill. I also lifted a head on spray with stock gm bolts so I think if it's apart it should get a head stud kit to keep it together longer

vettenuts

iTrader: (4)

I have been told to just clean well up to and including honing the block with a stone to reduce the Ra to an acceptable level. So what is everyone doing for block prep for the Cometics that "aren't" having leaks?

KONG

iTrader: (4)

point taken

TA455

Think you might have DCR and SCR reversed in the above statement.