OutToWinPAHC

iTrader: (10)

So I am on a budget and I am swapping engines. My LS6 bottom end has a tick noise and I found a nice chunk of steel stuck on the magnetic drain plug.

Anyhow in the future I want to build a 408 stroker motor with ported / milled L92's, but for now I want to get it up and running without going nuts.

So I will be swapping out the LS6 bottom end for a LQ4 with low low miles. I don't want to spend anymore then I need to so I want to reuse my setup. I am gaining a little displacement, but loosing compression with LQ4 bottom end.

I have ported 243 heads stock 64.xx cc surface, to increase compression with stock head gasket I would like have them milled down. What is the max I should mill without clearance or other issues? I run a MS3 cam lifting .610.

blsnelling

iTrader: (4)

Some have gone as far as .050", but most say .035" is the safe max. That's what I'm doing with the 243s on my LQ4 build. You'll end up with about 59cc heads. That will give you 10.1-10.2:1 on a LQ4 shortblock.

OutToWinPAHC

iTrader: (10)

Good info, but at 74cc with the 317 heads weren't the LQ4 10.0:1 I was hoping to get closer to that 10.5:1 mark.

.035, I'm gonna keep that number in mind, because 59cc is what I had in mind.

blsnelling

iTrader: (4)

You could probably get there if you went with .040" gaskets, but I've been scared off from Cometic with all the water leaks. Otherwise, that's what I'd be doing.

blsnelling

iTrader: (4)

I believe the LQ9 has 10:1 and the LQ4 only 9.4:1.

OutToWinPAHC

iTrader: (10)

Yeah I was wrong on those stock compression ratings. No I avoid cometic, I have had issues. I think I will use OEM gasket at the stock .055 thickness.

Main goal is to keep power the same, or gain a pony or 2. Displacement helps, just trying to keep compression in line.

blsnelling

iTrader: (4)

I'm going to have to dig back through my findings, but I think I may have given you some misinformation. I think you'll get 10.2:1 without milling the 243 heads, and about 10.7:1 if you take off .035". Hopefully someone with more experience can clarify.

OutToWinPAHC

iTrader: (10)

Good stuff, hopefully your correct because that would be an on par displacement increase.

Spoke to my machine shop they priced $200 for .035 off and to mill the intake side to keep shape.

So all said and done it should be this matched to a D&D T56 through a Spec 3

-59cc ported 243 heads, with Patriot racing dual gold springs
Texas MS3 605/610 238/242 114LSA
-LS7 Lifters, LS2 lifter trays, TR pushrods, Scorpion rocker arms 1.7
-Stock low mile LQ4 with GTO pan, LS2 timing gear and chain, ported LS6 oil pump, LS6 valley / engine covers
-Ported / honed Weiand intake, 85mm TB, LQ9 coils, Electric water pump, 10% underdrive

blsnelling

iTrader: (4)

I'm paying $80 to have mine milled .035". I didn't plan on doing anything to the intake side. Is that necessary?

Sales2@Texas-speed

iTrader: (5)

Keep in mind if you mill those heads and run that camshaft, you will have to flycut your pistons to regain sufficient piston to valve clearance!

OutToWinPAHC

iTrader: (10)

Damn, is that just because of the heads, cam, piston set up, or because of the .035 milling? I tried to look info up on the LQ4 piston design with no luck.

Damian

iTrader: (89)

D: All of the above.

OutToWinPAHC

iTrader: (10)

Damn that's a bubble burster because I cant build the stroker just yet. My assumption would be the piston clearance vs large cam on these LQ4's. What is the max lift on a LQ4 with a 64 or 59cc 243 head then. Forgive me I don't dabble enough with it, and solid LQ heads cam info hard to find.

Sales2@Texas-speed

iTrader: (5)

I responded to your PM

For the record, you can run the MS3 and enjoy it, but not with the LS6 heads milled that far.

blsnelling

iTrader: (4)

Can you comment on the resulting compression ratios?

Sales2@Texas-speed

iTrader: (5)

To run the MS3, you'd be looking at a best case of 63cc chambers if you don't flycut. That will net you right at 10.4:1 static compression with a GM MLS gasket in the mix. This is less than ideal for a street/strip car, IMO!

Now you could go with some 61cc chambers and a .040" gasket and run the 228R or even the TorquerV2 and have much better average power and a much more well-rounded combo! This combo nets you right about 11.0:1 static compression.

The_Rizzle

iTrader: (4)

w/ 4.00 bore, 3.622 stroke, .051 gasket thickness, 4.060 gasket bore, and piston .006 out of the hole, 6cc pistons (mathematical estimate) and 64.5 cc chambers, you get 10.3. At 59cc chambers - 11:1.

blsnelling

iTrader: (4)

Wow. I didn't realize it would be that high. Perhaps I should stop looking at .041" thick gaskets. I don't want any more than 11:1 compreesion.

OutToWinPAHC

iTrader: (10)

Hmm the 11.0:1 would be nice. Perhaps I should just mill these ported 243 to unsure straight, perhaps .005 off and swap cams from my MS3 to the 228R. I autocross, sunday drive and show it.

blsnelling

iTrader: (4)

11:1 is fine on premium pump gas with a good tune.