View Poll Results: 10.75:1 or 11.5:1
Voters: 88. You may not vote on this poll
11.5:1 Cr?
You'll be okay... as long as the ICL is 112 or higher (232/234 112 LSA with no advance) and you're not milling more than say .020".
I dunno about that but the stock valves will help out a little. You will still need to measure to be safe.
I am running a 230/234 111+2 with no mill and .054 MLS gasket. Heads are the 5.3 stage 2.5 (2.02 intake/1.575 exhaust valves). I couldn't mill or run a thinner gasket and stay safe. I realize the bigger valves and tight LSA with advance cost me some PTV but still think you will be very close milling to 59cc and doubt you'll clear if you throw in the .040 Cometic HG.
I would talk to a builder who's done a bunch of LS1's or TSP (no offense intended JF
) before I pulled the trigger just be sure.BTW my unmilled 5.3's put me about 10.75-10.8-1
Also if you can run .040 and not mill you will improve quench and lose no flow (milling will cost you a tiny bit) so that would be my first option.
Last edited by SOMbitch; Oct 11, 2008 at 03:50 PM.
What way are you leaning? I would aim for 11.5:1 with a moderate sized cam. Unless you measure PTV clearence during your build, its just an educated guess whether or not it will clear...and by how much. Every motor varies slightly so be weary of someone saying "oh I did it you'll be fine". Always best to verify yourself when you're pushing PTC clearences.
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From: >>>_FRISCO_MUSCLE_<<<
How do I measure PTV during the build? Also, should I get the head work done first or should I lock in to a practically cam first? Pred-Z gave me a custom grind I'm pretty much stick with it.
11.8-1 with Comp Cam-232*-234*@.050", .595"-.598",112LS. 4100lb car w/driver. 11.90-12.00 with 347, 11.40's@117-118 with 382. Drive anywhere. 241's with ETP Stage 2 cnc. .040" gasket. Measure PTV with modeling clay and the gasket you plan to use. I took 2 factory lifters apart and rigged them to be solid. Put in the cam and 2 lifters, (I checked both sides), and rotate the motor to get the valves to squish the clay. Carefully take off the heads, not to mess up the clay, and take a caliper and measure where the valves left the imprints. I had .108" on the exhaust and .127" on the intake which is more than enough. There is lots of help on this site. Good Luck.
Last edited by 382ssz28; Oct 22, 2008 at 10:23 PM.
Custom ground cam would work. With a .040" gasket and milling the head around .020" (59cc chambers if it started around ~62), you'll end up with enough clearance for something as large as a 234 XE-R duration intake lobe on a 114 ICL. That should give you around ~.060" clearance on the intake side if you're using stock 2.00" valves or are using the recessed vavle PRC 5.3s. For a lot of power throughout the range and good drivability, I think a lower 230s duration cam is the ticket on a 346.
A good off-the-shelf grind would be the Torquer 2 (Comp XE-R 232/234 113+0). It'd be ragged edge close ~ .060" P-t-V clearance with .040" gaskets and 59cc chambers and 2.00" intake valve, so you'd have to measure. But, the stats would be 11.8:1 SCR, 8.7:1 DCR, and a late intake valve closing of 49 (perfect for a 7k RPM 346 with a FAST Manifold). It'd make for a real top end screamer that has power throughout the range due to the early intake valve opening and high dynamic compression. Plus, it has relatively mild overlap, so it'd idle and behave pretty good on the street.
nice alot more percise than i could have wrote it
i had this came with a a stock set of 243 and a 40 mil gasket made 428 h 410 t to the wheel i loved the power band very tourqey down low but screamed up top and it liked the spray gained over 200 ftp on a 100 shot and we all know hp sells cars and trq wins races
A good off-the-shelf grind would be the Torquer 2 (Comp XE-R 232/234 113+0). It'd be ragged edge close ~ .060" P-t-V clearance with .040" gaskets and 59cc chambers and 2.00" intake valve, so you'd have to measure. But, the stats would be 11.8:1 SCR, 8.7:1 DCR, and a late intake valve closing of 49 (perfect for a 7k RPM 346 with a FAST Manifold). It'd make for a real top end screamer that has power throughout the range due to the early intake valve opening and high dynamic compression. Plus, it has relatively mild overlap, so it'd idle and behave pretty good on the street.
nice alot more percise than i could have wrote it
i had this came with a a stock set of 243 and a 40 mil gasket made 428 h 410 t to the wheel i loved the power band very tourqey down low but screamed up top and it liked the spray gained over 200 ftp on a 100 shot and we all know hp sells cars and trq wins races
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Doesnt Patriot offer heads with welded chambers to achieve desired compression? Wouldnt that be the way to go? Some welded ls6 heads that havent been milled? That would give you compression and you can run a big cam? I may be wrong tho?
Patriot use to take the 317 truck heads and weld the chambers. Then they milled them to the desired compression ratio. 317s and 243s have the same combustion chamber design, just different volumes. They called them 'LS6 Style' CNC heads. Now they actually take 243 castings and cnc them.
317 heads have 72cc chambers. They welded them and cnc'd them to make a 64cc chamber just like the 243. Then they would mill them to 59cc if you wanted. It was a cheap way to sell ls6 'style' heads since 317 castings are much cheaper for them to buy.
Ok I got ya. But I dont see why you couldnt add a little material to the chamber and not mill them? And then you have your compression bumped up with out moving the valve any closer to the piston...am I wrong?
Try to get all the compression you can without milling the heads. When you mill the heads you tighten your PTV clearance. So with that said you could run a stock deck 243 head but run a slight smaller head gasket and get 11:1 compression out of it. Go to this link and play with this compression calculator that I made and figure out for yourself what you want. Obviously you want the most compression with the most PTV so you can run larger cam profiles so take a look at this and see for yourself...
https://ls1tech.com/forums/generatio...alculator.html
Here is a list of stock chamber volumes on various LSx heads:
317 heads = 71.06cc chamber
241/853 LS1 heads = 67.67cc chamber
243 LS6/2 heads = 64.45cc chamber
706 5.3L heads = 61.15cc chamber
https://ls1tech.com/forums/generatio...alculator.html
Here is a list of stock chamber volumes on various LSx heads:
317 heads = 71.06cc chamber
241/853 LS1 heads = 67.67cc chamber
243 LS6/2 heads = 64.45cc chamber
706 5.3L heads = 61.15cc chamber
Last edited by LSxPwrDZ; Apr 23, 2009 at 12:21 AM.
Well, you will want to measure for yourself, but we had tons of clearance with 243's milled to 59cc, stock MLS gasket, 2.055/1.6 valves and a VRX3 cam (226/228 on 114+4). I would think you would do well with a 228 grind and milled heads.
More compression = more power everywhere.
It's enough to close the gap in peak power as .75 CR points generally can be viewed with around 3-4% in power gains. At 400rwhp, that's enough for a 228 cam to effectively bridge the 15rwhp its down vs a 238ish cam.
But because the 228 cam already is up in the bottom end and midrange versus the larger cam, the added compression will only help it make a ton more throughout the whole RPM range.
Ideally, with a willingness to flycut, you could go with ported heads that have been milled down, thinner gaskets for better quench, and then run a large cam to make even more topend power and shore up any softness in the bottom of the curve.
It comes down to what your goals are, what sort of drivability you want, and what sort of mods you are willing to invest in. With a more restrictive intake tract and exhaust, the difference in power between a larger cam and smaller cam will be less than what you're expecting.
I voted for more compression and less cam if those remain your options.
It's enough to close the gap in peak power as .75 CR points generally can be viewed with around 3-4% in power gains. At 400rwhp, that's enough for a 228 cam to effectively bridge the 15rwhp its down vs a 238ish cam.
But because the 228 cam already is up in the bottom end and midrange versus the larger cam, the added compression will only help it make a ton more throughout the whole RPM range.
Ideally, with a willingness to flycut, you could go with ported heads that have been milled down, thinner gaskets for better quench, and then run a large cam to make even more topend power and shore up any softness in the bottom of the curve.
It comes down to what your goals are, what sort of drivability you want, and what sort of mods you are willing to invest in. With a more restrictive intake tract and exhaust, the difference in power between a larger cam and smaller cam will be less than what you're expecting.
I voted for more compression and less cam if those remain your options.
just believe me and install patriot LS6 stage 2 heads 59cc and G5X3 without flycutting your CR will be at 11:00 , my buddy tried this combo and he pulled +450RWHP , talk to LMP performance and see what they will answer u , good luck
, good luck Last edited by PONTIAC SLP; Apr 29, 2009 at 04:58 AM.