: ( 6.0 MS4 Question
11-15-2007, 02:00 AM
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: ( 6.0 MS4 Question So here's the deal.
I'm doing a 6.0 build. Im using the stock shortblock from a 6.0 truck motor. It has the Dished Pistons.
Now i know on a stock cube ls1 engine, you can run the ms4 with just barely enough valve/piston clearance. Well, i have some Stage 3 Patriot heads that have been Milled slightly. Now i know if that was going onto a stock cube ls1 we would be having some issues with clearance, but since i have the dished pistons maybe i might be ok?
if not, what if i picked up a set of thicker head gaskets? Maybe some Cometics? (if anyone knows the part number on some thick 6.0 cometic head gaskets please let me know
).
I think with the stock dished 6.0 pistons and some cometic head gaskets i might be able to do this without having to flycut my pistons.
Any input would be highly highly appreciated.
Thanks.
I'm doing a 6.0 build. Im using the stock shortblock from a 6.0 truck motor. It has the Dished Pistons.
Now i know on a stock cube ls1 engine, you can run the ms4 with just barely enough valve/piston clearance. Well, i have some Stage 3 Patriot heads that have been Milled slightly. Now i know if that was going onto a stock cube ls1 we would be having some issues with clearance, but since i have the dished pistons maybe i might be ok?
if not, what if i picked up a set of thicker head gaskets? Maybe some Cometics? (if anyone knows the part number on some thick 6.0 cometic head gaskets please let me know
).I think with the stock dished 6.0 pistons and some cometic head gaskets i might be able to do this without having to flycut my pistons.
Any input would be highly highly appreciated.
Thanks.
11-15-2007, 06:24 PM
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So even though the heads are slightly milled it will be fine, and i wont have to flycut?
Believe me, there will be plenty of vid's once we are finished. It's a garage project so im taking my time. Hoping to be done in the next few weeks.
Any more info?
Believe me, there will be plenty of vid's once we are finished. It's a garage project so im taking my time. Hoping to be done in the next few weeks.
Any more info?
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11-16-2007, 02:51 PM
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well these i have are dished. i bought the whole short block from a guy off here and the arent flat all the way across them like my 5.7 ls1 pistons were,, they have a dish all the way around it, not dished for the valve they just arent flat all the way across, dished may be the wrong term to use but i dont know how else to explain it.
its like theres a raised edge around the outer edge of the piston about a quarter of an inch around the circumference then they dish down in the middle of the piston not sure how much tho...
its like theres a raised edge around the outer edge of the piston about a quarter of an inch around the circumference then they dish down in the middle of the piston not sure how much tho...
11-16-2007, 03:06 PM
#14
The engine is a 6.0 lq4 and comes factory with dished pistons. The comp ratio is 9.4 to 1. The lq9 had flattops and comp is 10.1 to 1. If the heads you have are 243 castings and theyre milled .020 comp should be about 10.7. Stock 317 6.0 heads are 72 or 74 cc cant remember and the 243's are
64 cc minus whats milled. Stock 243's on a lq4 yields 10.4 to 1 comp so that is my estimate. You should be very careful with cam selection or your static comp may be too high. Pay close attention to your valve overlap. See the cam sticky to figure out how to compute it. Hope this helps.
Chris
64 cc minus whats milled. Stock 243's on a lq4 yields 10.4 to 1 comp so that is my estimate. You should be very careful with cam selection or your static comp may be too high. Pay close attention to your valve overlap. See the cam sticky to figure out how to compute it. Hope this helps.
Chris
11-16-2007, 03:56 PM
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It does help, I believe my heads have 64cc chambers. They are the patriot Stage 3 6.0 heads. I dont know if what difference that makes but...
Any more info guys?
Any more info guys?
11-16-2007, 06:58 PM
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well these i have are dished. i bought the whole short block from a guy off here and the arent flat all the way across them like my 5.7 ls1 pistons were,, they have a dish all the way around it, not dished for the valve they just arent flat all the way across, dished may be the wrong term to use but i dont know how else to explain it.
its like theres a raised edge around the outer edge of the piston about a quarter of an inch around the circumference then they dish down in the middle of the piston not sure how much tho...
its like theres a raised edge around the outer edge of the piston about a quarter of an inch around the circumference then they dish down in the middle of the piston not sure how much tho...
11-16-2007, 08:18 PM
#17
Personally, I would not recommend going to a thicker gasket for valve clearance. I would recommend checking the deck clearance (the distance the pistons are in the hole, or exposed from the hole, at TDC), running a gasket that puts the piston within .030 to .035 of the deck at TDC, and checking for adequate clearance (usually .080" Intake, .100" exhaust).
Moving the cylinder head deck away from the piston reduces the squish in the chamber as the piston approaches TDC, and ultimatley makes the engine more prone to detonation, despite the slightly lower compression ratio.
If the original poster is going to run the MS4, even 10.7:1 may be on the low side for what that cam wants. Using PianoProdigy's DCR calculator, I figured a 7cc dish and .055 thick gasket would give approx 9.4:1, and 0 dish gave 10.1:1. With a 64cc head milled .020, the compression with dished pistons and a .040" thick gasket comes out to 10.84:1. The problem is, that cam bleeds a lot of cylinder pressure with it's late closing intake valve, so the Dynamic Compression comes in at less than 8:1.
Overlap will not affect the dynamic compression, but the VE's that generate more overlap (tight LSA, longer durations) are more likley to create a valve clearance issue
Moving the cylinder head deck away from the piston reduces the squish in the chamber as the piston approaches TDC, and ultimatley makes the engine more prone to detonation, despite the slightly lower compression ratio.
Originally Posted by topher455
The engine is a 6.0 lq4 and comes factory with dished pistons. The comp ratio is 9.4 to 1.
If the heads you have are 243 castings and theyre milled .020 comp should be about 10.7.
You should be very careful with cam selection or your static comp may be too high. Pay close attention to your valve overlap. See the cam sticky to figure out how to compute it.
If the heads you have are 243 castings and theyre milled .020 comp should be about 10.7.
You should be very careful with cam selection or your static comp may be too high. Pay close attention to your valve overlap. See the cam sticky to figure out how to compute it.
Overlap will not affect the dynamic compression, but the VE's that generate more overlap (tight LSA, longer durations) are more likley to create a valve clearance issue
