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Probably netting good compression with those heads though. Small chamber iirc? I'm gonna have to settle for 10.5 which puts dynamic right around 8.05:1
Last edited by Pwnage1337; 11-27-2018 at 07:45 AM.
Probably netting good compression with those heads though. Small chamber iirc? I'm gonna have to settle for 10.5 which puts dynamod right around 8.05:1
hey before you swap to those LS3 heads, how far you gonna go? I would score a set of 0243 64cc heads and thinner head gasket. Probably bump you up to 10.5 compression ratio. If you want more go with the 799 heads they are 62cc head. Both cc'ported they flow a chit ton of flow. Not sure on what intake your gonna run.
I have a LQ9 in my 85 vette, she sure is a fun engine to run. LS3 heads on a 6.0 you need 3.73 gears to make them work enough so they pay back. Ya those LS3 heads are cheap but you have to buy a bunch of extra bits to get them to work. Those old cathedral heads work as well. Bunch of outfits make cathedral heads that can flow with any LS3 head. I like that fact that you don't have to run the cam sensor wires up front.
hey before you swap to those LS3 heads, how far you gonna go? I would score a set of 0243 64cc heads and thinner head gasket. Probably bump you up to 10.5 compression ratio. If you want more go with the 799 heads they are 62cc head. Both cc'ported they flow a chit ton of flow. Not sure on what intake your gonna run.
I have a LQ9 in my 85 vette, she sure is a fun engine to run. LS3 heads on a 6.0 you need 3.73 gears to make them work enough so they pay back. Ya those LS3 heads are cheap but you have to buy a bunch of extra bits to get them to work. Those old cathedral heads work as well. Bunch of outfits make cathedral heads that can flow with any LS3 head. I like that fact that you don't have to run the cam sensor wires up front.
Keep us posted on the build.
I think the aftermarket LS3 heads he is or wants to use are 64cc and land him at the 10.5:1 ratio. Going with the 799 head w/ 62cc only bumps him to 10.7:1 and will probably give up ~30+ hp with the cam he is planning on using.
I think the aftermarket LS3 heads he is or wants to use are 64cc and land him at the 10.5:1 ratio. Going with the 799 head w/ 62cc only bumps him to 10.7:1 and will probably give up ~30+ hp with the cam he is planning on using.
Exactly. I think the aftermarket heads flow characteristics will net me more power than the .2-.3 bump in compression.
Beyond that, the stock LS3 manifold is actually pretty decent, much better than the LS6/LS2
I think the aftermarket LS3 heads he is or wants to use are 64cc and land him at the 10.5:1 ratio. Going with the 799 head w/ 62cc only bumps him to 10.7:1 and will probably give up ~30+ hp with the cam he is planning on using.
The GM L3 cnc that I had were 68cc and would have bumped my compression of my LQ9 to 10.5 area. You could send your 317 heads off the LQ4 to get shaved and cnc'd.
Curious on what the plan is for the rods? I installed ARP rod bolts into mine. Heard that the gen iv rods are stronger than the gen 3 rods.
The 20HP gains of LS3 will only be at rpm's above 5500 rpm, at 2000 rpm you'll lose 20HP
The GM L3 cnc that I had were 68cc and would have bumped my compression of my LQ9 to 10.5 area. You could send your 317 heads off the LQ4 to get shaved and cnc'd.
Curious on what the plan is for the rods? I installed ARP rod bolts into mine. Heard that the gen iv rods are stronger than the gen 3 rods.
The 20HP gains of LS3 will only be at rpm's above 5500 rpm, at 2000 rpm you'll lose 20HP
Worth it!
And they will make more power from about 4400-4500 on.
Nice video, amazing how much power you can get out of stock heads. Those 799 head is off 5.3L engines and 210cc intake runner (bone stock) made almost same power as a LS3 255cc head, that LS2 intake is the biggest power disadvantage to that LY6 6.0L engine, which comes with 0823 heads. The 823 head are a truck head similar to the 821 head, but without the hollow stem valves. Also heard from TSP that the 823 head cnc'd will out flow slightly a cnc LS3 head.
That video also used a bigger camshaft than what the op and you are using. I'm going with an aftermarket head with 230-240cc intake runner, they still make good power down low and almost flow like the LS3 head.
I'm planning on going with a 4in stroke and either 4.03 or 4.07 bore, which works better with the better flow head and makes way more grunt. Mix in some power booster, you better hang on.
Krusty, you have one heck of car. Glad your sharing your LS building experience. Really enjoy chatting with you all things LS engines, as the in the C4 section is lacking. To bad we can't get a chance to chat with you face to face.
I want more low end grunt as I plan to run 6-12psi of boost at some point,
Nice video, amazing how much power you can get out of stock heads.
This is kind of my argument for the LS3 head on a 6.0L. You don't have to do anything to it and it rips. I think all those articles and comparisons of the late 2000s and early 2010s of the cathedral vs rectangle port heads were intentionally skewed by the aftermarket manufacturers and the speed shops that had a lot invested in inventory and R&D of their CNC ported cathedral heads. No way the manufacturers or the guys that invested money in a pricey set of cathedral ports wanted the public to know that they could achieve or exceed their power goals with a $300 cylinder head. Most all of the aftermarket sponsored shows like Engine Masters, Road Kill etc... won't feature the LS3 head because it damages the "good deal or hp per $" perception of their sponsor's products.
I give it to the cathedral port on the low end, I just don't really know of anyone tinkering with a budget 6.0 that wouldn't trade the 20hp/tq down low for the 20hp+/~10tq+ up top.
This is kind of my argument for the LS3 head on a 6.0L. You don't have to do anything to it and it rips. I think all those articles and comparisons of the late 2000s and early 2010s of the cathedral vs rectangle port heads were intentionally skewed by the aftermarket manufacturers and the speed shops that had a lot invested in inventory and R&D of their CNC ported cathedral heads. No way the manufacturers or the guys that invested money in a pricey set of cathedral ports wanted the public to know that they could achieve or exceed their power goals with a $300 cylinder head. Most all of the aftermarket sponsored shows like Engine Masters, Road Kill etc... won't feature the LS3 head because it damages the "good deal or hp per $" perception of their sponsor's products.
I give it to the cathedral port on the low end, I just don't really know of anyone tinkering with a budget 6.0 that wouldn't trade the 20hp/tq down low for the 20hp+/~10tq+ up top.
This is something I realized too little too late when I was already in a decent built gen 1 sbc 383. The AFR heads for gen 1s are nice out of the box heads but the fact that you can find a $300 set of LS3 heads that someone is tired of seeing in their garage that flow just as much or better is a testament to the LSX platform. You’ll shell out five times the price of a used set of LS3 heads for aftermarket gen 1 stuff that isn’t junk, but in terms of LS capabilities, it’s just “meh”.
The LS platform is at an age now where so many parts are flying around for sale, there’s almost no excuse to not do an LS motor. Guys are tripping over these parts and cussing at them taking up space...deals are everywhere. The days of, “just buy a C5” are long gone for arguments not to do a swap.
This is something I realized too little too late when I was already in a decent built gen 1 sbc 383. The AFR heads for gen 1s are nice out of the box heads but the fact that you can find a $300 set of LS3 heads that someone is tired of seeing in their garage that flow just as much or better is a testament to the LSX platform. You’ll shell out five times the price of a used set of LS3 heads for aftermarket gen 1 stuff that isn’t junk, but in terms of LS capabilities, it’s just “meh”.
The LS platform is at an age now where so many parts are flying around for sale, there’s almost no excuse to not do an LS motor. Guys are tripping over these parts and cussing at them taking up space...deals are everywhere. The days of, “just buy a C5” are long gone for arguments not to do a swap.
The gen I is limited by it's design. For somethng to remain mostly unchanged for 40 years and still contend with the best at the end of the line is impressive. The jump from LT4 to LS1 wasn't as drastic as people make it seem. LT4 to LT4 is huge but another 20 years of technology advancement is a good thing. The LS took everything GM learned from racing the small block for all those years and brought them to the stock platform. Better valve angle, port geometry, intake design etc. Stepping into a stock LS1 is the same as having a hot GEN I. Technology is a great thing. My only problem is the engine is larger and it is kind of ugly. The GEN I is pretty to look at imo lol. Other than that, LS all the way.
Originally Posted by Krusty84
This is kind of my argument for the LS3 head on a 6.0L. You don't have to do anything to it and it rips. I think all those articles and comparisons of the late 2000s and early 2010s of the cathedral vs rectangle port heads were intentionally skewed by the aftermarket manufacturers and the speed shops that had a lot invested in inventory and R&D of their CNC ported cathedral heads. No way the manufacturers or the guys that invested money in a pricey set of cathedral ports wanted the public to know that they could achieve or exceed their power goals with a $300 cylinder head. Most all of the aftermarket sponsored shows like Engine Masters, Road Kill etc... won't feature the LS3 head because it damages the "good deal or hp per $" perception of their sponsor's products.
I give it to the cathedral port on the low end, I just don't really know of anyone tinkering with a budget 6.0 that wouldn't trade the 20hp/tq down low for the 20hp+/~10tq+ up top.
Engine masters is more about busting long perpetuated myths not so much what port shape is best. For what it is, they do a damn good job. And Roadkill... Isn't the only LS in the muscle truck and isn't that running stock cathedral ports? There isn't much done right on there and that is kind of the point lol. Again, technology marches onward. I would expect the ls3 head to be an improvement over the older LS1 and 2 heads even ported...
How are you approaching the install? This site lists parts for C4 conversion as a kit or individual pieces.
That's a good link! Thanks for the info. I have been looking for someone who was building a header with 1 7/8 primaries for these cars and didn't find any until now.
I am going to use a Holley Mid-Mount accessory drive. The packaging on it is really tight, it includes all the brackets and is loaded with the alternator, PS pump, AC compressor, etc. Pretty much bolt up and run. It looks like it will fit well inside of the frame rails of the C4, because the packaging on it is pretty narrow. https://www.holley.com/products/acce...parts/20-185BK
The car is already being run on a FAST system, and it is capable of controlling the LS engine so no need to go after any engine rewiring. That was a big player in making the decision to go to an LS, was that the engine control strategy was already in place. (at least while its N/A)
At this point I'm not sure if i want to pull the trigger on headers. If I do, i want the ones with the 1 7/8" primary, but a grand is a lot of money to smoke on just a set of headers. When the car ends up being boosted, it will be run on manifolds (hint hint) to keep as much heat in the pipe as possible.
Jeremy
Last edited by Pwnage1337; 11-28-2018 at 02:09 AM.
11-26-2018, 10:03 PM
