862 vs 243 heads

Street Performance of The 706 Head. It’s worth noting that the 706 heads have a larger combustion chamber than the 862 heads, which measures at around 71cc. While this might sound like a disadvantage, it can actually be helpful for engines running on lower-octane fuel or those using forced induction.

The 243 head has 2.0" intake valves and 1.55 exh. The 706 uses 1.89 and 1.55 respectively. The 243 is an excellent head, but losing compression coupled with a larger intake valve in a tiny bore engine isn't a good combo in comparison to the 706. I would pull the 706's and freshen them up and have a good valve job done on them.The 241 castings feature 205cc intake ports, 70cc exhaust ports, and a 2.0/1.55 valve combination. The hot factory heads would be the LS6 (243 castings), but even the stock LS1 heads can be made ...Milled 243 Heads Shorty Headers 18" MagnaFlow CAI Tube w/stock Air Box Bone555+6VEFCpe+2ZERO(02)6kRPMabuse.hpt Bone555+6VEFCpe+2ZERO(02)6kRPMabuse.hpt. 01-27-2018 #2. cobaltssoverbooster. View Profile View Forum Posts Senior Tuner Join Date Dec 2008 Location Nevada Posts 4,452.Jun 2, 2023 · Here’s a quick data sheet on the specs of 799 heads. Due to the similarity, 243 heads should follow the same characteristics in normal situations: Combustion chamber volume: 64.45cc. Intake port volume: 210cc (sometimes seen as 209cc too) Exhaust port volume: 75cc. Intake valve diameter: 2.00 inches.The first has to do with port shape. The LS6 and the later LQ9-LQ4 heads used reshaped intake ports and D-shaped -- as opposed to oval-shaped -- exhaust ports for better flow: 200 cfm intake and 70 cfm exhaust for the 241's, and 210 intake and 75 cfm for the 243's. The second major difference is that the LS6 heads used hollow, sodium-filled ...C5 Tech - LS6 valves vs stainless aftermarket in 243 heads - Curious if you guys running 243 heads keep the stock valves or replace them with aftermarket that might help flow. Looking to pick up a set of 243 heads needing hardware and work them over myself. I imagine the LS6 valves are not undercut like the stainless...

also like skunk said they have less ptv vs a cath port..about .050 less valve drop on the intake thats why youll see a ly6 (ieon block l92)cam combo around 7.5-8ivo vs a cath youll see cams in the 11.0ivo range..ls3 being all alum can go .5 more do to the extra growth of the block..this isnt a exact number for ivo because different lobes an spring pressure also come into play.but it gives you ...Sort by: Add a Comment. J8ke_Stampede. • 1 yr. ago. There's no debate, it's been proven the 862/706 heads will make more power than the 317's. 317's and 241's are the worst factor LS heads. It's also not only because the chamber size and compression ratio either. 862/706 heads have higher velocity and better coefficient of discharge. 8.The 706Vortec heads are even slightly superior to the commonly found 862 heads. The reason is that the 706 heads are SPM (semi-permanent mold) made, while the 862 heads are sand cast. The SPM method is considered to be a more consistent process, but once you port the 862 head, any difference to the 706 head goes away.An improved version of the stock LS7 cylinder heads, the LSX-LS7 heads feature a 12-degree valve angle, giant 2.200/1.610-inch valves, 270-cc as-cast ports, and six-bolt-per-cylinder bolt pattern for use on aftermarket blocks. The upper echelon of GMPP's aftermarket cylinder heads is an evolution of the C5R castings.Is it worth it to get them cnc'd vs having the ls1 heads cnc'd? I thought the 2004 GTO had 243 heads My ride is a 2002 Camaro SS SLP #3296 with 30k, LTH, 3" Y, CME, Frost tune, K&N, ported TB, Blackwing lid, Bellows, MSD, Denso Iridium, and 85mm MAF, Bilsteins, Eibach springs, SLP strut brace, Adj. Panhard, TA Girdle, UMI, Pro 5.0, Nitto …For cam choices, we went right to the Comp Cams catalog and selected cam profiles designed specifically for the cathedral and rectangular-port heads. On the cathedral-port side, we chose a ...The Pro 243 irons also feature a wider flow microslot than the 223s which made for better low-face forgiveness. They also feel smoother through the turf. The Mizuno Pro 243 irons retail for $1400. Overall. Given that the Pro 223's and 243's are meant to be the more forgiving Mizuno models, the Mizuno Pro 243's do in fact surpass the 223's.3012 posts · Joined 2008. #1 · Apr 14, 2012. I have a 2004 Aluminum 5.3 with 70k miles that has 862 heads on it. I also have a set of 243 heads off of a 2009 Aluminum 5.3. Which heads should I use? I've been told the 243's flow better and the 862's supposedly raise compression .5 a point.

10 Apr 2018 ... Comments10 ; Comparing Stock LS Heads with Flow Numbers. Eric Weingartner · 16K views ; LET'S TALK TECH-243 VS 862. Richard Holdener · 119K views.Re: 5.3 Chevy 862 valve job porting questions. by CGT » Fri Aug 30, 2013 1:43 pm. The 862's I have seen have the throat WELL over 90% with no material for a bottom cut. It will take a bigger valve to be able to get a decent valve job on that head, judging from the ones I've seen. SMITHBERGRACING. Guru. Posts: 1100.Here’s my thinking. The 243 has. 2.00 intake and 1.55 exhaust with a 65cc combustion chamber. The 706 has. 1.89 intake and 1.55 exhaust with a 61cc combustion chamber. If I have a set of 2.00 intake valves put in the 706 with the smaller combustion chamber wouldn’t I have a better head with more compression and that’s not counting if I ...Get ready to feel the G-forces as we navigate the exhilarating terrain of power and performance. 862 LS Heads aren’t just components; they’re the driving force behind an automotive revolution, and the journey has only just begun! DIY Adventure: Installing 862 LS Heads Like a Pro. Time to get hands-on, gearheads!However, the main distinguishing feature of the 862 cylinder head design is its unique ability to dramatically enhance air compression delivered following porting. While some may argue that the 243 heads are better, 862 heads deliver improved airflow, quality, performance, and power. Moreover, 862-cylinder heads are compatible with many cars.

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Suicidal Racing. 862 are for my ls1 an will make it around 11.9-1 compression and my lq9/ls3 combo will be around 13.5-1..the extra compression going from 10.2-1 on my ls1 to the 11.9-1 should be worth 30hp,the motor has a big cam (243/251 with 23 degrees of overlap) so it really needs the extra compression.The primary benefit of porting and polishing 243 heads is improved airflow. This allows for better combustion, resulting in increased horsepower and torque. Additionally, porting and polishing can lead to improved fuel efficiency, as the engine is able to more effectively use the fuel it receives. If you’re looking to improve the overall ...Mar 11, 2023 · Intake and Exhaust Ports. The intake and exhaust ports on the 243 heads are larger than those on the 799 heads, which allows for more air and fuel to enter the engine. This can result in higher horsepower and torque output. However, the smaller ports on the 799 heads can provide better velocity and airflow at lower RPMs, which can be beneficial ...The LS4 is a 4th gen, 5.3 l aluminum small block engine that was used in GM cars between 2005 and 2009. They had cathedral port cylinder heads and used Active Fuel Management (AFM). The LS4 cylinder heads came with two casting series numbers - 799 and 243. The combustion chamber volume is 65cc.Among the Dart Pro 1 LS offerings is a 225cc cathedral intake port head with a 62cc combustion chamber and 2.05/1.60-inch stainless valves. The advantage to this head, besides the improved airflow, is the 6cc smaller chamber that will bump up the static compression over a half a ratio—from 10:1 to closer to 10.6:1 (and perhaps more).

Feb 13, 2020 · The 706 Vortec heads are even slightly superior to the commonly found 862 heads. The reason is that the 706 heads are SPM ... these are basically 243 heads; See All 5 Photos. Vital Specs for 706 ...Why are Chevy 706 Heads better than 317 or 862 Heads? 706 Heads Vs. 317 Heads; Most people tend to prefer 317 heads as they have improved ports, same as 243 and 799 Heads, which are more expensive. However, 317 heads have larger combustion chambers of 71.06cc, which will cost performance, especially on a naturally aspirated engine. This ...These large-runner heads have a 12-degree valve angle, like stock, and are compatible with factory LS7 rocker arms and stands. The heads can accommodate 1.625-inch-diameter springs, and several are available. A 4.125-inch-or-larger bore is required. Base price is $1,130 each, fully assembled, through Summit Racing.GM's 5.3L LS1 head casting serves as the basis for this high compression / naturally aspirated oriented 3.900" bore specific offering. With your 5.3's, lightweight Manley Race Master Stainless valves, and lots of available P2V this is a great option for 440-480rwhp 3.900" bore builds. Our GM 5.3L CNC work will generate 11:1 compression on a ...302 heads on a 360 would lack upper rpm hp and basically become a cork. Too lil port volume/cross section. If they were full ported, then you may have something good . In stock form you are comparring the 360 that flow roughly 215cfm w/1.88 int and 165cc vs 302 heads that flow roughly 170cfm w/1.78 int with 124cc port volume.The 799 heads will need to be milled a bit to get the compression ratio back to where it needs to be. That will determin what pushrod to go with. The stock heads should be something like 61.15 cc. The 799 heads should be 64.45. . 1994 SFBD extcab longbed 20/22 406sbc . Project thread.5.3 vs Vortec 350 in a Jeep; Changed direction on project. A1000 fuel regulator questions; Fuel boiling.... Breaking up at 5k and above RPM; ... 862 vs. 243 Heads; Holley Tunnel Ram; Easiest way to rig starter? perf rpm; 5.3 teardown/build; started my swap; Help with Rad Fans; FYI for Performer RPM users!!Mar 2, 2021 · The combustion chamber diameters can play a big role in hindering flow and performance. The 706/862 combustion chamber diameter measures out at around 3.670" and the 243/799 combustion chamber messages out at around 3.880” and giving the fact that the LM7 5.3L engine bore is 3.780" this more than likely has something to do with the power loss ...40 posts · Joined 2018. #46 · Jan 20, 2020. Your 6.0 block is a 4.00 inch bore, you have to run a LS3 type head 5.3 and 4.8 have smaller bores. There are tons of heads out there yours probably came with the 799 castings like my 6.0 did.

check out this video were the guys from brian tooley racing swapped on a set of stock l83 (lt-based) heads onto a gen 4 5.3l ls. check out the power gains offered by the lt heads, custom cam and l86 intake on the ls. also tested an intake upgrade, comparing the l86 intake to the btr long runner trinity! share this; 0;

It still used 799/243 heads but also utilized variable valve timing and had flex-fuel capability. Chevy also used a 5.3L engine that was only in vans produced from 2010 to 2014, known as the LMF engine, identified by a number 4 in the 8th digit of the VIN. ... some include 1218 springs and the Elgin 228/230 cam. If your truck has 862/706 heads ...The other option, assuming one or both heads are having actual issues, is to hit a local junkyard and pull another set of 862's for <$100, clean them up, and slap them on. 2004 Silverado 1500 (ish); 2005 Silverado 1500. 1964 C60; 1985 K30 Detroit Diesel.In contrast to the 243 heads, the 862 cylinder heads are typically made of cast iron, which makes them heavier but also more durable. They have smaller ports compared to the 243 heads, which can limit airflow to some extent.118. Intake valve is 2" on the 241, exhaust valve is same size as the 862. If planning on 241 heads on a 5.3 you will lose compression and hp. The Fleet... 2003 Suburban- 5.4 L59 331CI 10:5.1 Compression -Built by ME. 2004 Avalanche- 5.7 LS1 -NOT built by me. 2005 Silverado RCSB- 5.7 LS6 -Built by ME. Reply With Quote.To 2007 head issues #243 vs. #799. C6 Tech/Performance - 2007 head issues #243 vs. #799 - I read a thread not long ago on C6 general about a difference in the heads on the born in Oct. 06 C6's that GM used, they used #799 heads as opposed to #243 heads. The person who wrote the thread said his numbers on the dyno where significantly off from ...Trick flow 228/230, K&N CAI, Beehive Springs,Hardened 7.4 length Push rods,Spintech Catback Exhaust. The rest of the car has stock manifolds,stock intake,stock cats,stock 241 heads. I pass smog and put 365 to the wheels and 352 pounds of torque. I have a simple set up and I will be installing AI 243 heads and shorty Headers with in this month.I am beginning to find and spec all the parts I need to start the 6.0L LS swap for my 2002 Silverado. A significant key to the success of this build is the c...After installation of the heads, offset rockers, and FAST LSXR intake, the LS3-headed stroker pumped out 581 hp and 543 lb-ft of torque. Note the LS3 heads increased both peak power and torque, though the rec-port heads did lose out to the 317s below 4,000 rpm. Despite the slight loss down low, torque production with the LS3 heads bettered 500 ...

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Feb 13, 2020 · The 706 Vortec heads are even slightly superior to the commonly found 862 heads. The reason is that the 706 heads are SPM ... these are basically 243 heads; See All 5 Photos. Vital Specs for 706 ...249 posts · Joined 2017. #1 · Oct 30, 2021. I have a set of 862 heads with the notch and I just had them surfaced.I didnt realize the notch thing on early ls engines so want to use these heads since I had some work done to them.I was wondering what head gaskets for this style of heads with 20 psi of boost.thanks in advance. Like.C5 Tech - Difference between 241, 243 and 853 heads?? - Whats the difference? I have 853's, which heads are good for porting and which flow the best? Thanks. Log In; Register; Forums. ... 853, 862, casting, chamber, combustion, differance, difference, head, heads, ls1, number, ported. Back to Subforum. C5 Tech. View Next Unread '99 Stumbling ...Sort by: Add a Comment. J8ke_Stampede. • 1 yr. ago. There's no debate, it's been proven the 862/706 heads will make more power than the 317's. 317's and 241's are the worst factor LS heads. It's also not only because the chamber size and compression ratio either. 862/706 heads have higher velocity and better coefficient of discharge. 8.Good deal guys. but two different casting facilities. Makes one wonder, and the idea of a aftermarket ported or polished heads more important, The two different 243 heads, one with the triangle sand cast mark and the 243 head without the triangle sand cast mark were 5-7 hp and lb ft difference. Has any one flow bench tested the stock 799 heads ...OP: difference is one is sand cast (853) and rougher feel where not machined and the 241 is smooth cast. Early 853 heads can not be used w MLS gaskets and later ones can. the difference is the deck surface where the head gasket goes around the perimeter there is a large notch that will not compress the gasket surface.doing math an saying you have 2cc worth of valve notchs i got you around 12-1 comp wise with the 58.5 in for head cc an pistons out .006..with the 60cc 243s i got you at 11.8-1 with 2cc notchs,.006 out and .040 gaskets..hope this helps. I had them actually cc'd after I removed em.. 61.5.. Steve. 408, th400, 1100rwhp..Jul 16, 2007 · St. Jude Donor '03. 853 and 241 are basically identical. 853 was used on 99-00 LS1 engines. 241 was used on 01-04 LS1 engines. They both have a 66.67 cc combustion chamber (10.1 CR), 200cc intake runners, and 70cc (round) exhaust ports. The 243 head is the 01+ LS6/LS2 head.Sort by: Add a Comment. J8ke_Stampede. • 1 yr. ago. There's no debate, it's been proven the 862/706 heads will make more power than the 317's. 317's and 241's are the worst factor LS heads. It's also not only because the chamber size and compression ratio either. 862/706 heads have higher velocity and better coefficient of discharge. 8.The Gen III have 862/706 Gen III heads, and the Gen IV have 243/799 heads. The 862/706 heads have smaller combustion chambers than the Gen IV, raising the compression ratio when swapped... ….

Get the best deals for ls 243 heads at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items! Skip to main content. Shop by category ... GM LS 706 806 862 241 799 862 243 CYLINDER HEAD REBUILD SERVICE 3 BUISNESS DAY. Opens in a new window or tab. Remanufactured. $459.99. Save up to 10% when you ...The 241 castings feature 205cc intake ports, 70cc exhaust ports, and a 2.0/1.55 valve combination. The hot factory heads would be the LS6 (243 castings), but even the stock LS1 heads can be made ...oil catch can, Pacesetters LT Headers,3500 Stall, K&N CA, bmr drag bags. We can port and valvejob your 243's, install the larger 2.02"/1.57" stainless valves, and the PRC .650" lift dual springs all for $1200. That makes them the equivalent of our PRC Stage 2.5 heads, just with your used castings. Additional milling is free of course.Talking about cleaning heads and valves. Discussed when a valve job is needed compared to recommended. Chamfering the edges of the combustion chambers after ...Brawler LS3 Style CNC Ported Cylinder Heads w/ TSP .660" Spring Kit and Titanium Retainers $ 1,836.99. PRC 15-Degree 220cc As-Cast Cathedral Heads $ 1,820.69.My plan is to rebuild the spare block from the inside out with all new bearings, BTR "Torque" cam, Weiand aluminum intake, and then port/polish the heads. CMIIW: I've been told there is no major difference between the 706 and 862 heads once you work them over. So I'd be okay having the 862's ported/polished/rebuilt rather than my current 706's.This program works on the following head casting numbers: 243. 799. 317. 035. Now you can get this porting service on your cylinder heads at an incredibly low cost! Simply follow this procedure: Remove the cylinder heads from your car. Disassemble cylinder heads to completely bare condition.Apr 30, 2024 · 862 heads vs 243. The 862 casting number represents the 862 cylinder head. The 862 heads came on all LQ9 6.0 engine blocks and are completely interchangeable with the 243 cylinder head. Both the 243 and 862 heads have the same 64cc combustion chamber, but there are some very slight differences in the pore size of the two heads.See my Signature for full the mods. I have comp cam 222/224 566/568 112lsa. Yes 05 has 6.0L motor vs 5.7L. If you are just make a swap from stock 241's to stock 243's then 15-20rwhp would be a "safe" expectation..... maybe use a cometic gasket set to get the CR up a bit and the quench better for some extra power. 862 vs 243 heads, The Gen III have 862/706 Gen III heads, and the Gen IV have 243/799 heads. The 862/706 heads have smaller combustion chambers than the Gen IV, raising the compression ratio when swapped directly., Jan 21, 2022 · RPO L99 and LS3 cylinder heads are aluminum with 68cc combustion chambers, rectangle intake ports with 257cc runners, D-port exhaust with 87cc runners, 2.165˝ intake valves and 1.590˝ exhaust valves. These heads can be CNC-ported to improve on flow and milled for higher compression. These heads are almost the same, but the L99 heads used a ..., 706 heads tend to be more popular than 243 heads with those who run naturally aspirated engines. While they don’t have the same size combustion chamber they also don’t have the tendency to lower the compression ratio and reduce horsepower. When looking to replace your heads, they offer a high degree of consistency since they are ..., Ajit Mohan, the head of Meta in India, has left the firm and agreed to join rival Snap, according to sources familiar with the matter. Ajit Mohan, the head of Meta in India, has le..., Friend of mine has a set of 243 casting heads that came off of a LS2/GTO engine. I have a stock 5.3 I'm working with, with the 862 casting heads, and... in this thread in this sub-forum in the entire site, The LS 243 Cathedral Port cylinder heads are renowned for their exceptional performance capabilities over the other cathedral port offerings. These heads are designed to maximize airflow and combustion efficiency, taking advantage of the LS6 engine's power potential. With their cathedral port design, larger valves, and improved airflow ..., 863. Rectangle. 4.750" +- 0.003". 12604861. 12610716. 12675872. Share this article. We've tried to boil down the GM part numbers, casting numbers and other LS cylinder head information into an easily usable (and ideally definitive) cross reference. Note that we're not perfect and some of this data may not be perfect so use it for what you will., 64nailhead. 4523 posts · Joined 2012. #5 · Jun 13, 2020. Here's your decision - the 317's will work better if you're looking for boosted 1000+ HP, but the 243's will work better everywhere below that. Something to keep in mind, old school SBC and SBF static and dynamic compression ratios do not apply to LS heads., Head gaskets are essential components of an engine, and when they fail, it can be a costly repair. Knowing the cost of head gasket repairs can help you budget for the repair and ma..., 243, 853, 241 heads? Jump to Latest Follow 5K views 4 replies 5 participants last post by bladesofsteel Aug 6, 2010. runoveryou Discussion starter 249 posts · Joined 2008 Add to quote; Only show this user #1 · Aug 5, 2010. Do any of these stand out from the others in performance from a stock stand point? ..., hivoltagedriver. Port and polish on a set of 243's is usually ~20hp. A set of ported 243's on your LS1 should make a sizable difference, especially with a cam. '09 PSM G8 GT w/ Premium & Sport packages. Go: Kooks 1 7/8" LTs, catless mids, Corsa, VCM OTRCAI, Rick C. AirRam intake and ported TB, tuned by me., 862 heads: These are also compatible with 5.3 engines, similar to 706 heads. However, they offer slightly less power potential. 243 heads: A popular choice for LS enthusiasts, they provide higher power gains when matched with the right cam. Cam swapping with 5.3 engines typically benefits from using LS3-type springs. These springs improve valve ..., The price difference for 799 an 241 heads is because the 799 is a twin to the 243 an have better ports an 64.54cc chambers where the 241/853s have not as large of a port an are 67cc..your 862 is actual the smallest chamber head being 62cc but their down side is smaller valve size an slightly less flow then 241/853 heads.., The 862 heads are an excellent choice for any GM vehicle with an LM7 engine. Although the design is meant for high-performance settings, it performs well in the Avalanche, Express, Silverado, Sierra, Yukon, and other trucks or SUVs from the late 1990s to about 2007. You know if you’ve got an LM7 engine by looking at the eighth digit of the ..., The 243 having a blunt front end, you would expect it to be slower than the pointy 6.5 front tip. However, its body build allows for a larger volume of powder, which boosts its muzzle velocity significantly. Although both cartridges recorded high speeds, there is a slight difference that sees the Grendel lose., The 243 heads flow 10 cfm more on the intake side, and like 7 cfm more on the exhaust side (if memory serves me correctly). The combustion chamber is a difference of 3cc smaller on the 243's. Valve sizes are identical in both sets of heads. I know that when replacing heads you should have them worked (e.g.- valve job, and such)., Jan 5, 2023 · The 243 vs. The 799 Cylinder Head. As you have most likely caught on by now, these two cylinder heads are practically the same. The main difference between the 243 and 799 cylinder heads is that the 243 was used on older engines from GM Research, while the 799 has been used on newer engines from multiple manufacturers., 3712 posts · Joined 2009. #6 · Dec 4, 2009. batboy said: Think you are mixing up your facts. It's like a 25 HP gain by swapping in casting 243 (LS6/LS2) heads on a LS1. The LS2 already has the same casting heads. The only difference in the LS6 heads vs. LS2 heads are the light weight sodium filled valves., The Gen III have 862/706 Gen III heads, and the Gen IV have 243/799 heads. The 862/706 heads have smaller combustion chambers than the Gen IV, raising the compression ratio when swapped..., 243 vs 862 Heads: Unveiling the Key Differences bhagwan vaisnav 1 August 2023 243 vs 862 Heads: Unveiling the Key Differences In the world of engine heads, the debate between 243 and 862 heads has long…, we compared 243 heads to 862 heads, ported, chamber work & big valve. let's talk tech, anyone ever see a set of stock 243 heads flow 270+ cfm? we compared 243 heads to 862 heads, ported, chamber ..., The 799 head is designed and made to be compatible with high-performing LS engines, such as 4.8L, 5.3L, 5.7L, or 6.0L, etc. These vehicles require maximum airflow, making the 799 head an ideal choice. On the other hand, the 862 head is compatible with LR4, LM4, and LM7 and such engines where low torque is more essential than better …, Received 26 Likes on 26 Posts. I took my 243 heads and had them cleaned up ( polished ) cleaned up ruff edges, but not ported. Had them milled to about a 62-61.5 cc chamber or something like that. run a 224/224 581/581 112+4 comp cam. comp 918 springs, comp rockers. Smith brother push rods., Great cylinder-head airflow has been a key enabler of the LS-Series' exceptional performance. Chevrolet Performance delivers those power-building attributes to you with a range of production-style aluminum heads — from the LS6 heads for smaller-displacement engines to LS7 style heads for 427-inch-and-larger combinations, our aluminum heads benefit from Chevrolet Performance's extensive ..., When I first started playing with engines (don't go there, I'm old), and the heads had worn valve guides, it was common practice to either: a)Get them knurled. or. b)Get the stock guides replaced with bronze guides. Bronze guides were considered "THEE best", aka "the shit". Now I'm reading "If you have bronze valve guides you NEED roller rockers"., The 243/799 heads made more power than the 317's in back to back N/A, and boosted, dyno pulls on the same motor. Sounds to me like you've already convinced yourself the 317 is the better head, so I'm not sure why your on here asking. Besides, from your post, headers are too small, so the head choice may be irrelevant., The LS3 was run with a Holley HP management system and FAST injectors. With stock heads, the modified LS3 combination produced 552 hp at 6,400 rpm and 513 ft-lbs of torque at 5,000 rpm. After installation of the TFS Gen X 255 heads, the power numbers jumped to 571 hp at 6,500 rpm and 525 ft-lbs of torque at 5,200 rpm., IMO, a 243 CNC head and LS6 intake (or spend the chese for a FAST 92) will definately make a great street motor. i made peak power at 6000 rpms and shift at 6600 rpms. its a mule and could last forever if i didnt decide to spray it all the time . 1999 Pontiac Trans Am. Save Share., The engine also had 799 or 243 casting heads which are closely related to the LS6. The engine has flex-fuel capability. In 2010, the LC9 gained VVT as well as pistons with valve reliefs, and compression dropped from 9.9 to 9.6:1. … For LC9 engine specs, read this: LC9 5.3L Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs ..., 345. red. 2002 SS. porting your heads would prolly be the best bang for buck i know you can buy a set of 243's ported for 1300 but i know youll see atleast a 20hp gain thru the rpms with a set of AFRs or TFs versus ported 243's but then again youll spend 2400-2700 on those heads. 05-30-2010, 07:15 PM #3. sloroller., 806 is the casting # of the heads . Its on the front corner . 806 is the worse flowing LS1 head and has perimeter valve cover bolts .They came stock on the 98-99 F bodys . 241's are a little better . I believe they came on 00-02 . 243's are the best of the 3 . 243's in stock , untouched form will add @ 20-25 RWHP over 806's and 241's., WHAT STOCK LS HEAD MAKES THE MOST POWER? WHICH CAM SHOULD I RUN IN MY 6.0L? WHAT IS THE BEST STOCK 6.0L CAM TO USE? STOCK 6.0L UPGRADES! ARE THE 706/862 HEAD..., 2752 posts · Joined 2011. #1 · Jun 25, 2012. Ok, just got my 243`s today. Not my first set of head porting, but it is my first LS set. Im pretty comfortable were im at with them right now. They are at the roughed stage, waiting on my roll kit. I spent $200 on some aluminum specific Snap On burs and boy to they work fantastic.