lq9 243 or l92 heads
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Staging Lane
Joined: Jan 2008
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From: South Carolina
lq9 243 or l92 heads I have a 2003 lq9 was running it in my 2003 z71 with 243 and a small cam... It ran strong but I have since bought a 1998 Camaro doing a t56 swap and installing the motor sold the small cam and was planning to do a little head work on the 243 and buy a bigger cam.. But while I've had it tore down I have gotten a chance to pick up a set of l92 heads I'm assuming off a 6.2 and a ls3 car intake. Been doing research everyone I talked to said to do the swap.. But I'm worried about compression and low end with these heads.. Also worried about the ptv issues and what cam would work great with this set up..If NE one has done this and or has NE info it would be great thanks ace
Ported 243s flow about what stock LS3 heads flow on the 4" bore. The difference is the 243s have a smaller port, smaller (and lighter) valves, and will have more compression.
I'd send the 243s to Frankenstein Racing and let them port it and port match your intake to it.
I'd send the 243s to Frankenstein Racing and let them port it and port match your intake to it.
Can't really quantify it scientifically, but if the engine is in the 346-400 cubic inch range, to me the cathedral ports feel like they have better throttle response than the rectangular ports
TECH Veteran
Joined: Sep 2014
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From: Mississippi
I'll approve that message!! LS3 headed motors are very PICKY about cam selection especially those motors under 408ci......
Thread Starter
Staging Lane
Joined: Jan 2008
Posts: 86
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From: South Carolina
Yeah I was trying to find a cam for it been looking most say to run the l92 and ls3 intake yall are the first to say different. I can pick up the heads intake and roller rockers for 850 only reason I was thinking that route
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Joined: Sep 2014
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From: Mississippi
That's a great buy to be honest. Just watch how it's cammed. It's easy to over cam these heads or kinda miss the hot spot cause of the larger splits these cams see.......
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Not speaking from actual experience here but there is a thread going on over at the bullet on this very topic. Votes going both ways but good arguments for the LS3 heads.
Many people posting very good results with them. Most are preaching the same as Tuskyz28 pick your cam carefully and don't over cam and you'll make good low end power that pulls to 7k.
Many people posting very good results with them. Most are preaching the same as Tuskyz28 pick your cam carefully and don't over cam and you'll make good low end power that pulls to 7k.
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Staging Lane
Joined: Jan 2008
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From: South Carolina
Yeah I got to find someone with a good ideal on the cam and some numbers that they are putting down etc. Seen there are few that mill them also so I'm trying to figure everything out so it will be near perfect lol.. I have seen a lot of people talking about how the ls3 heads like smaller cams better.. Does anyone know what the casting number should be on the heads that I'm looking ay
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From: Mississippi
Depends if you plan to stay N/A or spray it. You simply can not beat a stock L92 head for the price. Mill it .030" and you have decent compression but you may have to fly cut the pistons. Fly cut pistons will be a weak point if you spray or boost the car. Sure a cathedral port can be ported to flow the same as a stock L92 but that is a big chunk of change. Not to mention the LS3 intake out flows any other ported stock intake. If I ever get back into a 3rd gen projects I plan to run am SBE LQ9 with an LS3 top end.
I had an LS3 top end on my LS2 and loved it. It was a high end monster. Heads were milled .030", pistons fly cut and an off the shelf GT-11 cam. Car picked up almost 40 rwhp from the heads and intake alone. The heads easily out flowed the cam put the car was completely streetable, idled near stock, got 30 mpg's on the highway and had 10 second potential. I have nothing but good things to say about an L92 head on an N/A combo.
I had an LS3 top end on my LS2 and loved it. It was a high end monster. Heads were milled .030", pistons fly cut and an off the shelf GT-11 cam. Car picked up almost 40 rwhp from the heads and intake alone. The heads easily out flowed the cam put the car was completely streetable, idled near stock, got 30 mpg's on the highway and had 10 second potential. I have nothing but good things to say about an L92 head on an N/A combo.
Careful taking advise from folks with vehicles 1500lbs lighter with better gearing.
I know guys argue that the L92 come on trucks but they come on DBW trucks, the DBW can mask lowend response issues and GM put them on a bigger bore.
Assuming stockish sized tires on each 4.10s in a truck are similar to 3.42 in the Camaro, slightly numerically lower actually, but you also need to consider the truck weighs half again as much in many cases. Most of us don't have regular cab short bed 2wd trucks, 4wd extended cab hits 5000lbs in a hurry instead of 3500 for the f-body.
I am going to vote for cathedral. You probably aren't going to give the L92s enough gear(4.56+) or stall 3500+ to make them really shine.
Cheap parts aren't cheap unless either they are the right parts or you flip them for profit.
Using the wrong cheap parts makes them expensive in a hurry.
I know guys argue that the L92 come on trucks but they come on DBW trucks, the DBW can mask lowend response issues and GM put them on a bigger bore.
Assuming stockish sized tires on each 4.10s in a truck are similar to 3.42 in the Camaro, slightly numerically lower actually, but you also need to consider the truck weighs half again as much in many cases. Most of us don't have regular cab short bed 2wd trucks, 4wd extended cab hits 5000lbs in a hurry instead of 3500 for the f-body.
I am going to vote for cathedral. You probably aren't going to give the L92s enough gear(4.56+) or stall 3500+ to make them really shine.
Cheap parts aren't cheap unless either they are the right parts or you flip them for profit.
Using the wrong cheap parts makes them expensive in a hurry.
Thread Starter
Staging Lane
Joined: Jan 2008
Posts: 86
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From: South Carolina
My car I'm going to run 4:11 or 4:56 gears and it's a t56 car and the motor is already together not looking to tear it down to fly cut so that what I'm trying to see what I can do or get by with and I'm completely understand the cheap part or the needed part that why I'm getting and looking at all pros and cons.. Also I really only run 1/8 mile tracks with the car here and there I usually only drive the car to shows and races and raise a little hell with it lol. Thanks
People get really stuck get stuck on CFM but typically don't discuss port velocity or chamber design.
It's definitely possible for a better flowing head to make less peak horsepower & probably have a lower average horsepower# on the dyno.
There are plenty of really good running cathedral port motors out there.
It's definitely possible for a better flowing head to make less peak horsepower & probably have a lower average horsepower# on the dyno.
There are plenty of really good running cathedral port motors out there.
Here are a few quotes from another forum.
6.28@107 1.33 60ft
Ive run many engines in the same car. Last two back to back were a 346 LS1 with stg2 ported cathedrals, 224/224/112, LS6 intake did 380ish whp ran 12.1@112 and was a SWEET street car as it almost never blew the tires off.
Next engine box stock L92 longblock with a 222/230/114 cam, LS3 intake and otherwise identical parts/gears etc. Same exh and other components as LS1 set up. Ran 11.8 @120 blowing the tires off 1&2. Lots more in it.
On the street? The square port heads make so much more snap that its almost impossible to just roll out smooth WITHOUT blowing the tires off. The increase in torque below 4000 RPM is so noticeable it feels like a completely different car. Up top? Damn thing WAILS too, pulls to 7200 with that little cam.
Next engine box stock L92 longblock with a 222/230/114 cam, LS3 intake and otherwise identical parts/gears etc. Same exh and other components as LS1 set up. Ran 11.8 @120 blowing the tires off 1&2. Lots more in it.
On the street? The square port heads make so much more snap that its almost impossible to just roll out smooth WITHOUT blowing the tires off. The increase in torque below 4000 RPM is so noticeable it feels like a completely different car. Up top? Damn thing WAILS too, pulls to 7200 with that little cam.
I did an article on a guy's mustang a few years ago. Basically a fox body with an LS conversion.
Had iron 6.0, TH400, 4800 stall, 4.10 gears, 28" slicks, and was about 2980 race weight.
Had stock LS3/L92 heads.
Went 9.9@137.
I don't think I've ever come across a 317/243/799 headed 6.0 that ET'd that good and ran that strong of a MPH.
Had iron 6.0, TH400, 4800 stall, 4.10 gears, 28" slicks, and was about 2980 race weight.
Had stock LS3/L92 heads.
Went 9.9@137.
I don't think I've ever come across a 317/243/799 headed 6.0 that ET'd that good and ran that strong of a MPH.
I've got L92 heads on my GTO, BTR cam 22X/23X 114 LSA. Putt putts around town just fine at 1k rpms in 6th gear. Heads are stock, I purposely didn't shave them because I wanted the compression drop 10.9:1 -> 10.4:1 because I'm going to turbocharge my car. I don't feel like I gave up any throttle response or low end compared to when I had my 243s, but I also was running the stock cam with my 243s.
As mentioned by others, I think people over cam the L92/LS3 heads and then are disappointed with the results. Don't need as radical of a cam as the cathedral heads.
Honestly, with as much luck as people have turbocharging the 5.3L's, my rect. port heads are pretty much the only thing keeping me from selling my LS2 and dropping in a Gen IV 5.3L. I don't want to give up my L92's.
As mentioned by others, I think people over cam the L92/LS3 heads and then are disappointed with the results. Don't need as radical of a cam as the cathedral heads.
Honestly, with as much luck as people have turbocharging the 5.3L's, my rect. port heads are pretty much the only thing keeping me from selling my LS2 and dropping in a Gen IV 5.3L. I don't want to give up my L92's.
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Thread Starter
Staging Lane
Joined: Jan 2008
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From: South Carolina
OK thanks also does be one know how much I can mill off and be in a safe zone not to have to fly cut? I know the cam plays a factory just didn't know if anyone here has a set up like I'm looking to do