Why do people hate on stock ls3 castings
#41
Even a 10* temperature/baro swing would change power output more than that, Your butt dyno must me pretty damn sensitive lol
#42
#43
Truck Engine Head vs Hendrick Engine Head
OK, as we know the GEN-III LS-1 engine had MANY PROBLEMS.
The Truck Engine (LS-7) was designed in that era with improvements though many problems were found especially with the head/camshaft fix/valve distance from wall.
The LS-2 was designed later from those learned improvements.
The Hendrick Head engine (L-92 & LS-3) was an IMPROVEMENT of the LS-7 by the NASCAR Engineers.
My CHOICE is based on requirements though when possible I FAVOR the LS-2 head.
I LIKE the HIGH SWIRL smaller port, valve placement, rocker arm placement of the LS-2 design.
The "smaller" port has a higher gas velocity allowing for a larger intake lobe at the same torque.
The LS-2 "HIGH SWIRL" design is GREAT for a Turbo/SC engine with BIGGER Exhaust valve size possible.
Lance
The Truck Engine (LS-7) was designed in that era with improvements though many problems were found especially with the head/camshaft fix/valve distance from wall.
The LS-2 was designed later from those learned improvements.
The Hendrick Head engine (L-92 & LS-3) was an IMPROVEMENT of the LS-7 by the NASCAR Engineers.
My CHOICE is based on requirements though when possible I FAVOR the LS-2 head.
I LIKE the HIGH SWIRL smaller port, valve placement, rocker arm placement of the LS-2 design.
The "smaller" port has a higher gas velocity allowing for a larger intake lobe at the same torque.
The LS-2 "HIGH SWIRL" design is GREAT for a Turbo/SC engine with BIGGER Exhaust valve size possible.
Lance
#44
#45
Nevermind. I realize there's no point in arguing with you. I just know that I enjoyed cruising around in cars with a lot more low end torque than cars that didn't seem to come alive until 3500RPM. Maybe you're different. Maybe you like buzzing up to 5500RPM to pass a soccer mom in her minivan. Different strokes for different folks as they say.
#46
Nevermind. I realize there's no point in arguing with you. I just know that I enjoyed cruising around in cars with a lot more low end torque than cars that didn't seem to come alive until 3500RPM. Maybe you're different. Maybe you like buzzing up to 5500RPM to pass a soccer mom in her minivan. Different strokes for different folks as they say.
So basically you have an engine with 12 more cubes that makes better power everywhere and dominates the ls2 when the both go cam only....
If you're going to make an argument for cathedral heads like you seemed to try a different metric because it does not look good at all
#47
The ls3 actually has less compression, 10.9 vs 10.7. It has 12 more cubes and no it doesn't have a more aggressive tune. The ls3 knock sensors are VERy conservative and so is the timing.
So basically you have an engine with 12 more cubes that makes better power everywhere and dominates the ls2 when the both go cam only....
If you're going to make an argument for cathedral heads like you seemed to try a different metric because it does not look good at all
So basically you have an engine with 12 more cubes that makes better power everywhere and dominates the ls2 when the both go cam only....
If you're going to make an argument for cathedral heads like you seemed to try a different metric because it does not look good at all
#49
This is an interesting theory but the LS3 head was developed after the ls7 and was based off that design, naturally they had to make some cuts vs the ls7 head though. So your theory doesnt tseem to hold much water about it being designed for the ls7 but failing
Also I keep hearing these talks about it being a lazy head but it seems every engine with those heads outperformas its cathedral counterpart. Even 6.0 engines that came with both make more power and TQ with the ls3 castings.
And as mentioned an ls3 which has 12 more cubes and a similar cam asbolutely dominates the ls2 everywhere in the rpm band. Much more so than a couple degrees on a cam and 12 CI would dictate.
Also I keep hearing these talks about it being a lazy head but it seems every engine with those heads outperformas its cathedral counterpart. Even 6.0 engines that came with both make more power and TQ with the ls3 castings.
And as mentioned an ls3 which has 12 more cubes and a similar cam asbolutely dominates the ls2 everywhere in the rpm band. Much more so than a couple degrees on a cam and 12 CI would dictate.
In all seriousness, I do think the LS3 head is better for 5500 rpm up performance and racing than cathedral ports. However, the cathedral has proven itself excelling in the 5500 and lower rpm. I drive more in the under 5000 rpm range. In a race only engine sure go big LS3/LS7. The majority of dyno results that I've seen that were apples to apples or close seemed to back this impression up.
It's really Windsor head vs Cleveland head argument to me.
I have an acquaintance that for fun filled in the ports on a Cleveland head with epoxy and improved street ability, throttle response and horsepower. The stock LS3 runner could likewise probably be improved by carefully filling at least for stock 376 cube applications. I guess that's to be expected since the port was initially designed for 427 cube initially.
I'm probably joining the "LS3 club" with my 416 build - the LS3's are not the Trick Flows I want but it's what my budget can afford. I do wish I had never purchased the ERL 416 and just built a LS2 403 I'd planned and kept the cathedral heads.
Besides giving an LS3 a beat down with LS1/LS2 stuff is just as much fun as stomping an LS1/LS2 with a mid 90's LT1 or mid 80's TPI or a carb'd small block chevy
Variety is part of what keeps the car hobby fun.
BTW - LS3 intake manifold is excellent and better than its factory cathedral counter parts. It's the one bright spot in having to go to LS3 heads for my 416 build.
Last edited by 99 Black Bird T/A; 04-18-2017 at 03:42 PM.
#50
http://www.superchevy.com/how-to/engines-drivetrain/1247-626hp-ls3-stroker-build-supersize-me/
This engine made 1.495 hp per cube. It made great power for only a 235 intake duration cam but look at the torque curve on the engine. Looks like a hill.... hard to achieve that flat curve all the way across the graph.
This engine made 1.495 hp per cube. It made great power for only a 235 intake duration cam but look at the torque curve on the engine. Looks like a hill.... hard to achieve that flat curve all the way across the graph.
That's a down right ugly curve.
Would love to see that it made at 2500 rpm
#51
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Joined: Aug 2009
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From: Coast of San Mateo County Between Pacifica & HMB
My .02, on stock LS3 heads is that they have been mis-cammed
so often they have gotten a bad rap. On a 4.0" bore or larger
with 3.62" stroke compared to stock 243s
6-8* less intake duration for the same RPM
range seems a good place to start, with ~+8-12* Exhaust
Split NA, ie 228/234 for 243s becomes ~222/230 for LS3s
235/243 becomes ~229/239, as RPM increases split increases.
this is with long runner plastic intakes, and efficient exhaust
systems.
so often they have gotten a bad rap. On a 4.0" bore or larger
with 3.62" stroke compared to stock 243s
6-8* less intake duration for the same RPM
range seems a good place to start, with ~+8-12* Exhaust
Split NA, ie 228/234 for 243s becomes ~222/230 for LS3s
235/243 becomes ~229/239, as RPM increases split increases.
this is with long runner plastic intakes, and efficient exhaust
systems.
#52
#54
Guys, it's not cathedral versus rectangle/square. It's not the entrance shape to the port, although square/oval ports are better than a cathedral shape for a port.
It's the AREA of the port and throat that matters the most, period. All ports are limited by their MCSA (minimum cross sectional area).
Repeat after me, A-R-E-A...
It's the AREA of the port and throat that matters the most, period. All ports are limited by their MCSA (minimum cross sectional area).
Repeat after me, A-R-E-A...
#55
TECH Fanatic
Joined: Aug 2009
Posts: 1,828
Likes: 234
From: Coast of San Mateo County Between Pacifica & HMB
Nice curve! What is your Compression,Header Size, & LSA?
Hmm +8* Exhaust Split......
#56
I realized that a couple of weeks ago.
Exactly my sentiments!!! And it doesn't have to be "a truck engine" to do that, either
KW
KW
#57
#58
Navyblue..... we all know the LS3 head is the most poorly misunderstood cylinder head it is but after all NO ONE I've seen has yet to figure them out. Aftermarket.... a different story.
#59
A lot of good arguments here for each side. Still contend that a smaller group know how to get the square port to work well vs. the cathedral in the 370 to 416 c.i. range. If your building a motor in that c.i. range and can't afford to get it wrong.......cathederal
Last edited by 64post; 04-19-2017 at 01:03 AM.