-- The twin screw 2.3L Eaton R2300 blower is a new generation supercharger optimized to significantly reduce noise and parasitic drivetrain loss compared to older blowers.

-- The belt system and accessories such as the water pump are optimized to work with the supercharger

-- GM specifically chose a milder cam with less lift for the LS9 in order to have a smoother idle and more refinement compared to a Z06 LS7 engine

-- The LS9 uses forged aluminum pistons, cast-in sleeves, titanium rods, special high-swirl heads and reinforced headgaskets

-- Exhaust manifolds are stainless steel short tube 4-1 headers optimized for cold start emissions

-- The oiling system has piston cooling jets. It is dry sump like the Z06 LS7 but with increased capacity.

-- The LSA engine in the Cadillac CTS-V (and rumored to be in an upcoming ZL1 Camaro) is based on the same design but further emphasis was placed on noise reduction. The exhaust manifold, pistons, and crank were all optimized for decreased noise compared to the LS9 ZR1 engine.


It just shows that there is no substitute for an engine that was actually engineered for its power output. An LS3 + aftermarket supercharger kit does not have all the little reinforcements and refinements of an actual LS9.


GM has a bunch of this info buried in their website here: http://archives.media.gm.com/us/powertrain/en/product_services/2010/gmna/10car_us.htm .

3/22/2011 7:11:16 PM

that twin scroll is old tech though just new to eaton... its about time they dropped the old school roots type.

piston squirters rock but the rest i don't find that special...

i think the coyote is a more unique engine... but that's me...

and you didn't mention it has a variable timing pushrod cam...

3/22/2011 8:05:31 PM

Quote :

"that twin scroll is old tech though just new to eaton... its about time they dropped the old school roots type."

To me the document implies that it is an updated twin screw due to a four lobe design.

"Efficiency gains with the four-lobe rotors are substantial, compared to comparably sized, previous-generation superchargers: approximately 20 percent more airflow, with an improvement in thermal efficiency up to 15 percent. Moreover, parasitic power loss-the amount of power the engine uses to operate the supercharger-is reduced 35 percent. That improves both supercharger response time and the engine's overall efficiency."

Clearly twin screws have been around a long time. The Ford GT had one. I'm not an expert on blowers. Maybe this is just GMspeak and they are adopting to a twin screw design that has been around for a while.

Quote :

"piston squirters rock but the rest i don't find that special..."

There's a bunch of other little stuff that I didn't mention. The piston crown is saucer-shaped and the piston has an anondized top ring groove. It has 9 flywheel bolts instead of 6 to improve clamping. It has a special lightweight crank angle sensor trigger wheel.

Some of it is sort of "catch up" stuff that you figured they would have had by now, like floating wrist pins and sodium-filled exhaust valves. The dry sump is pretty badass but personally I think the R35 GT-R is more innovative in the way they prevented oil starvation without needing a dry sump by using crossover pipes for each bank.

Quote :

"and you didn't mention it has a variable timing pushrod cam..."

That's because it doesn't. The L99 on the automatic V8 Camaros do though.


What made me look into all this was when I saw an LS3 Camaro but down ~700whp on Piedmont Custom Motorsports dynojet over the weekend. I was wondering what the differences were between a regular 6.2L LS3 and an LS9 which was engineered for boost.

3/22/2011 9:01:24 PM

Cool I was going to ask if the 9 had the variable timing cam. But I hot hurries by the lady.

The heads are pretty sweet too passing emissions on what I assume is a new rendition of a wedge head?

How much boost does it run ?

3/22/2011 9:06:27 PM

By the way, Eaton's twin screw blower is not a traditional Roots design (which is indeed horribly inefficient)...it is actually a compressor of sorts, moving the charge from front to back, I believe, instead of simply passing from top inlet to bottom discharge in typical Roots blower fashion.

Sodium cooled valves have been around since WWII, and were primarily developed for use in radial aircooled aircraft engines, especially ones with multiple rows of cylinders. Sodium conducts heat assloads better than steel or titanium...but at the cost of valve strength. Of course, you get a valve hot enough, it's gonna fail.

3/22/2011 9:37:56 PM

its also now now a 557 hp outboard...

http://www.seven-marine.com/motors/

3/22/2011 10:29:34 PM

Quote :

"a new generation supercharger optimized to significantly reduce noise"

Well that's no fun.

3/22/2011 10:32:47 PM

Quote :

"Some of it is sort of "catch up" stuff that you figured they would have had by now, like floating wrist pins and sodium-filled exhaust valves"

The titanium rods, special swirl heads and sodium filled exhaust valves (as well as the titanium intake valves) have been around on a vette since the z06 and obviously the rest of it has been around for much longer in other cars. I can think piston squirters in 1992 in a production engine from Porsche for example.

I was hoping for a bit more info, like what does "the belt system that is optimized to work with supercharger" mean exactly? More grooves? (If you have more details would love to hear it). On demand freewheeling alternator? I'd love to see something other than those that's actually innovative, but I'm not holding my breath.

Anyway, I thought the windows at the bottom of the cylinders for better pressure equalization was neat btw.

3/22/2011 11:39:56 PM

Just to keep things in perspective, this is what we're talking about here:

3/23/2011 12:07:04 AM

Quote :

"I was hoping for a bit more info, like what does "the belt system that is optimized to work with supercharger" mean exactly? More grooves? (If you have more details would love to hear it). On demand freewheeling alternator? I'd love to see something other than those that's actually innovative, but I'm not holding my breath. "

Well see that's the thing about GM small block V8's in general. They're hardly ever "gee whiz" engines with stuff you've never seen before in production, like BMW's new V8's which have the exhaust ports on the inside of the V instead of the traditional location. The same can be said of Ford's new 5.0 Coyote V8. There's very little that you've never seen before.

What I appreciate about this LS9 engine is all the little things that went into designing this engine from the ground up.

"To tailor the 6.2L LS9 to the Corvette's engine bay, the supercharger drive is integrated into the main accessory drive system. The LS9's two-belt accessory drive has one belt turning the air conditioning compressor and alternator, and another operating power steering, the water pump and the supercharger.

The supercharger requires the most force to turn, so its circuit uses a wider, 11-rib belt. To compensate, the LS9 water pump has improved bearing capacity. Bearing diameter is increased from 16 mm to 19 mm, compared to the LS7. To allow a common power steering pump with other small blocks V-8s, the LS9 pump is spline driven through a bracket and bearing system that takes the load off the supercharger."

The document I am reading is http://archives.media.gm.com/us/powertrain/en/product_services/2010/gmna/Stories/Gen%20IV/Gen%20IV%20Car/10_LS9_n.doc


What's interesting is that the LSA Cadillac engine uses a completely separate 8-rib belt for the blower instead of beefing up the water pump drive belt like on the LS9. They also used cast iron exhaust manifolds and cast pistons specifically because they have less noise. Both the LSA and LS9 use what they are calling "roto casting" for the heads which may be common but I'm personally not familiar with. Basically they rotate the part as it cools to remove microscopic air bubbles.

3/23/2011 5:38:41 AM

hah i was going to say something about 240s having piston oil squirters since at least the '91 and up models

3/23/2011 6:45:38 AM

Quote :

"The titanium rods, special swirl heads and sodium filled exhaust valves (as well as the titanium intake valves) have been around on a vette since the z06 and obviously the rest of it has been around for much longer in other cars. I can think piston squirters in 1992 in a production engine from Porsche for example. "

The early 90s subaru 2.2 legacy turbo had piston squirters (and no intercooler)
My 427 side oiler has sodium filled exhaust valves and i haven't touched it in 20 years.
(i do think dad put the valves in in the 70s though)

I don't think i'd want the supercharger on the serpentine belt... its 10x as likely to kick the belt of and then you cant drive your car at all.

Twin screw as zxappeal is different from the roots type blower that eaton has typically used in production cars... however kenneybell and Lysholm switched to twin screw in the late 90s. I have no proof but I'm pretty sure they've always been 3 & 4 "lobe" (for lack of a better term since they aren't really lobes like a roots blower) however i don't think that saves any power or noise i believe its the two screws not compressing against each-other but against the case is where the efficiency gain comes from.

3/23/2011 6:46:06 AM

LINEAR HORSEPOWERS

FLAT TORQUES


arghx bringing the cool back to the garage, +1 would read again.

3/23/2011 8:09:11 AM

^ I agree i would also like to note that i argue to learn sometimes lol.

Its a bad habit but a good way to learn something.

I've been wondering that if you were to remove a bunch of functions from a can bus ecu (monitoring the status of the window switch for instance) if it would have a higher resolution for monitoring the engine? I'm not talking making fuel timing etc. tables larger, i mean actually making sure the engine is where it needs to be more often.

3/23/2011 8:32:42 AM

Quote :

"I've been wondering that if you were to remove a bunch of functions from a can bus ecu (monitoring the status of the window switch for instance) if it would have a higher resolution for monitoring the engine? I'm not talking making fuel timing etc. tables larger, i mean actually making sure the engine is where it needs to be more often."

Well are you talking about monitoring data across the CAN or directly from analog sensors (water temp etc)? Also, there is a low speed and a high speed CAN protocol. The low speed bus is mostly for less important things like body electrical functions (power windows etc). The high speed bus is usually used for more critical powertrain functions. Here is the basic CAN architecture for a 2nd gen Prius:



Keep in mind that GM gets their ECU from Bosch just like some European makes like VW/Porsche and BMW. GM calls the Gen IV small block ECU an "E67" which is probably an internal GM designation. I know GM's direct injected engines use something from the Bosch Medtronic family of controllers like VW does. I'm not a powertrain engineer but I suspect the hardware for GM's engine controls were mostly designed by Bosch and GM might customize the product a little bit for a particular application.

3/23/2011 9:09:06 AM

Cool, for some reason i thought everything was talking the ECU.. I didn't know everything was controled independently and spoke to each other as needed.

3/23/2011 3:07:34 PM

it varies a little bit with the manufacturer's design in terms of the number of control modules and the role each module has.

3/23/2011 3:25:00 PM