Yea, we know - the automotive press has featured a whole bunch of Corvette ZR1 content lately (including us!), and readers are probably getting a bit tired. However, we figure that a cutaway of the mighty supercharged LS9 should be interesting enough to justify yet another post on the revived King of the Hill.
Painted in monochrome silver as GM is wont to do, this particular display isn't particularly photogenic. Still, we were able to capture some details that aren't easily observed in 2D drawing or press releases, so click through the jump for a variety of shots.
Here's a great shot of the helical rotors, but due to the paint, the specialized Teflon coating isn't visible. We have no idea how the rotors are fabricated, and GM's not talking - let's assume that it's a relatively exotic and expensive process.
Slightly unexpected was the use of straight-cut gears, which tend to be noisier than those cut on an angle. We wouldn't object to a bit of blower noise from under the hood, and besides, the loudest whining is likely to come from owners of more-expensive exotics.
This is the bypass valve, which provides an alternative route around the supercharger during part-throttle operation. This improves part-throttle fuel economy by reducing the pumping losses of the blower.
Located at the bottom of this shot is the driveshaft for the supercharger - the drive pulley (off-screen to the right of this shot) is located about a foot ahead of the rotors.
This shot clearly shows the intercooler assembly mounted atop the supercharger. In an actual ZR1, the clear window in the hood would be directly above this component. Note the ribbing used on the roof of the blower housing to help improve heat dissipation.
The heavily-dished piston is clearly evident here - it takes a lot of dish to reduce the compression ratio on an engine of this displacement, especially when combined with a small combustion chamber as utilized on the GenIII/IV engines.
That, folks, is one nicely-shaped intake port. After "spending" so much horsepower to compress the intake charge, it'd be a shame to restrict its entry into the combustion chamber, and so the LS9 attempts to give the air a straight shot into the cylinder. The titanium valves are 2.2 inches in diameter; this is larger than what would normally be used on a naturally-aspirated engine, but the airflow requires of this engine far surpass that of GM's other 6.2L V8s.
These two passages provide routes for coolant into and out of the intercooler. Located off to the bottom right of this photo is the throttle body.
Getting the spent charge out of a forced-induction motor is an important task, and so the free-flowing exhaust ports combine with hydroformed tubular headers to create a path of least resistance.
Silver paint hides the beautiful color of natural titanium, which is used for the connecting rods. The pistons are forged, although that's difficult to tell from this particular angle.
While the camshaft used in the LS9 is significantly less aggressive than the bumpstick used by the higher-revving naturally-aspirated LS7, it still uses a healthy amount of lift. These lobes also have a fairly aggressive profile, which quickly opens and closes the valve and thus makes the most out of each actuation cycle. Roller camshafts make such profiles practical, but the valvesprings end up with a rather difficult job as a result.













Reader Comments (Page 1 of 1)
DIRETTORE @ Jan 15th 2008 9:00PM
*****
?? CAN ANYONE PLEASE FIND OUT IF THE ZR1 + CTS-V WILL BE AT GENEVA???
THANK YOU!!!
Godzilla @ Jan 15th 2008 9:28PM
Nice . very nice.
pd @ Jan 15th 2008 9:07PM
I love it keep it coming. Sure beats the DAILY Mustang articles.
b1377 @ Jan 15th 2008 9:23PM
Excellent Photos & commentary!!!
Eric Biran @ Jan 15th 2008 9:35PM
This is the first application I've seen of a roots type supercharger where the intake and the drive pulley are at the same end. Trucks tend to have the intake on top, and for packaging constraints, cars usually have them at the end opposite the pulley. Up until recently, all dumped the air downwards, but the STS-V and XLR-V changed that.
But even those have the intake for the supercharger at the back of the engine. The ZR1's blower also points upwards, but the intake appears at the front. The bypass valve being at the front supports that conclusion. Actually, now that I look a little closer, I see a bit of the cutaway intake passage to the rotors just below the SC driveshaft here:
http://www.autoblog.com/photos/2008-detroit-corvette-zr1-ls9-engine-cutaway/583900/full/
They clearly packaged as tighly around the drive shaft as possible to allow the passage sufficient clearance.
asdfff @ Jan 15th 2008 9:40PM
I can't wait until this motor trickles down into the aveo! Its going to be sweeeet.
Nucbuddy @ Jan 15th 2008 11:22PM
Indeed. I figure the Aveo will probably go to supercharging -- with a displacement drop -- someday, to gain a fuel-economy improvement.
asdfffs @ Jan 15th 2008 9:41PM
You don't impress me. Dork : P
John @ Jan 15th 2008 9:43PM
I love the car but I'm wondering a few things. Since the C6R just went to ethanol, and this car has FI, putting two together it seems like it would be very cool if they made this car E85 compatible. Seems like they could develop a setting that allows high boost to generate more power. Maybe that's something for the aftermarket? Or the next one?
Thanks for the cutaway photos.
why not the LS2LS7? @ Jan 16th 2008 1:13AM
GM said something about the large injector nozzles required to get enough ethanol into the cylinder at WOT would reduce the fuel flow accuracy at low revs/throttle openings enough that the throttle response wouldn't be smooth enough.
True? I dunno. But that's the story I think.
3seriesisking @ Jan 15th 2008 10:43PM
Bitchin'......simply bitchin'.
HotRodzNKustoms @ Jan 15th 2008 10:53PM
Eric, thank you so much for the technical commentary you've been providing us. It is a real treat to be able to read something intelligent unlike these mindless fan boy comments we've been getting **coughGodzillacough**.
Godzilla @ Jan 16th 2008 12:57AM
Who's "**coughGodzillacough**"? I have to agree that the technical commentary is indeed insightful. Now I will feel the LS9 is worthy to be put into my John Deer tractor/lawn mower.
ronnie @ Jan 16th 2008 1:46AM
Nice Engine . . . really great! hand up to you!!!
:)
http://cars.ozfreeonline.com
RLQ @ Jan 16th 2008 5:17PM
I want this engine in a Factory Five GTM.