The pistons are dished to...
The pistons are dished to lower the compression ratio to a detonation-avoiding 9.0:1. These blower-specific units also have a thick crown and reinforced pin bosses, while their gold-colored top coating is a ceramic material that reduces heat absorption.
To further reduce piston temperatures-especially...
To further reduce piston temperatures-especially under boost-Thomson Automotive machined the cylinder block to accept oil squirters. It's a precise, multi-step process that taps into one of the block's primary oil passages. The squirters themselves are carburetor air bleeds.
A set of new GMPP LSX-LS9...
A set of new GMPP LSX-LS9 six-bolt cylinder heads match the intake ports of the LS9 supercharger manifold and offer greater clamping strength than the standard four-bolt heads. The heads are filled with stock 2.16-in titanium intake valves and aftermarket (but stock-size) 1.59-in Inconel exhaust units.
Valvetrain details read essentially...
Valvetrain details read essentially like those for a stock LS9, including the stamped, non-roller, 1.7-ratio rocker arms. The valvesprings are matched to the secret-recipe camshaft.
This photo shows the basic...
This photo shows the basic LS9 blower case installed on the engine, with the blower drive and other components still awaiting installation. Note, too, the wet-sump oil pan. The customer for this engine didn't want the more elaborate (and space-consuming) dry-sump-style oiling system.
Because the supercharger would...
Because the supercharger would be blowing into a larger-displacement engine, it wouldn't generate the same boost level as a stock LS9. Thomson Automotive had a new, smaller-diameter pulley machined to spin those four-lobe rotors more quickly, pushing boost back up to about 12 psi.
Another pulley required for...
Another pulley required for this combination was the integrated damper/crankshaft pulley. Because the engine didn't use the stock LS9's dry-sump system, a slimmer wet-sump oil pump and shorter-snout crank were employed. However, the engine still required a wide, multi-rib damper pulley that would place the 10-rib serpentine belt (and narrower A/C belt) at the same position as the stock LS9. Thomson got that custom damper from ATI. It's shown here at left, with the LS9 pulley on the right.
Additional assembly details...
Additional assembly details include the LS9 water pump and a custom, aftermarket front drive kit that relocated the alternator and other accessories higher on the engine to facilitate installation in the vintage Corvette project vehicle. Note the excellent belt wrap, which is essential for preventing slippage on a non-cogged belt drive.
The Eaton blower draws its...
The Eaton blower draws its pressurized air charge through an electronically controlled 90mm LS7 throttle body. Interestingly, it is mounted upside down from its position on the LS7, in order to accommodate the tightly positioned belt-drive system.
Even the smallest details...
Even the smallest details were carefully covered, including inserting colder spark plugs to help stave off detonation. For this engine, it was a set of Autolite Racing 3933 plugs.
On the dyno, the LS9-blown...
On the dyno, the LS9-blown LSX engine produced about 12 psi of boost to help make a safely tuned 710 hp and 780 lb-ft of torque on 93-octane pump gas. Note the stock LS7 exhaust manifolds, which Thomson cites as helping generate the most power and torque possible in this configuration-even more than long-tube headers.
After the dyno testing was...
After the dyno testing was completed, Thomson dressed up the engine by powdercoating the valve covers and the top of the blower case the same Chevy orange color as the block. Look closely and you'll see that the factory "LS9 SUPERCHARGED" logo was milled off the top of the blower case, too, giving this hybrid 7.0-liter a more custom appearance.
Thomson Automotive's flexplate...
Thomson Automotive's flexplate kit allows GMPP's LSX454 and LSA crate engines to be used with popular automatic transmissions and torque converters. The kit includes the flexplate, adapter hub, and bolts for $119.95.
GM Performance Parts' LSX454 crate engine and the supercharged LSA crate engine each use a crankshaft with an eight-bolt rear hub that doesn't match the standard six-bolt pattern of conventional GM automatic transmission flexplates-including the popular Hydra-Matic 4L80-E. To address this issue, Thomson Automotive designed a flexplate kit that features a factory GM eight-bolt flexplate and a custom-machined adapter hub. The flexplate is also modified to accommodate the bolt patterns of popular aftermarket torque converters.