Turn Key 402ci
For this build I enlisted the help of Turn Key Engine Supply in Oceanside, California, and engine builder Chris Pollock, whom we have to give major props to. Considering our dyno session was scheduled for the following day, these guys had the entire bullet built from scratch to finish in a matter of hours. Then again, when your business is in the habit of cranking out 40-plus turnkey engines a month, it's just another day in the office.
Now I'm not going to give you a history lesson, but I do want to point out that the LS1 first debuted back in '97, and while it may seem hard to swallow, the newfangled LS variants are already going on their 10th year! Point being, it's not that new, folks. If you aren't familiar with the 6.0L LS2, don't sweat it. It's still in the same platform as the Gen III LS1/LS2 and the 5.3L and LQ9 6.0L truck engines. Matter of fact, all the parts available for this engine family are interchangeable, and it closely resembles the LQ9 truck motor, with the exception of its aluminum construction over the cast iron. Other differences include the relocation of the cam sensor from the rear of the engine to the front and the loss of dual knock sensors in the valley pan, which are now located on the side of the block.
Getting on to the mule, the initial plan was to build on a cast-iron LQ9; however, after pricing out bare blocks, we learned that the aluminum LS2 was only $300 more. Given the similar construction, it only seemed fitting to try something new. Besides, a motor that weighs significantly less only adds to the cool yet functional factor when dropped in between the fenderwells of any street machine. I'll let the following pages reveal the sordid details, including the price breakdown, the components used, and the dyno results.
If you're curious as to my interpretation of this month's test, I will say that the overall results left a permanent impression. Considering the LS2 churned out well over 560 hp and 520 lb-ft with excellent idle quality at 13 inches of vacuum, it's a true driver. And yes, that's on 91-octane. As an added bonus, we swapped the camshaft and went up another 8 degrees of duration, improving on our numbers with over 580 hp and 530 lb-ft, all the while maintaining 10 inches of vacuum at idle. As for the older Mouse, it was impressive, to say the least, but it's far more aggressive and lends itself as more of a weekend brawler when compared with this LS2. That said, dollar for dollar, at least in this comparison, the 402 LS2 proved that it can not only produce serious power, but with a relatively mild build it's perfectly suitable for the street. I'd like to see what this combination could produce with a stout solid-roller, but that's a story for another month.
Inside is a complete Lunati LS1 Pro Series stroker kit assembly featuring a 4340 forged crankshaft with a 4-inch stroke, 4340E billet rods, forged pistons, and main bearings. Yeah, this baby isn't going to break anytime soon, and the added rigidity will allow for aggressive testing in upcoming issues. One thing we need to note is that the crankshaft featured a 24-tooth reluctor wheel, which was swapped for a 58-tooth wheel to work with the Edelbrock controller. |
Like the LS1/LS6 and LQ9 blocks, the LS2 features a six-bolt main. The inner bolts were torqued to 58 ft-lb, 55 ft-lb for the outer, and 25 ft-lb for the cross-bolts. |
One of the biggest advantages of the LS engine is having the ability to swap camshafts with minimal effort. All you have to do is remove the front timing cover, loosen the rocker arms, and slide two rods to support the lifters. Keeping that in mind, we started small with the 230/232 duration at 0.050 (PN XER281HR) and later stepped up to a larger 238/240 duration stick (PN XER287HR). |
Unlike the 406ci, we produced 583 hp and 530 lb-ft on 91-octane and through the mufflers.
Peak power was had with a 72/79 jet combo through a 750-cfm Mighty Demon.
We used 13⁄4 Hooker long-tubes with mufflers for every pull.
The front timing cover, oil pan, and valve covers are all factory issue.
Turn Key offers this trick-looking balancer for $280.
Bare aluminum LS2 blocks can be had for only $995.
Dart 225cc Pro 1 LS1s are true bolt-on pieces and retail for only $1,620.
To help keep the timing in check, we used a Motion double-roller timing chain. The raised ridge is where the cam sensor takes its reading. | 
Head gasket of choice was a factory 6.0L steel gasket that measured 0.057 inch compressed, giving us 11:1 compression with the 62cc-chamber Dart 225s. | 
Rather than using the factory lifters, we went with Comp Cams Pro Magnum hydraulic-roller lifters, specifically designed for high-rpm floggings. |
Unlike the LS1/LS6 and the LQ9 block, there are no bosses for the dual knock sensors in the valley pan; instead they're placed on the side of the block. Also, if you're using an older LS1/LS6 processor, be sure to use the correct knock sensors, as the LS2 knock sensors feature a two-wire design over the previous one-wire setup and are incompatible with the LS2 processor. | 
Moving the air is a set of Dart Pro 1 LS1 cylinder heads. Cast out of 355-T6 aerospace alloy, they feature 2.05-/1.60-inch intake/exhaust valves and a 225cc runner volume (205s are also available) and can flow as much as 313 cfm on the intake port and 214 cfm on the exhaust at 0.600 inch lift. | 
While the ports are as cast from Dart, the combustion chambers are bowl-blended on a five-axis CNC machine and available in a 62cc configuration. |
While the ports are as cast from Dart, the combustion chambers are bowl-blended on a five-axis CNC machine and available in a 62cc configuration. | 
An added bonus to the Lunati stroker kit is that everything comes balanced and ready to be assembled. Included are plasma-moly file fit rings with billet rods measuring 6.125 inches in length. | 
Since the intake rocker-arm stud extends through the port, it's a good idea to use sealant to prevent any oil from seeping in. To keep the head mated to the block, we used a complete set of ARP head studs. The smaller upper bolts were torqued to 23 ft-lb while the larger bolts were set at 70. |
Completing the valvetrain, we used a set of Comp Cams 1.75:1 roller rockers with a 3⁄8-inch stud. | 
Expect to dab a little sealant on the four corners of the front and rear cover prior to mounting the oil pan. It's also important to note that on any stroker combination, you'll need to place a washer, measuring 0.110 inch, underneath the windage tray to prevent the crank from rubbing into it. | 
Again, even with the manifold, there's no sealant here. Simply press in the factory rubber O-rings. If you can't get them through your local GM dealer, Turn Key can take care of your needs. |
The end product is eye-fetching, isn't it? While we chose to utilize Westech's MSD coil packs and wires, you can shave off $680 if you have access to the factory pieces; however, you should be aware that the MSD unit is designed to work with the factory electronics and will be offering a programmer to control every aspect of ignition timing. | 
We gained an additional 5 hp by using a 1-inch tapered four-hole Super Sucker spacer from High Velocity Heads, netting us the final 583hp figure. | 
If you plan to use an LS2 block like we did with the LS1 Edelbrock manifold and controller, be advised that you'll need to do a slight modification. The LS2 uses a 5-volt cam sensor, whereas the LS1/LS6 and LQ9 use a 12-volt cam sensor. Since the controller was originally designed to read the 12-volt sensor, you'll need to reverse the two outer wires to change the polarity. This works well, but by the time you read this, it'll already have been addressed. |