The LS7 is by far the most powerful production motor ever made by GM, not to mention being one of the most powerful naturally aspirated V-8s made by any manufacturer. Its 427 ci of fury is darn near the most fun you can have with your clothes on. Actually this motor is so sexy it makes you want to take your clothes off, which is exactly why GM enthusiasts have been foaming at the mouth since its introduction. GM Performance Parts hoped to prey on these very desires by placing one of its fully assembled, handbuilt LS7s into a 1999 Camaro Z28 for the purpose of showing just how easy it could be.
The 1999 Z28 was the perfect vessel given that F-body owners represent a large chunk of the market for GMPP, and also because its light, aerodynamic chassis and solid rear axle would best demonstrate the LS7s potential on the track. As you'd expect from the vast similarities between Gen III and IV motors, the retrofit was relatively easy (by hot rod standards). The greatest challenge was accommodating the dry sump lubrication system, which required relocating the battery to the trunk and installing a BMR tubular K-member. The stock oil tank (minus two inches of height) now resides in the battery's place with custom-made oil lines and fittings. For clearance and to adapt the F-body accessory drive scheme, the GM engineers used a Z06 A/C compressor and ATI Super Damper balancer. On this project the intention was to stay with a cable throttle, as most F-body and hot rod owners would prefer, which meant ditching the LS7 electronic throttle in favor of a UMI 90mm unit. A custom wiring harness was also put together by the GMPP engineers, and connected to a prototype MEFI-4b computer. Plans are to release this Marine-based speed density computer with fine-tuned spark and fuel tables for others looking to retrofit LS7s into their sinister rides without using MAF and electronic throttles.
With the custom tune developed by the engineers (with the help of UMI Performance), and a few other goodies this stock LS7 puts out a good bit more than the 505hp version in the Z06. For starters a set of Kooks 1 7/8-inch stainless steel headers, Y-pipe and a 3-inch MagnaFlow cat-back provide significant improvement over stock exhaust. A BMR torque arm and subframe connectors were used in conjunction with a Strange S60 rear end to bulletproof the driveline, enabling solid launches on slicks at the track. The beefy 35-spline axles and enormous 3.73 ring gear were sure not shatter, unlike the questionable stock pieces, even with the mighty LS7's potential. A set of 4.56 gears have replaced the 3.73s, as the Camaro is no longer likely to see highway duty as it did on the Hot Rod Power Tour, which along with a SPEC aluminum flywheel helps spin the motor up to its 7,200 rpm red line. Similarly the stock LS7 clutch and pressure plate have been traded for a track-friendly unit from Centerforce to engage a stock Tremec T56. For the purpose of keeping things as realistic as possible and using as few mods as necessary, the rest of the Camaro is kept pretty much stock. However, the results speak for themselves-and you can only imagine the seemingly endless potential of this monstrous motor. Suddenly owning an 11-second car that runs and drives like a stocker became a whole lot easier.
DRAG TESTING THE LS7 CAMARO AT MILAN
The GM Performance Parts LS7 Camaro dripped bad attitude from the first minute I saw it at Thomson Automotive. GMPP's Jamie Meyer and I had dropped by one August morning to do a photo shoot before we continued on to an LSX block presentation. We would be back to collect the Camaro later that day to head up to Milan, but I wanted to get a little seat time first.
Thomson Automotive has worked hand in hand with GM's engineers in the past to create cool hot rods that push the limit, and in early 2006, GMPP engineer Shawn Smith contacted Brian Thomson about doing a Camaro with a swapped-in LS7. Starting with a crate LS7 and an old GM Engineering F-body mule, this project came together in the spring months and was ready to roll by the Power Tour.
It was the first time I'd laid eyes on this 427-swap hardtop, and I was impressed: Though the flat black paint and black Z06 rims try to keep this puppy low-key, the exterior, replete with SS hood and rear spoiler and enhanced by the ballsy GMPP TEST VEHICLE graphics on the doors and rear LS7 badge, is about as understated as a kick to the jimmy.
The same goes for the massive 427ci LS7 under the hood. Though it's far from the ill-tempered race motors that our carb-loving brethren run, there's something about an LS7's idle that stops you in your tracks. Definitely not rowdy, but only because something--in this case a MEFI-4b ECU--is trying like hell to hold it back. And this mill was also enhanced by a set of headers, which gave it an even more sinister tone. The 427 sat between the fenders like it belonged there, a tribute to Thomson Automotive's outstanding fabrication.
Drivetrain upgrades included a Strange S60 with 4.56 gears, a new driveshaft, and an aftermarket clutch. The Thomson crew had been going through clutches like crazy, and only hours earlier had bolted up a new Centerforce dual. I hopped in and was pleased to find a clutch pedal with very manageable pressure. The big crate engine was cracked off and allowed to warm up a bit, then I rolled out with Meyer riding shotgun. The LS7, not yet up to operating temperature, was ultra-responsive and didn't much care for the 25-mph speed limit. Immediately, I noticed a gear change issue with the T56--playing around with quick upshifts and heel and toe downshifts revealed that it was hanging up between gears. Once up to temp and on a two-block straight, I selected First, eased out the clutch until we were rolling, and punched it.
The LS7 exploded to life, screaming to rpm unheard of with its lesser LS siblings and shredding the 275mm Goodyear radials. The nose skated left, then right as I corrected, and finally settled down as I rolled off the gas, wide-eyed. Wow, that's sick! Later that afternoon, I made the hour-long trek up to Milan Dragway with Shawn Smith riding shotgun. Even without the front sway bar, this Camaro handled well at highway speeds, and though I fought the T56 all the way up to Sixth gear, once there the sounds and feels were like that of a near-stock F-body. Even with the 4.56s, revs were right around 2,500 at 70 mph according to the Racepak display. And even though we weren't using the A/C and had the windows down, the exhaust sound was dignified. My eyes slipped down and found a sweet digital wide-band O2 readout, mounted right ahead of the B&M shifter in the console--nice touch!
Once at Milan the Camaro was teched, then I rolled over to the pits, where some of the Thomson Automotive crew--Brian, Lazlo, and Mike--were waiting. The plan was to get some solid street-tire runs, then swap over to a set of slicks. As the lanes had just opened, I made a beeline for the starting line.
In preparation for the run, I removed the floormat, adjusted the seat forward a bit, rolled the windows up, and threw on the Simpson. I did a small burnout and pulled up to stage, but the clutch pedal crashed and I ended up fouling. I kicked the pedal a couple times, it felt OK, so I launched anyway. Three difficult shifts later and a lame 15.24 at 111 flashed. The next time around, I repeated the burnout and was pleased to find that the clutch was fine. A soft 2,200-rpm launch netted a 2.15 60, and battling to Fourth gear rewarded me with a 13.58 at 111. Though I didn't want to wear the clutch out early, I headed back to the staging lanes for one last shot before parking it--I was just starting to settle down and some headway had to be made with the gearbox. Ten minutes later, I was scalding the hides in the burnout box, but a high 3,000-rpm launch on the radials blew the 60-ft: 2.34. The trans was smooth at first: I wasn't able to powershift, but the 1-2 and 2-3 weren't hanging up in Neutral as before. But when it came time to grab Fourth, the six-speed made it clear that attempting a quick shift would be dealt with severely. I missed the gear and coasted across the stripe, settling for a 12.80 at 102.
Back in the pits, the natives were restless: this was a way faster car than I had been able to prove, and Thomson and Smith took a spin to see what was up with the trans. They came back reporting no problems, so Brian and I went out. The trans trouble finally reared its ugly head with Thomson behind the wheel and unable to powershift, and it was determined that in order to get gears changed with any success, I would have to throw the T56's health to the wind and really muscle the shifter.
After a quick burger and cheese fry dinner, I again donned the helmet and rolled into the pits. By now, the Wednesday Night Test & Tune crowd was thick, and a couple of oil-downs meant I would have lots of time to think about this rocket. Though the trans was a concern, I was still blown away by this combination: the 4.56s were perfect for the quarter-mile, though on street tires the first two gears were pretty much useless when the LS7's big torque came online. The clutch was holding fine and had a nice pedal feel. And the high-rpm sound, even through my helmet, was wicked.
Nearly an hour later, I finally pulled into the box. Second was selected, and I dumped the clutch and hazed the Goodyears. I eased off the brake and let the 'Maro's momentum carry me to pre-stage. I quickly noticed that the long cooldown had benefited the trans, which was moving between gears much easier. I grabbed First, eased into the stage bulb, and revved the 427 to 2,700. When the tree came down, I breathed on the gas while slipping the clutch. The street tread latched onto Milan's surface and I was yanked to a 1.85 60-ft. Seven thousand came quick, and I brutally muscled the shifter into Second, then Third. It still wasn't allowing a powershift, instead stopping briefly in Neutral before slipping into the next gear. This run was coming together, and when Fourth was dialed in, I knew I was flying. The LS7 strained past 7,000 as I crossed the stripe, recording a 12.43 at 115.08.
"Finally!" Meyer exclaimed as I cruised back to the pits. "Now we have a test car!" One more street-tire run was made 70 minutes later, but the 1.86 60-ft couldn't make up for the crunched-up gearbox: 12.95 at 105.
Back in the pits, Lazlo and Mike swapped the street radials for a set of slicks, and I hauled tail to the lanes. It was now almost 8 p.m., which meant that Milan would be closing soon. The T56 was giving me more trouble on the way to the burnout box, and after smoking the brand-new meats big-time, I staged up. The last thing I wanted to do was stall this rocket on the slicks, so I gassed it until just over five grand was showing on the tach and side-stepped the clutch. WWWWHHHHAAAAA-aaaaaaahhh, the LS7 groaned, pulling my head into the cloth seat and recording a 1.67 short time. I again abused the shifter through the gears but had to settle for molasses-slow shifts, and flew through the traps--limiter kicking in immediately--with a 12.61 at 112. I was now down to the last run of the night, as the lanes had been closed off after I rolled in. I was joined in the pits by the Thomson crew, Jamie Meyer, Shawn Smith, and Lisa Reffett of GMPP, and Mark Whitney, who had earlier put the smack down on Meyer's stock Trailblazer SS with his tuned TBSS. With one run left the GMPP folks were adamant about going for broke and suggested that I leave off of the limiter--um, sounds good to me!
Just after 9 p.m. I pulled the bad black F-body into the water and executed a big Second-gear burnout. A crowd gathered on either side as I found the lane's groove and eased up to the lights. Once pre-staged I took a deep breath, jammed the shifter into first, and crept up until both yellows were lit. I let the tree come down, floored the throttle, and when the Racepak showed 7,000, dropped the clutch. The slicks bit, the nose yanked up, and my head whipped back, but my eyes strained to look down at the tach, which was already nearing redline! I clutched and rammed the shifter into Second, marveling at how fast the revs were climbing. Third hung up just a bit but took, and with insane acceleration taking hold, the slicks--set at a low 13 psi--started to make the car sway. I applied minor correction to the steering wheel and jammed Fourth gear. The finish line loomed immediately, the LS7 banged the limiter, and it was over: 1.56 60-ft, 12.00 at 115.07.
When I tried to pull it out of gear before hitting the return road, the lever was stuck in Fourth. Turns out that a shifter fork was bent--the trans was done and this GMPP rocket disappeared into Thomson's trailer.
It was sick fun being able to test the GMPP LS7 Camaro at Milan. A marvel of engine-swap ingenuity, this F-body has an easy 11.60 in it with a good trans, and carries no ill effects along with that timeslip. It's a great world indeed when you can drop in a reliable crate motor with this kind of power, and instead of worrying about the engine, turn your attention instead to how the rest of the drivetrain and the car itself will handle the power. A killer car, and a killer crate engine.--R.J. Special thanks go out to the GM Performance Parts staff, the Thomson Automotive staff, and Mark Whitney for all of their assistance.
|Car:||1999 Chevrolet Camaro Z28|
|Block:||LS7, 427 cid|
|Heads:||LS7, titanium 2.20 intake, sodium filled 1.61 exhaust valves|
|Cam:||GM 211/230 duration, .591/.591-inch lift|
|Rocker arms:||Steel 1.8:1 ratio|
|Throttle body:||UMI 90mm|
|Fuel injectors:||Stock 40 lbs/hr|
|Ignition:||Stock coil on plug|
|Engine management:||Prototype speed density, tuned by GMPP|
|Exhaust system:||Kooks 1 7/8-inch long tube headers, Y-pipe, MagnaFlow cat-back|
|Driveshaft:||Strange chrome moly|
|Front suspension:||BMR K-member, stock A-arms and springs, 1LE Koni shocks|
|Rear suspension:||BMR torque arm, 1LE Koni shocks, stock Panhard bar, control arms, and springs|
|Rear end:||Strange S60, 35-spline axles, 4.56 gear, posi|
|Front tires:||Goodyear F1 275/40/17|
|Rear tires:||Goodyear F1 275/40/17|