LT1-Powered Chevy Camaro Z28 - The Final Countdown
Our LT1-powered Z28 project car The Grape Of Wrath makes its final voyage down the quarter mile.
From the August, 2009 issue of GM High-Tech Performance
By Johnny Hunkins
When we last updated you on...
When we last updated you on TGOW, we had just installed these suspension components from BMR Fabrication. We went with just the bare bones package, consisting of lower rear control arms, relocation brackets, adjustable Panhard, stock-mount adjustable torque arm and lowering springs. At full retail, the system set us back just $869.75.
As a daily-driven street car,...
As a daily-driven street car, the BMR parts had to satisfy our criteria of driveability, improved visual stance, and better drag strip performance. We got all three by choosing control arms with polyurethane bushings (they're quieter). Stance was aided by BMR's lowering springs, and drag strip traction was improved with LCA relocation brackets. We don't recommend lowering a fourth gen. without LCA relocation brackets due to the compromise in the geometry of the instant center, which occupies an imaginary point below the car with lower springs and stock LCA mounting points.
BMR's adjustable torque arm...
BMR's adjustable torque arm allows the user to set the pinion angle for best traction. The idea is to set enough down angle to the pinion so that at launch the wind-up results in an angle which is complementary to the tailshaft/driveshaft angle. Too much down angle can result in binding, broken parts and axle tramp; not enough angle can result in breakage or poor traction.
Almost simultaneous with the...
Almost simultaneous with the installation of our BMR suspension last fall, we experienced a failure of the Optispark unit. We quickly ordered this new one from GM Parts Direct, which was installed for us by reader Rich Trepczynski of Warren, Michigan. This set us back time-wise, and a follow-up drag test was impossible for the remainder of 2002.
With TGOW back in New Jersey...
With TGOW back in New Jersey again we were ready to test late in the fall of 2002, but the East Coast was socked with its worst winter in seven years. As this picture shows, we continued to drive TGOW daily through the worst of the snow, proving that you can't put much stock in what the safety Nazis say about RWD.
Project Grape Of Wrath is at an end, at least for the foreseeable future. The last bolt has been turned so it's time to run the final track tests and for our readers to evaluate the relative success of our venture. Back in the July 2002 issue, we set forth some lofty goals--to run 12s with a stock-motored LT1 F-body. We'll tell you up front that we didn't accomplish this, but we did come darned close, and we didn't even perform all the basic mods we planned.
Having said that, we would still classify our results as a success. As the accompanying chart shows, we managed to run a best ET of 13.16 without any internal mods to our 103,000-mile engine. Not only have the valve covers never been lifted, but no computer tuning to the PCM (either to engine or trans) has taken place. Moreover, we accomplished this with modest 3.42 gearing at full weight with 50-state-legal parts.
You'll recall that our last round of mods consisted of a BMR suspension system. We went with just the basics and restricted our parts list to lower rear control arms, LCA relocation brackets, adjustable Panhard bar, a stock-mount adjustable torque arm and lowering springs (see, "The Air Down There," March 2003). At that time, we were unable to track test due to a failure of the Optispark system. Once this was repaired, we were already into the harsh winter weather--in fact, it turned into the worst winter in seven years.
We'll let the results speak for themselves (check the results chart with mods and ETs), but we think with a few more inexpensive tweaks and some more testing, 12s are definitely within reach. Two important areas we did not address are WOT dyno tuning and converter lock-up. The first of these items would involve using either custom PCM tuning such as offered by Ed Wright, Hypertech or Superchips, or by a tunable in-line box like the Mass Airflow Translator Plus which is available through Ramchargers Performance.
As for the second area of opportunity, eliminating converter lock-up, we feel we're going through the traps at far too low an engine speed--around 4900 rpm. TGOW launches hard and rockets through First and Second gear, but noses over dramatically midway through Third with lock-up, dumping about 300 rpm in the process. Dyno tuning has shown peak power to come at 5600 rpm, well above our current trap speed rpm. This explains the weak trap speed relative to ET and could possibly account for a tenth or more in lost ET. It's nothing $10 and a trip to Radio Shack can't cure, namely an in-line switch to disable the converter lock-up, and a 15-ohm resistor to trick the computer into thinking the solenoid is engaged.
You be the judge. We've seen enough guys max out on the stock LT1, so we know 12s are possible with a totally stock motor. We think it's more a question of tuning, testing and tweaking than throwing money around, we just ran out of time. Still, we shaved over 7 tenths off our ET without so much as touching a rocker arm, and that says a lot about the potential of this potent fuel-injected small-block!
Looking The Part
It has always been our contention that the performance needs to go in before the cosmetics start bragging, and it's no different with TGOW. Since we knew we had a good runner, we decided we could finally make some small improvements, starting with a new paint job from Classic Restoration of Sloatsburg, NY. (You'll remember they performed our header and exhaust install back in our January issue.) Our Purple Pearl Metallic paint was pitted and dulled beyond repair, so we selected a new color, this one a 2003 Ford Mustang hue called Dark Shadow Gray Clearcoat. (Begging the question, should we change TGOW's name to "The Gray Of Wrath?")
We then ordered some carbon fiber emblems from RK Sport. These replace the factory "Z28" badges found on the fenders and rear valence. We also replaced the crest emblem on the nose and the rear bowtie emblem with carbon fiber pieces. Later on down the line once the paint has fully cured, we'll be adding RK Sport's "Big Attitude" graphics, otherwise known as SS stripes. Bringing up the rear, we tacked on a three-piece "duck tail" spoiler from RK Sport. This was painted at the same time as the car and matches perfectly.
These small improvements have changed the way we look at the car. Suddenly, it's new again, and that's saying a lot now that you can't buy a new Camaro any more!
Suggested TGOW Reading
-- "Screamin' Deals," May 2002. How to buy an LT1 F-body on a budget. We buy a 1994 Camaro Z28 with an automatic transmission for $6000.
-- "The Grape Of Wrath," July 2002. We name our newfound Camaro The Grape Of Wrath and take it to the track for the first time to get baseline performance figures.
-- "Rolling Stock," September 2002. Wheel fitment and tire tech with Centerline Telstar wheels and Mickey Thompson ET Streets.
-- "Steppin' Stones," September 2002. First bolt-ons (SLP and Holley) and track test. Mods include TB airfoil, skinnies and slicks, 3.42 gears, subframes, 160-degree thermostat, cold air induction, and fan control switch.
-- "Beat The Heat," November 2002. Install TransGo shift kit, Vigilante torque converter and rebuild 4L60E trans. Track test again.
-- "Exhaustive Effort," January 2003. Install Hooker shorty headers, Corsa cat-back exhaust, Dynomax cat-con and MSD wires. Track test and dyno test.
-- "The Air Down There," March 2003. Install BMR suspension components. Optispark malfunctions before track testing can occur.
-- "Scan It!," March 2003. Install Ramchargers LT1 Scanmaster diagnostic tool.
|Best ET, All-Stock: January 27, 2002, all stock, radials, Atco, NJ|
|Stock Baseline Average:|
|Best ET, Round One Mods: March 21, 2002, E-town, NJ. SLP cold air intake, SLP 160-degree thermostat, SLP 3.42 gears, Zexel HD differential, SLP fan switch, SLP subframes, ET Streets, skinny fronts, Center Line Telstars, Holley airfoil|
|Round One Average:|
|Best ET, Round Two Mods: May 10, 2002, E-town, NJ. Vigilante converter, TransGo shift kit, trans cooler, Dynotech trans rebuild|
|Round Two Average:|
|Best ET, Round Three Mods: June 27, 2002, E-town, NJ. Hooker shorty headers, Corsa exhaust, Dynomax cat-con, MSD wires|
|Round Three Average:|
|Round Four Mods: March 27, 2003, E-town, NJ. BMR suspension, new Optispark |
|Round Four Average:|
|Average Improvement from Round Three:|
|-.32 sec.||+2.2 mph||-.06 sec.|
|Total Average Improvement:|
|-.73 sec.||+1.7 mph||-.22 sec.|
When the winter cleared in...
When the winter cleared in late March of 2003, we set up a test date at Englishtown, NJ. The balmy 60-degree temps meant we'd get good results by icing down the intake manifold. Note the extra ice bag on the SLP cold air induction. This increases air density slightly and has been a normal procedure for our testing over the past two years.
We were pleasantly surprised...
We were pleasantly surprised by our test results, which yielded a best ET of 13.16/102.0. Even more remarkable was the incredible consistency in our ET. We changed nothing over the course of the test session, making six runs in total. ET never varied by more than 5 hundredths all day long--a testament to the efficacy of our BMR suspension. Moreover, our all-time best 60-foot time improved from a 1.82 to a 1.75, a considerable feat for a completely stock LT1 engine in a full-weight car.
12581 U.S. Hwy. 301 N.
Holley Performance Products
1801 Russellville Rd.
Bowling Green, KY 42101
Center Line Wheel Corp.
Mickey Thompson Performance Tires
4670 Allen Rd.
MSD (Autotronic Controls Corp.)
140 Blaze Industrial Parkway
105 Pierce Street
Corvette Specialty Center
26900 Jefferson Ave.
Hi Pro Transmissions
GM Parts Direct