1 We anxiously wanted to...
1 We anxiously wanted to see how well the GN's latest
If you have been following our "Turbo Buick Basics" series then you know that, like any project, we've had our challenges. But at long last it is starting to come around. While still on low boost (18psi) the time had come to strip test our buddy Tim Cairone's Grand National. Tim was delighted that the GN had never ran so well or felt so powerful. Yet all this power meant that we'd need some way to contain it. Enter a set of components from G Body Parts and UMI Performance. While thrashing to get the test done before Atco Raceway closed for the winter, G Body managed to get us a set of air bags shipped out that would allow us to dial-in the rear with some preload and add some bite. Meanwhile UMI Performance's Lift Bar Set-Up was on the way for part two of the strip test, which would improve the suspension geometry and eliminate any lower control arm flex or deflection. And since we also had a set of 27x10.5-inch slicks lying around, we decided to throw them into the mix in our quest for better traction. Follow along to see what happened.
2 With the GN on a lift,...
2 With the GN on a lift, with the suspension hanging, it was easy to install the air bags. Get any air out of the bag while compressing and folding it to squeeze through [and into] the coil spring. The barbed end for the air hose must be facing upward (top).
3a The spacer/protector can...
3a The spacer/protector can be placed on top of the air bag and...
3b ...The air hose secured...
3b ...The air hose secured to the barbed end.
4 We routed and secured the...
4 We routed and secured the air hose away from the hot tailpipes with the air valves accessible at the rear of the gas tank. Air Lift recommends a minimum of 5psi in each air bag.
5a Before taking any hits...
5a Before taking any hits down the 1320, we let the air out of the bags and made sure there was 15psi in the small 26x8.5-15 M/T slicks. For the baseline, without any air in the bags, our best 60-ft (5-psi boost launch) was a tire-hazing 1.73 short-time along with an 11.78 at 117.23.
5b Tire spin was evident...
5b Tire spin was evident from 20-30 feet out as well as 150-feet out after the shift to second. We added 5psi to each bag, which improved hook for what seemed to be a no-spin 1.65-second sixty-foot and an impressive 11.65 at 117.56 mph 1/4-mile (hardly any spin shifting into second).
Dyno And Dragstrip Results |
Mods |
HP |
TQ |
60-FT |
E.T. |
MPH |
| Stock, 13 psi |
208 @ 4000 |
256 @3000 |
2.10 |
14.25 |
95.53 |
| Chip, 17 psi |
210 @ 4000 |
320 @ 3000 |
|
|
|
| Valvesprings, fuel pump, hotwire |
238 @ 4100 |
358 @ 3000 |
|
|
|
| 42-lb Injectors, chip, 19psi |
240 @ 4000 |
405 @ 3000 |
2.10 |
13.63 |
100.55 |
| High-flow exhaust |
276 @ 4000 |
440 @ 3000 |
|
|
|
| 58mm turbo, 20psi |
303 @ 4500 |
440 @ 3500 |
2.31 |
13.50 |
104.68 |
| 3-in. downpipe, boost controller |
303 @ 4500 |
450 @ 3000 |
|
|
|
| ADPP, ported throttle body |
325 @ 4500 |
446 @ 3000 |
(Trans Failure) |
| Rebuilt trans, 2800 stall converter |
289 @ 4500 |
465 @ 3100 |
1.65 |
12.28 |
108.11 |
| Roller cam, ported heads, headers, 17psi |
339 @ 4000 |
465 @ 3800 |
|
|
|
| 62 turbo, hi-flow intercooler ends, 20psi |
372 @ 4800 |
515 @ 3500 |
1.97 |
12.28 |
112.34 |
| Chip, port turbo, w/g puck, tune, 18psi |
365 @ 4700 |
554 @ 3400 |
|
|
|
| Air bags, lower control arms |
365 @ 4700 |
554 @ 3400 |
1.55 |
11.41 |
117.94 |
6 Next we tried 10-psi in...
6 Next we tried 10-psi in the right-side bag and 8-psi in the left. Staying with a consistent 5-psi boost launch the Turbo Buick produced its best ever 1.63 sixty-foot and 11.58 at 117.77 mph. We tried to launch at 8psi boost, which only slowed the GN to a tire hazing 1.70 and 11.69 e.t.'s.
7a To obtain an 8-psi boost...
7a To obtain an 8-psi boost launch without tire spin, we ordered a set of lower control arms (LCA) from UMI Performance. The UMI Performance '78-'87 GM G-Body Lift Bar Set-Up is designed to greatly improve traction, correct lost geometry to work with axle torque to load the chassis of the car, forcing the rear wheels downward while pushing the tires into the ground for harder launches and improved 60-foot times.
7b Constructed of boxed mild...
7b Constructed of boxed mild steel tubing, 0.120-in. wall with 0.188-in. thick mounting plates—all completely CNC machined for exact tolerances and fit. Each lift bar features sway bar provision holes placed in the correct pattern to maintain the sway bar level with the rear end. Also featured are grease-able Energy Suspension bushings that reduce deflection, but keep these arms 100% streetable. The UMI Performance lift bar set-up claims to not affect ride height while keeping ride quality.
8 Here's a last look at the...
8 Here's a last look at the wimpy stock stamped steel LCA with rubber bushings and factory sway bar in place. Be sure to block the front wheels and jack-up the vehicle to a good working height.
9 Thoroughly read the provided...
9 Thoroughly read the provided instructions. Installation is done one side at a time. Begin by removing the rear tire and unbolting the LCA from its rear mounting point. Let the LCA swing down. Do not remove the LCA from its front mounting point.
10 On the machined bottom...
10 On the machined bottom surface of the (rear end) pinion yoke housing, place a magnetic angle finder (available from UMI Performance) and record the angle (ours was -1 degree).
11 The bottom (machined surface)...
11 The bottom (machined surface) of the relocation brackets, which are marked driver and passenger side, must be parallel and at the same recorded angle as the pinion. Place the angle meter on the bottom of the relocation bracket and pivot the relocation plate (bracket) until the angle matches the angle measurement taken from the pinion yoke housing. Be certain that each plate (two on each side) has the same angle measurement before tack welding the two exterior edges of each plate. Also, be sure the mounting tab of each plate is facing inward towards the LCA (not outward as pictured).
12 Here we fully welded the...
12 Here we fully welded the outside of the relocation brackets to the rear axle. After cooling, the LCA was reinstalled into the bracket using the supplied 1/2-inch bolt (do not tighten until the other side is done). Once the same procedure was done to the other side, the bolts can be tightened and the sway bar installed. The GN seemed to have a firmer ride (not too harsh) with better road handling, and it didn't seem to squat during launch at the strip.
13a GN owner Tim Cairone...
13a GN owner Tim Cairone swaps to our trusty 26-inch slicks and a set of skinnies. We even pumped 'em up to 45-psi to lower rolling resistance. Usually lightweight front skinnies will lower the e.t. a tenth and add 1-mph to the trap speed.
13b After seeing how our...
13b After seeing how our UMI lift bars faired, we planned to swap over to a set of 27x10.5 ET Street DOT slicks in the hopes of getting every last ounce out of the chassis before the track closed for the winter.
14a Weather was a cool 47-degrees...
14a Weather was a cool 47-degrees on the final day of Atco's season. Even with an 8-psi boost launch, there wasn't a hint of tire spin enabling the Buick to run its best ever 1.55 sixty-foot and 11.41 at 117.94 mph (with only 18-psi full boost)!
14b Before installing the...
14b Before installing the lift bars we couldn't launch at more than 5-psi without tire spin. Check out the GM High-Tech YouTube page for video of the pass.
Since we had a set of 27x10.5-inch slicks lying around, we figured we'd give them a shot and see if we could hit a 1.50 short-time with a larger footprint. Unfortunately the taller tire appeared to kill some of the gear and slowed down the turbo spool-up, anchoring it to a 1.71 short-time and a best of 11.70 at 117mph. Perhaps a looser converter might have been a better match to the taller tire. We plan to make a few more changes over the winter and crank up the boost come spring time, so stay tuned.