1987 Buick Grand National Fuel System & Exhaust Upgrades - Turbo Buick Basics

Part 2: Upgrading The '87 Grand National's Fuel System And Exhaust

Dan Foley Sep 1, 2009 0 Comment(s)
0909gmhtp_01_z 1987_buick_grand_national_fuel_system_exhaust_upgrades Performance_fuel_injectors 2/25

Once the boost (stock 13 psi) is cranked up on a Turbo Buick, bigger injectors are needed to prevent a lean condition. We stepped up to Racetronix 42-pound, flow-matched injectors (PN 01D030X). The stock 28-pound injectors were tired and couldn't handle the additional juice flowing from the new Walbro 340 fuel pump and "Hotwire" harness (also from Racetronix) we installed in Part 1. Since we're messing with a 20-something-year-old motor, we upgraded to the Racetronix Injector Harness (PN RX-G77-INJ-A) to replace the baked old wires and connectors.

In the last installment our willing friend, Tim Cairone, let us take his bone stock '87 Buick Grand National in a time warp back to the 80's.

By using today's technology and help from seasoned Turbo Buick experts, we'll be able to show owners of stock TRs (Turbo Regals) how to safely increase the power and driveability. For the recap, after establishing a bone-stock baseline (dyno and track testing), we tried a custom chip from Cotton's Performance for 17 psi boost and 93-octane on Tune Time Performance's dyno. The chip did its job and increased the boost from the stock 13 psi to 17 psi. Power rose from 256 to 320 lb-ft of torque and 208 to 210 rwhp (gains of 64 lb-ft and 2 hp). While dyno testing we learned of an inherent lean condition common to the Turbo Buick when cranking up the boost. We didn't want to waste the head gaskets, like many of the TBs back in the day, so we attempted to cure our lean condition with a new Walbro 340 (PN RX-G77-FPA) fuel pump and fuel pump "Hotwire" kit (PN G7-FPWHG) from Racetronix.

After speaking with nearby TB experts Jose Torres and Dan Smith (Jose Motor Sports), we replaced the stock valvesprings with mid-90's LT1 springs, at their suggestion. This taught us the first must-do's for a TB-beef up the fuel system and get rid of those wimpy valvesprings before turning up the boost. After installation we were back at Tune Time testing the new fuel system and valvesprings. This test showed us gains of 28 rwhp and 38 lb-ft of torque. We were stoked about the power gained, but disappointed to find out we still had a lean A/F (air/fuel) ratio. Tune Time's Matt Hauffe suggested the original 106,000-mile, 28-pound injectors we not up to the task. So we ordered a set of flow-matched 42-pound injectors from Racetronix. This is where we left off in Part 1, with our total power gains of 102 lb-ft of torque and 31 hp (from bone stock).

We intended to strip test from the stock baseline of 14.25 at 94.53 mph to see the ET improvement from changing the chip, fuel pump, "Hotwire" fuel pump harness, and valvesprings. However, Mother Nature wasn't having it. So we moved up to the 42-pound injectors. Right after installing the larger injectors the 3.8 Turbo was running pig rich with black smoke belching out of the tailpipes. We tried leaning out the programmable fuel parameters (a feature of the latest chip technology), but it still ran too rich. After speaking with Jack Cotton of Cotton's Performance we learned you must replace the chip with one designed for the appropriate sized injectors and injector pulse width. So our friends at Cotton's Performance burned us a new chip for the new 42-pound injectors.

The TR seemed to be running smoother and more responsive with the new chip and larger injectors. We noticed the V-6 was now seeing 19 psi of max boost (we'll need to install an adjustable boost controller soon). To play it safe we added 5 gallons of 110-octane race fuel before filling it with 93-octane pump gas. With that we made another dyno date at Tune Time just to be sure the A/F was safe enough to finally strip test. On the ride up to Toms River (30 minutes from home) Tim remarked how much stronger his car felt with the new chip and injectors. What he felt turned out to be a big torque gain. The dyno showed us an increase of 2 hp along with 47 lb-ft of torque! The A/F was slightly lean at 12.1 to 12.2. We left the A/F alone since we had the protection of the race fuel.




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