If you've been following Blue Thunder, GMHTP's Third-Gen. Firebird Formula, you know that I've been looking to improve performance, but on a budget. While I have made a few exceptions as in the case of the SLP Firehawk wheels, I have kept to the low-buck theme for the most part.
Since the dawn of computer-controlled vehicles, and more specifically the late model musclecars, the computer chip has often been considered the first performance modification, with an aftermarket exhaust system coming in a very close second place. The computer chip is a relatively inexpensive affair along with being an easy part to install. This makes it great for all performance enthusiasts from novices to experts.
As the project's budget dwindles, Blue Thunder is left with just a few performance options, and I thought that a computer PROM chip should be one of them. With that in mind, I called up Fastchip in Tulsa, Oklahoma and spoke to proprietor Ed Wright about BT and what he could do for it.
Fastchip sells a Stage 2 computer chip for TPI cars for $159. While Fastchip doesn't make any performance claims, they do say that they have the fastest chips. The price was right too.
I simply told them that we needed a chip for a 1989 Firebird Formula TPI with the 305/5-speed combination. With the chip in hand, BT headed to Danny's Pro Performance in Keyport, New Jersey to give its brand new Dynojet dynamometer a good workout. Danny's is a full service auto repair shop that also performs performance modifications, and with the dynamometer, advanced tuning can be had along with horsepower and torque numbers.
Blue Thunder's baseline run was made with the initial timing at 6 degrees, and fuel pressure at 42 pounds with the vacuum line off. The numbers came up as 204 horsepower and 267 lb.-ft. of torque at the wheels. This was quite a bit off from the 237 horsepower and 305 lb.-ft. of torque we saw on the SLP SuperFlow dyno, but the initial timing was at 8 degrees then. This is not to say that there is 30+ horsepower in those two degrees, I would be more inclined to think that the difference was in the two dynos, or Blue Thunder losing power in some way. I'll have to get back to SLP to know for sure, but I now had a baseline from which to compare the chip to.
Dan Ryder of Danny's Pro Performance performed the chip swap, which begins with removing the car's computer that is located on the passenger's side under the dash. A few screws released the lower panel and then the computer itself. Danny disconnected the harness, and then opened the access cover to exchange the chips. It's a fairly simple process that took all of about five minutes to complete.
Blue Thunder was never able to make a full pass, as the air/fuel ratio went lean. We increased fuel pressure in five-pound increments until we were at 70psi. The car wouldn't run very good at part throttle, but we did manage to get the air/fuel ratio to a somewhat safe range, but the Bird didn't like that kind of fuel pressure. I called up Ed Wright and he told us that this was the first time anyone had actually called for a chip with the 305/5-speed combination on a mass air-equipped F-body, so he offered to send us another one to try. He also requested the air/fuel numbers from the dyno pull which we faxed over to him.
Ed Sent two chips back and asked us to try them both. We ran the first chip and the air/fuel ratio was much better--and so was the power. Horsepower had jumped to 215.9 and torque came in at 275 lb.-ft. The next chip we tried brought us the exact same results, until we bumped the fuel pressure to 44psi, which netted 218 horsepower and 278 lb.-ft. of torque. An hour-long cooldown had us up to 220, but the 218 number was a more real result of what one could expect, as it was achieved at an operating temperature of 160 degrees.
We then hooked up a Snap-On scanner to monitor the engine during the last few dyno pulls. To our surprise, the computer was taking out up to 10 degrees of timing as it evidently was hearing knock. I called up Ed and he didn't think that there was enough timing in the car to cause that, but he said he would send another chip with a less aggressive spark advance.
Despite the evident knock retard, Blue Thunder still picked up 14 horsepower and 9 lb.-ft. of torque at the wheels. There was also a very noticeable seat-of-the-pants improvement in throttle response and power. Blue Thunder felt very snappy but at the track, BT did not see an improvement in elapsed time.
It was, however, solidly back in the 14.20s. Our first pass netted a 14.22 at 96.84 and our second was a 14.25 at 97.03. Sixty-foot times were 2.12 and 2.14 respectively, and there may have been a run in the teens if I hadn't missed fourth gear on my first attempt, which had a 2.11 short time.
A few days later, I received another PROM chip and it was back to Danny's Pro Performance for another dyno session. This time I had the scanner on every pass to check for knock retard, and there it was once again. We noticed that Blue Thunder's fuel pressure had somehow moved up to 47psi since the last dyno session.
Power output was steady at 215 on the first run, but we noticed that the computer was still in open loop mode, so we waited until it was closed for two more runs, which resulted in 218.6 and 218.8 horsepower. Closed loop seemed to be the way to go, and the car only needed to be at 160 degrees to accomplish that.
After conversing with Ed Wright again, he mentioned that excessive carbon build up can increase compression and cause spark knock, so Ryder hooked up Blue Thunder to the MotorVac system. This unit cleans the injectors, valves and combustion chambers and actually improved power a bit too. We saw a gain of 1 horsepower and 1 lb.-ft. of torque, but more impressive was the fact that we saw a gain of up to 5 horsepower in the low to mid ranges. Knock retard was still evident on our next dyno pulls, but was limited to 7 degrees rather than the 10 we had been seeing.
The first run after the MotorVac netted 219.8 horsepower. This was with the 47psi of fuel pressure. We backed the pressure down to 43 for the next run and power fell slightly to 219.0. Ryder set the pressure to 46psi, which produced 221.3 and we backed that up with another run at 221.0. This was still with nearly 7 degrees of knock retard.
We were running out of time and I still wanted to make a few more passes at the track to try and make good on the extra power from the Fastchip PROM, so I bolted over to Englishtown where our sister publication, High Performance Pontiac, was holding a shootout.
On my first hit, I saw the number one light up after the four as I sped through the traps and I knew it was a good run. A 14.18 was the result, and mph had jumped to 97.22. My short time was 2.14 seconds. The Raceway Park staff had done an excellent job of prepping the track so I launched harder this time, and covered the first 60 feet in 2.06 seconds. The quarter flashed by in 14.10. The very next run, I nailed the same short time, but somewhere between the shifts, I picked up and crossed the stripe in 14.00 seconds. Various curse words and expletives vaulted from my mouth even though one would have thought that an improvement was good. I wanted the 13-second ET though. I pulled the air filter in desperation, but could not make any headway on the 14-flat pass.
One of HPP's entrants was an LS1 car owned by Roy and Stacey Fender, who happen to own F-body Motorsports in Huntersville, North Carolina. They were watching my progress and offered to let me use their Mickey Thompson ET Streets. It was five minutes to five o'clock and our track rentals are usually over at five, but Mike Thomas of our ambulance crew told us to do what we had to do. Stacey's brother Dale Hawkins and I swapped the wheels and tires and made way to the 1320. I knew Blue Thunder would benefit from the weight reduction, and maybe I could whittle down the 60-foot time with the sticky tires.
BT's limited slip unit aboard the ailing Australian 9-bolt axle cried uncle, even sitting in a puddle of water. I was finally able to clean off the water by riding out of the burnout rather than powerbraking, and pulled to the line. I let the clutch out at 3500rpm. The car bogged and then the clutch slipped and slowly applied power to the asphalt. The clutch slipped slightly at the 1-2 and 2-3 shifts, but I saw 13-something flash up on the board. On the return road, I rubber necked to see a 13.98. I was fairly happy with that result, but knew there was more in the launch, and the Centerforce clutch in the Bird definitely does not like heat. Despite the slippage, my 60-foot time was 2.03 seconds and much better than I had been able to achieve on street tires.
On the next run, I gave the ET Streets a quick rollover and then staged. This time the launch was harder and there was hardly any clutch slippage. The 60-foot came in 2.01 seconds, and I crossed the stripe at 13.89 at 98.03.
Did I cheat to get the number? Who cares! I have two 13-second passes and that's good enough for me. I've said in the past that Blue Thunder had the mph to run in the 13s, but the clutch has a weird engagement that does not allow a really aggressive launch, short of sidestepping the left pedal, and this has prevented me from really hammering the first 60 feet of track.
Each performance modification I have made has produced some sort of power gain, and usually decreased ET. Blue Thunder has gone from 191 horsepower to 221, and shortened its time on the 1320 from a 14.90 to a 13.89. That's pretty good progress, but now that I've got Blue Thunder in the 13s with just bolt-ons, it's time for some big fun as there is a set of heads and a custom camshaft waiting to go in next. If I get a little crazy, there may be a bottle of laughing gas in the future too. Stay tuned.