'We're stoked! And at the same time, we're still driving a 14-secondwhite '91 Firebird. Though you voted on CarCraft.com that a guy coulddrive it without looking like a Nancy, and a girl could drive it andprobably look hot, we'll still feel geeky until we can produce a12-second timeslip.
So were on it. Using basic cooling and tuning steps, and opening up theintake and exhaust, we drove the 'Bird to a corrected 14.19 at 95.94mph. Considering that the '88 Firebird that we built in 2001 ran 14.40on nitrous, we'd say we're ahead of the game.
But there's more. When we bought this thing about two months ago, wewere hoping for easy speed for low dough. But the car barfed everycritical TPI-specific part that controls idle and driveability then gothot in traffic and stalled (see it on CarCraft.com). So we're behind alittle in money spent but way ahead in speed. Our plan is to prove thatyou can go 13s in one of these cars without cracking the seal on theengine or opening up a bottle. Then later we will spray our way into the12s.
Fuel System: Critical Stuff
What we didn't mention in the first story is that we solved a lot ofproblems by replacing the injectors and fuel pump. These parts areactually a lot more affordable from MSD and Holley now that the car isnearly 15 years old. The MSD injectors are 22 lb/hr and are listed asfactory replacements. The Holley in-tank fuel pump will flow up to 255lph at up to 110 psi fuel pressure. Good if you are going to spray itlike we are. Just look at it like adding a new carb and electric fuelpump on an old musclecar.
First Run: 15.00 @ 91.23
We could call this a baseline, but really the car wouldn't always startor run when we got it, so the baseline would have us burning to theground at the top end of the racetrack after a 20-second run. Instead,by the first run we'd already performed a basic tune-up, replaced mostof the fuel system and computer, and modified the cooling system with acooler thermostat and electric-fan switch. You can expect a healthy carto run 15s at high altitude or mid 14s at sea level. On street radialswe ran an observed 15.00 at 91.23 mph, or 14.519 at 94.30 using thestandard NHRA correction for Los Angeles County Raceway.
Intake: Easy Power
There's an ugly restriction in the intake tract on '89-and-later SpeedDensity cars and it's worse for earlier MAF-tube sufferers. The firstreal performance piece we added was a cold-air induction system from SLPPerformance Parts. It eliminates the stock air box and allows cold airto be picked up from the factory hole in the firewall. Installation isstraightforward and the kit includes parts to relocate the charcoalcanister to the driver side of the engine compartment by the battery.
The new SLP system is actually slightly cleaner than the stock dual-catsetup.
Aftermarket intake runners are the soup du jour for TPI guys, and SLPmakes a set that are actually easier to install than the stock piecesbecause of the thicker mounting flanges. These things are worked to makepower by enlarging the intake tubes and removing the first inch or so ofmaterial between the runners where they mate with the plenum,essentially extending the plenum area. More plenum, more torque. Thenext trick is to cut the plenum divider and the gasket to match, but wedecided to keep the first set of mods strictly bolt-on.
Exhaust: No Parts Runs!
If you are going to do one thing to your TPI car it should be installinga good set of headers. We've seen 0.60-second gains at the track on a305 five-speed Z28, and when you see the stock stuff, you'll know why.The cast-iron manifold feeds all the exhaust ports into one centralizedtube that takes a 45-degree turn into a small collector. It's like GMhated it. The new SLP tubes slide in from the top pretty easily afteryou pull all the emissions stuff out of the way. We switched thespark-plug wires to 90-degree-boot style with a generic Summit set andbolted them up. The collectors use a doughnut combined with a variationof the ball-flange design that matches the stock stuff. The sting is the$654.95, but they're already thermo-coated and with a monster-thickprimary flange and the trick collector they're not gonna leak.
Both tips exit on the driver side. Here we dropped one tailpipe anddented it so it wouldn't fit. We threw it in the trunk for the mufflerguy to fix.
Beyond that, it's worth the $89 to get the SLP header-installation kitthat converts the dual-cat system found on '89-'92 cars into a bigsingle. It makes it so you don't have to go to the parts store, not evenonce. The two-into-one pipe from the headers joins a 3-inch elbow thatconnects to the cat. We used a Random Technologies 3-inch catalyticconverter that bolted directly to the after-cat via another ball flangebut required a weld where the SLP elbow met the Random inlet. Since wealso needed to weld up the A.I.R. tube and seal the unused bung on thecat (it's universal), we took the Pontiac to Speedway Muffler in Gardenawhere Wayne zipped it all up for $35.
The after-cat needs no explanation other than it bolted directly to thefactory mounts, has both tips exit on the driver side, and sounds mellowlike a refined version of the old Turbo IIs you liked in high school. Atfull-throttle there is no harsh glasspack rattle.
Second Run: 14.66 at 92.82
We were hoping for 0.50 off the first run because that's what a goodexhaust system will bag you on these cars. We missed it by a bit andhere's why: In the past, we've used a system that basically equates to astraight shot from the back of the cat to a tail pipe using what isreferred to as "adjustable" exhaust. It's loud. Also, as we mentionedbefore, the intake runners will benefit from the plenum porting. Thosetwo restrictions likely cost us a tenth or two. We ran 14.75 at 92.01mph with crazy wheelspin, then bolted on a set of 26x11.50-16 ET Streetson '91 Z28 wheels, set the timing to 15 degrees, and found a 14.66 at92.82 in it that corrects to 14.19 at 95.94.
So we're zoomin', and tenths away from a 13-second pass with only acouple of bolt-ons. The other news is that we're bummed that we alreadyspent about $2,500 to get the thing to run right, but that will changewhen we add a few more parts that will take advantage of the intake andexhaust mods and go fast. Love it? Tell us on CarCraft.com.
The Cost of Cool
