🔧 BUILD Quest for improved 4th gen Fbody drivability

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I wanted to update this thread (June 2023) with a more detailed summary of the 14-year journey with my 1998 Trans Am. In my day job, I'm an automotive journalist, so I drive a lot of performance cars, and every winter when the TA is under the cover I’m tempted to buy something new after driving the latest and greatest all year, but then every spring I get back behind the wheel and regain enthusiasm to keep at it. My goal over the last couple of years was to give it as much updating as possible to build a well-rounded late-model muscle car that blurs the line between muscle car and sports car, just how the new Camaro and Mustang have evolved over the years. And to get there, I had to correct a lot of self-inflicted mistakes that ruined the car’s drivability without much gain. This is quite the write-up for an only mildly interesting car, but verboseness comes with the territory, so here we go:

I bought the car from my cousin’s husband in 2009 for $4,000 with 100,000 miles. Their priorities shifted and the car was in need a lot of maintenance; it ran poorly, had dry-rotted tires and was in barn storage so it came with a family of mice for no extra charge.

What I bought was a stock 98 Trans Am with 16-inch wheels, sleek beak hood and SLP loudmouth exhaust. I immediately added drag radials, addressed the maintenance items and went to the drag strip, hoping for high 12s, low 13s because that was my expectation after being on LS1Tech for 5 minutes. HA. Well, the fastest F-Bodies run those times in later build years with 3.23/3.42 gears, LS6 intakes and factory production tweaks to the cam/heads. In stock configuration with loudmouth exhaust, my 98 with 2.73 gears, LS1 intake and 853 heads ran anywhere between 13.6 and 14.0 seconds, which was slower than my (at-the-time) daily driver mildly modded Grand Prix GTP.

From there, I added a Yank SS3600 torque converter and rear tubular lower control arms, which knocked 8/10ths of a second off the quarter-mile time to run consistent 12.8s; sub-frame connectors also went on at this time and really helped clean up the rattles and looseness of how the car flexed over bumps.

And then I ruined the car for a few years with poor choices.

I put a lot of trust into a performance shop that picked an inappropriate cam and didn’t put the effort into tuning. The car wouldn’t start when hot, it inconsistently idled and the torque converter tuning would make the car lug and vibrate. It was really a couple of miserable years with a loud, annoying and slow car. The cam was 231/235 .617/.621 113+3 with stock heads and a really mismatched powerband for an auto car with 2.73 gears. The car also had an LS6 intake, 42-pound injectors, 1 3/4 headers, off-road Y-pipe and Magnaflow exhaust. From there, I found a new tuner who fixed all the drivability issues so it drove much nicer, and then added 3.73 gears.

I had it dyno’d a few times in this configuration. The initial shop’s dyno spit out 401 rwhp. On a Dynojet at Dean's Performance with the revised tune, numbers were 370/345 in third gear with the converter unlocked. And then I had it dyno tuned from Speed Inc where it made 380 rwhp and 355 rwtq on their Dynojet. But it I was still disappointed at the track, running a best 12.0 at 113 mph. Looking back, that initial shop’s first dyno was laughable considering the trap speed and how poorly the car drove.

During this time, I also played a lot with the exhaust, finally settling on a Kooks catted Y with true merge, versus the ugly T-merges from previous designs that created that awful hammering sound at part-throttle.

And then I decided to take a big swing at the car. Up to this point, I had been running QA1 shocks at the back with drag radials, while up front was stock shocks/springs and summer tires. I hated how the car drove with a clear imbalance between the front end’s tightness and rear end’s looseness. I also had a drag-oriented short torque arm. So off all that went and in come the final suspension setup: Koni shocks, Strano springs, Strano sway bars, UMI long torque arm, double-adjustable lower control arms, adjustable panhard bar and a few other things. Holy smokes. Besides the converter, it was probably one of the biggest changes to how the car drives. Tight, controlled, responsive. It was like driving a car 20 years newer, instead of a bucket of bolts like how it drove with the old suspension.

Under the hood, I had Pat G from LS1Tech spec out a combo that would give stock-like drivability but with 11-second potential. It consisted of a pair of 799 heads (Z06-equivalent) pulled from a junkyard, which I had cleaned up and checked out, and an EPS cam with the following specs: 222/226 .626”/.626” 115 LSA +3, as well as a refresh of the valve train with trunion upgrade on stock rockers instead of something fancy the other shop installed. With this milder cam and upgraded heads with more compression, the car saw a giant torque increase under the curve, and power was much more usable and better matched to the auto trans. Now, I was making 390/375 to the wheels on Speed Inc’s dyno, but with a lot more power and torque under the curve and stock-like drivability.

That resulted in 11.82 @ 115 mph, and it has trapped as high as 117 mph. I consider this very impressive because it drives like it did when stock and power is accessible all over the place. Since then, I’ve installed a chrs1313 A/C ram air and have a dedicated set of C5 17-inch wheels with Hoosier drag radials to try and hit 11.50s, but my last time to the track with the setup was a bust because (as I discovered afterward) the throttle blade wasn’t going WOT thanks to the throttle cable adjustment being unclipped.

I still enjoy driving the car. I debate what to do with it (sell or keep) because I also feel a sense of stewardship to keep this car on the road looking and driving as good as I can make it. All the kids in the neighborhood turn around and give it a thumbs up when I drive past, and my kids (2 and 5 years old) call it “Dad’s Trans Am.” They pretend work on their cozy coupe (like dad’s car). I know it’s superficial, but I don’t think I’d get that kind of engagement in a CTS-V or newer car. Or maybe I would, because they could actually ride in a car that properly fit child safety seats … the debate continues.

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Bru

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Doing work with the Mother’s PowerBalls, Mother’s Mag & Aluminum polish, Adam’s tire shine. I stripped the wheels way back when, sanded them and then polished, but always forget how good it looks after fresh balls of power. I tried this spray-on clear one time but couldn’t get the hang of it, so just use a thick paint wax on the bare wheels. It likely burns off after a couple drives, but it helps for a little bit.

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Bru

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I replaced the evap solenoid a couple years ago but it might be time to replace the canister. I still have some issues with gas coming out of the neck vent tube when full and driving spiritedly around corners, so that was one thing I wanted to do next. I thought that was my diagnosis when I poked around before, but I don’t recall.
 

Bru

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2021 plans include 11.50s with the same baby cam (PB is 11.82) so here’s the start:

Chrs1313 ram air. It’s the AC version so I don’t expect the full gains of the non-AC version but it will help. The SLP lid never sealed that well so I’ll get er sealed up and slap this bad boy in.

Got a Mighty Mouse catch can on the way too. I noticed oil dripping out of my bandaged PCV system.

Then hero pass weight-reduction and a sticky tire to get into the 1.5s 60-foot (PB 1.61).

Unrelated, but I also want to even the ride height. There might be some sway bar preload happening but my ride height is a bit wonky (pass front is low while the rest are the same). Shocks could be installed weird too so will check that out.

Unladen:

Front driver: 26.5 — Front pass: 25 3/4
Rear driver: 26.5 — Rear pass: 26 3/4

Ram air, which will jut out below the air dam (the pictured top side will, the silver side is the air box side)

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Bru

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Resembles the Fast Toys ram air.
The Super sucker Ram air on Barney is ABS plastic and has a lower scoop section.

What tires are you thinking about ? 17" ?

I could be swayed one way or the other, but here are options I’m considering. Either will be mounted on a set of extra rims. Mickey ET Street R or Hoosier DR2.

C5 wagon wheel 17x8.5: My dad has a 99 C5 with the painted wagon wheels. He upgraded to chrome 2000 wheels and offered the 17s to me. The painted 17-inch wagon wheels are very lightweight. They’re a a half inch narrower, and aren’t polished, so they’re lighter than my 17s. 275/40/17 - A little wider than what came on them and probably what should be ran on an 8.5 inch rim. I see little potential for problems though.

16-inch stocker: 16x8. Narrower than the 17s but more sidewall. 255/50/16. Lighter still than my 17s and wagons. I might be leaning somewhat this way because I changed the shocks from Bilstiens to Konis since the last time. And while these are adjustable shocks, they’re only adjustable in rebound and not compression, so while I could get more travel out of the front by loosening them up there’s no adjustability in the back that would help. So I’m thinking the extra sidewall would give me a little more give.

That’s where I’m at.
 

Bru

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Two updates: catch can arrived, Mighty Mouse Mild unit.

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And I picked up my pop’s 17-inch wagon wheels for the rear to be mounted with a drag radial. I think I settled on the Hoosier DR2 because of availability, and lightness.

One wagon wheel weighed 19.5 pounds, which with a 22-pound Hoosier DR is 41.5 pounds. That’s down 11 pounds per wheel compared with the 01-02 WS6 wheels with Nitto 555R’s I previously ran.
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Gav'sPurpleZ

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A couple notes for the Can install:
1. the fittings only need to be "snug" not tightened with the hand of God ( add tape to a crescent wrench to prevent scratches )
2. My neighbor and I installed the can in the mount only to remove it in order to install the hose on the fittings. it was a bitch so having a 2nd person did help. There are no zip ties or clamps, this would be why the fitment is super tight.
3. Be sure to hear the click / snap when installing the breather/filter on the top.

(y)
 
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