🔧 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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Lead Pipe

Faceman
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Nov 4, 2010
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I really like the sound of the slp dual dual muffler with headers and no cats. I went through 2 mufflers before I got this one.

I picked up this system and have to get it installed. I'm going to have a cut out welded in too. I have the borla mouth and absolutely hate it. It was worse with the stock stall but still is absurdly loud.

I miss the days of my stock like idle GT-11, stock mufflers and 124 mph traps....
 

Camarokid327

Fear of speed bumps but slowly getting over them.
Jul 24, 2013
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Car looks good and sounds great man! Those are some good numbers for a mild cam, untouched 799 heads, and stalled auto. :bigthumb:

stock exhaust & cutouts ftmfw

x2

I started off with the the good o'l Loudmouth 2 set up when I was only bolt ons, and that was tolerable but as soon as the cam went in I hated it. So I went back to the stock muffler and added a 3" e-cutout. Best of both worlds in my opinion. Plus the neighbor probably appreciated it too haha
 

Typhoon

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Sep 25, 2011
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I'm teased every time I get in a new muscle car like the Mustang, Challenger or Camaro, wanting that kind of drivability with the same power. It's crazy to think that a bone stock car with kitty cat drivability can easily put down high 300s in the poverty V8 version, which is something I wanted to mimic in my rattle trap mullet-mobile.

Not sure what your budget it is but down the road, do something like Syp did with a LSA blower except use a stock LSA or LS9 cam. More power than you have now and stock drivability. Factory is hard to beat for street manners.
 

wolfe

in black sheep's clothing
Jun 2, 2008
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I really like what you are doing and have just told myself a week or so ago that I'm gonna do the same in my Camaro. I'm gonna keep the MS4 cam that I have, even though it's a little on the large side, it drives great. Speed Inc really did a great job with the tune. I do however want to change my exhaust set up. With long tubes and a true 3" dual it's just too fucking loud to try to sneak out of the neighborhood early in the morning. I see something with quieter mufflers and a cut out in my future, some more suspension work, and possibly a brake upgrade.
 

Typhoon

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Sep 25, 2011
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Would that work with cathedral port heads? Not sure how much of the cowl would have to be cut either, but I like the idea considering all of the LSA blowers that are available, and their cost.

Would have to switch to LS3 heads. I dont have any experience with the LSA blower. But if clearance was an issue you could run the LS9 set up which is shorter and Ive actually seen in a 4th gen fbody. Unfortunately its no where near as budget friendly.
 
I picked up this system and have to get it installed. I'm going to have a cut out welded in too. I have the borla mouth and absolutely hate it. It was worse with the stock stall but still is absurdly loud.

I miss the days of my stock like idle GT-11, stock mufflers and 124 mph traps....

How many miles a year do you put on your bird?
 
Not much. Maybe 2000-2500. This year I probably wouldn't have broke 1000 if I didn't go to Madison for power tour.

I put roughly 3000 miles on my Camaro a year and I thought that's like weekend status and those sound rules don't apply to vehicles on that status. That is the reason I was asking. Then again I haven't done a heads/cam yet for the full on noise.
 

Lead Pipe

Faceman
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Nov 4, 2010
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I put roughly 3000 miles on my Camaro a year and I thought that's like weekend status and those sound rules don't apply to vehicles on that status. That is the reason I was asking. Then again I haven't done a heads/cam yet for the full on noise.

I have never been a fan of loud cars. I had a powerflo set up on my camaro and swapped out the corsa that came on my vette for stock mufflers when I put a cam in it. My car isn't cammed yet, it's just obnoxious.
 
I have never been a fan of loud cars. I had a powerflo set up on my camaro and swapped out the corsa that came on my vette for stock mufflers when I put a cam in it. My car isn't cammed yet, it's just obnoxious.

I understand. I want the best of both worlds with a cutout and a better muffler than my SLP2 but I'm trying to decide on how much more money I am willing to throw into my exhaust as it's too fresh to get refreshed. Would be nice if my I wasn't 4spd auto. :(
 

Bru

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My car has never been that fast, and definitely not fast enough to make dealing with a lumpy cam, loud exhaust and noisy drivetrain worth it, so this year I took transforming the car into a more street-able configuration.

Previous setup was this cam, 231/235 .617/.621 113+3, and stock heads with LS6 intake. Car ran 12.0 at 113 mph and made 380 rwhp and 355 rwtq. It did alright - cam with stock lifters and Yella Terra rockers was noisy and the problematic 98 PCM never seemed to drive as smoothly as I hoped; it needed more tuning than a quick dyno tune could cure. Here's what the old cam sounded like:

http://www.youtube.com/watch?v=wMohYGtwYcw

Now, I'm running a "sleeper" cam, not for any deceiving qualities but just to make as much, or more, power as before but with a smoother driving experience more like stock. Pat G from LS1Tech spec'd a cam for what I was looking for and spit out 222/226 .626”/.626” 115 LSA +3.

I had Speed Inc throw in the cam and a set of stock cleaned-up 799 heads (243 equivalent) as well as trunion upgraded rockers and LS7 lifters.

Dyno results with the new setup was 389 hp and 373 tq with a massively improved drivability. The car purrs at idle and doesn't shake back and forth, plus there are fewer vibrations and overall is just a whole lot nicer to drive. Also been getting much better fuel economy than before.

Joe%20Bruzek-%20Trans%20Am_zpstbbw1yjc.jpg


Track results: 11.829 @ 115.44 mph.


5d33dab1a7737af03042256f219ff895.jpg


Track results are in. I posted in the other thread but will update here. Ran well for a baby cam and I think there's more in it. One run had a 116.5 mph trap but the Nitto 555Rs couldn't handle everything it had out of the hole. Still impressed that the tires, for their poor reputation, had a 1.61 60' in it with lowered suspension and stock-style shocks. Previous best on the old cam and stock heads was 12.00 at 113 mph. With a better tire and a chrs1313 ram air I think the car could be closer to mid 11s.

5d33dab1a7737af03042256f219ff895.jpg



http://www.youtube.com/watch?v=I3VCC4k_k58
 

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