Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!
This is going to serve as a “build thread” for my Bullitt Mustang. More than anything else, I am writing this to serve as a guide into what my experience has been repurposing and modifying a car, good and bad. Hopefully it’ll help others from not making similar mistakes.
Some things to note: I am writing this after having owned the car for 5 years. So, this will serve as a diary for a car (and a driver) that has transitioned from a slow, boring boulevard cruiser to a rig that is capable of some very decent lap times and great reliability on track.
I have decided to organize the build thread with new posts representing new stages/modifications/experiences. I am too lazy to include part numbers and specifics. With that being said, if YOU have specific questions/want part numbers, let me know and I will provide them.
The starting point:
A completely stock, newly re-powered 4.6L one owner car with 125k on the ODO.
How the car drove stock:
Extremely underdamped, horrid understeer. On stock 400tw Pirelli all season tires. I honestly hated the car at first, and I was coming from a 2001 bullitt. The car felt huge, heavy and had no bite behind whatever “sleeper” bark vibe ford was going for. Drove+autocrossed the car like this for 1.5yrs, car was used as a commuter for me as I studied engineering in college.
CHAPTER ONE: A mostly street driven car meets its new lifestyle.
First Round of modifications:
FRPP Rear Sway bar
I can tell you, 4 years later, that the above modifications represent the biggest “bang for the buck” modification that I have ever done to the car. I still remember the feeling of taking that first on ramp with the new suspension setup. Incredible.
Corbeau FX1 Pro Leather Seat w/Corbeau bracket and double locking sliders
Blowfish racing tow bracket
FR500 KR Mufflers
The above modifications really solidified the car, and I drove it in this configuration for about 2 years. The car performed well for my intentions: monthly autocross, weekly backroad togue runs. The bad was the corbeau seat. The seat itself I was very happy with (at the time), but the mounting bracket and sliders were a joke. I could move the seat around and hear the sliders clicking left/right. Another issue I encountered with the seat: During a hard on the brakes heel toe scenario, the flat bottom of the corbeau seat meant my butt would literally slide forward in the seat under braking because I didn’t have my foot against the dead pedal to brace myself. A really bad feeling to have. This failure led me to my next purchase, a schroth quikfit harness. With the harness on, the whole setup felt great. I would only use the harness for autocross and spirited driving, but I realize years later that I was very lucky and very stupid back then.
Chapter Three: My suspension geometry is wrong(??)
Maximum Motorsports rear lower control arm relocations brackets
Ford BOSS 302S rear lower control arms
Maximum motorsports non-adjustable panhard bar
The above 3 items made a somewhat noticeable difference to the car. Cost wasn’t that high, installation wasn’t difficult, however the difference in performance wasn’t that substantial either. The panhard bar made the biggest difference, while the rear lower control arm brackets made literally zero difference as far as I could tell. Weirdly, even with this setup the car still had wheel hop the couple times I took it to the drag strip. The best I could muster was a 13.50, I was pretty proud of this considering it was on my 6th ever pass at a drag strip.
Chapter Four: The vanilla pea-shooter turns into (a bit) of a fire-breather:
Fourth Round of modifications (more powaaaaa):
FRPP Intake Manifold
BBK Ceramic Shorties
Steeda Underdrive Pullies
FRPP 24# injectors (replaced as a maintenance item)
FRPP Throttle Body
GT500 Front Lower Control Arms
Brake Cooling Ducts
Motul RBF600 Fluid
This is where the car was about 1.5yrs from where I am today. This round of modifications made the biggest difference other than the original FRPP handling pack kit. I had grown SO tired of having an engine that died off in the last 800-1000rpm. Not anymore. The car made peak numbers of 313whp @6,000RPM and 308wtq @5,000RPM. Peak gains of 16whp compared to stock engine, TQ is the same. Lost 9wtq from 3,300-4,000RPM. Tq numbers below 3,300RPM are the same as the stock engine. Low RPM horsepower is the same. Basically lost out on 10tq in the mid-range. Gained an average of 36WTQ and 24WHP from 4,800RPM to 6,600RPM. The car has such long legs now and doesn't die off at high RPM like the stock engine did. The lack of slope on the TQ and HP curve above 5krpm is invaluable. It just doesn't stop pulling, but at the same time isn't "peaky" since the powerband is so wide....(from 4,500RPM all the way to 6,600RPM).
Throttle response was way up and overall feel of the car was so much more lively and motorsport-y thanks to the lightened components and deletion of the CMCV’s.
It was at this point that I did my first ever track day with the car. Enter auto club speedway, speed ventures ROVAL. Taking it very slow for the first 2 sessions, I started to gain confidence for my 3rd session. I had been running a data logger to check engine temperature, and noticed that my ECT’s got up to 225-228°F at one point or another. This was me driving at only 5-6/10th’s on a 90°F ambient temperature day.
To summarize the first track day:
300TW tires got greasy and useless by minute 15/16 of a 25 minute session, despite my mediocre pace.
The stock cooling system had nowhere near the capacity to handle the energy put out on a racetrack.
The stock coolant gauge is useless, reads the same whether you are 180°F or 230°F
Stock-like brake pads quickly turned to mush despite cooling ducts.
Track driving is really fun.
So, on nearly all fronts, I had a heat management issue. Cooling system, braking system, tires. I quickly realized that track driving puts components into temperature zones that they were not designed to work in. With that being said, the next steps for me would be addressing the 4 above deficiencies.
Even though this track day was over a year ago, I still remember every minute of it. This was a day that, as corny as it sounds, changed me forever. Coming from a pretty well-versed autocross background, the tight, technical nature of streets of willow immediately made me feel at home, yet the straight away’s gave me a chance to let the engine sing like it never had before. Not only that, but I distinctly remember the first time I really “nailed” a section of the track at a good pace. I yelled in excitement and couldn’t stop smiling. Another distinct memory from the day…I had almost no traffic while out on track. The feeling of having an open racetrack in front of you all to yourself….It was mesmerizing.
In hindsight, the car in this configuration absolutely was trackable for a mediocre driver. You could track this setup year round, but you would only be able to get 1-2 hot laps in if you were in anything above 75°F ambient temps. Brake fade at that time was non-existent, so I thought I had that part of the heat management equation figured out…..As you could guess, I was wrong. I did 4 track days and 3 autocross events with the car in this configuration. 3 of them at streets of willow, one at buttonwillow. My times on this setup were:
Streets of Willow: 1:30.1
Given the above times, I was still a new driver, but pushing enough to still highlight deficiencies in the car. So, I was able to focus in on what needed to be done next.
So to summarize:
NT01’s are badass, even in smaller than optimal size. SUCH a good learner tire.
Stock brakes with a high temp compound are feasible for someone who drives on track that is new/not that fast yet.
Oil pressure, oil temperature and water temperature autometer gauges
Hankook RS4 Tires
Track of the day: Streets of Willow
This was a huuuuuge step for the car. Or, at least I thought.
Oil cooler worked great. Oil temperature worries were (and have no longer been) a thing. Ever.
Having actual gauge readouts was invaluable.
Hankook RS4’s seem to grip just as well as NT01’s in everything except braking. RS4’s are more prone to getting greasy+sloppy than NT01.
My previous findings with the braking system being adequate were now rendered false. Car was plagued with inconsistent brakes as I became a better driver.
Engine coolant temperatures are still an issue. Bigger radiator+distilled water did not solve my cooling issues. I could feel the car heat soak and die off towards the end of sessions and as ECT temps rose.
I got a LOT of track time on this setup. I got 8 track days and 4 autocross events out of the RS4’s, G-loc pads and centric blank rotors. On this setup, my new top times were:
Streets Of willow: 1:29.3
Big Willow: 1:37.1
Laguna Seca: 1:47.0
Final notes on this setup:
In hindsight, this was an incredible setup to learn on. The lack of grip from the small 255’s meant that the car was playful, and great for teaching driving dynamics. The coolant system, although undersized, was usable even in hot summer months. Anyone who is interested in tracking their car, this is the bare minimum that you must modify IMO. You can be PLENTY fast on this setup, all while being reliable, having a low consumables cost and increased safety+reliability from using mostly OEM parts. I recommend anyone who is new to performance driving to KEEP their car setup like this for at least a season.
So, I had finally addressed all the previous issues I had. How did the car drive, now that my dream to join the “big leagues” had been realized and the modifications had been made?
Honestly, the car drove like crap. Despite dropping from a 2:05.1 to a 2:01.5 without even trying, I hated the way the car drove. Excessive body roll, ludicrous amounts of brake dive and a wandering front end under braking. The car had a shaking front end. The bucket seat that used to hold me in so well now all the sudden is useless, and despite my fitness regime and being young, doing a lap with this much grip made my entire upper body sore. I was all over the place and so distracted by how poor the car felt, I couldn’t get what felt like a “good lap” in.
Brake fade non-existent at current pace
Tire fade non-existent at current pace
Vented hood lowered IAT’s reduced heat soak.
Car is now underdamped
Horrid wandering felt in front end under hard braking
Big tires make me realize my steering rack is shot
Chapter Eight: Band aides can make all the difference
Post Track Day Modifications:
Falken RT660 315/30/18
Sparco Circuit Seat w/solid mount
-3.5 degrees camber, -.4 toe
Track of the day: Streets of Willow, CCW
At this point, the last 2 events I had been to with the car were honestly a let down. I was disappointed in how much less fun the car had become with the 18x11 wheels and tires. So, I gave myself a month to reset, rethink, and get some work done to the car. I got the sparco circuit bucket seat installed and was feeling great. Then, the Friday before the event, these beautiful sticky bois arrived. Enter the Falken RT660, in all of its 315mm of glory.
After getting these bad boys mounted, I was STOKED to be back at my home and at my OG track, Streets of Willow
All things considered; it was a phenomenal day. The car ran great, felt great, and I couldn’t have been happier. It was amazing how much more civilized the car was on these falken tires. Let this be a lesson to you all: don’t ever buy used performance tires.
So, the tires…..Well, good and bad news.
The Falken RT660:
A good tire, just not good for me.
Lets get down to it. I think there are 5 ways to measure the performance of an HPDE tire.
Ability to manage heat
Ability to sense when the tire will slide
Since I only have one event on the tires, I can only speak to the first 3.
Street manners for this tire were -phenomenal-. Like, seriously good. This tire rode as well as the 400tw all seasons that I had on my car when I first got it. The only bad thing was the noise. Definitely a noisy tire.
At the track:
This is a FAST tire. I can also tell you, with confidence, this is an AUTOCROSS tire. Some huge pros and cons here.
Great overall grip when cold
Good steering feel and response. Not as good as RE71r though
Good grip when warm
Very talkative, easy to feel. I knew exactly when the tire was going to let go. It gave nice audible warnings. Much, much more talkative than AO52’s.
Fairly inexpensive. 315/30/18 was almost exactly $1500 shipped to my door.
Horrific tendency to overheat. Like, seriously. I have -never- had a tire overheat this badly for me. I tried 3 different HOT psi’s…32psi, 34psi, 36psi. After 3 warmup laps and then 2 hard, 10/10th’s laps, the tires were DONE. I am somewhat used to this, being that I drive a heavy car. What I wasn’t used to was the fact that a cooldown lap, no, even TWO cooldown laps, would not get these tires back into their ideal temperature range. Between traffic, managing temperatures and me screwing up corners, it was impossible to get a perfect lap with these tires. And so, that why I ended up with a 1:26.1, rather than the 1:25 time that I was shooting for.
I can tell you with -absolute- certainty that these tires will not last a 20 minute HPDE session with our cars.