Mach 1 as a dual purpose street-track car (DE)

[shogun32]

would like to point out these AJ Hartmann brake deflectors.

seems tiny compared to say @GTP mandrel bent items.

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[GTP]

seems tiny compared to say @GTP mandrel bent items.

Thanks @shogun32 .
My current version is now about 10% more area than the name brand. And better rim clearance too.

 

[VictorH]

First long road trip with real street tires. Now 880 miles into what will be a bit over 2,000 mile round trip. Running Michelin PS4S in stock sizes and I have to say, they are excellent. Probably not the "best" street tire but really good on the freeway. No tramlining, pretty good in light rain and overall track really nice and straight. Cup2 are a huge compromise in comparison.
I'm sure you guys with automatics are getting better freeway MPG but with manual trans running 2200-2400 rpm in 6th gear I'm getting real 21 -22.0 MPG, measured by gas pump-to-pump. The trip computer reads 2 MPG high. I can live with that.
The other thing, though I'm on stiffer springs, the car is such a good freeway cruiser. Comfortable, quiet, smooth enough, but can be a bit rough on multiple expansion joints or bad asphalt.

Will be meeting up with DerKlink to run Ozarks International Raceway tomorrow. Really looking forward to it. Will post up some pictures of that soon after.
Road, gas station, rest area and various stops. Great trip car.

 

[VictorH]

Great day at Ozarks track. Met up with DerKlink (Marc) with his '21 Mach 1. Weather was mostly good except for a late afternoon shower.
For those who have never been the Ozarks track is really nice, super scenic, great layout and very technical. If you don't like blind corners this track is NOT for you. However once you learn the lay-out it has a great rhythm and flow. Some really fast sections, a few slow corners and lots of elevation change (big time). Full street set up alignment wise seems to be just fine there. Not really that hard on brakes and not too hard on tires either (but of course very driver dependent).

 

[VictorH]

Thoughts on the S550 platform for track use. More and more convinced that the S550 is one of the more forgiving and easy to drive platforms for track use. The Ozarks track has some really tricky spots, particularly turn 1 which is a left-hand, down-hill (looks like 7-8% grade) and off-camber. More than a few times entered , turn 1, just a bit too hot and had a longer than desirable 4-wheel drift going mid-corner to "exit" however, car kept it's alignment with direction of travel, didn't really need any "fixes" just patience and a few small steering corrections.
Other part of the track the car is undulating across elevation changes at angles sometimes with bumps, but the car kept its composure and never got really out of shape. The suspension is really working to keep everything planted and stable.

I'm still really impressed how good the rear-end traction is. You have to really have to do something silly to get the rear-end loose, not saying it can't be done but it takes some work doing things you probably shouldn't be doing. Despite that, the car will really nicely trail-brake into the sharp corners and rotate around.

Spoke to a guy and rode a session with him, who had track pack GT500. Man those cars gain speed at an incredible rate. Anyway, he's had two other Porsche GT3s and currently has a '19 GT3 RS as well as a GT4 RS. Obviously, super high-performance track cars, but he told me that most fun car of the group on track was the GT500. Not because of power but because the chassis is so good and the margin of control is so much better at the limit than the Porsche GT cars. This is one person's opinion but it's believable.

For my use and ability I think the S550, particularly the Mach 1, is the best overall package in terms of performance, utility and track worthiness. No regrets. Still have 1,200 or so street miles to go home (making a big round trip of things), and will use the cooled seats, enjoy the stereo and be amazed that the day before the car was traveling at triple digit speeds, generating good cornering forces (street tires after all) and providing huge fun on track.

 

[VictorH]

Track Tip:
For those of you with standard heated and cooled seats, you probably know that they are not optimal for track use. I think the standard seats are one of the most comfortable seats around compared to many other cars I've owned. Just got back from 2,600 mile road trip and they were great, no sore back, temp is always right using either low vent or low heat, really a great overall set.
Okay, so the problem at the track is they are NOT very supportive at all and for many of us you will tend to use your left lateral knee for support, in corners against the door or whatever interior body panel on the left side, to keep your body positioned. Consequently at the end of a track weekend your left knee will either be bruised, red or just generally uncomfortable sometimes with an abrasion. The way to avoid this is to use a knee pad turned sideways on the left knee. See photos below. Absolute cure and solution for this problem. The better you tires, the higher the G-loads the more you need this. Works for me, it's inexpensive and makes your track outing much more comfortable.

 

[VictorH]

I'm always looking for ways to incrementally improve my car to better fit me and my driving style. Had noted both on telemetry last Fall and sometimes on my own when driving on track when applying high brake pressure for 1.25g+ braking sometimes my foot would also, at the same time, hit the accelerator. If you depress the accelerator too much the car will cut power to the engine, but either way it's not ideal. Consequently, trimmed off a little bit of my widened throttle pedal and will see if that does the trick.

Will also be changing some items on my front-end to make it a bit quieter on the street and have a fuel system upgrade coming too.

 

[VictorH]

Going to be a few days before I install this as I want to run down my fuel level, a lot. Still need to reassemble front end and waiting for coil-spring isolators to come from Energy suspensions. Then the fuel pump should go in. Hoping I will then be able to run track with fuel level below 1/2 and not have starvation issues on those left hand sweepers.

 

[VictorH]

As per another post on this forum, I've added the aero-strakes from the S650 DH. Requires a few small modifications but overall an easy install. The aero benefit probably really small but some of the tracks I run, the speeds will be high enough for them to do a little work,

 

[VictorH]

I haven't updated this set of posts in quite some time. I still have the car and it's still great for my use. What's happened since 2024? Nothing bad, car is completely reliable, doesn't burn any oil even with track use. Some observations and updates.
1) Found out the "hard way" that the car needs an alignment every 8-10 track events. I think what was happening was I was updating or changing suspension items and then getting car re-aligned here and there. Then had a good long stretch with no alignments. Went to VIR last Fall and even though, same car, same driver, tires that might be a bit tired, I'm running a full 8 seconds per lap slower than my usual. In addition, the car was loose in sections where it's normally planted, so much so that it required correction on my part, at the top of upper esses going 100+mph. Turns out front camber was fine, but toe was out of adjustment and particularly in the rear the toe was OUT (probably good for drifting or maybe autocross). Anyway, got it fixed and now I know, I'll need to keep track of that.
2) I've been very happy with PFC brake rotors front and back. They are outstanding and durable and now due for replacement at all 4-corners. However, I can no longer recommend them as I can only get replacement front rings from PFC in Spain (absolutely nothing in the US and the actual production plant is 90 minutes away from me in SC) and no rear rotors are available and probably never will. Race shop in NC says they can get me some custom-made rear rotors which will fit the V3 spring retention system, but this will require a trip to NC to drop off one rotor so they can take measurements. Defeats the purpose of the easy change ring change system if you can't get replacement rings.
3) Tires are an ongoing challenge. Cup2s have gotten more durable over time, but more expensive and have slightly less performance than competitors. I've got 1 1/2 track days on a set of Tempesta P1 tires. They have good track performance, start at 25 psi cold to shoot for 32PSI or so coming off track. Didn't find any decline in performance over the course of a 20-25 minute session as each lap was getting quicker and quicker as I went along. I'm not a pro driver otherwise lap 2 would be the best one and then the tires would decline from there. In regards to wear, they have a pattern in the front that makes me think they won't be durable. Might have 2 at most, more days in them. I'm inclined to go to RE-71RZ for my next set as the older versions had really good life and respectable performance.
4) Fuel starvation. Never a problem again since changing to KPM fuel module, can run well into reserve range with no evidence of fuel starvation. The main problem with becoming a more proficient driver over time is your gas mileage keeps going down. At VIR I'm using 7-8 gallons per 20-25 minute session. That means I have to tank up after every session now. I know, Boo Hoo, but I remember the days when I could easily run 2 sessions, sometimes 3 depending on the track. VIR is pretty fast, average speeds are in the mid 90 mph and the car just guzzles gas. I know the GT500s drink gas even more prodigiously than mine and that's just normal life for them.
5) Suspension mods. The stock suspension is really SOFT. It works on track but, almost everyone will stiffen up the front and rear. I'm running 325 in lb, fronts and 1200 in lb rear springs which, to me is a nice, happy compromise for street and track. Some might not like it as it's reasonably firm, but not harsh. I still have stock MagnaRide system which has a little trouble keeping up with those spring rates but it's still good enough for me.
You may have seen under trans and drivetrain forum that I've replaced my diff bushings, added front lower control arm bearing (on the rear) and just yesterday aftermarket rear toe arms. Will be going for alignment next week. I now have no rubber bushings in the rear suspension, it's all on bearings. On the road it feels now, no different than stock (limited miles so far) and happy with that. I don't recall what brand of front tension arm bearings I I switched to, but now they are starting to pop and creak at times. They have maybe 15,000 miles on them. The rear control arm bushings I used are from UPR and those seem to be high quality. They have a bit of taper which makes starting them easy and they are knurled in the middle which is helpful when pushing them in with the press to make sure it's still all lined up as its going in. Also, the interference fit is very good, I've seen Cortex and I think Steeda are so loose you can almost push them all the way in by hand. I don't think that's good, even though perhaps it's okay. I prefer a nice tight interference fit which the UPR has.
6) Brakes- The stock set up with good rotors and pads is really excellent. My car, with a proper VBox set up, measures 1.5G of braking force with full, max ABS braking. I really can't tell when ABS activates as it's not like the older systems and you don't feel any pulsating through the brake pedal. I have been sticking long-term with Cobalt friction XR-2 in front and XR-3 in rear (I"m on street tires, no slicks ever). I used these on another track car and they were also uniformly excellent. Good initial bite, nice release characteristics (I don't know what poor release characteristics would feel like) and they NEVER fade and are just super consistent regardless of condition or situation. They last reasonably long too. Of course all the good pads are getting more expensive but brakes are one area where saving money on parts might not be the best choice. Yes, I would like a better rear caliper set up but the stock system seems to be adequate, pad taper is not too bad (I can rotate from inside to outside given no wear sensor on track pads) and they haven't given any problems.

Overall, still really happy with the set up. Reliable, durable, parts are generally available and not at all like some of the European makes and for the money the performance is really excellent. Yes, there are lots of faster cars but I'm not really looking for a car that can run to 60 mph in 2.5 seconds or less, but if someone comes out with a street car that can pull 1.5G in the corners, then I would be interested. Might be a long time before we see that, in a price range for regular people, yes hypercars soon will reach that, but of no interest to me.
Happy tracking and have a good weekend.

 

[Dana Pants]

I don’t know why your alignment is moving, but mine definitely does not, and I’m mean enough to bend front struts. Did you double check the shop’s work with a torque wrench?

 

[VictorH]

Aren't you an autocross guy? I used to autocross, it was a lot of fun, but unless things have changed in the past 20 years, it's completely different than running on a race track.
The biggest stress and load to the car is running curbs, at speed. That's one of the primary ways that alignments go out. The last alignment I had was at a race shop and their alignment guy told me that no OEM cars hold their alignments for long periods of time, with track use, unless they have an "alignment lock out kit." I don't know what that is, or how it works but I and my friends don't have anything like that. I have two C8 Z-06 friends and both have had their front alignments change so much at a track event (two different events) that their steering wheels were no longer straight when traveling straight. It was fixed and never came back, but goes to show the loads and stress are probably different, than most (or all) autocross events.

 

[Turbeau]

The alignment lock out is likely for the rear factory ecentrics. I’ve heard of alignments going out on our cars after a good track session, curbs on track, etc. Rear subframe movement, soft rubber bushings (which you have addressed) and weak factory vertical links all contribute to alignment changes. The back end getting loose or darty under hard braking can be indicative of this. I’ve also heard under hard braking the front can cause camber/castor changes. A lot of guys replace the lower rubber bushings with spherical. I upgraded all of my rear arms to AAD, use the Steeda subframe bushings and braces, and SPL arms and rods in the front. Since changing my settings remain much more consistent (but will still move with a hard curb strike or off at the track).

 

[Dana Pants]

Autocross...

Its true that 95% of my car's abuse is autocross. And a lot of my autocross friends are accomplished/competitive track drivers. 95% of the time, when an alignment is adjusting itself, the issue is one of two things:

1) Aftermarket eccentric bolts with insufficient clamping load
2) Lazy alignment shops not torquing things
3) Honorary mention: an off-track that damages the vehicle in some way.



Specifically to the S550 rear toe links, the torque spec is 129 ft-lb. That means that with one hand you have to hold the eccentric in place with a breaker bar and with the other hand you have to angrily push into the torque wrench with a force quite similar to torquing your lug nuts with 1 hand. You really owe it to yourself to get under there and check.

 

[RTR077]

@VictorH how do the fuel starvation issues manifest themselves?

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