Vorshlag 2011 Mustang 5.0 GT - track/autocross/street Project

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We started on 255mm tires and quickly moved to 265mm, 275mm and finally 295mm wide street tires. And when it came to R-compounds we tried 275, 285, 295, 305, and 315mm widths ranging from Kumho to Hoosier.



We tested briefly in 2012 with the 345/35/18 rear Hoosier A6, and it had ferocious forward bite on these nearly 14" wide tires (13.9" section width/13.2" tread. The 315/30/18 is only 11.8" of tread/12.5" of section width, fully 1.4" narrower), but they rubbed the inside body structure and fenders badly under cornering (before the Watts Link). The rubbing caused other handling issues, and a huge smoke screen, so we shelved that size for a while. When we cut and flared the front fenders (to clear the new 18x12" wheels) I had every intention of doing the same to the rear fenders, then upgrading the front to 335mm and the rear to the 345mm tire again. I met with considerable resistance from Amy about "cutting on her car", but I'm wearing her down.


The 345mm rear Hoosier was wider than the stock rear fenders could accommodate and made lots of tire smoke from rubbing

As we noted many times in our Time Trial events this past year (with 15 separate NASA events in 2013) my fastest laps were almost always my first or second lap, barring traffic problems. On one or two rare occasions I ended up making my best lap on hot lap 3, but that was always due to a driving mistake or traffic on previous laps. The Hoosier A6 is a temperamental tire and works best in ambient temps from 50-60°F, and more often than not the lap times fell off a full second per lap after the first. We were also only getting 20-30 hot laps per set of tires before they are GONE.


Tires that only work for 1 or 2 laps, coupled with slower cars in front = TT traffic frustration!

My theory is that with another 20mm up front and another 30mm on the rear that our "golden lap zone" of ideal conditions could be expanded from 1 or 2 hot laps to maybe 3-4 hot laps. That is a big improvement for Time Trial that could have allowed for faster lap records at a few events in 2013 where I had serious traffic issues in the first couple of laps (more times than I can count). Not to mention a potential increase in mechanical grip from the additional two or three inches of tire on the ground at each axle. And possibly an increase in total tire life? That +20/+30mm change is not a small increase in tire width.



Another area we dabbled with late in the 2013 season was adding downforce, which I think still has more room for improvement on this car. While Vorshlag is first and foremost a suspension shop we have been seeing more and more aero development creep into club level road racing and time attack/time trial competition, and we were finding lap time improvements using aero changes very late into the season. The 10" long front splitter we added right before Miller, that many told us was "too long to be effective", coupled with our front grill block-off and ducted hood made more front downforce than the APR GTC-300 rear wing could match. That meant that at high speeds the car had an aero imbalance, and it was prone to oversteer. I cannot emphasize enough how loose this car was at Miller with that long front splitter, and we ran out of AoA on the rear wing to stabilize the car in high speed corners. Nothing like going 150+ sideways, wee!



To "fix" this we lopped 4 inches off the front of the 10" long splitter (well, actually a spare we had), right after returning from Nationals. Magically the car was balanced once again at the 150+ mph corner entry speeds we saw at TWS in late September, and was faster than ever at ECR in November. But it always nagged me... if we only had more rear downforce wouldn't that bigger front splitter be better overall? With some of the latest rear wings on the market having 14" and even 16" long chords and 70"+ widths, there could be a more efficient and more effective wing to test on this car, then we could bring the Big Splitter back (we kept it, just in case).



As I mentioned in my previous posts we would have liked to get into S550 chassis development as soon as possible, and run the 2014 season in NASA TT2 class with the new Mustang (a bump up on power and/or down in weight from TT3, going from 9.5:1 to 8:1 pounds per hp) but my hopes of acquiring one of these in the early spring of 2014 and prepping it to race for most of that year seem to be dashed. At best we might see a car in early August. So recently we began our ST2/TT2 build on an E36 BMW LS1 car, then our paying customer shop work picked up so much (we're building a number of race cars and LS1 swaps for people right now) that this project was delayed. Meaning, if we mothball the 2011 GT we won't have a car to race at all for many months, which pains me. That's half the reason I quit the secure engineering jobs I had in the past - to start a business, create products tailor made to racers, and then using our racing as "testing"!


We have a lot of work left on our ST2 BMW LS1 project before it is ready to race

Long story short, we're going to take our red 2011 Mustang and keep racing and developing with it as long as we need to, until the ST2 car is completed or until the S550 is here and prepped. This might mean an entire extra year competing in the red 2011 GT, known jokingly around the shop as the "pretty pony". And that's one thing I aim to do - make it look less ugly, with a new rear wing, proper metal flares blended into the bodywork, and a more low key graphics theme - say good bye to white strips visible from space!


This is the worst looking pair of flares on any car I've ever owned, and that's saying a lot

Those prototype plastic front fender flares we made look OK at 100 mph, but up close, they ugly. Sure, these were aerodynamically efficient but we have plans to make proper METAL flares welded to the front and rear fenders to cover the much wider Hoosier tires. Amy is still complaining about cutting the rear fenders on "her car" to clear the bigger meats, but I've got the Mustang at the shop all day, there's a fresh blade on the SawsAll, and possession is nine tenths of the saw.... I mean the "law".

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We've got a few ideas in mind to keep pushing the performance of this 2011 Mustang on track. We know some of our TT3 records are soft, so it might be nice to bump them up a bit. And we're running some all new track configurations this year so we could try to nail down some more. But then again, TT2 is faster, and would be challenging to try to compete there in Texas and at NASA East Nationals. We beat some of the TT2 records last year in TT3, and with less weight or more power (or just more development on the TT3 set-up) we could feasibly reset some of those and nail down some wins. And if we went ahead and bumped the red 2011 to TT2 it would be an easy transition to bring the BMW LS1 ST2 car up to speed, accumulating points in the same class all year. Which way to go then?

Where To Race - TT2 or TT3?

Before we start this bench racing section I have to post the new NASA Super Touring rules, revised for 2014. This is the basis for the TT classing and rules, and there are some changes that affect TT2 and TT3.

New 2014 rules: http://www.nasaproracing.com/rules/Super-Touring.pdf

Lots of little changes in the new ST rules, and they look good. I like that the 4 door exemption is being cut in half, as this factor never really hurt most of cars that could come in both 2 or 4 door models.


The E36 BMW 2 door and 4 door chassis weigh almost exactly the same, but the 4 door used to have a +0.4 modifier bonus but now is only +0.2



The new 2014 revised Competition Weight modifier chart for ST, above, is easier to wade through and penalizes the super light cars more (sub 1800 pounds = -2.0 penalty!). I like this since the sub-1800 pound cars with driver aren't really "cars" per se, not by any modern definition. Just for grins here is the old, more complicated Competition Weight modifier chart from the TT rule set, below.



For 2013 the TT3 class was the most popular TT class in the NASA Texas at almost all of the 14 race regional competitions we had last year (and at NASA Nationals). And Vorshlag had a decent set-up there, winning 13 of the 14 regional TT3 races in this car, mostly with the pre-August '13 aero changes and narrower front wheels. We could feasibly develop the car further and do better in TT3 again, but for grins let's see what it would take to make the jump to TT2. At first glance it would seem like the jump would be easy, as it is "only a 1 point weight to power ratio change", going from 9:1 to 8:1. Just lose a few pounds here and there and race it, right? In reality it is much more complicated than that.



First let's back up and analyze our current TT3 setup with respect to power, race weight, and ratio modifiers:

2013 TT3 race weight was 3770 pounds with driver. I'm about 210 with my gear on and we've been using 3/4 tank of fuel to ballast up that weight (and to avoid fuel starvation - I usually go out in each session with a nearly full or totally full tank). Latest DynoJet chassis dyno pull was a best of 419 whp, after we added the new air snorkel, but it made 430 whp in the past (more on that "missing power" in a second). Here's the 2013 and 2014 TT3 ratio calculations:

TT3 Unadjusted Wt/Power Ratio = 9.0
Non-OEM aero = +0.4 (*penalty) - note this changed from -0.5 in 2013
Running 3700-3799 pounds = -0.5 (*bonus) note: we used a +0.6 bonus for 2013
Adjusted Wt/Power ratio = 8.9 (the adjusted limit at this weight was also 8.9 in 2013)

3770 pounds / 419 whp = 8.99 currently

So if you noticed we were a little over the 8.9 ratio needed at this race weight, almost by 0.1, which is a good bit. This means we could really have run as low as ~3730 pounds at this power level, or run a few hp more on the dyno at 3770, and not get dinged. That is just part of the cushion we like to run, just to stay squeaky clean and legal. As much as others have pushed me to I won't cheat, and I show these ratios and calculations publicly and have our TT classing paperwork at every event for anyone to look at. In 2 years, 20+ TT events, and probably 40 weighings on this car we've missed weight twice, both times by 5 to 7 pounds, and we fixed it shortly after (and ran faster at the proper weight in later sessions).



But how can we get this car down to an "8.0 ratio", to be competitive in TT2? We think there is a bit of power to be had in the exhaust, as this setup used to make 430 whp and did for quite some time. The catalysts we are running are a few years old, and one of them is smashed a little and might have a busted catalyst matrix, causing some flow restriction. Removing the cats and making a shorter/lighter race exhaust might uncork that 10-12 whp and get the power back to where it was before (from 419 to 430). But other than that there is no more "easy power" to be had. Everything we could do to add 20-30 more hp would cost thousands of dollars (build a race motor) and virtually every bolt-on mod that might be done would just move the rev range up and likely lose as much or more power below 5500 rpms. So let's stick with 430 whp, for the most simplicity, reliability and lowest costs.

3770 pounds / 430 whp = 8.76



Hmm, we're still way off the mark at that power level. What about losing a bit of weight? We think that ditching the over-the-axle exhaust section and the pair of relatively heavy Flowmaster mufflers in favor of a lightweight "dumped" system like we built on the custom Boss 302-S exhaust we built (see above) could shed as much as 40 pounds off of the current system (see below). We dropped more than that on the 302-S exhaust. We could also replace the bloody slip-fit joints from the headers to the exhaust (which always leak just a little and we have to tack weld in place) in favor of proper 3" stainless V-band flanges.



Then there is the rear seat, which when removed would drop another 35 pounds, with hardware. So with exhaust changes and rear seat removed that is the "easy" 75 pounds to lose. All could be quickly undone and involve almost no cost (well the exhaust would take two mufflers, some mandrel bends and about 7-8 hours to fabricate and weld, but who's counting!).

3695 pounds / 430 lbs = 8.59

If we do something about the fuel starvation issues, maybe with a new fuel tank sump or surge tank, that could mean we wouldn't have to run nearly a full tank. We run almost full now, which is 16 gallons, and at 6 pounds per gallon for gasoline that's 96 pounds. Running only a 20-25 pound fuel load, with a proper fuel tank pick-up, surge tank or even a small fuel cell, might help us drop up to 70 pounds of fuel weight...

3625 pounds / 430 whp = 8.40

We're making some progress but we need a lot more. Let's look at some interior bits that could be removed to drop more pounds. That carpet likely has some hefty insulation under it. It needs to come out and be weighed. And the air conditioning compressor, accumulator and condenser core are not only heavy but the condenser core is blocking air to the radiator. Is there another 90-100 pounds in weight savings here, not even touching the under-dash bits? Could be.

3525 pounds / 430 whp = 8.18

So with a little bench racing we're getting closer to the 8 pounds per hp goal, but don't forget about the TT modifiers. Since we are moving to TT2 there's no more +0.4 penalty for "non-stock aero" (formerly 0.5), yet there's still a bonus for running a race weight heavier than 2999 pounds... scroll up to the Competition Weight adjustment chart for that modifier (now a -0.5 bonus, which used to -0.6).

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Looks like if we got down to 3500-3600 pounds there is still a -0.3 bonus, which means we could add even more power and still be TT2 legal, yikes. You kind of have to back into this weight penalty/bonus deal by first choosing a race weight, looking at the Competition Weight table of modifiers and then figure out your final ratio that way. It takes a couple of iterations but isn't hard to do. With a guess at 3525 pound minimum weight (where we think we could get without cutting up the car) that is a -0.3 modifier bonus, which is helpful.

3520 pounds / 457 hp = (8.0 - 0.3) 7.7 ratio (legal ratio at this race weight for TT2)

Yikes, that's a big jump... so we would be going from TT3 with an adjusted 8.9 ratio to TT2 with a 7.7 ratio. Even after dropping another 250 pounds we would still be 27 whp shy of the limit for the class. Another way to look at it is that at 3520 pounds the car would be 207 pounds overweight for 430 whp. Yikes... that's a lot of power to find (read: pay for) or a lot more weight to lose (450 pounds lower than we are now, which is impossible without radical chassis surgery and/or without exotic materials). So maybe a 100% competitive TT2 build is not in the cards for this 2011 GT... and I'm OK with that. What about a "semi-competitive" TT2 car?



Say we get that "easy" 200-250 pounds out of the car, add the bigger rear wing, flare the sheet metal properly and run the wider 335/345 tires, then ballast back up to TT3 weights -or- run sans ballast and just jump into TT2 with a +200 pound heavy car? Again, we did pretty well last year in TT3 and even beat TT2 lap records a few times at 3770 pounds. With more tire, more aero and less weight we might still be able to sneak in a few TT2 wins until the dedicated ST2/TT2 car(s) are built? Who knows. It gives us some extra performance and classing flexibility with minimal spending.

Again, there is no easy way to add another 30 whp, as the only "easy" bolt-ons left are bigger cams and a different intake manifold design (bigger cross section, shorter runners). Yet we know that these mods will likely lose power below 5000 rpms over what we have now. The popular Boss302 intake is a known "power shifter", adding a few points of peak power up top but killing as much or more power below 5500 rpm, so that's a dead end. The other ways to add power to an engine are to improve the Volumetric Efficiency, add compression or displacement, or add boost - none of which are easy or cheap to do. I like having a bone stock engine from throttle body to exhaust port, as it keeps the factory 5 year / 60K powertrain warranty intact, hehe.



So while I will consult some folks smarter than me and see where we can lose more weight (without cutting away big parts of the car) or gain more power (without getting into the motor), we will likely just try to improve the TT3 performance, drop as much weight as we can easily undo, and ballast up closer to the class limit... and remove the ballast and run TT2 as-is, when it makes sense. We will also make a separate ballast package for whenever Amy drives, as we are running as "Team Vorshlag" in 2014, and she and I will split driving duties. At least this way we can run the same transponder and won't screw that up, heh. Just need to make a very visible, quick to install chunk of driver ballast to make up the differences in our weights.

MCS / S197 Shock Test Video


In-car video from Nov 3rd track test with MCS TT1 coilovers on 2012 Mustang GT at ECR

Shannon just uploaded the 720P high def version of the Tom's Lap Timer video that I talked about in my last forum update. In the video above you can now see how the MCS non-remote singles work on this somewhat bumpy track. Driving this car was effortless (exception: hanging on in stock seat was difficult!) at 9/10ths, and we put in several hot laps with some traffic in an HPDE4 session. I didn't make any crazy passes and we got held up on every lap, yet we still managed to put in that 2:07 lap there.



The 255mm street tires (Nitto Invo) were worn smooth out, but car owner Jan has since ordered 18x11" Forgestar F14s from us (that just arrived) and we will be installing some fat 295/35/18 BFGoodrich Rivals onto those next week. This Mustang is nearly bone stock, with a 100% stock powertrain, some Carbotech XP16 brake pads, and the MCS shocks and Vorshlag camber plates. Real monotube adjustable dampers absolutely transform these cars on track, yet with the valving turned down this daily driven Mustang rides beautifully (550F/250R rates). I think with the 11" wide wheels and 295 Rivals this car could dip into the 2:03-2:04 zone, which is just FLYING for street tires. In comparison, a truly bone stock 2012 GT runs about a 2:12 lap at ECR, from what we have seen and timed (we tested our 2013 GT on 18x10" wheels and 295mm Nittos for our "baseline" numbers).

USCA Event at TMS is On!

There was an event we were in danger of missing in the early part of 2014 if we didn't have a street car to race - the Ultimate Street Car Association's TMS event March 21-23, 2014. This is the new series created by Jimi Day/FM3 Marketing to serve as the qualifiers for the big Optima Challenge shootout after SEMA, and we want to be there in this Mustang, which is a real street car. We hope to be on proper 335mm Rivals this time, too. Keeping the 2011 around will allow us to make that event in our own back yard, which is exciting. Road course, autocross, speed stop and some car show portion.


Time for some fat street tires and a run at the USCA event in March!

NASA @ MSR-Houston Jan 19-20, 2014

First NASA event of 2014 is right around the corner, as we race 12 months out of the year here in Texas. The MSR-H event is being run this year in the CCW format, opposite of 2013, so any TT3 winning time will be a track record, and possibly TT2 as well. So Amy and I will enter as "Team Vorshlag" and run whichever class has more cars, and if we can get to 5 in a given class maybe somebody will win some tires. The attendance looks pretty light right now, but that is typical for this January event - which could have really cold or windy weather, rain or fog (the fog last year delayed the start of the event) - but being Houston that could change at any minute and turn into a warm sunny day. Most people wait until the last possible minute to enter this event, which drives the NASA folks nuts!




With this renewed focus on the red 2011 Mustang and a split of TT3 & TT2 goals for 2014, we have a lot of prep work to do in the next few weeks to make MSR-Houston, unless we just take the car "as-is". I don't want to do that, of course! We almost never run the same set-up twice in a row - continuous development makes for continuous improvement. The initial changes we have planned (exhaust, flares, tires, weight) are still much less work than is needed to finish the ST2 BMW, which needs 200+ hours of work to be a running, driving car + time for testing and sorting the new set-up. We will continue to work on that ST2 BMW as time permits but for now we'll concentrate on 2011 Mustang development until the 2015 Mustang gets here.



We are doing a tire test tomorrow at ECR in the Mustang (320mm Continental slicks vs 315mm Hoosier A6) so I will report back on that soon.

MUCH more soon!