Eh, this is the most ad-heavy board I read. I don't fault them that, it's how you make money, but calling it light on ads is a bit much.
But yes, Vorshlag's board also sucks. It at least appears to behave like the rest of the world regarding formatting, pics, etc., but the interface is clunky.
At least GRM doesn't do the embedded ads in text or in between posts!
That's true. Those things are truly hateful.
I'm in IT so I get to call people names. Since OP is an idiot who doesn't know how to Forum....
Vorschlag wrote:
Maximum Effect from Minimal Investment
This time we're NOT starting with a $40,000 brand new car, we're starting with an aging 24 year old... well.... beater. This car was purchased by the previous owner for $3000, and then he sold the interior bits and some other discarded parts and recouped $1000 of that, so it was s cheap starting point ($2K!). He then semi-prepped it for TT use but got busy with other projects and he suddenly wanted it gone - so it will soon come to our "secret offsite shop" to knock out the repairs and finish race preparations in the next 4 weeks.
Why did we choose this car? Well it happens to be "base classed" particularly well, and once people who know TT classes see where it ends up they might cry foul - but is has been classed there for many years and I've been waiting for someone to build one. We will document all of the modifications we do openly, show all testing performed looking for every ounce of speed, and post any race wins or losses along the way. Like we tend to do with all of our builds, we will be pouring over the rules looking for the optimum modifications allowed, and with several 25+ year veterans of amateur and pro racing working at Vorshlag, we know how read rules and seek out the most advantages possible.
"Rulebook Research" and bench racing is part of the fun of building a new race car, for us, and we've probably spent over 25 hours so far just looking at the "free" mods allowed in TT. We have run countless permutations allocating every point in the class (it isn't going to jump up a class), and going over every tire width/compound option, but there are still many unknowns in this build. Will an aero trick worth two points be worth more than a cat-back exhaust? We'll test that. What about this +10 point compound narrow tire vs a much wider +2 point tire? Testing it. Can it meet the power-to-weight limit? We'll dyno test the car early and often through the build. This is going to a gutted/stripped car with NO compromises for street use at all, which we believe gives us the best chance for success. Daily driven cars haven't won many (any?) TT national championships with NASA in a while. This car has some great prep by the previous owner but it still needs some basic upgrades before it is fully track ready. We need to swap out the radiator for a racing-duty version, add an oil cooler, build in some major front brake ducting, install a proper racing seat (have one sitting in the lobby that I will steal), bolt in some harnesses and wrap them around a 4-point roll bar (initially; cage will be done hopefully by the February event). It also needs tires, a new windshield and a few other small repairs. Again, this is a CHEAP car to start with but when we're done its going to be embarrassingly quick on track. Cheap and Quick!
My final reason for building and racing this car in 2015 is - I'm a degenerate racing junkie, and I was clawing my eyes out thinking I was going to miss the next race season. Sure, I'm bummed that we cannot have the TT1 car built in time to run with NASA this year, so this was my only possible racing option. But I figured that running in a quarter century old beater has to be more fun than NOT racing anything at all, right?
So get on with the answer already! Sheesh...
This is the car we're building. It looks great, from this angle. This photo was staged perfectly - its a mess from any other angle!
This is it. What you are looking at is a 1992 Chevrolet Corvette 6-speed that is bone stock, except for being stripped of a nasty old interior. This is a base trim level car with the factory 5.7L "LT1" (Gen II) 300 hp iron block V8 and ZF S6-40 6-speed manual transmission. It has the strong Dana 44 rear axle assembly (not the Dana 36 that came in the early C4s and automatics). This particular car has 68K original miles and from the angle shown above doesn't look at all like a $2000 car. Regardless of how clean it looks now it was still a hot mess when purchased.
The entire interior is gutted, even most of the dash. We will finish what was started and put the dash cap back on
I will go over the issues on this specific car as we chronicle the repairs and upgrades to it this season. The previous owner (Brian Matteucci) has done a lot of repairs and refurbishment, and even a couple upgrades but we still have a laundry list of safety updates to tackle, as well as a few performance mods to "max it out" for TTC class points. We are keeping the car legal for TTC class so there aren't a whole lot of "points" we can burn on upgrades, so the car will remain stock in many aspects. Luckily, a stock 1992 Corvette doesn't suck!
Why is the C4 Still A Worthwhile Track Rat?
To understand why we consider this 24 year old car still relevant, we need to look at how this car was designed and what it came with that was ahead of its time. Here is a brief look at the C4 generation Corvette, which was produced from 1984 to 1996.
We're already getting to work on this 1992 Corvette at Vorshlag. Parts are ordered and it was detailed by yours truly
GM calls the Corvette chassis the Y-body and it has been produced from 1953-current in 7 distinct chassis generations (see the Corvette Wiki). The "C4" generation was designed in the early 1980s and was delayed a bit before launched as a 1984 model (there was no 1983 Corvette). This chassis was a huge leap in sophistication from the C3 chassis it replaced. None of the subsequent Y-body chassis were this revolutionary - C5, C6 and C7 all share design aspects of the C4 and are instead mostly refinements (yes, the C5 had some serious updates!). The C4 was the first "Billion Dollar Chassis" design in the history of automobiles - and it doesn't share anything with any other GM chassis, so there was nothing to be gained for another, mass produced chassis (exception: almost all engines developed in the Corvette make their way into the F-body chassis and others).
With fairly low production numbers each year this has got to be a "loss leader" for General Motors at only about $40,000 when this car was new in 1991. And now with 3 newer generations of Corvette following the C4, this chassis has bottomed out in resale value - its not old enough to be considered a classic but its not new enough to be worth a lot of money. Some year C4s can be had for next to nothing, and even the later C4s can be snatched up cheap if it has any issues (like this one) and made into a low buck race car faster and more sophisticated than 75% of the cars at any given NASA race weekend. And this 1992 model one of the best of the C4 generation.
Engines: The C4 had 4 major engine designs in its 13 year run (1984-1996), which began in 1984 model with the abysmal Cross Fire V8. This was a horrid, 205 hp, early attempt at a fuel injected V8 and a complete carryover from the outgoing 1982 C3 Corvette. The Crossfire L83 has ZERO redeeming qualities and was only used for one model year in the C4. Starting in 1985 was the 5.7L L98, better known as the Tuned Port Injected or "TPI" V8. These long runner intake equipped V8s had LOADS of low end torque but petered out above 4000 rpms. With aluminum heads this "Gen I" Small Block Chevy (SBC) made decent power for the early 1980s (230 hp then up to 250 hp) but stuck around far too long (through 1991 model).
This was followed by the revolutionary 300hp 5.7L "LT1" Gen-II V8 in 1992, considered the first new design in the Small Block Chevy's long history (hence the Generation II engine; the LS1 in 1997 was the Gen III). There's tons of data out there about this motor, of course. In 1996 there was a special edition version of this motor called the "LT4" made 330 hp. Lastly, during the middle of the C4 model run was the LT5 DOHC V8 that came in the ZR1 (1990-95, 385-405 hp), which was a technological marvel for its time but was quickly overshadowed by the all aluminum OHV V8 that came out in the C5 - the LS1.
The Gen-II LT1 engine was unique in that it only lasted 5 model years, but it was also used in the 4th Gen F-body (1993-97 Camaro/Firebird) and the Caprice/Impala (1994-96 B-body) as well as one Cadillac (1994-96 Fleetwood). The reverse flow cooling was a big change but other than the bump to 10.5:1 compression ratio, produced very little benefit, and this "reverse" cooling style (heads cooled before block) was dropped in the Gen III LS1. The distributor (Optispark) is very unusual; it is driven by the camshaft and tucked behind the water pump. It is somewhat problematic and prone to water damage, but the later '95-96 "vented" style works better and aftermarket versions better still. The intake manifold is about as far from the TPI motors as you can get - it has larger but very short runners which produce a higher RPM range and a much flatter torque curve than the tractor motor curve of the TPI.
The Y-body LT1 always got 4-bolt main bearing caps (the other's all had 2-bolt mains), but the 1992 Corvette's LT1 is unique in one key way. The TPI motors (1985-1991) all used a crude form of Fuel Injection called batch fire port injection, and used a Mass Air Flow meter to meter incoming air into the engine. These early MAF designs used a circuit board that was in the airstream and were problematic from day one. The 1993-96 Y-body and 1993-97 F-body LT1/4 engines went to a more modern hot wire element MAF with the electronics housed outside of the airstream. But for the 1992 Corvette (and 1993 F-body) this new EFI system wasn't ready and for one model year only GM went with a speed density air metering system (no MAF). This uses Manifold Pressure Sensor along with a atmospheric pressure sensor to read incoming air. This lack of a MAF means a lack of a restriction in the airstream for that one year - and the 1992 model ran the strongest of all of the LT1s in stock form.
The manual transmissions used in the early C4s (1984-88 models) was a Doug Nash designed "4+3" transmission – a 4-speed manual coupled to an automatic overdrive on the top three gears. It was designed to improve fuel economy but was mostly a steaming pile of crap. For the 1989-96 model Y-bodies, GM went to the Germans and they offered up the S6-40, made by ZF. It is an unusual transmission and parts are hard to come by, and shops have popped up like ZFDoc that specialize in rebuilding these brutes. This trans is nicknamed the "ZF6" and is big, heavy and very strong, if a bit noisy. With 6 speeds and 2 overdrives (.75 in 5th and .50 in 6th), it made for excellent fuel economy. The Borg Warner/Tremec copied these overdrives for the later T56. With the ZF6 tall 2.68 first gear, the "black tag" version is rated to withstand 450+ ft lbs of torque (and is much stronger with a modern carbon synchro upgrade). To quiet the noises, GM used a heavy dual mass flywheel, which tips the scales at over 40 pounds. The clutch is also strong and the Dana 44 rear differential out back is also a brute. The limited slip unit in these 44s tends to last decades... and I hope so because we're not touching it. The halfshafts are big beefy aluminum tubular units with U-joints (cheap to replace!) instead of CV joints, and the driveshaft is built the same way.
The body is fairly aerodynamic (low height, low drag, small front area) and works well at high speeds. The body panels are made of fiberglass - which is good considering it has some chunks missing, and fiberglass is easy to repair. Some damned fool drove this car through a barbed wire fence back in its' checkered past, which damaged the front bumper cover and body panels on the left side. The driver's door was trashed but the replacement doesn't match the car's white paint well, so that will likely get repainted at some point. I will patch the fiberglass that is damaged myself and prime it for later repaint.
continued below
^---Terry (Fair) does not like paragraphs, does he? 
DILYSI Dave wrote: Eh, this is the most ad-heavy board I read. I don't fault them that, it's how you make money, but calling it light on ads is a bit much. But yes, Vorshlag's board also sucks. It at least appears to behave like the rest of the world regarding formatting, pics, etc., but the interface is clunky.
I really only see the occasional ad up in the header. Havent seen any others. I'd say this is the forum I frequent with the least ads.
Is this an interactive build or a look at this build? Imma gonna ask a question anyway. How do you like circle track type seats for road course/autocross cars? I'm considering that exact seat for my Emod car but am not sure if I will enjoy or regret the 10.5" deep rib supports.
nocones wrote: Is this an interactive build or a look at this build? Imma gonna ask a question anyway. How do you like circle track type seats for road course/autocross cars? I'm considering that exact seat for my Emod car but am not sure if I will enjoy or regret the 10.5" deep rib supports.
We use Kirkey "ProDrag" style seats in our autocross car--no big rib "wings", but plenty of lateral support on the backside.
FSP_ZX2 wrote: ^---Terry (Fair) does not like paragraphs, does he?
actually he does, forum software is ripping out the returns for some reason.
Thanks for the cross post mr. IT.
For whatever reason, posts in quotes always take out the paragraph formatting.
Forum bitching aside, this is still a very cool build. 
It is.
DILYSI Dave wrote: It is.
not yet, but it could be. if our forum software wasnt the suck apparently. unless the threads he's linked to have more than pictures of what it's going to look like and the parts they plan to use. by cool i mean low buck and by low buck i mean like having a pro shop build an ls powered e30 m3 knockoff challenger and claim it cost $2010 because pros did the build in their free time or something. all kidding aside, it is nice to see a c4 getting some attention in the world of "c5 z06 or nothing for track car" that seems to be the norm here when it comes to vettes.
FSP_ZX2 wrote: ^---Terry (Fair) does not like paragraphs, does he?
Actually...the version posted everywhere else has great formatting. The GRM forum software strips out everything and makes it one huge blob.
nocones wrote: Is this an interactive build or a look at this build? Imma gonna ask a question anyway. How do you like circle track type seats for road course/autocross cars? I'm considering that exact seat for my Emod car but am not sure if I will enjoy or regret the 10.5" deep rib supports.
This one is more interactive than most. Terry should be posting a lot of "this is what we are GOING to do" rather than just "this is what we DID".
And I like the seats too. I've used them before in builds. They are easy to work with and mount, though you do need to build a back support. The issue that most people have with them is that they either buy the el-cheapo economy versions, which is basically an aluminum box, and sucks, or they don't get the right size. There is a reason these come in 15 sizes. They don't use much padding, so sizing is critical, just like jeans. If you have a truly odd body size/shape, they can be custom made to your measurements. Once you get into the super-delux seats with all the options, the price does approach/surpass the cost of the similar composite seats, but again, it's easier to integrate these into the cage.
For this one the seat is slightly oversized so we can make a poured foam seat. That's not accurate, as we will actually make what's know as a "bead seat" insert. We'll make one out of true motorsports materials for this car, and out of alternate, less expensive materials for one of our fabricators V8 swapped E30.
Hey all, sorry for going a bit postal in my first post here in a long time. I have tried in the past to port our relevant build threads to GRM, because I truly love the mag and dig the folks that frequent the forums here. The forum software, being "unique", just makes it especially difficult to cross-post here without starting from scratch or spending an hour or two reformatting everything.
A lot of you remember us from our 2009-2011 GRM $20XX Challenge effort, which we cleaned up, added some cool parts to and sold after winning the $2011 Challenge. I've wanted to build another, better, faster Challenge car but have been over-ruled (by Vorshlag staff and the Big Boss, Amy) many times.
I have written a lot build threads like this one, and usually post them to a handful of about a dozen different forums - if they have an audience that is receptive and gives good feedback, and if they use UBB or common HTML for posting. The GRM forum has good readers and gives good feedback (as shown here already), but the forum software butchers my posts no matter if I use UBB or HTML. Its gonna take a LOT of work to get it viewable here, and no amount of coding tricks can ever make up for some of the limitations here. And while I appreciate whoever ported over the first 2 posts (of 4), the formatting got jacked up pretty hard and it looks like a giant word blob with pictures stacked in weird ways. If this is the only forum you know then it seems normal, but it is hacking up our posts.
I spend a lot of time making my forum build thread posts look pleasing to the eye, and try to make them enjoyable to read and with enough pictures and tech to be worth your time. Many of the build threads I've written have hit 250,000+ views, and a few have even tipped 1,000,000, so there are people crazy enough to read these long-ass posts.
The "Danger Zone" thread wasn't posted here initially because in the first post (13 days ago) I wasn't giving out the make/model/year of the car yet. Its some marketing idea that we have used in the past to get people engaged and posting feedback, and it worked well on the GRM $2010 build (we didn't release the engine choice until very late in the build - and even posted some obviously fake engine pictures like the one above). Of course, not posting the make/model/year of the car violates GRM forum posting rules, so I waited until the 2nd series of posts, where we did release that info to TRY to post. And it was a frustrating hour of testing that went haywire.
After seeing the number of views and responses I will try again to get my 2nd set of posts viewable here. The pictures might not have URL links to larger rez versions and some of the other links might not work, and the paragraph formatting will likely be jacked, but I'll try. I think I can use some external software to do a find/replace for the funky text formatting rules here... just know that it will be an extra PITA.
testing two small images linked to larger rez images. It works in preview but always "stacks" them
I think we can bring some usable "Tech" to GRM in our builds, like we have in the past. Our GRM $2010 build really was made in my home garage using fairly basic fab tools, and with 15 volunteers and about 1500 hours of work we made a decent little car. We've come a long way since then and now have a small, dedicated crew of top notch fabricators, engineers, and mechanics - all with lots of racing experience. We are using a cheap car once again - a $3000 Corvette - and will have to be following some strict class rules/modification limits to do well in NASA TTC. It should be a fun build to watch and we do always look at everyone's feedback. Sometimes it takes us in new directions.
Thanks for your patience!
Terry Fair @ Vorshlag
sorry too busy drooling over Bane...
Our GRM $2010 build really was made in my home garage using fairly basic fab tools, and with 15 volunteers and about 1500 hours of work we made a decent little car. We've come a long way since then and now have a small, dedicated crew of top notch fabricators, engineers, and mechanics - all with lots of racing experience.
...low buck build...
Jed, Knowing pretty much every person who helped on the 2010 build, yea it was low buck. Every person put hours in the evening and weekends to prep the car. I think 2 guys came over from his shop to help. All the others just happen to be car people friends and can turn a wrench and have fab experience on their own. How much time do some others have wrapped up in there builds?
This was built at Fair's house too. Which is nicely setup, but in no way a pro shop. I have most if not all the same tools he used to make the car. It never hurts with how anal he is too with the cleanliness.
I have a build that could qualify had I kept the original drivetrain plans. Though, I sold that and have a more expensive one. Thuogh I can say that the car will have 1000+ hours in it in fab time by the time its done just because of the build it will require.
nocones wrote: Is this an interactive build or a look at this build? Imma gonna ask a question anyway. How do you like circle track type seats for road course/autocross cars? I'm considering that exact seat for my Emod car but am not sure if I will enjoy or regret the 10.5" deep rib supports.
Jason McDaniel (who is an engineer that works here at Vorshlag; aka: modernbeat) answered this already, but yes, we use aluminum seats on many builds. Sometimes its the only thing that fits. They CAN be comfortable but come in a lot of sizes and shapes. I always like to "test sit" in any new racing seat before I buy and install it.
We are a dealer for Cobra, Sparco, Momo, OMP, etc - and I love the fixed back composite seats - but they are quite pricy and often more difficult to mount than an aluminum seat or a tubular steel bodied bottom mount seat. But the FIA tends to favor the side-mounted composite designs, and that's what you have to use in certain forms of racing.
The past few years have seen some racing bodies loosen up on some of the rules regarding aluminum seats, but generally they WILL ALWAYS need an additional seat back brace in almost all forms of road racing because they will NEVER have any FIA testing or approval. And generally they do need some additional seat back bracing because, well, they are a good bit weaker in some areas...
Good example of this was when a customer shipped us an UltraShield seat for his Subaru WRX (runs 200+ mph top speed events) and was at our shop for a massive cage upgrade (still underway, see below). The seat came via UPS truck and of course they crushed the box. The seat was damaged beyond repair. The way this aluminum seat failed was remarkable - it folded in half, quite easily. We bent it back (again, with very minimal effort) and it is being used it in the car for mock-up (for lower mounting) until the replacement arrives.
My point is that aluminum seats are WEAK in bending along the back, generally speaking (there are some exceptions). In some cars where the cockpit is VERY tight (some Corvettes and all Miatas) it isn't noticeable because the car is hugging the seat. But I've noticed "floppiness of aluminum seats" when road racing a car with these designs that didn't have a seat back brace. Even autocrossing - the seat backs can and do flex a lot, and it can be very distracting. Virtually all road racing bodies require aluminum seats (and any out of date FIA seat) to have a rigid seat back brace bolted to a roll bar, which is a very good idea on all aluminum seats. The difference in seat movement with and without the back brace is remarkable.
I/O Port racing makes a nice little seat back brace kit which we've used many times. It has some assembly required. We used a pair of these on the UltraShield aluminum seats in our E30 and it made a huge improvement to the seats' rigidity.
Composite seats have a lot more seat back rigidity, by their nature of construction. They tend to be 4-8 pounds heavier than a comparable aluminum seat, and 2-3 times as expensive. They also tend to only be "side mount" capable, as they have to get threaded inserts installed into the composite and molded in place. Aluminum seats can be drilled through on the sides or bottoms for bolt-through mounting, but they should get big, hardened washers to spread the loads of these bolts to prevent tear out.
That's my quick story about aluminum seats.
Terry Fair @ Vorshlag
Mad_Ratel wrote: sorry too busy drooling over Bane...
Understood.
This car has had a lot of fans over the past 4 years. Sure wish someone would buy it. 
Thinkkker wrote: Jed, Knowing pretty much every person who helped on the 2010 build, yea it was low buck. Every person put hours in the evening and weekends to prep the car. I think 2 guys came over from his shop to help. All the others just happen to be car people friends and can turn a wrench and have fab experience on their own. How much time do some others have wrapped up in there builds? This was built at Fair's house too. Which is nicely setup, but in no way a pro shop. I have most if not all the same tools he used to make the car. It never hurts with how anal he is too with the cleanliness. I have a build that could qualify had I kept the original drivetrain plans. Though, I sold that and have a more expensive one. Thuogh I can say that the car will have 1000+ hours in it in fab time by the time its done just because of the build it will require.
Then you guys have some of the nicest damn home garages I've ever seen in my life!
Project Update for December 29th, 2014: This is an unexpected update - I'm going to break "radio silence" early because too many of you have guessed the car we are building before it's first race. Many of the guesses were hilarious and infinitely entertaining, and some of them were pretty good ideas for TT builds. More importantly this little project got some engagement and feedback. I'm always looking for feedback and comments, in case you have a better idea or way to do something, so keep it up! Now let's get to the answers to "The What and the Why" in this update.
Lucky guesses and True Detectives
Here were the initial clues I put in the first post, then some follow up clues on social media and various replies to questions and guesses on the forums. The clues became more specific as more folks chimed in with better ideas and guesses. If they gave their reasoning in their replies I would often answer yes or no, which led to more clues over the past few weeks.
All of these things were 100% true. The "Danger Zone" name was the only red herring, heh. That last clue was what triggered an avalanche of correct guesses. Jason Newman was the first to guess correctly - and he knew he was right a week before anyone else - with only about half the clues. That guess gets him a free Vorshlag T-shirt! Several others guessed "C4" along the way as well.
My Past Was Also A Hint
It helped that Jason knew more about me than most - he was a racing friend from college, when I raced in and helped run the largest collegiate sports car club in the country, the Texas A&M Sports Car Club. This was a club with over 150 members when I was there and we had one of the best autocross sites in the country - an old air force base that the school owned (Riverside Annex).
Left: My 1994 LT1 6-spd Corvette Z07. Right: One of three V8 1992 Camaro 1LE/B4Cs (ex-pursuit) I owned
We set up huge autocrosess there, joining multiple runways at times. We also had lots of fun at nearby Texas World Speedway (TWS) running annual time trial events we called Aggiecross. This little college club was holding Time Trials back in the late 1980s, which didn't happen in NASA for decades. A lot of us worked at TWS while we were in school, and when we worked corners for PCA HPDE events we got free track time in our clunky, broke-ass student cars as well.
Left: My ex-pursuit 1987 Mustang LX 5.0 was one of 6 Foxes I've owned. Right: Amy's 92 Mustang GT and my 1969 Mustang (C Prepared)
During my time racing with TAMSCC, both during college and after, I ran in a variety of cars. Since I was the proverbial "starving student" while in school many of these cars were crappy and cheap, but most of them still V8 powered and RWD. When I met Amy she had an 86 RX7 but once she raced in some of my cars she jumped to Mustangs and then Firebirds. Between us we've owned about 16 pony cars (Camaros and Mustangs) of various years, from 1969 through 2013 models. Two years after graduating I landed my second post-college job, which allowed me to commute from the same town (College Station). I was making great money in an oil field mechanical engineering position, and had extremely low living expenses. At one point there I owned 7 cars, including two project builds and an immaculate two year old Corvette (the white 1994 shown above).
Left: Amy's supercharged 1994 Trans Am on 17x11" HREs. Right: Her 1998 LS1 Formula
I tell you this because knowing what I used to own and race in my "Pre-Vorshlag Days" (nowadays I typically do NOT buy the cars I want but instead buy cars that need suspension development) helped clue in some old friends that knew this was to be a LOW budget build, but that somehow I knew it would be fast. Three amigos of mine were the ones to ferreted out the last few clues and got to the correct answer without question, before I confirmed it to them privately. These guys knew me too well, and were more racers from my days running with the TAMSCC: Matt Miller, John Scheier, and Doug Willie
Yet nobody correctly guessed that we'd keep it in TTC class.
Project Danger Zone Is...
So get on with the answer already! Sheesh...
This is the car we're building. It looks great, from this angle. This photo was staged perfectly - its a mess from any other angle!
This is it. What you are looking at is a 1992 Chevrolet Corvette 6-speed that is bone stock, except for being stripped of a nasty old interior. This is a base trim level car with the factory 5.7L "LT1" (Gen II) 300 hp iron block V8 and ZF S6-40 6-speed manual transmission. It has the strong Dana 44 rear axle assembly (not the Dana 36 that came in the early C4s and automatics). This particular car has 68K original miles and from the angle shown above doesn't look at all like a $2000 car. Regardless of how clean it looks now it was still a hot mess when purchased.
The entire interior is gutted, even most of the dash. We will finish what was started and put the dash cap back on
I will go over the issues on this specific car as we chronicle the repairs and upgrades to it this season. The previous owner (Brian Matteucci) has done a lot of repairs and refurbishment, and even a couple upgrades but we still have a laundry list of safety updates to tackle, as well as a few performance mods to "max it out" for TTC class points. We are keeping the car legal for TTC class so there aren't a whole lot of "points" we can burn on upgrades, so the car will remain stock in many aspects. Luckily, a stock 1992 Corvette doesn't suck!
Why is the C4 Still A Worthwhile Track Rat?
To understand why we consider this 24 year old car still relevant, we need to look at how this car was designed and what it came with that was ahead of its time. Here is a brief look at the C4 generation Corvette, which was produced from 1984 to 1996.
We're already getting to work on this 1992 Corvette at Vorshlag. Parts are ordered and it was detailed by yours truly
GM calls the Corvette chassis the Y-body and it has been produced from 1953-current in 7 distinct chassis generations (see the Corvette Wiki). The "C4" generation was designed in the early 1980s and was delayed a bit before launched as a 1984 model (there was no 1983 Corvette). This chassis was a huge leap in sophistication from the C3 chassis it replaced. None of the subsequent Y-body chassis were this revolutionary - C5, C6 and C7 all share design aspects of the C4 and are instead mostly refinements (yes, the C5 had some serious updates!). The C4 was the first "Billion Dollar Chassis" design in the history of automobiles - and it doesn't share anything with any other GM chassis, so there was nothing to be gained for another, mass produced chassis (exception: almost all engines developed in the Corvette make their way into the F-body chassis and others).
With fairly low production numbers each year this has got to be a "loss leader" for General Motors at only about $40,000 when this car was new in 1991. And now with 3 newer generations of Corvette following the C4, this chassis has bottomed out in resale value - its not old enough to be considered a classic but its not new enough to be worth a lot of money. Some year C4s can be had for next to nothing, and even the later C4s can be snatched up cheap if it has any issues (like this one) and made into a low buck race car faster and more sophisticated than 75% of the cars at any given NASA race weekend. And this 1992 model one of the best of the C4 generation.
Engines: The C4 had 4 major engine designs in its 13 year run (1984-1996), which began in 1984 model with the abysmal Cross Fire V8. This was a horrid, 205 hp, early attempt at a fuel injected V8 and a complete carryover from the outgoing 1982 C3 Corvette. The Crossfire L83 has ZERO redeeming qualities and was only used for one model year in the C4. Starting in 1985 was the 5.7L L98, better known as the Tuned Port Injected or "TPI" V8. These long runner intake equipped V8s had LOADS of low end torque but petered out above 4000 rpms. With aluminum heads this "Gen I" Small Block Chevy (SBC) made decent power for the early 1980s (230 hp then up to 250 hp) but stuck around far too long (through 1991 model).
This was followed by the revolutionary 300hp 5.7L "LT1" Gen-II V8 in 1992, considered the first new design in the Small Block Chevy's long history (hence the Generation II engine; the LS1 in 1997 was the Gen III). There's tons of data out there about this motor, of course. In 1996 there was a special edition version of this motor called the "LT4" made 330 hp. Lastly, during the middle of the C4 model run was the LT5 DOHC V8 that came in the ZR1 (1990-95, 385-405 hp), which was a technological marvel for its time but was quickly overshadowed by the all aluminum OHV V8 that came out in the C5 - the LS1.
The Gen-II LT1 engine was unique in that it only lasted 5 model years, but it was also used in the 4th Gen F-body (1993-97 Camaro/Firebird) and the Caprice/Impala (1994-96 B-body) as well as one Cadillac (1994-96 Fleetwood). The reverse flow cooling was a big change but other than the bump to 10.5:1 compression ratio, produced very little benefit, and this "reverse" cooling style (heads cooled before block) was dropped in the Gen III LS1. The distributor (Optispark) is very unusual; it is driven by the camshaft and tucked behind the water pump. It is somewhat problematic and prone to water damage, but the later '95-96 "vented" style works better and aftermarket versions better still. The intake manifold is about as far from the TPI motors as you can get - it has larger but very short runners which produce a higher RPM range and a much flatter torque curve than the tractor motor curve of the TPI.
The Y-body LT1 always got 4-bolt main bearing caps (the other's all had 2-bolt mains), but the 1992 Corvette's LT1 is unique in one key way. The TPI motors (1985-1991) all used a crude form of Fuel Injection called batch fire port injection, and used a Mass Air Flow meter to meter incoming air into the engine. These early MAF designs used a circuit board that was in the airstream and were problematic from day one. The 1993-96 Y-body and 1993-97 F-body LT1/4 engines went to a more modern hot wire element MAF with the electronics housed outside of the airstream. But for the 1992 Corvette (and 1993 F-body) this new EFI system wasn't ready and for one model year only GM went with a speed density air metering system (no MAF). This uses Manifold Pressure Sensor along with a atmospheric pressure sensor to read incoming air. This lack of a MAF means a lack of a restriction in the airstream for that one year - and the 1992 model ran the strongest of all of the LT1s in stock form.
The manual transmissions used in the early C4s (1984-88 models) was a Doug Nash designed "4+3" transmission – a 4-speed manual coupled to an automatic overdrive on the top three gears. It was designed to improve fuel economy but was mostly a steaming pile of crap. For the 1989-96 model Y-bodies, GM went to the Germans and they offered up the S6-40, made by ZF. It is an unusual transmission and parts are hard to come by, and shops have popped up like ZFDoc that specialize in rebuilding these brutes. This trans is nicknamed the "ZF6" and is big, heavy and very strong, if a bit noisy. With 6 speeds and 2 overdrives (.75 in 5th and .50 in 6th), it made for excellent fuel economy. The Borg Warner/Tremec copied these overdrives for the later T56. With the ZF6 tall 2.68 first gear, the "black tag" version is rated to withstand 450+ ft lbs of torque (and is much stronger with a modern carbon synchro upgrade). To quiet the noises, GM used a heavy dual mass flywheel, which tips the scales at over 40 pounds. The clutch is also strong and the Dana 44 rear differential out back is also a brute. The limited slip unit in these 44s tends to last decades... and I hope so because we're not touching it. The halfshafts are big beefy aluminum tubular units with U-joints (cheap to replace!) instead of CV joints, and the driveshaft is built the same way.
The body is fairly aerodynamic (low height, low drag, small front area) and works well at high speeds. The body panels are made of fiberglass - which is good considering it has some chunks missing, and fiberglass is easy to repair. Some damned fool drove this car through a barbed wire fence back in its' checkered past, which damaged the front bumper cover and body panels on the left side. The driver's door was trashed but the replacement doesn't match the car's white paint well, so that will likely get repainted at some point. I will patch the fiberglass that is damaged myself and prime it for later repaint.
continued below
continued from above
Where Did This Car Come From?
So about 3 years ago an old friend, Brian Matteucci, wanted to build a NASA Time Trial car. He was a long time autocrosser and former SCCA W2W Club Racer and watched what we were doing in NASA. He liked the cost-to-seat-time ratio of the TT series of classes, which was why we were in it as well. I helped him understand the NASA TT rules as well as the confusing TT classing formula and points classing system. We bench raced several builds over a few weeks and came up with the C4. That was no accident - because we had both raced these in the past. My history with Matteucci goes way back to about 1989, when he was a racer in the Texas A&M Sport Car club racing in a notchback 5.0L Mustang... I was about a year ahead of him and happened to be racing the same exact type of car.
We were competitors and friends through college, both helped create a new and popular autocross class called Super Street Mod in 1990 (we used this class to help push the SCCA to create Street Mod), and were roommates after college when we both worked at our first jobs in Houston as engineers. He and I both used to love digging through rule books looking for ringer cars and rules to exploit. After college we both autocrossed C4 Corvettes for a time - he was in a 1987 Z51 while I raced a 1994 Z07, both in SCCA's Super Stock class. When his 87 Corvette's fuel pump died on day 2 at Solo Nationals one year he co-drove my C4 - and hated it. ;)
My 1994 Corvette Z07 running in Super Stock at Solo Nationals in 1998. It was on Hoosier DOTs but was otherwise bone stock
The differences between our cars was dramatic back then - at low speed autocrosses - but it was obvious to both of us that the LT1 was far superior to the TPI engines at higher speeds. Already owning a C5 Z06, when he suggested a letter class TT build 3 years ago I immediately suggested another Corvette, but one that was a 100% dedicated, no-compromise race car build. Jason and I here at Vorshlag had often talked about the TTC classing of the late C4, and after some discussion with Matteucci, he agreed that it had a lot of potential in this class. He went out and bought this mess for $3000, sold off the interior bits for $1000, and had a $2000 platform to build a TT lettered class car from.
During the next 2-1/2 years Matteucci proceeded to strip hundreds of pounds out of this car and replaced lots of broken OEM bits (24 years can take its toll on anything), while testing it at various autocross events along the way. He did this while he was very busy with work, building a new house and shop, building a chump car, and autocrossing his C5 Z06. In December 2014 he got to a good stopping point and I bought the car for a great price - along with a promise to let him co-drive the car with me in NASA TT. Amy and I did that last year and it was a good way to get us both out on track for less money spent - which fits this project well.
With our "Team Vorshlag" entry we can both drive the car for one entry fee, doubling the chances for a fast time (two sets of eyes and brains are better than one). Matteucci worked at Roush Engineering for several years, and while there was responsible for building and developing a fleet of Bonduraunt school cars when Ford was their supplier in the 2000s. He lived at the track for many months, driving these cars for hours every day, so he's no stranger to finding a good track set-up: he was paid by one of the biggest engineering/racing companies in the world to do just this.
Left: The factory power steering cooler is a huge double-pass unit. Right: I pressure washed underneath to help find an oil leak
Last but not least, Matteucci was also the designer of our first three initial camber plate designs when he started Motor-Force Engineering back in 2002. We bought his company (and IP) back in early 2006 and several of the current Vorshlag camber plates can trace their roots back to his initial designs. Other than some manufacturing aspects and tweaks to materials and coatings, they are for the most part unchanged. So he has a long history with me and Vorshlag, whether he wants to admit it or not, heh. When I picked up the car on December 20th I gave him a bunch of Vorshlag swag, which was part of the deal with the car - he has to wear this stuff at the track, especially if he is the one who gets the wins!
TT Classing Looks Solid
So if you look at the NASA TT (and PT) classification for Corvettes something jumps out at you (go to page 20 of the TT rules) - most Corvettes either require a dyno test for an initial base classing (C1-C3) or are just shoved straight into TT1/2/3 numbered classes (C5-C7). The lone exception is the C4 generation, which has 5 separate letter class listings:
MODEL........................................BASE CLASS...... MIN WT
Corvette C4 ('85-'91)............................ TTD**......3223
Corvette C4 ('92-'96) (LT1)................ TTC*.......3203
Corvette C4 (LT4 option) (330 hp)...... TTC**......3350
Corvette GS ('96).................................. TTC**......3350
Corvette ZR-1 ('90-'95).......................... TTB*........3500
While the TTD entry for the 1984-1991 "TPI" Corvettes might look the most attractive place to start at first glance, the minimum weight is higher yet they make a lot less power (230-250 hp) than the LT1s. With two stars it is already -14 points out of 19 in TTD class, and strapped with TTD's 245mm base tire size, so it would be nearly impossible to stay in TTD class, meaning it would need a lot of work to be competitive in TTC. Of course upclassing adds 20 points to play with, so it might make the 12:1 power to weight ratio of TTC, with some dollars and points burned on engine upgrades. The two LT4 powered cars (all 1996 6-speed cars and the '96 GrandSoprt) have an extra star (-14 points in class) and extra 150 pounds of minimum weight, but the only advantage being +30 hp over the LT1 it is not ideal (plus they are worth more money used). Likewise the ZR1 has +300 pounds more minimum weight (and boy were they heavy!) and its up a class (TTB) and has one star (-7), plus these are somewhat rare and pricey, and expensive to maintain and upgrade. Yuck.
So the lighter, rugged and simple 1992-1996 LT1 cars are really the best bet, in my mind. TTC seems like an odd place to class the 1992-96 LT1 Corvette - and it might well be, but it is pretty old and I doubt many (any?) have been competitively run in NASA TT or PT. We shall soon find out if this base class makes sense, because that's where we are going to run it.
TTC 1992 Corvette Build Basics
While several folks guessed we would be building a "C4 in TTB", nobody guessed the TTC angle. And why would you? With the base classing of TTC* we only have 14 points to play with in class, so how could it be as "fast" as I predicted? For one, it doesn't need any points spent on power mods to meet the max power-to-weight ratio, as it will easily make the 12:1 limit for the class. So we save points there. How do I know? I owned a nearly identical 1994 Corvette that I had dyno'd on a modern DynoJet, where it made 277 whp in bone stock form, back in 1996 (these cars were a hair under-rated at "300 hp" crank). Another TAMSCC racer (Mike Mclure) owned a 1996 LT4 Corvette and dyno'd it at 308 whp the same day on the same dyno (also under-rated by the factory). If you know your dyno numbers, you will see that the LT4 makes almost exactly what a stock LS1 makes in a C5 (~310 whp), and the LT1 just a little bit down on that.
Left: The 12" front brakes are adequate but can be upgraded to 13" rotors "for free" (no points). Right: The ABS system is ahead of its time
The factory brakes are also ahead of other cars from this era and not much if any off of the C5. GM developed its best ABS systems on the Y-body and this 1992 model has one of the best of the generation. And while the 12" diameter front brakes seem a little wimpy on the Base Trim Model, which this car has, they aren't total junk. The calipers are twin piston floating PBR units, a cast aluminum design used on the Y-body, F-body, and even the SN95 Mustang Cobra, to name a few. We have found a way in digging through the rules and Base Trim Level of the 1992-96 Corvettes to upgrade the discs to thicker, 13" diameter discs for zero points (more on that soon), so that saves us points and only costs a few dollars.
We will show better suspension pics in the next update, but these will do for now
Suspension is very advanced for the time period, and better than what many of us race with on brand new cars from today. Forged aluminum uprights at both ends pivot on double A-arms up front and a multi-link rear IRS. Both ends are sprung by a composite transverse leaf with factory monotube Bilstein dampers. Other than some freshening and an alignment we're going to leave that pretty much alone.
Last up is the tires. The late C4 was designed to house massive wheels and tires (factory used 17x9.5" on almost all packages and up to 17x11" out back). While we won't be making flares to house big wheels, which is kind of one of our "go to" first mods, we will blow almost ALL of the available class points on tires (more on that next time).
Why not bump up to TTB? Sure, we think this car could be just as competitive there at this class' more aggressive 10.5:1 pounds-per-hp ratio, but it would allow for a lot more mods, and that costs $$. The goal of this is to keep costs down, but with +20 more points to play with after upclassing we could easily spend an extra $10,000 chasing down the points and the top cars in TTB (S2000 + E46 M3). While this would be fun, that's not our goal for the 2015 season. We want to instead focus on the "free mods" that TT allows as well as spend our precious 13 points as wisely as we can, as well as show some of our best "race prep" and safety upgrades - that are the same for virtually all classes.
In the next post we will sow our first few mods - brakes and shocks - that are both zero point upgrades. We will also show our first point mod and show the behind the scenes upgrades and race prep.
What's Next?
I always close my build thread posts with a teaser for the next entry. Well we haven't done much to the car yet, so there's still a lot of track prep to knock out. We did order OEM replacement brake parts and shocks, all zero point upgrades which I will explain in my next post. The next biggest things the C4 needs before the first event are all safety related.
In early 2014 our crew here built the cage and did all of the fire/safety/lighting upgrades for a 1987 Corvette convertible that was initially run in Lemons and Chump but lately has been competing in WRL series endurance events (also known as - the Poorvette). We learned a lot working on that car that will apply to this TTC build, of course. One of the items we will replicate on our car is the roll cage, but due to time constraints (3 weeks to go!) before the first race we will only make the main hoop, harness bar and rear downbars (4 point roll bar) for now.
We will go back and complete the full roll cage structure this car after the first event, to make everything safer (and to add some more ballast weight). Unlike this black 87, our 92 C4 has a roof - but its just a bolt-on targa panel, like all hardtop C4s. That removable roof panel makes it easier to build the cage and provides some aerodynamic advantages over the drop top, but the rear (glass) hatch main roof support structure will still be in the way and make this one a bit more challenging to build.
Left: This is the seat we'll be using in the TTC car. Right: An adjustable seat back brace is visible in this pic
Another area that needs some attention fast is the seat mounting. The OEM seat that came with the car BROKE at an autocross event, which Matteucci warned me about ahead of time. We bought this Kirky 56700LW aluminum seat (see above left) for the Poorvette, but the driver wanted something different so we were stuck with it. This TTC4 project will get a lot of those cast away parts, some of which are brand new. Since the seat is a touch on the big side (17" width) we will make a poured foam seat insert, as well as a seat back brace tied to the cage (see above right)
Due to the weird floor structure of the C4 chassis (some parts are composite and some are sheet metal), and some damage from a previous owner (aka: the Crack Head that tore up the interior and drove through the barbed wire fence), we need to repair and reinforce the floor areas. These cars are tricky to safely mount a racing seat into, as well as ballast plates, both of which we will need to do. The car is already 200 pounds under minimum weight (including a 200 pound driver) and that will only worsen as we (legally) replace OEM body panels and rear glass with lighter weight alternatives. We will run this car at the 3203 pound stated minimum weight and NOT burn points on running a lower weight. Running lighter might seem advantageous but we would have to lower the power output as well (the 12:1 ratio doesn't change for TTC class even if you burn points to "run lighter than minimum").
Two zero-point mods Matteucci already added include the Moroso 20185 road race LT1 oil pan (allowed under TT rules, page 36), which at $288 includes more capacity, a Kicked-Out Sump and Trap Door Baffling for improved oil control, built-in Windage Screen and a port for an oil level sensor. The QuarterMaster 7.25" triple disc clutch ($599) and flywheel are also zero point mods (see page 36) and knocked nearly 50 pounds out of the drivetrain mass. It makes this little LT1 rev quite nicely and shift very well at speed - but driving it around at low speeds is a BITCH and it unlocks a LOT of transmission noise. Don't have accurate pics of these mods yet, but when we take them apart I will get better images and weights. I will include these "zero point" aftermarket part upgrades costs into our build budget, below.
Budget to Date
I don't like showing what I paid for cars, so for the purchase price shown is what Matteucci paid for the car three years ago (he bought it well!) - which was a running, full interior car but fairly rough inside when he got it. He cleaned it up a lot and I've cleaned it up further (spent about 8 hours detailing it this past weekend). On any OEM replacement parts we swap out I will show a "common street price" for what we use. Instead of showing labor costs I will show the logged hours spent on each task + material costs on anything we fabricate. The safety gear will be shown separately, as this is all entirely optional in a TT car, but still important to keep account of. The goal is to spend at or below $7500 for the car + performance upgrades + materials + one set of consumables.
Car Purchase: $3000 Recouped into budget: -$1000 for interior Quarter master clutch: $599 Moroso oil pan: $288 Kirky racing seat: $0 (safety upgrade, $328 retail) Total Spent so far: $2887
That's all for this time. I will post another update before the first race, January 17th at MSR-Houston, where we will debut the car in NASA's TTC class with me and Matteucci at the wheel. That's assuming everything goes smoothly! The next update will show some actual work being done besides my initial clean-up, and I will also lay out more of our game plan for the season, including which tires we plan to run with. They are 30mm smaller the stock size, but it will make sense why soon.
Cheers,
Terry Fair at Vorshlag Motorsports
OK, I found some software to do a lot of "replacing" of normal code with the format this forum requires. That took half an hour to hack apart. The double "side-by-side pictures never will come out correctly on this forum. They look correct in the PREVIEW but always "stack" in the final post. Close as I can get. There doesn't seem to be an "underline" function so that was just bolded. Good enough...
Thanks - Terry @ Vorshlag
Thanks for the information. What do you think of the deep wrap around bolsters of a circle track seat (kirkey 56lw type) vs the smaller side bolsters and shoulder support of a "road race" seat (ultrashield rallysport style) vs a drag race type seat with the shallow bolsters and no shoulders (ultrashield spec Miata)
Thanks keep up the good work.
You'll need to log in to post.
