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PostPosted: Mon Jan 12, 2015 10:15 am 
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Wow. There's certainly a lot of testosterone on display throughout this "blog" (and did I really just see a cross section image of the earth?).
Hope you can make it to a SE regional event this year. :)

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PostPosted: Tue Jan 20, 2015 6:48 am 
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Project Update for January 16th, 2015: The first stage of "initial race prep" is completed and I'm going to try to write a QUICK update before we load up and I head down to Houston (in the next few minutes!) for the first NASA Texas event of 2015. We had a lot of parts delays but the crew at Vorshlag got everything on the "MUST HAVE" list completed. They only worked on this car over an 8 day period - due to other cars on the schedule. Big thanks go out to Olof, Ryan, Brad and Jon for all their hard work and long hours over the past week and a half. Thanks also to Jason and Tim for helping pick the mods and source the parts we used. Now all I have to do is drive the thing well... but I have a good back-up driver in Brian Matteucci, thankfully.

Brake Upgrade

The last week was a blur, as we had a lot going on in the shop with other customer cars, the phone rings off the hook in January (everyone waits until now to order parts for the new race season), and we're still gearing up for our new CNC machines - which has been a royal PITA. I had a birthday this week, and tons of other crap going on, and I usually work seven days a week playing catch-up on Vorshlag stuff on the weekends. But last weekend I stole a day away to swap on the front brakes.

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Left: The 12" front brakes are adequate but can be upgraded to 13" rotors "for free" (no points). Right: The two rotors in question

So the 1992-1995 "Base Trim Model" Corvettes all came with these wimpy looking front brakes, shown above. These include the 12.0" diameter x .810" thick vented rotor and PBR twin piston aluminum caliper, which I detailed a bit in my Dec 29th build thread post (post #5 for most of the forums). And I hinted that we would be able to upgrade from the 12" to the 13" rotor set-up for "no points". Normally this is a +2 upgrade, and we only have 3 total points left to play with. I'm saving those for later so we pulled the trigger on the correct rotors, calipers and caliper brackets back on Dec 23rd.

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The measured weights for the two front rotor sizes were pretty close to the spec sheets from Centric. Since nobody seems to want to work the last 2 weeks of a year in the USA, we didn't see these parts until late last week (around Jan 9th), and I started installing them on Saturday the 10th. The right front set-up went on fine, but I got bogged down cleaning the front suspension and wheel well...

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It was worth it seeing the beautiful, forged aluminum uprights and control arms after 45 minutes of brake cleaner and WD-40 plus some elbow grease got 24 years of gunk and grease build-up off of the metal. Be careful with brake parts cleaner as it is pretty aggressive, but it cuts through the thick caked on grease well. Once I started to see metal underneath I switched to WD-40, and used WD-40 only on all of the plastics and rubber seals. Decades of road dirt wipes off after a little soak with WD.

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Cleaning the gunk showed me a split ball joint boot, which we will replace in another round up upgrades later (along with all of the original, crusty rubber suspension bushings - which can be replaced with any non-metal bushings). The old bits came off easily enough and the new 13" rotor and longer caliper bracket went on. And yes, we gained a solid 7 pounds in the rotor upgrade, but its "good" weight. This is cast iron that can both soak up brake heat and more rotor area and vanes to help radiate brake heat. This car will be 3203 pounds with driver and ballast and that's a lot of mass to slow down for thin little 12" brakes at both ends.

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The 2-piston sliding PBR calipers (3.56 pounds) are familiar to me, as I've used them on SN95 Mustang Cobras and 3rd gen 1LE/B4C Camaros in the past, as well as on my 94 Corvette - which had the Z07 package and these larger "J55" option 13" front brakes. The J55 calipers are wider, and the J55 caliper bracket (2.56 pounds) is longer, but neither is much heavier than the "base" brake parts.

How are we getting to use the "bigger" J55 brakes from the Z51/Z07/ZR1/GrandSport models without points? Well the trick is this: all 1996 Corvettes models came with the larger J55 brakes, including the base trim model. And the listing for the car we have (1992 Corvette) is listed as 1992-96 Corvette (non ZR1, non-LT4). So we're updating to the base trim level brakes for the 1996 model car, since the 1992-96 cars are listed on the same line (again, not the 1996 LT4 or Grand Sport). We can also play around with swaybars and springs from the 1996 base trim model cars, which we might do later. Here's the rule that makes it all happen...

Rule 8.5, page 41 of the TT ruleset for 2015:

Updating of parts between different model years of the same vehicle model is legal provided that the competing vehicle is both in the same model group listing (same line) in the Table in 8.2.2, and in the same generation of that vehicle model, and that the entire assembly is replaced. Backdating of parts between different model years of the same vehicle model is legal provided that the competing vehicle is both in the same generation and is in the same or higher base class. No interchange of parts between assemblies is permitted in order to create a new assembly.

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Just like in SCCA Solo, this "update/backdate" rule can be exploited to your advantage. It takes a lot of research and sometimes rummaging in junkyards, but it is there as a tool for dedicated racers to use. It helps to have factory manuals as well, which we do (thanks to Matteucci).

Again, this is a simple bolt-on upgrade and we have to use OEM (or OEM equivalent) parts to make it legal. No 2-piece rotors, no aftermarket calipers, this is all real deal GM bits. The brackets are from GM and the calipers are rebuilt GM calipers. So getting the right front corner swapped to the J55 bits took less than half an hour. I added blue loctite to the caliper bracket bolts, torqued it all to spec, re-used the old brake hoses (we will make stainless lines when we have time) with new crush washers, installed new caliper retaining pin and E-clip, easy.

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Then a friend stopped by the shop mid-day Saturday and convinced me to go see the Interview at the Alamo Draft House. The movie was hilarious and I'm glad I went, but it put me behind on the right front brakes. No worries, I'll do it Sunday.... nope! Amy made me go write the eBay ad for our TT3 prepped 2011 Mustang, which I did then started writing the massive OUSCI 2014 write-up, which I finished today and promptly deleted (it was too harsh).

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So on Monday I came in and the guys were working on other items on the Corvette, so I got to work on the left front brake upgrade. As soon as I tried to put the left front caliper on, DOH! It didn't fit.

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The box had the correct J55 caliper bracket (which moves the caliper out for the 1" larger diameter) but the wrong caliper casting. It was too narrow by almost .300" and would never fit over the thicker rotor (.300" thicker). Crap. We had ordered the right parts, and the part number on the box from Centric was correct, it just had the wrong damned part in it. Oh well, stuff happens. We took these pictures, sent them to Centric, let them kno how urgently we needed the right part, and hoped for the best.

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Left: original Delco/Bilstein dampers. Right: New Bilstein OEM replacements went on

Luckily they got the right caliper to us just in the nick of time (Wednesday the 14th!). The OEM replacement shocks also arrived at the same time (also ordered in December and also very very late) and Olof and Brad got all of that installed when I was out running errands that day. We replaced factory base trim model "Delco Bilstein" dampers with the OEM replacement Bilsteins that were listed in our Bilstein dealer catalog. The two original rears were blown and the new bits matched up perfectly. These are non-adjustable and are considered replacement OEM dampers available, so they are a "zero point" install.

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We re-used the Carbotech brake pads Matteucci had purchased for the OEM brakes, which were XP12 front and XP8 rear. A little soft for my tastes but they were brand new so we will use them for this first event. We pushed some Motul RBF600 through the lines and it felt good. Too many other fires to put out to get to brake cooling this time around so we'll keep an eye on the fluid and Alcon temp strips at this first event.

Tires and Wheels Installed

The Hoosiers arrived this week Olof dismounted the 7 year old crusty 275/40/17 A6 Hoosiers that were on Brad's 17x9.5" SSR wheels. Then he mounted the 245/40/17 Hoosier R7 tires and balanced them. They did all that while I was at lunch one day and I didn't get to weigh the wheels without any tires, so I'll have to do that next time, but I can do simple math. Just weighed an old 275 Hoosier that was removed (22.40 pounds) and the weight of the wheels+old tires (38.76 pounds) that puts the 17x9.5" ET55 SSR wheels at about 16.4 pounds each. Not too shabby.

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The SSR wheels were a bit dirty so I cleaned 7 year old brake dust off of the inside barrel and spokes with more WD-40 and some elbow grease. The 245 R7 looks so tiny to me, after a season of using 345 A6 Hoosiers, but it doesn't look bad on the car.

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We will see if burning 10 of our 13 class "mod points" on tire compound was worth it this weekend. This is an experiment that could pay off big or fail miserably.

Roll Bar, Harness, Seat and Fire Bottle Installed

With only 8 days of shop time we were not able to build a full roll cage (that will be a 3 week job by itself) but Olof did manage to get the roll bar built, reinforced, and mounted.

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A big time suck on this job was making the aluminum cover plates. These are necessary on a fiberglass bodied car to cover the access holes in the body to the steel frame.

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Again, on a traditional steel bodied/unibody chassis car this step is not necessary at all. But its a Corvette, and has to be a pain int he ass. Olof used card stock to make templates (below) that cover the access holes, then transferred this into .065" thick 3003 aluminum sheet.

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The sheet was cut, bent and welded at the joints to make a box-like shape that fit the funky fiberglass tub shape and covered the openings with about a 1/2" overlap. Then a few holes were cut to add small stainless steel button head bolts and riv-nuts were added to the fiberglass (these are special ones we use just for fiberglass, with a different grip length than normal sheet metal riv-nuts)

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A silicone bead was added to the perimeters of the fiberglass and these four, somewhat elaborate aluminum covers were then set in place and bolted down. These will now keep water, dirt and debris from spraying up from the tires and getting into the passenger cabin. Olof did a superb job and they look great and fit tight around the roll bare tubes. These can be removed and the roll bar unbolted for when we go back and finish the roll cage. Similar plates will be needed up front at the additional 2 lower points of the 6-point cage design.

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We knew we were going to be WAY too light for the class minimum (3203 pounds) and would need anywhere from 90-200 pounds of ballast. On Tuesday we were getting a little tight on time so I asked Ryan to step away from a cage job he was working on and make the ballast weight bracket from some heavy 1x2" tubing. I was thinking of something basic but he made this beefy assembly with a slick, threaded top cap that fits over a 2" tube.

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For ballast I purchased new 45 pound "olympic" style barbell plates with a 2" center hole. Typically cast steel weights like this cost around $1/pound, which is what I saw at a few places like WalMart. But after doing some shopping I found the best price at Academy sports, who had a wider assortment of better looking plates to choose from. These 45 pound plates were $31 each, or about $.68/pound. Sure, you can slum around on CraigsList and maybe find some mis-matched weights for around $.50/pound used, but its very hit or miss. Save yourself some hassles and go to Academy. If you want something more compact you can usually buy lead for $1/pound at plumbing supply stores, but just wear a mask when cutting or grinding on this stuff.

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I didn't get any detail shots but the factory seat mounting studs (which are reinforced and rated for carrying up to 300 pound passengers) were used with some BIG bolts cut down on the lathe (and drilled/tapped to fit over the seat studs) go down from the top to secure the rack in place. You could pick the car up from this set-up and the 2" tube fits tight to the plates in sheer. At a minimum we will run 90 pounds of ballast here plus 120 pounds of fuel in the 20 gallon tank. Once we replace the 46 pound glass rear hatch with plexiglass we will add another 45 pound plate to the ballast box.

continued below


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PostPosted: Tue Jan 20, 2015 6:49 am 
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continued from above

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The factory seat mounts are reinforced with extra steel from the factory, but we added more. 1/8" thick steel plate wraps around the stock stuff and was stitch welded to the floor as well as wrapped around up into the tunnel and frame on the sides, where it is bolted or welded for more support. The harness anchors for the lap and anti-sub belts are from G-force. These eyelets allow the clip-in ends from a Cobra/Schroth 6-point Profi-2 harness to attach. These are my favorite harnesses and made by Schorth in Germany to FIA specs. This set has 2" upper shoulder straps to better work with he NecksGen HANS device I will be wearing this weekend.

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As usual, any "pretty" pictures you see here were shot by shop manager Brad with his Canon gear. The rest of the pics are from my "potato-cam" Galaxy S4 camera phone or my Nikon D90, which I can't seem to use worth a damn. The shoulder harnesses were wrapped around the harness bar tube with the proper wrap technique as specified in the diagram on page 42 of the NASA CCR.

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Last but not least, a 2.5 pound fire extinguisher was added. This is a small "Halotron" (Halon replacement) hand held fire bottle that can be used to put out small electrical, oil or grass fires and doesn't leave a big mess of dry chemical or foam residue behind. We add these things to every track build possible, even when they have a full fire "system" with multiple nozzles. No need to blow a big bottle when all you have is a little grass fire under the car after pulling off track into dry grass. We used the Drake quick release mount here, which we have used a half dozen times. CNC aluminum, roll bar or floor mounting with the same kit, and one pin can be pulled for fast bottle removal but it stays tight and rattle free when racing. Good stuff.

Weight Check!

Now you've seen how crazy I am about dropping weight and weighing everything in this and other build threads. Weight is the enemy! Lowering weight helps all acceleration vectors, be it braking, forward acceleration or lateral acceleration (cornering). We do a LOT to lower the weight on any race car build, and this car has gone from about 3300 pounds stock (we never weighed this car with the interior but that's what my 1994 Corvette weighed) down to about 2720 pounds. This weight drop was from lighter wheels, no interior, no passenger seat no side or rear glass, and no HVAC bits. The air conditioning compressor has been removed as have the headlights. The lighter wheels and tires help, too.

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Left: 2841 pounds with fuel but no driver or ballast. Right: 3200 with driver, fuel and ballast

We have added about 60 pounds in the roll bar and about 120 pounds of fuel (its nearly full) and the heavier J55 brakes and it was sitting at 2841 pounds. That's a solid 700 pounds lighter than our TT3 Mustang was without ballast or driver! Sadly we have to weigh 3203 pounds with driver (or else we have to burn points to run lighter), so ballast went back in in the above right picture to get us there. The plexiglass hatch should help remove about 30-35 pounds out of the 46 pound OEM glass, but it might not arrive in time, so we will save that 3rd 45 pound plate for then.

Classing Sheets, Dyno Test and Custom Tune

So we haven't built "letter" class car for NASA TT or PT before, but have helped a number of people class their cars. The base classing + mod points thing is nothing new to us. Just like TT# (numbered) classes, the TTx (letter) classes have an adjusted power to weight ratio. In TT3 the class has a 9:1 ratio but we were able to get ours to 8.8:1 with the adjustments. Likewise, TTC's base 12:0 pounds per horsepower limit has some adjustments as well, namely with a smaller tire...

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Using the 245mm tire has had so many benefits and this is just one more - we get a 0.8 ratio bump for this small tire. That might not seem like a lot, but when you are at 3203 pounds it is nearly 20 extra horsepower allowed...
  • 3203 pounds / 12 = 266.9 whp (267 rounded up, in favor of the driver)
  • 3203/11.2 = 285.98 whp (286 rounded up, in favor of the driver)

Which is a good thing, as it was going to be hard to only make 267 whp even with a dead stock engine, manifolds, cats and muffler. We had the car over at True Street Motorsports yesterday and they were able to coax 284 whp and 331 wtq out of this 24 year old, bone stock iron block LT1, through the stock cats, manifolds and exhaust. Not too shabby. It even sounds better after the tune.

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Above: Video of the stock LT1 motor at idle and revving, after the dyno test.

We have our dyno plot and classing sheet attached below. As you can see we've started with TTC + 7 penalty points, which left us with 12 points to play with. We got one back for running 245mm tires (-10mm below base class tire) for 13 points total. We burned 10 on the Hoosier R7 and still have 3 points to play with. We will be very stingy how we spend those this season, so stay tuned to see what we invest these points in to make Danger Zone faster.

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Left: The SAE corrected dyno plot making 284 whp. Right: TTC classing sheet with points

Last Minute Tweaks and Fluids

The Moroso oil pan for this motor is huge and the motor now holds 8.5 quarts of Mobil 1 synthetic oil (15W50 is my preferred weight for track cars), with a fresh Wix oil filter. Olof went over the car and filled out a NASA tech form but we still need to get a Logbook issued for the car at the event, so the plan is to leave Dallas early and make the 4.5 hour trek to south Houston on Firday and get there before dark. Then I can set-up the trailer, unhook, unload the C4, get the logbook tech and weighing, and make sure we have our ballast set correctly.

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I couldn't leave the massive openings in the hood where the pop-up headlights used to be so I asked Olof to make some aluminum brackets to bolt to the inner hood structure and to the existing holes in the headlight covers. Those went on and now forms a fairly seamless clamshell hood surface. The front turn signal and corner light assemblies were also reinstalled to fill holes. We will go back and make flush mounted aluminum covers later, when we have the time.

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Brad jumped into the Danger Zone this week as well and did a lot of wiring and some light fab work to the Corvette. He used to race a C4 himself and knows the car all too well. The wired AMB transponder from our TT3 car was moved to the C4 and Brad made some brackets for that, wired it up to a lighted switch (sometimes its handy to turn off the transponder - if we want to make another entry in the same car with the 2nd battery powered transponder we have). He also got the rear brake lights to work, after repairing some cut wires.

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He made an aluminum panel to mount the switch in the center dash area as well as the 3-port "power panel" shown above. This was a cheap Amazon.com purchase which arrived in only a few days for $31 shipped. This panel has waterproof covers over a 12 Volt cigarette lighter port, a volt meter and a stack with dual 5 Volt USB ports (one a high amp and the other a low amp draw - see detail image above). Very slick little package that should prove handy when it powers my onboard vidcam and AiM SOLO timer. I will report back with how well this worked, or not.

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The formed, lightweight, plexiglass rear hatch we ordered a week and a half ago arrived this morning so there's no time to fit it, so we reinstalled the OEM back glass. Order Desk Manager Jon wrapped the "ugly" mis-matched door with white vinyl. He also designed, cut and mounted graphics for our logos, "DANGER ZONE", Hoosier and Bilstein decals, and some class/number decals for all sides of the car.

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Its time to load up so I didn't get the final pics... tune in next week for the post race update to see the final look, or look for it on Facebook with this hashtag #DANGERZONE.

What's Next?

The only thing on my RADAR right now, outside of cutting metal next week on our new CNC machines (tooling is FINALLY here!), is the race this weekend at MSR Houston. I will be paddocked with Costas, Matt White and other friends probably near Turns 16-17.

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We are running MSR-H in the Clockwise direction this time (they alternate the direction for NASA events every other year), so I haven't run this track layout since 2013. The video above shows the lap record I managed in the TT3 car 2 years ago, on the skinny 315 tires. The lap record for TTC is currently a 1:50 but I think we might be able to manage a 1:46 if everything manages to stay together on the car...

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http://www.nasa-tt.com/Texas_Track_Records/p2046_articleid/11

We have a pretty crazy class lined up: Our 92 Corvette, a 2003 Mini Cooper S (fully race prepped) and a 2005 Mazda RX8 (fully race prepped). Talk about an odd mix... and we will once again be the heaviest yet most powerful car in class, just like we were in TT3. I will post up more details after this weekends race. Until then...

Cheers,

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PostPosted: Tue Jan 20, 2015 1:43 pm 
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Nice to see someone breathing life into a C4. That said, it reinforces why pretty much everyone just gets a C5.

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PostPosted: Tue Jan 20, 2015 3:39 pm 
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Cobra4B wrote:
Nice to see someone breathing life into a C4. That said, it reinforces why pretty much everyone just gets a C5.


The issue with C5s in Time Trial is that they go straight to the TT# classes, which can be a major expenditure just to tread water. The C4s are classed in TTD and TTC which allow some budget conscious builds to be competitive.


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PostPosted: Tue Jan 20, 2015 6:27 pm 
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Good point... we did get screwed out of PTA. I've spent a good $10k since :(

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PostPosted: Wed Jan 21, 2015 1:14 am 
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Fair wrote:
2003 Mini Cooper S (fully race prepped)


Uh, not quite race prepped. I had to remove the baby seat from the back before I put it on the trailer. I drive this thing to work. I even still have heated seats.

Congrats on the great lap on Sunday!

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PostPosted: Wed Jan 21, 2015 7:21 am 
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284 against a 286 limit is living dangerously... fits into the project nickname though

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PostPosted: Wed Jan 21, 2015 9:47 am 
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Right at the hp/wt limit and flat/peak torque of ~330lb-ft from 2k rpms?...wow. This car may very well be unbeatable. I need to watch my mirrors as from the sounds of things this car is only going to get faster. Kudos Terry!

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PostPosted: Wed Jan 21, 2015 9:59 am 
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PoBoyR6 wrote:
Right at the hp/wt limit and flat/peak torque of ~330lb-ft from 2k rpms?...wow. This car may very well be unbeatable. I need to watch my mirrors as from the sounds of things this car is only going to get faster. Kudos Terry!

Nah, you crushed it in TTB and were a solid 3 seconds quicker than Danger Zone! Nicely done.

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That new helmet livery you had was MONEY. Liked the fade from checkers to maple leaves, left to right. 8)

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