View Single Post
Unread 01-05-2016, 03:17 PM
Fair!'s Avatar
Fair! Fair! is offline
I blame the internet
Join Date: Jul 2004
Posts: 6,081
Default Re: Vorshlag Budget TT Build: Project DANGER ZONE

continued from above

That's where I had Olof place the inlet ducts. "Just drill a 3 inch hole and bolt them in right there", I told him. The inlets are directly underneath the factory headlight holes, taking in high pressure trapped under the nose that isn't being fed to the radiator inlet. There's ample room under the hood (with the flip-up headlight assemblies gone) to route the hoses up and over to the brake backing plates.

Due to concerns Jason and I both had about air pressure bleeding off laterally towards the edge of the nose and bypassing this brake cooling inlet, I had Olof make a little aluminum "brake canard". This is a little air dam that forces some air into a closed pocket to feed the brake inlet. Yes, I know this might incur some aero penalty for TTC. We are going to test with and without these in place and we will add rivnuts in place of the rivets used to attach these little air walls, so we can test with and without them installed.

The brake hose routing looks fairly straightforward, but of course we haven't tested it on track yet. It might rub the wheel at full lock, but since the car is still in the air with the wheels off we haven't checked that yet. A piece of the plastic inner fender liner was trimmed to route the 3" hose below the top of the wheel, but we will see how it fits when the wheels and tires are mounted and its back on the ground.

Last but not least the car is getting a new set of factory lower air dam plastics. Again, we bought these many months ago just never got around to it. The old bits are beat up and the left sides is held on with Gorilla snot and is half falling off. The new air dam bits will help push more air into the waiting duct for the radiator or the two brake inlet ducts.


Another piece I had purchased way back in January of 2015 that never made its way onto DangerZone was a pre-formed and pre-cut polycarbonate rear hatch from Five Star Bodies. This 1/8" thick, pre-trimmed, formed rear plastic glass was to replace the 46 pound OEM glass rear hatch section.

Removing weight was the primary goal, but with our new 2016 minimum weight numbers going up now this might not make as much sense.

Of course we did this before the new weight numbers came out, heh. Oh well, being able to move weight from up HIGH (stock glass) to down LOW (ballast) is always a good thing. I'm eyeing that 80 pound hood as well.

Once the glass was removed from the factory hinge at the back of the B-pillar factory roof structure, Olof drilled two matching holes in the trimmed-to-fit and pre-bent Plexiglass. Then he built a frame to give it some support at the lower front corners out of thin wall 1/2" tubing. The two Quik-Latches just arrived and those will take the place of the (broken) rear hatch release. Now we can get into the rear area without crawling through the cage and yanking the emergency release cable in the back.


So if you've read this thread before you know we had some trouble with the original 1992 ECM (Engine Control Module, or computer) after the rebuilt motor went in, that caused us to miss our last NASA race of the year - the car wouldn't start reliably. After days of diagnosis and parts chasing we had finally realized it was a bad ECM. Well we cannot find a new 1992 ECM, anywhere on the planet. 1992 Corvettes had a "one year" ECM - 93 was different, 94-95 was different again, and 96 was also unique. There are no 1993 ECMs left either, but back in October we found plenty of 94-95 Corvette computers available, both new and rebuilt, and our tuner said the later computers were easier to tune for track use. So the quest to convert this to a 1994-95 EFI harness was underway in October.

Instead of trolling junkyards for 20+ year old Corvette engine harnesses, which will bound to have some cracks and wiring breaks, we had a new one built using our 1992 OEM wiring harness for layout. We found several breaks in the existing 1992 harness already - which makes for nightmares when diagnosing EFI issues and the way this one will be built will be the perfect OEM replacement - 100% stock in form and function, just not with 25 year old wiring and broken connectors.

We had to find 1994-95 MAF, intake tube and other small parts to convert this car fully

We are trying out a new harness supplier, but they assured us it will be identical to an OEM 1995 Corvette harness and plug in, no issues. As long as it mimics the OEM harness and we use an OEM 1994 or 1995 ECM, this should be a zero-point change, as all 1992-1996 LT1 Corvettes are listed on the same line.

The harness took a few hours to label the connectors (any emissions or cruise control related connectors will be removed, which again, is legal for TT-Letter) and disconnect everything all the way to the ECM and firewall, and even some bits that went down to the ZF 6-speed. We should hopefully see the replacement harness by the end of this week, which will give us just one week to get the engine dyno-tuned again before an upcoming track test at MSR-C on January 16th.

That's what the engine bay looks like now, above left. The 1992 harness was been shipped off weeks ago (they have to re-use some connectors, which are not being made any longer) and it will look like the 1994-95 engine bay soon (above right). We already have an OEM replacement MAF and intake tubes, shown there. Luckily this 1994-95 stuff is available and not costly (new Delphi MAF was about $100).

I will show this all wrapped up and hopefully running well again in my next post.


Since this was only a partial update I'll have another that will show the completion of all of the above work (hopefully) posted after the next NASA event. That assumes a lot of things happen in a timely fashion over the next 2 weeks and that our test at an SCCA Club Trials event goes off without a hitch.

Sadly these were the only two tracks we ran the Corvette at last year, but we'll be hitting them back-to-back weekends in January 2016. This time the car will have a newly rebuilt engine, no fluid leaks, better engine and brake cooling, and hopefully some reliability. There were major issues with the C4 at both tracks in 2015 - a leaking rear seal at MSR-H kept us to 1-2 lap stints before we were black flagged, and oil smoke from a worn out engine kept getting the car black flagged at MSR-C in one lap or less. No more of that nonsense!

We ran a 1:43.7 lap at MSR-H in 2015 (still the TTC track record) and hope to better that by a good margin this year. We never got an official time in TT at the MSR-C event but, but I did run a 1:25.0 in the TT Warm-up session, which was my only complete lap of the weekend in that car. That was 2 seconds faster than the old TTC record at the time, but another TTC car reset the record on Sunday to a 1:24.424 (Mark Schnoerr's E36 M3). Hopefully #DangerZone can go quicker than those times at both tracks? The SCCA Club Trials event doesn't really have "classes", per se, but it will be a good practice for when NASA comes back to this track in March 12-13, 2016.

That's all we have planned so far for the 2016 season - after the January SCCA and NASA track events we will see how we stack up in class for the year and go forward from there, either with refinement or possibly even changes to move to a new class (if the added TTC weight is a big hindrance). We will also have Amy's red 2001 BMW 330Ci at these two events, which is the new #JackDaniels TTD classed E46. For the C4 we have to have the rebuilt harness installed with a 1994-95 ECM (of course now there are none to be had, ugh!), the engine re-tuned to work with the 94-95 MAF, the Plexiglass rear hatch painted and latched, the front brake ducting wrapped up, and maybe some other small changes if there is time. Check back in a few weeks to see if some what happens...

Reply With Quote