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[Function And Form] Sleeper DIY 10-Second Turbo C3… Part 15

Carl tries to choose between the BMW DCT and 4L80e transmissions, and makes his first quarter-mile pass!

As we wrap up the final episodes, can Carl get this beast into the tens, and which transmission will his first pass be made with? If you missed any previous episodes for Carl’s 10-second turbo build, (or need a review), here are the links: part one, part two, part three, part four, part five, part six, part seven, part eight, part nine, part ten, part eleven, part twelve, part thirteen, and part fourteen. Each episode is a quick read, with lots of pictures.

Bonus Feature: Compilation of Carl’s videos at the end of each episode, including the first drive!

Viewer Advisory: This build has some serious meat on the bones, as Carl has some crazy technical skills (especially with electronics), and he is going to tap into all of them to turn his 1977 Stingray into a 10-second quarter-mile monster!

When we left off, Carl fell in love with the idea of having a BMW DCT transmission in his 10-second build, noting “DCTs are 7-speed, electronic, dual wet clutch transmissions with almost instantaneous shifting. Shifting can be slow and soft for cruising or quick and aggressive for racing.”

As Carl still wrestles with which transmission to use, he starts to see if the BMW DCT will even work. First, he pulls the starter out of the Vette to do a test fit in the DCT, and says, “It doesn’t fit. Needs some metal removal from the transmission. The adapter ring is ok. The starter needs about 11-12mm clearance.

The work begins.

Carl gets the marker out
Then he uses a cutoff wheel to make the clearance
And now the starter fits fine

Carl pauses the BMW DCT mock-ups for now, and decides to stick with his tried and true 4L80e transmission as he heads to the track for his first quarter-mile run! Here is a comprehensive summary of his first track day:

Tech folks said I had to limit my runs to 11.0 because aftermarket power adder cars, in addition to roll bar stuff, need a scatter shield and an aftermarket harmonic balancer to dip into the 10s. That wasn’t a problem for me since I only wanted to do some shakedown passes and logging and tuning… The track was relatively empty. I get in the staging area and my lane is already moving, so I rush to get everything on and didn’t have enough time to get the logging set up.

First pass was with 21psi on the Mickey Ts. 4 psi target in first gear and 7psi target in 2nd and 3rd. I’ve never tested the burnout mode transition to drag mode before, so I was looking forward to seeing if it worked as designed. Touch screened to burnout mode, first thing the touch screen did was remind me that I hadn’t put the shifter into 3rd (keeping the shifter in 4th or OD is dangerous in a 4L80E at the track. drums spin faster). Shifted to 3rd, hit the line lock, pumped the brakes a couple of times and did a perfect burnout. Burnout mode is programmed to only upshift to 2nd. At the end of the burnout, the touchscreen automatically changed to drag mode.

Light turns green, I take off. I never matted the pedal. The car seemed to have a lot of power just pedaling it at partial throttle. So I got off the gas and onto the brake before the 1/4. I never had this car over 85 before, so it felt fast. Here’s the time slip.

So, without further ado, what did Carl run on his very first pass?

Well, with only a 13-second pass was Carl happy? He succinctly remarks, “Great first pass. Everything working as planned“, then goes on to do a second pass, but this happens.

On his second pass, Carl kept the same boost settings, got a good burnout, and while shifting into second gear heard a bang that sounded like the driveshaft and pulled over to the shoulder. As you can see, all five studs were sheared off. Thankfully there was no damage to the Vette, and after investigating the cause his course of action was clear:

(1) Replace studs with a larger size, (2) Re-do the hub-centric to directly fit the wheel and put a lip in it so it can’t move, and most importantly, (3) check the lug nut torque more often on the street and every single time at the track…”

On our final episode next week, Carl makes his decision on which transmission to use permanently, then takes a handful of quarter-mile passes in his quest to hit the 10s. Will he succeed? We have the fastest-growing Corvette community on our Facebook page, with over 161,000 followers (42,000 since January!). Come join other hardcore enthusiasts and let me know what you think so far of Carl’s 10-second turbo build, Douglas B.

Video Compilation

Video 1

From Part 2

Video 2

From Part 3

Video 3

From Part 11