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Speed Week 2016: Changes to the Challenger 2

Economists, in case you haven’t noticed, tend to get things wrong a lot. Anticipating this, they like to end their formulations with a particular latin phrase—ceteris paribus—that basically says, “Hey, if this thing doesn’t work out, my numbers weren’t wrong, the world was wrong.” The literal translation, roughly speaking, is “all else unchanged,” and it’s actually a great way to go about building a fast race car. If you only make one change in-between runs, it’s easy to isolate the precise effects of that change. By taking this slow and steady approach, you’re able to avoid the classic mistake of fixing something that isn’t broken, and you don’t end up with the racing equivalent of New Coke. 

But here’s the thing. We’ve been rained out for two years in a row, and we’ve had a lot of extra time on our hands. So we ended up making five major changes and some other minor ones. Is this the most conservative approach? Absolutely not. But what can I say? No one has ever accused me of behaving like an economist. Here’s the rundown on what’s different for the Challenger 2 in 2016:

Clutch Package:
This was the only mandatory change. The original clutch layout didn’t allow for enough free-play travel in the candlesticks. Each run caused them to wear slightly, which eventually resulted in the blowout we experienced on our 419mph backup pass. If you’re trying to picture the problem, imagine only letting the clutch of a street car halfway out while slamming your other foot down hard on the accelerator. You’ll definitely go forward, but there’s going to be a lot of heat, and probably a burnout. We fixed the problem by repeatedly re-machining the original parts, eventually removing a total of .625 thousandths of material. This increased clearance should prevent component rub going forward. 

Gear Ratios: 
Unlike a lot of the other cars that race Bonneville, the Challenger 2 runs dry blocks. Their optimal power band is somewhere between 5300-5600rpm. Last year, when we exited the final speed trap at 424mph, our computers measured both engines at closer to 4700rpm. We’ve modified the gear ratios in order to boost this number. This should result in faster overall acceleration, which is absolutely essential on a fixed length course, because we only have so long to get up to our maximum speed. 

The Shocks:
We didn’t experience any problems with excessive lift last year, but it remains my biggest safety concern. The Challenger 2’s shocks are custom made for us by King, and we worked with them to change the rebound control to keep the front end sucked down as much as possible. This was more of a fine tune, but it also gave me a chance to add a blow-over light to the cockpit. What’s that? A potentiometer monitors the position of the shocks and tells our RacePak data systems what changes are occurring to the car in terms of ride height in real time. If that number increases past a certain threshold while the car is going over 300mph, a bright red light on the dash will start flashing, letting me know to cut the engines (and hang on). 

It’s hard to see unless you know where to look, but the Challenger 2 now has wings. Or winglets at least. We’re talking inches rather than feet. Two small front canards, one of either side of the nose, should provide additional downforce to the front of the car. For the rear, we’ve added an under tray. This will create a zone of negative pressure, helping to evacuate mixed-up air from the sides of the car. Why is that necessary? The exhaust from our headers is confusing the air flow in that area a bit more than our aerodynamicist, Tim Gibson, would like. This should address the problem. Finally, we added some reverse louvers to the bodywork in order to expel more of the internal heat generated by the engines. It was getting pretty warm in there, and we didn’t want to risk damage to the electronics. 

We increased the percentage of nitromethane in the blend being fed to the engines by 5%. That means we’re now running 80%. Vroom vroom. 

That’s where things currently stand in terms of the car as we pack up for Speed Week. There are some other changes of course, including replacement of all the decals with hand-lettered artwork from Dennis Jones. Listed below this post you’ll find the scheduled dates for the 2016 Bonneville season. We’ll share more here as we get closer, but in the meantime you can follow us on basically all forms of social media with our crew handle, thompsonlsr. 

2016 Bonneville Dates:
- SCTA Speedweek August 13-19
- USFRA World of Speed September 10-13
- Mike Cook's Shootout September 15-20
- SCTA World Finals September 27-30

Dave Despain Show Appearance

Danny will be Dave's guest on tonight's episode the of The Dave Despain Show on MavTV. It premiers at 8:30pm ET/PT, and will repeat later in the evening. A teaser is embedded below. Be sure to check it out!

2014 Year in Review (Video)

As you've probably heard, the 2014 Bonneville World Finals were cancelled do to rain. It was our last opportunity for a full course record pass, which means our plans will be delayed until the 2015 season. Were we disappointed? Absolutely. That said, 2014 was a tremendously successful year for us. As far as we can tell, we reached the 400mph mark faster than any other piston car ever. To celebrate that, our friends at Mickey Thompson Tires put together this fantastic video. See you next season! 

The Challenger II Will Run at Bonneville World Finals (edit: Cancelled due to Rain)

Hi everyone. I'm pleased to announce that the Challenger II's final runs of 2014 will take place at the SCTA's World Finals event in Bonneville, Utah. The meet begins Saturday, Sep 27th, and goes until Friday, Oct 3rd. This year's competition has been expanded to a full "Speed Week" size event, and should be a great capstone to what has been a fantastic opening season for the restored and updated Challenger II.

The car has only run three full course passes so far, but has already achieved a speed of 419mph. We hope to keep building on that strong foundation to set a new AA/FS record before the end of the season. That said, we are well aware of just how difficult that is, and will continue with the steady and methodical approach that has served us well up to this point. 

I'd like to take a moment to thank all of our major sponsors, including Mickey Thompson Performance Tires, Galpin Ford, Hoenig Concrete Plants, and Airaid®. I'd also like to extend my sincere gratitude to the many other companies and individuals who have supported our efforts through product consideration or individual contributions. A full list is available here. As always, the project is hungry for addition funding. If you'd like to contribute personally, or know a company that would benefit from the unique exposure we can offer, please have a look at this page.

Finally, the project has been generating a lot of attention across all forms of media. If you missed out, Ann O'Neill wrote an amazing piece for CNN, Deepa Bharath put us on the front page of the Orange County Register, and Hot Rod Magazine did a great in depth profile of the project. And that's just the tip of the iceberg.

Thanks for sticking with us!

Danny Thompson

World of Speed Update 4: Bad News

Hey guys. This is a relatively short entry that will be updated with more detail tomorrow evening. The short story is that we didn't get the record. The car left the line harder than it ever has before. It was a rocket ship start, but when I hit 6000rpm, one of the clutches failed. The car dropped into neutral and I navigated safely away from the course. We're very disappointed, but not discouraged. This would have been the car's third full run ever, so it's still early days. We haven't had any major issues up to this point, which is sort of a miracle in this sport. 

The initial plan was to fly in parts for Cook's Shootout, which was supposed to start on Friday, but I'm hearing that it may be postponed a few weeks. If that is the case, we'll head home and prep the car for more runs next month. I'll keep you up to date as I learn/figure out more. Thank you for all the support. 


World of Speed Update 3: 419mph

What a great day for the Challenger II and the whole THOMPSONLSR team. As of this moment, we have qualified for the AA/Fuel Streamliner record. We averaged 419mph during the final mile and went a bit faster out the back door. To make things official, we have to back up today's run tomorrow morning. If we are successful, we're in  400mph club and the record books. 

We started out a little later in the day than I would have liked, which gave the salt time to warm up and soften. That said, the surface was much better than yesterday, and the car felt more composed during the run. Going that fast that quickly was an unbelievable thrill. The mile markers were blazing by.

The streamliner is currently in USFRA impound. We got four hours to work on it after the last run and we used every second of it. I'm delighted to report that everything checked out well. The engines were strong, the fuel system is holding, and the tires are ready to roll. We've got a lot of work ahead of us, and getting the record is by no means guaranteed, but we're all feeling good and ready to go after the big number with everything we've got. 

More news tomorrow. See you then. 



World of Speed Update 2: 390mph

Boom! The Challenger II got to stretch its legs on a full length course for the first time since 1968, and boy was it exciting. The streamliner reached an average speed of 390mph, just a few mph shy of the class record. This was, in effect, the last of our "test runs," and we were able to prove that the dry block engines could survive a full five mile run. (And boy did they.) 

We had a few problems early in the day, mainly to do with our fuel setup, but we got them solved relatively quickly and lined up with the other cars. We've never actually gone over 300mph in an event before (only in testing), so we ended up in a lower speed line and had to wait out much of the day. That gave the sun time to soften up the salt, which meant that conditions were decent but not ideal. However, the car handled like champ, and we should be able to avoid most of those problems during our next run. 

We have a few changes to make tonight, but we're going to go back out tomorrow morning and see if we can exceed the current record and earn ourselves a spot in the 400mph club. Full speed ahead!