Rob Dahm: What It’s Like to Race Ken Block’s Hoonicorn and Almost Win

How do you break in a project car? Is it a few light hits at the dragstrip? A collection of restrained, big-toe-only cruise miles? If you’re Rob Dahm, you line up next to Ken Block’s physics-defying Hoonicorn, buckle your tuning lap top into the passenger seat and turn the amp to 11.

If you’re not in the loop, Rob built a wild, one-off, turbocharged, 4-rotor Wankel engine and stuffed it between the fenders of an equally wild, tube-chassis FD RX-7. Oh, and it’s all-wheel drive–because the first half of the recipe wasn’t crazy enough.

The creature creation churns out a face melting 1,400hp and Dahm was invited to do battle on Hoonigan’s “Hoonigan vs the World” YouTube series where Dahm would race Ken Block’s infamous Hoonicorn Mustang. The Hoonicorn is a fearsome beast in its own right with a twin-turbocharged, methanol-fed, Roush Yates–built V8, and all-wheel drive. Dahm not only put up a commendable fight–even winning one of the heats– he proved that a garage-built machine can go toe-to-toe with a professionally built one and if that doesn’t give you a case of the gearhead warm and fuzzies, nothing will. We caught up with Dahm to see what that experience was really like.

Holley: What was it like to race the Hoonicorn?

Rob Dahm: There were so many things going on all at once, so many firsts for me, that it’s beyond comprehension. Not only [was] I racing the Hoonicorn, I’m shaking down the car and launching it for the very first time.

Holley: Really? That was your first time running the car?

Rob Dahm: Yes! There were no secret shakedowns. That was the first time racing the car, shifting the car, launching the car, going to 1,400hp, and the whole time … I’m next to Ken Block and all of the cameras are on. It’s a way to christen a vehicle that really can’t be topped.

Holley: How did you feel the car did for its first time out?

Rob Dahm: It was a beautiful, glass cannon. I beat him on that one augmented race, where I got the hit, but it showed the whole world the capability of the car, my driving, my tuning, all the work I’ve done was validated because it almost took down the Hoonicorn for real. There’s a comment on YouTube that said “multi-million-dollar race team almost loses to guy in his garage” and that couldn’t have summarized this any better.

Holley: It’s hard for viewers to get a sense of how fast you and Ken were going in the race. How long was it and how fast did you go?

Rob Dahm: In 1,000ft, we got up to 140mph and change. For being a street, that was nuts. I was getting into 6th gear right at the finish line. When my hood came off, that was over 100mph! We were hauling a$$. That kind of speed in a one-off car I built myself gave me many reasons to be scared.

The drivetrain on Dahm's car consists of a Holinger RD6 sequential, manual transmission mated to a stock Nissan R32 GTR Attesa transfer case. The front differential is sourced from a RWD E30 M3 but flipped 180º to drive the front tires. The rear diff is a Winters Quick change.

Holley: There is some seriously wild suspension under this. Where did it come from?

Rob Dahm: The guy that engineered the Hoonicorn [Ian Stewart from ASD motorsports] is a huge rotary guy from New Zealand. I found out who he was and called him and he said “the Hoonicorn’s never going to do anything other than drift and I’ve wanted to see my creation dominate at road courses, and street driving,” and that was what I was reaching out to him for. He goes ‘Here’s the front suspension for it.” After that, he got busy so I started figuring out what the rest of the parts on [the Hoonicorn] were by calling vendors directly.

Holley: Does this car have a name?

Rob Dahm: Yes, and it has a really good meaning. I call it Ahura. The story behind Mazda is that it’s a mix of the founder’s name but it’s also a religion [Zoroastrianism]. In it, there’s a god called Mazda and Ahura Mazda is kind of like the ultimate being. My dream was to take this car and make it the ultimate Mazda.

Dahm's engine is a one-off, all-aluminum 4-rotor Wankel engine that owes much of existence to custom machined parts. The factory Mazda parts are limited to S4 NA rotors and 13b rotor housings. Rob designed the injection setup which uses 4 injectors per rotor. Fuel is supplied by a Holley VR1 Brushless pump and pressurized air is courtesy of a massive, 106mm Garrett GTX5544R turbo.

Holley: When you came up with the idea for this project, what was your skillset like for building cars compared to now?

Rob Dahm: Oh man, I was a very basic car enthusiast with a computer background outside of cars. I could wire a car, poorly, but it always worked. I could take my engine out, but I wouldn’t take it apart, or at least if I did, I wouldn’t be able to put it back together. I had no fabrication experience at all. JB Weld was my only friend at the time. There’s a world of difference between then and what I can do now. I am the judge jury, and executioner on that car. I’ve assembled the engine. I’ve rebuilt the entire car and touched every single nut and bolt on it. Really, the support of companies like Holley and others have allowed me to DIY on a big scale. My [skillset] is an extreme scale of nothing to something, but I love to show my audience that is possible.

Holley: What did you learn about the car during this race? What changes will you make?

Rob Dahm: There’re a couple things I want to improve, specifically on the engine. At low RPM, you’ll hear the car shut off and die. There’re no injectors close to the engine. They’re all the way up top on the intake. Below 3,000rpm it always goes lean. I’m also gearing the car up to be able to turn really tight. Obviously, we’ve proven that this thing can drive straight but I want to be able to do all different types of motorsports. I had an RX-7 that was a drag car and I hated it. My goal with this car is to have this ultimate vehicle that can go to all these different types of races and perform competently. My goal is to make this car as balanced as possible. It’s a personal obsession.

Holley: Last question. For those that don’t know, how did you meet the Holley Team?

Rob Dahm: That’s the best part of the story! It’s hilarious but kind of embarrassing. Years ago, I saw that my friends were going to LS Fest, and I’m like, “What the heck, there’s a whole celebration of the LS engine?” So, I made an Instagram post that said, “I’m going take my RX-7 and go be obnoxious and protest [LS Fest].” That got so much attention that I decided to swap a rotary engine into a Corvette and sneak into LS Fest. This whole video build series, which had LS Fest in the title, got so much attention from [Holley], and no one told me anything. So, I make it there on the last day {of LS Fest] and the car actually broke down. Some guy comes up to me on a golf kart and says “Hey you’re in the auto x parking lot. You can’t be here. Come with me.” We start pushing the car and right by the Holley booth, they start putting up rails around my car and open these wanted posters. They put me in LS Fest jail! I made my goal, I snuck in, but they were one step ahead. It was the coolest, most organic thing ever.