The newest “trick” up various teams sleeves lately seems to be the upturned exhaust exiting the side of the car – commonly referred to as “Bull horns” for their obvious resemblance to, well, horns on a bull. Why are so many people doing it? Seems to be a common topic on the message boards and pit area chat as of late. Is it just for looks? Does it really help the car go faster? Our findings so far are fairly conclusive that it is helping performance-wise, as well as improving safety as these high horsepower doorslammers push the limits.
The most recent racer with the “horns” to reach the winners circle was David Wolfe at the ORTC event, who literally dominated all weekend with his badass radial ‘Stang. The car was virtually unchanged from its last outing except for one minor detail – the new exhaust exit location coming out the side, and tilted slightly towards the rear of the car. After resetting the drag radial 1/8th mile record nearly every round and eventually taking the event win with ease we knew there was something to this.
So what is the basic theory behind this idea? To put it simply – it is the upwards thrust from the exhaust. There have been a lot of nay-sayers to the idea, but if you’ve ever seen a Top Fuel Car drop a cylinder mid-run, you’ll notice the car will have a tendency to become un-stable and tends to want to jump to one side. This is due to the sudden change of thrust forces that the cylinders are displacing during an incident free run. Obviously the torque forces at such a high horsepower application will also factor into this.
So why not just run zoomies then if they work so good at providing the much needed front end downforce? On a blower car where the rules allow it, run them for sure! It’s probably the simplest solution, but trying to finagle a set of zoomies to coincide with a turbo motor would likely create a fabrication nightmare, and adding a simple elbow to their existing fender-exit setup saves a lot of headaches. With that in mind however, Steve Matusek plans to implement a set of zoomies for this very reason on his new twin turbo 2010 Mustang build. A unique approach, but it should work well.
So who else will we see running them? Guys like turbo Todd Moyer, SCT-backed racer Mike Murillo and Pro Street/ADRL contender Coby Rabon have all already made the switch with tons of success – all three of these guys have run their personal bests to date with the upturned “horns” and we’re sure that many teams will follow this trend since it’s obviously working; as Murillo simply stated, “They work.” Onofre’s Texas Star Chevy II Nova put a unique twist on the same idea by routing the exhaust to exit upwards through the fender, knowing that keeping the front end down would become more difficult with the fresh big block under the hood.
John Mihovitez at the controls of Matusek’s old Mustang also added the upturns, and coincidentally made it to the semi-finals in its PSCA debut with this setup – pretty impressive. Accufab‘s very own George Klass gathered a few notes from their experience at Fontana’s PSCA race with “the horns” as well. Harry Hruska from Precision turbo told the team before they ran, that this setup will make a lot of downforce and he wasn’t joking around. Klass’ first observation was that the car was hitting the wheelie bars harder then before – also noting that if you angle them back a little you’ll get less downforce. It has become an awesome chassis tuning tool, in the way that if you angle just one side back more than the other, it allows you to tune the chassis’ launch in order to compensate for the expected torque twisting.
We’re sure the skeptics are already saying, well there’s got to be some disadvantages right? Well there are, but they aren’t much to worry over. The difficulties that teams have experienced are having to remove the horns to get the car in the trailer, but a simple V band clamp makes removal easy. The only other potential problem is bumping into the hot exhaust in the pit area – but we haven’t heard of any incidences where this was a serious problem, as always – be aware of what’s going on around you in the pits and you won’t have to worry about it.
So there you have it, multiple teams are using it with much success and many teams have yet to try it but plan to. Not only is it a performance helper, keeping the front end down at 200+ mph trap speeds is always a big concern for teams in the safety department. They may look a little goofy to some, but if you can get over the appearance, they work excellent. Fact of the matter is, this isn’t just a styling trend.