Going Full Race Car
Last week, I received an email from one of our readers. Allen, an E36 driver with a growing addiction to track days, asked about the next steps he should take with his BMW. He’s already gone through many track-focused upgrades and was wondering what he needs to know about roll cages, fire suppression systems, fuel cells, aero, and basically when and how to go ‘full race car.’ Today, we’re going to cover all that and more in this week’s edition of Turner Motorsport Weekly.
Let’s break down the real question here: Allen wants to improve his 1995 M3 dedicated track car without losing its ‘momentum car’ status. When building a car, or taking it to its next iteration, there has to be an ultimate goal. Since I don’t want to get super specific here, we’re going to cover the process rather than individual parts, but Allen and all you dear readers should be able to take a roadmap away from this article. So where do we begin?
You need to consider what the purpose of your car will be. For Allen, it’s a dedicated track car, but not something that needs to meet the requirements of a series. If you fall into that same ‘just for fun’ category, you have a fairly open-ended direction. Just go with what you like and what helps you improve in the way you want to. However, if your goal is to race in a series, you will need to build your car to that series’ certain specs. So, step one is to figure out why you are building your car.
Step two is to prioritize your upgrades. Allen asked about roll cages, fuel cells, fire suppression systems, and aero components. Something Bill Griffin and Don Salama have both stressed is to not over-build your car. You should not make a change until you have reached the limit of that system in your car and recognize a need to improve it. If you are suddenly limited by traction, that’s when you should consider making incremental changes to your wheel, tire, and suspension setups. Never make a change because you ‘think’ it will make you faster. Make the change because you are now limited by that component or system in your car. Your upgrades will realistically be decided for you by your abilities and the limits of your car. If you aren’t exceeding the limits of your tires, then you don’t need to buy grippier tires until you find that limit.
In step three, once you have figured out what your needs are, you can decide on how extreme you should go. If you are upgrading from stock suspension to coilovers, how much coilover do you absolutely need? With Allen, it seems like he has reached the limit of several systems, which is why he’s considering it. So let’s look at each of his systems and offer some insights.
|
|
| Roll Cage
If you are spending any time at the track, you really need something to keep you safe in terms of a roll bar, half cage, or full cage. What you need will depend on your purpose for the car and any racing series you may want to pursue. If you are just going out for fun and still drive your car on the street without a helmet, but want something to keep you safe, a bolt-in half cage that allows you to run a harness and will keep you safe in the event of a rollover is a great option. If you never drive your car without harnesses and a helmet, you can go as crazy as you want with a full cage. However, if you are looking at SPECE36 or another similar series, you need to follow their exact requirements.
So, what does that mean for you? Your roll cage should depend on whether you street drive the car, what you need for your racing series of choice, and what your budget is. When should you put a cage in your car? When you absolutely need to.
Allen, for you, we suggest the Autopower Race Roll Cage for your E36. | | | Fire Suppression System
Again, this is going to depend on your car’s purpose. Every racing series requires specific fire suppression systems. If you’re looking to race in a series, then your choice is made for you. If you are just out to have fun but want to be safe, realistically, every car you drive hard should have some form of fire suppression. Let’s look at some options together.
| | Fire Extinguisher
This is the most basic form of fire suppression. It requires you to pull it out, spray foam all over your car, and be your own fire suppression system. I suggest a fire extinguisher in every car. I keep one in my E30 at all times and it never even sees track time. The downsides are extensive, though. It can’t work if you aren’t physically working it and it has to be accessible. If you wreck and are incapacitated or trapped and can’t reach it, then you effectively don’t have it, which means you have no fire suppression system. The benefit is that it is cheap and effective, provided you can get to it and operate it in time. For a car that sees track time outside of a sanctioned series, this is the absolute bare minimum but isn’t ideal. | | | Manual Fire Suppression System
Rather than operating a fire extinguisher, a suppression system is integrated into your car and engaged by a pull cable in the event of a fire. Since your pull cable will be within your reach at all times, if you are trapped in your car or something is preventing you from reaching where you would keep a fire extinguisher, you don’t need to worry. Just pull the cable and the DuPont FE-36 chemical will displace oxygen in your car to the point that fire can’t burn. However, again, there is a downside. If you are incapacitated or unconscious, you can’t pull that cable and your suppression system is basically useless. | | Automatic Fire Suppression System
An automatic fire suppression system is just like the manual system, except it uses a temperature sensor that senses excessive heat from an ignited fire and will automatically trigger your suppression system. This is beneficial because you don’t have to do anything. If you’re incapacitated, trapped, unconscious, or otherwise unable to operate your fire system, this will work without your input. However, there are some downsides here, too. You can accidentally trigger your fire suppression system if you hit the sensor and break it, say, while pressure washing your interior or installing/uninstalling interior components. It could potentially trigger if cabin temperatures exceed the temperature that breaks the sensor and activates your fire suppression system. An automatic system also introduces the risk that it doesn’t trigger as it is supposed to. While rare, that could potentially happen. So what is the best option?
| | Automatic/Manual Fire Suppression System
The best of all systems is one that has both an automatic trigger and a manual trigger. If, for any reason, your fire system doesn’t trigger, you can manually trigger it. If you are incapacitated and can’t manually trigger it, then the sensor will. It is the kind of redundancy that should be habitual for any drivers or pilots. Always have a backup plan for your backup plan.
The real question: when to do it? When your purpose is to just have fun, honestly, do what you are comfortable with. If you are ok with just a fire extinguisher mounted on your floor, then that’s all you may want. However, for the best peace of mind, a full system should be in every car that is dedicated as a track toy. Of course, if you are in a racing series, you must follow their requirements, which means that decision is made for you.
For Allen, we’re going to suggest a fire extinguisher as the minimum he will need. | | | Fuel Cell
Once again, if your racing series requires a fuel cell, obviously you have to go with the one they require. If you are just out having fun on a few weekends a year, you likely don’t need a fuel cell. Fuel Cells offer a few benefits, though. They reduce slosh, which attributes to weight transfer, and they can be mounted wherever you want, which allows you to play with weight balance. This goes back to what we said before: don’t just upgrade to upgrade. When you are chasing milliseconds and looking for ways to improve, a fuel cell can allow you to control a bit of your weight transfer in corners to reduce your lap times. However, if you have a perfectly good factory fuel tank, unless it’s just absolutely necessary, you are probably fine until a series requires it.
| | Aero
This is a big one. Aero is more scientific than I’d care to dive into. With a racing series, there will be requirements or specifications that limit what you can add. If you’re just looking for more downforce, though, you need to know a few things to start your research process. | | | Low Speed vs High Speed
If you are racing at low speeds, like in AutoX or road courses, you’re going to need more aero rather than less for it to be effective. If you just slap a wing on your car, all you’ll be doing is creating drag and no downforce. You will need to balance your downforce front to rear and think about what you are adding and why.
High Speed is going to be more of a balance between weight, drag, and downforce. You don’t want to limit yourself with weight and resistance, but you need downforce to stay planted at high speeds. I’m not talking about 120mph. I mean full-tilt, as fast as your car can go, for long stretches on high-speed tracks at the highest levels of competition. If you are in this category, you probably don’t need our advice. | | Back to low speed, you need to know what you are changing.
A front lip, front splitter, canards, undertray, rear spoiler, and rear diffuser are the typical aero upgrades. What you are effectively doing is trying to create more downforce, less drag, and induce high pressure around the car with low pressure under the car. This creates a vacuum effect and will help you stay stable on the track. When should you make these changes? When you need to. I know that sounds vague, but it’s true. It is always better to improve mechanical grip than it is to add aero components hoping to improve downforce.
The fact is, if you don’t have a wind tunnel, you will have a hard time knowing what to change and how much to change it.
However, if you just want the nuclear option, you need to think about what these components do. | | Front Lip/Splitter
This combo both reduces the space between the bottom of your front valance and the ground, which allows more air to divert around the car rather than flow under it, and also generates some downforce with the splitter by having the air press it down into the ground. | | | Canards
Dive planes, or ‘Canards,’ are small winglets on the side of your front valance that help direct air around the car, away from the wheels, and point it to the places where it can be a benefit rather than a limitation. They are used to move air towards your rear spoiler where it can be used to generate downforce rather than add resistance to even the boxiest of cars. | | Undertray
Perhaps the biggest improvement you can make, if you were to just make one, is adding an undertray or ‘flat floor.’ This is going to cover everything underneath your car that can create turbulence with a smooth surface that helps both reduce drag and reduce the air pressure under your car. Having lower air pressure under your car and higher air pressure above it is effectively downforce, which will help keep your car planted. | | Rear Diffuser
A rear diffuser helps direct air from underneath the car out the back through its strakes. You need to combine a front splitter, undertray, and rear diffuser together to help create a Venturi effect under the car, which just means the air moves more quickly underneath your car than it does around it. Bernoulli principle basics. | | | Rear Spoiler
A rear spoiler creates downforce on the rear axle and helps rear-wheel-drive cars stay planted under high speeds. However, they also create drag. What you need to consider with your rear wing is how air is directed to it. If you don’t have air directed to your rear wing, it isn’t doing anything other than adding weight and drag, effectively slowing you down. Canards and vortex generators are intended to help direct air to the wing and reduce the low-pressure area behind your rear window, above your trunk. This means air is flowing across your wing and generating downforce. Think of it as the opposite of an airplane wing.
Again, this is about as simple of an explanation as we can give. Without looking at a wind tunnel and making small, incremental, changes, you are not going to know what you’re doing besides bolting on parts. At the amateur level, it is always better to just increase mechanical grip rather than try to improve your lap times with downforce. However, if you’ve reached the limit of your mechanical grip, then you might want to consider making changes to your aero setup.
Allen should probably go with a Front Lip Spoiler, Fog Light BLock Off Covers, Skid Plate, Rear Diffuser, and a Rear Spoiler for some noticeable aero upgrades. | | | | | | | | In summary, most of these upgrades will depend on one of two things: whether your racing series requires them or whether you have reached your car’s limits in a certain area. That’s what I mean when I say you should upgrade these components when you need to upgrade them. Either your chosen racing series will demand it or your lap times aren’t getting faster because of a limiting factor in your car. So, if you are finding that your car is limited but you’ve made all the right suspension tweaks and found the most effective setup, it may be time to look into aero improvements. If you spend more time on the track than the street, then it’s probably a good idea to have a fire safety system that works under all situations, same for a roll cage.
Hopefully, we answered your questions, Allen! If you have questions about this article, about your build, or suggestions for a future article, I would love to hear from you! Just reach out to [email protected] and we’ll be here to listen. Maybe you’ll have your questions answered in the next edition of Turner Motorsport Weekly. |
|
| | |
