The old saying is “time is money.” Nowhere else is that a truer statement than at the dyno shop. When you rent time on a chassis dyno to test your vehicle’s performance — or if you hire a tuner to do the adjustments for you — every second is costing you money, lots of it. The trick is to use those expensive seconds wisely to ensure you literally get the best bang for your buck. The first step is having a plan and preparing your vehicle BEFORE you go to the chassis dyno. You don’t want to have problems while sitting on the dyno.
To find out what should be done to your vehicle in advance of your session, as well as other handy tips for tuning, we spoke to AJ Gracy, owner of Performance In-Frame Tuning in Napa, California. AJ spends his entire work day tuning all sorts of vehicles and he has seen some productive days on the chassis dyno, and unfortunately for some customers who weren’t prepared, some very unproductive days.
To assist people in being ready for tuning their car, AJ put together a list of tips on his shop’s website. AJ details a number of things to do to be prepared when you show up at his shop, like ensure your car doesn’t have any leaks, doesn’t overheat, and to bring an extra set of the correct size spark plugs.
One of the first things AJ mentioned when it comes to having a vehicle that is ready to be put on a dyno is good tires. If he sees old tires with cracked sidewalls he won’t allow the car on his dyno. This is for his safety, the safety of the people in the shop, and the well-being of the car. Running a vehicle on a chassis dyno means high speeds for the drive axle. Trust him when he says losing a tire at 130 miles per hour, or even faster, is a bad thing. There are plenty of YouTube videos showing the dangers of old tires exploding on a dyno.
AJ checks the D.O.T. manufacture date code on any tire that comes into his shop to ensure the tire isn’t too old. He also checks the tire pressure of the tires before doing any dyno tuning. Checking tire pressure is a two-fold advantage as the correct tire pressure lessens the opportunity for tire failure, and tire pressure can actually affect results on a dyno. So, to have consistent tests he ensures the tire pressure is accurate before any pulls are conducted. If you run street tires with treads or a race tire (like a slick) it is not an issue for the dyno, as long as the tire is healthy.
Another piece of advice from AJ is to know what your car has in it. It is important for the tuner to know what parts have been installed on the car, and if those parts will work in harmony. You don’t want to spend $150 an hour searching Google to figure out what type of injectors you bought from China. It is important that you have information on the car, like what the Mass Air Flow is, or what engine management system the vehicle has. In order for the tuner to make more power, he needs information about the parts. This will help the tuner adjust the vehicle to improve performance.
AJ also indicated that a bung for inserting a Air/Fuel Ratio meter in the exhaust header is a big help for tuning. He can use a tailpipe meter, however, the closer the sensor is to the head the better the readings are for tuning outside of wide open throttle. What is also important for tuning is having the ability to be able to change things. For instance, if you don’t have timing marks on your car because you added an aftermarket timing cover, then it is difficult for the tuner to time the car accurately. The more minutes adjustments like this take, the more money it is costing you. Ensure you have adjustability in your build, like an adjustable fuel-pressure regulator or different style intakes and/or air filters to try.
AJ understands that his customers want to improve their engine performance because, as a racer himself, he always strives to improve his own car’s performance. AJ competes in the National Auto Sport Association Time Trial Series and when his shop closes at night, it is his own Mazda MX-6 that goes up on the dyno to find some more horsepower and torque. AJ spends a lot of time tuning racecars: drag cars, drift cars, and road race cars in the Northern California area. Whether it is a racecar or a street car, the prep to the vehicle prior to it being brought to the dyno shop is the same. One other very important tip is to make sure the car has a full tank of gas before you show up. AJ has had many vehicles run out of fuel while making pulls on the dyno. No gas certainly slows down the process of tuning. And speaking of gas, if you want to use a specific type of gas (like race gas), you need to have that in the tank already. The dyno is no place to start the process of siphoning fuel.
“Replace your air and fuel filters before you show up,” says AJ. “Also, make sure your oil is changed and the oil level is correct. We are going to put some big RPM on the car and you want to ensure your engine is ready for that.” AJ also indicated he doesn’t want to see any check engine lights or error codes prior to a session. “Make sure all of those things are resolved before we start tuning. Otherwise we spend crucial dyno time trying to source engine code issues instead of tuning the car for power.”
One of the big things for a true car tuner isn’t what the horsepower number is, it is the improvement of the baseline numbers versus the final numbers when your car rolls off the dyno. Did your vehicle get faster? If you are at the dyno just because you want to snap a photo for Instagram of your car’s “big” horsepower number, you may be missing the point. The point is to make your car better. We all like “big” numbers, but it is the ability to improve a vehicle that makes the difference between social media braggers and actual racers. AJ’s advice, “Don’t be disappointed if your car doesn’t give you the number you thought it would. Instead, work to improve the car and make it faster.” Solid advice from a pro.
Another great point about dyno tuning is that it is a safe and legal place to run your car at high speeds. You can’t legally or safely do a 120 mile per hour pull on a public road with the tuner in the right front seat with a computer on his lap logging data. You also can’t have a tuner with a laptop riding shotgun around a racing track (well, you shouldn’t anyway). It is much more effective to have the tuner and laptop logging data while the car is on a chassis dyno. This is where real tuning can be done effectively.
Good luck on your upcoming dyno day. Based on the information above, now you and your car will be ready for a productive session.