If you’ve ever built a car or truck, you know what kind of problems can happen with a new build. It’s easy to miss things like loose fittings, a sensor that’s not plugged in, or any number of items with so much going on. Fortunately, you can work 95-percent of these problems out in your driveway at your leisure, and it won’t cost you a dime. But if you add a dyno session to the mix with a car that’s not ready, the stakes rise. Now, instead of you taking your sweet time, you’re at the mercy of a mechanic that should and will get paid for what you didn’t fix.
In this article, we’ll cover some of the more common mistakes made when people drop their projects off for a dyno tune. The West Bend Dyno Tuning crew will help us navigate some of the more common issues that can be avoided in most cases.
Fuel System Woes
So you hit the ignition key, and the pump turned on…that means it’s good to go, right? While having a functional fuel pump is essential, other things need to be considered with the fuel system. Surprisingly, fuel system issues are the number one thing encountered at West Bend Dyno Tuning.
Brian Wohlfeil, EFI Calibrator of West Bend Dyno Tuning said, “Over 70-percent of the problems with cars that come in for calibration have some fuel system problem. It seems that the fuel system is one of those expenses no one wants to budget for or may not even realize is an issue. High-horsepower vehicles require large injectors, lines, and fuel pumps. Then we add E85 to the mix, and even larger systems are needed. It is always best to reach out to your performance shop to find out how much fuel your combination will require, or use one of the free calculators online to get a rough idea.”
The Wrong Fuel
You’re on the way to the shop to get that new supercharger you saved up for installed and dyno’ed, and the low fuel light comes on. So you whip your ride into the gas station and fill up with 87-octane trying to save a buck or two. Congratulations, you just caused the shop a headache and cost yourself more money and Brad Riekkoff, Owner of West Bend Dyno Tuning can attest to this problem. “We’ve had vehicles dropped off with 87-octane fuel when in reality, the new boosted combination requires at least 91 or 93 octane to achieve the expected performance gains. If the incorrect fuel is in the vehicle, we drain it all out and add the appropriate mix.”
As you can imagine, draining fuel is complicated and a time-consuming process on late-model cars and adds to the overall cost. So remember, trying to save a dollar at the pump could cost you in the long run. Be sure and fill up with the correct fuel before heading out to a dyno session.
Have you ever put a car back together, went to start it, and maybe a fuel line wasn’t tight, or the transmission hose wasn’t secure? If you haven’t, we’re here to tell you it makes a huge mess. And then you get to clean up the vehicle and the floor while contemplating how dumb you are.
If you check the car over before dropping it off at the dyno for problems, you will be a hero. But don’t just take our word for it, Chris Degnitz, Shop Foreman of West Bend Dyno Tuning said, “Many clients bring us fresh builds that have been recently completed. It’s always a good idea to have a base tune file loaded into the computer for the first startup when possible. Starting and running the vehicle to get it up to operating temperature should be done, if possible, before taking the car or truck to the shop. The customer can then check for any leaks such as fuel, coolant, and exhaust. More time spent here will most likely be less time and money at the shop.”
Most of these types of problems can be solved before ever leaving your driveway. So, take your time and check over everything to alleviate any problems that you might have.
Spark plugs aren’t that big of a deal — you simply go to the parts store and tell the person behind the counter that the year, make, model, and that it’s four-wheel drive, and they will take care of the rest. Actually, don’t do that. Riekkoff said, “Spark plugs are essential for forced induction and nitrous applications. It’s not uncommon for people to overlook the spark plug heat range and plug gap. When switching to forced induction or nitrous combinations, spark plugs need to be colder than the factory spark plug to reduce the chance of pre-ignition/detonation. In these instances, the plugs also need to have a tighter plug gap to help eliminate possible misfires under high cylinder pressure.”
If you’re making more power, you need a colder plug and tighter gaps. If you don’t know what spark plugs you need, call someone that does. They will not only be able to tell you the proper heat range for your application, but they can give you the correct plug gap as well. This simple act will save the guys at the dyno a lot of time.
In our opinion, there is nothing scarier than bad wiring. A rat’s nest of wires with butt connectors running here and there is always a good indication of trouble to come. If you don’t know what you’re doing in the electrical department, find someone that does. Dropping off the car with electrical gremlins for a dyno session is a terrible idea, and Wohlfeil agrees. “When vehicles have electrical problems, they can become expensive and time-consuming to diagnose and repair. We see a multitude of issues, including poor connections, insufficient grounds, loose, bare wires, along with incorrect sizes of wiring being used. The absence of clearly labeled wiring makes it very difficult to locate specific problems while on the dyno.”
Failure to fix existing wiring problems will not only frustrate the dyno operator, but it’s also going to cost you money to have it fixed. What’s even worse, faulty wiring could cause your car to go up in flames before you even get on the rollers, and nobody wants to see that.
As they say, “You can’t tune around a mechanical problem.” And that statement is true; if you suspect an issue with your car, it’s smart to fix it before it hits the dyno.
“A vehicle may come in with an internal or external engine or transmission issue. While these concerns may be difficult for the average customer to know about prior to the dyno appointment, we see predicaments like these regularly.” Riekkoff continued, “Improper fluid levels, belt wrap, mechanical timing, and loose air intake tubes are some of the problems we see frequently and are normally an easy fix for the customer.”
Bigger Isn’t Always Better
In the words of Brian O’Connor, “I need NOS. Two of the big ones, and I need it by tonight.” But have you ever thought maybe the “Fast N Furious” lead didn’t need two of the big ones? Because unless he was spraying 600 horsepower down the throat of that lowly import, the standard nitrous bottle would have been fine.
Sometimes people have no idea what they need, so they order what they think they need. These are two very different things and should not be taken lightly because getting the correct parts for your application is essential. Bigger is not always better.
“Everyone wants the biggest camshaft in the catalog. While this may make the most peak horsepower, we typically see less usable horsepower and torque on the street. Without matching gear ratios, torque converters, and tire sizing, these engines can be miserable to drive from day to day,” said Riekkoff.
West Bend Dyno Tuning even goes so far as to check a restrictive air intake system. Riekkoff said, “We put a vacuum gauge in the air intake system if we suspect a restriction. We have found anything over 1.5-inches of vacuum in the intake plumbing during a wide-open dyno pull can absolutely leave power on the table. Short runner intake manifolds, long-runner intake manifolds, headers, and exhaust design combine to give the engine its unique power and torque curves. If they’re mismatched, the engine will not perform as the customer expects.”
In our time, we’ve used some of the most antiquated electronic equipment with less processing power than the original Atari gaming system. A lot of it was due to new tuning methods coming out when the first LT1 Camaro hit the market way back in the 1900s. However, with the products offered on today’s market, there is absolutely no reason to settle for a junk aftermarket ECU. There are some versatile units that are affordable.
Wohlfeil gave us some input from the dyno side of things. “Customers can justify spending their hard-earned money on mechanical parts. But, when it comes to optimal performance, mileage, and driveability, they may not know their options for controlling their engine and transmission. Some customers don’t realize the time and knowledge needed to make all the new parts work together and can’t comprehend the cost of the tuning process. Money spent here will most likely save money in the future.”
Most modern late-model vehicles have an ECU that can be reflashed to accommodate changes in volumetric efficiency, injector size, throttle body size, flex-fuel capability, and more. Riekkoff said, “The factory works well for over 95-percent of these applications. When combinations are very radical, or extra features such as boost control, nitrous, or water-meth need to be controlled by the ECU, an aftermarket unit should be used.”
In older vehicles, a late-model factory computer with a standalone harness or aftermarket EFI system may be utilized but which one is best? “Which one to choose will depend on what the car is used for and what options or future plans are in the works,” Riekkoff explained. “Most aftermarket ECUs can implement safety features, which may save an engine if there is a malfunction in one of its systems. Our advice would be to spend a little more time and money when choosing the computer to run your engine and drivetrain. You may pay a bit more upfront, but it could save you a massive headache later.”
Going Old School
Believe it or not, not everyone runs electronic fuel injection, and that’s OK. However, if you’re spending money on a new carburetor, choose wisely. If you want to screw up a good engine combination, put the wrong size carb on it; it will run terribly, have idle issues, get horrible gas mileage, and lack driveability.
“We still dyno tune many carbureted vehicles. The biggest failure we see with these vehicles is carburetor selection, and as we have said before, bigger isn’t always better. The proper size carburetor needs to be selected for optimum performance.” Brian Stockinger, Carb Calibrator of West Bend Dyno Tuning explained.”
Stockinger also gave us a couple of ways to figure out what size carb an engine needs. You can use an online calculator or do the math yourself. The formula for finding the correct CFM required for your engine is CFM = Cubic Inches x Max Engine RPM x Volumetric Efficiency (VE)/3456.
For example, a 400 cubic inch engine x 6000 RPM is 2,400,000. Now take 2,400,000 x VE (most engines are 80-90-percent). In this example, we will use 85-percent VE. So, 2,400,000 x .85 is 2,040,000. Now take 2,040,000 / 3456 is 590.3. Our math tells us that this engine will flow 590.3 CFM with this VE at 6000 RPM. So we may spec a 650 CFM carburetor for this engine. Your engine size, max RPM, and VE will vary.
In our opinion, this could be the most important thing on the list. There are a lot of people out there that shouldn’t work on cars, but they do. It’s in the dyno shop’s best interest to make sure the vehicle is sound before hitting the rollers. If it’s not, be ready to pay to have it fixed. They would much rather take a few steps to keep your car and crew safe than have a mishap.
“Customers may spend a lot of money building their dream car. However, they may lack the knowledge on how to properly and safely execute the build because there are many different areas to a vehicle. From driveshaft angles to poorly routed fuel lines, safety is our first concern,” Riekkoff explained. “We’ve even experienced cars dropped off with only two or three lug nuts on the wheel. These vehicles will see speeds and loads most likely never encountered on the street. If it can put our staff in danger, we require the safety hazard to be fixed before any tuning.”
If you are going to spend money on a dyno tune, do yourself a favor, do the research and make sure your car is 100-percent ready to go. We know how easy it is to get excited when your project is close to hitting the road but don’t take any shortcuts. If you use these tips from West Bend Dyno Tuning as a checklist, it will give you a solid start before hitting the rollers. Just remember the time spent preparing the car for its big day will save you a lot of money and headaches in the end and will allow the tuner to get the most out of your vehicle.