Here @StageFP we get a lot of questions about our software tuning and we’ve listed here some of our most asked questions about the process. If you have a question that you do not see listed send an email to [email protected]
Why do I need a tune?
When making modifications to your engine you change the dynamics of how the air moves through the engine. This requires adjustments to the ignition timing, fueling and also can cause issues to engine torque limiting safety measures.
The other reason why you would want to do this is the manufacturer leaves about 5 – 15% power on the table when it comes to naturally aspirated engines for fuel economy and to allow the engine to last more than a 50K miles with limited issues. Engines that came from the factory with a turbo or supercharger can yield more power than its NA counterpart.
Why does one tune cost more than another?
When talking about software tuning your engine we need to take in the factor of how long it will spend on our dyno and the behind the scenes cost of tuning software and hardware.
An example of this would be a 2012 Mustang GT vs a 2019 Mustang GT. Same type of engine, however, completely different engine computers. The 2019 comes with direct injection along with more 10x the amount of parameters that need to be adjusted, also with a higher HPTuners license cost, this all adds up to a higher cost for you the user.
This also factors in when doing a custom tune for naturally aspirated engine that has been modified with a power adder like a turbo or superchanger. More time and parameters need to be adjusted.
The last point for cost is quantity. We tune a lot of different makes and models here, but If we come across a model that we have not tuned before or is low production, we have to start from scratch. We have to make or buy an engine parameter mappack and spend more time on the dyno to get power to a safe level.
What does BHP, RWHP, TQ, mean?
BHP means Break Horse Power. This is a load method mostly used overseas and uses a calculation to show power produced at the engine. Here in America we use an inertia type dyno where you have a know factor (the weight of the dyno roller) vs how fast an engine can turn it to calculate torque.
This brings us to the next item on the list, RWHP this stands for Rear Wheel Horse Power. Since we use an inertia type dyno, we display our power numbers using this data type.
In order to get a horse power number, you first need to know what TQ (torque) the engine made. You take the mount of tq the engine made times this by the rotational speed (RPM) and then divide by 5252 will equal horse power.
Why does another shop show BHP or Engine horse power and not power to the wheels
The simple answer is the numbers are BIGGER! While it looks great on paper it does not translate well to real world power. Unless you remove the engine and put it on an engine dyno or have the correct calculated rotational mass along with the friction loss from the back of the engine to the tires on the dyno this is a calculated guess of what its making BHP or engine power..
We like to display what your engine is putting to the ground, this is way more accurate because you can see what your drivetrain loss is and how much of it is making it there. Clutch or convertor, transmission type, driveshaft, rear or front diff, axles and even the weight of your wheels will effect power loss.
A good rule of thumb (If you want to have a calculated guess at your BHP might be) is this, a Manual transmission on a rear wheel drive car loose around 15% power from the engine and automatics are closer to 20% or higher.
Does weather play a factor when dyno tuning my car?
Yes! Its a huge factor when tuning a car. So much so our dynojet has a Weather Correction Factor function, more on that in a bit.
lets take about air, its dynamic! It changes when it gets hot or cold, it gets thinner the higher you go in the atmosphere and thicker the lower you go below sea level. Like in the first question above, the reason why you need a tune is AIRFLOW, when air gets cooler it becomes more dense and when this happens you engine is able to draw more of it in and your engine computer will add more fuel (to a point). This combined with more ignition timing will result in more power. This is why early in the morning your car feels like a monster and like a dog in the afternoon.
What this means on the dyno it will show less power in 102F degree heat than it would in 50F. Also, Your engine computer is designed with safety functions to protect its self by removing ignition timing, fuel, changing cam timing, removing boost or even closing the throttle.
As for the dyno’s correction factors, there are 3 main type of correction that you may have seen online SAE, STD and Uncorrected. All 3 of them serve a purpose, lets talk about SAE VS STD, simple answer is STD has a lower correction factor and will display higher horse power numbers under higher temperatures and humidity. SAE is the OE industry standard and what we like to use here @StageFP, However it does not come without faults.
SAE and other correction factors do not “factor” in a heatsoaked intercooler on a supercharged or turbo engine. While the dyno is seeing the room temp at 102 degrees it does not see intake air temps at 160 – 180F after a pull. Just as stated above your engine will reduce power and the correction factors do not apply for this.
This is where Uncorrected comes into play. Uncorrected gives us a view of what engine made with the current weather conditions and helps a tuner out to dial in a power adder engine.
This is why the dyno is a TUNING TOOL and NOT the final word on how fast your car can be.
Why does my car make more power on someone else’s dyno?
Dyno’s are NEVER going to be apples to apples mostly because of the previous question above (weather). Also dyno weight, maintenance, load type and age can also play into higher or lower numbers. Its best to get a stock baseline on the same dyno you plan on using for tuning or to see results after a modification.