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Our Dyno

THE JM AUTOMOTIVE DYNO

Our dyno is a Dynotech Dyno made by Dyno Dynamics. It is capable of measuring 600hp steady state on both the front and rear beds. It is able to measure 1,200hp for power runs for front or rear wheel drive vehicles. 1,200hp per axle or 2,400hp total for power runs on AWD cars. That means we can dyno a FWD or RWD car that makes up to 1,200hp and AWD cars that make up to 2,400hp!

Why do we have a Dynotech Dyno?

We chose this dyno for its steady state abilities. While other dyno brands read higher than ours, our dyno can very accurately measure very small power changes. One of the most important things a dyno does is allow us to see changes in the tune that make more or less horsepower. A dyno is a tool that allows us to see those changes. Being able to quantify that the parts we just installed, 2 deg of additional ignition timing, leaner or richer AFR, change in cam timing, or 4 more psi of boost actually made more power is what the dyno is used for and our dyno does that with extreme accuracy. We have had several cars that we have tuned and put back on the dyno over a year later and the power graphs overlay almost exactly the same.

Some of the additional sensors our dyno can measure and log are:

  • Boost Pressure/Vacuum
  • Dual AFR sensor, one for each tailpipe for dual exhaust
  • Intake air temp probe
  • Fuel Ethanol Content
  • Fuel Pressure
  • Oil Pressure
  • Crankcase Vacuum
  • Knock, via Phormula Knock Detection System

We have an exhaust extraction system that removes exhaust at a rate of 6000 cfm with a fresh air intake, to keep the dyno room air clean and fresh. All air in the room is replaced every 3 minutes making it one of the best dyno cells in the Midwest. The exhaust system hooks directly to exhaust on the vehicle to fully evacuate all exhaust out of the room.

We have two massive fans that move 1,200 cfm of air each to keep the engine cool and provide plenty of fresh air to the vehicle’s air intake and intercooler. We also have 3 top mount intercooler adapters that funnel air directly into the top mounted intercoolers on Subarus to mimic airflow that would be seen on the road.

What are the different types of dynos?

When it comes to calculating horsepower not all dynos read the same. Dynos have different methods of calculating horsepower. Some use Inertia while others use Eddie Brakes to calculate horsepower.

One type is an unloaded or inertia dyno, such as some DynoJet Dynos. They use a large heavy drum to calculate horsepower. By knowing the weight of the drum and measuring the rate of acceleration during a full throttle pull. The dynos software can calculate the horsepower. One downside to an Inertia dyno is that they can only calculate power while the drums are accelerating. Holding the engine at a certain rpm to correctly map the fueling and timing at lower loads is nearly impossible. For example, if you wanted to tune the load cells of your car at 3200rpm and 3lbs of boost you can’t really do that.  The car will just briefly hit that specific cell and it makes it very hard to get accurate fueling and timing maps. That makes tuning the cruising portion of your tune nearly imposible, which is where you spend most of your time.

Another type is a loaded dyno. They also referred to as eddie brake or eddie current load absorption dyno. An example of a loaded dyno is Dyno Dynamics, the dyno we have. They use an electrical load that works against the engine’s power output and allows the engine to accelerate at a specific rate. While this happens, force is applied to a load cell, which the dynos software interprets into tractive effort, it then turns that into the horsepower and torque numbers we are used to reading. This also gives us the ability to hold your car at that 32000rpm/3lbs of boost and get the fueling spot on in that cell.

Do All Dynos Calculate the Same Power?

For whatever reason all dyno brands seem to read or output different horsepower numbers.  For example, if we have a car that makes 230 hp on our Dynotech, it can have a different power output on another dyno with no changes to the car at all. From testing we have found that if we take that same 230 hp car to a different dyno such as a Mustang dyno it will typically read 10-11% higher, or around 255 hp. Putting that same car on a Dynojet will net you 22-27% higher power reading, or around 285 hp. That shows you how much you can’t rely on dyno numbers as a comparison tool between cars.

Since almost every power number you see on the internet is close to Dynojet numbers, because you know who doesn’t want the highest numbers possible? We give all our customers two power graphs. One is the standard numbers our dyno makes along with the Shootout graphs. The Shootout graphs are typically within 3% of what your car would make on an unloaded dyno. These percentages only relate to an AWD car. Having a rear-wheel-drive car and if it’s boosted or not will have a different percent ratio for the difference in power readings from different dynos. The shootout graphs will still be within 3% to a Dynojet from our dyno.

Below are some examples of what we are talking about.

2005 STI PTE 6870 E85

The second picture shows the power a Subaru makes on our dyno. The blue line is wastegate pressure of 25psi and the black line is 42psi of boost. Nothing was done to the car from the time it was taken off our dyno and brought to the local Dynojet for testing. You can see that the wastegate pressure tune made about 27% more HP then our dyno HP and the 42psi tune made about 22% more power than our dyno HP. That should really show you how much dynos can read differently.

2005 EVO 8 PTE6466 E85

Here is another example. This EVO 8 was tuned here and the customer brought it to a dyno day at another shop with a Dynojet dyno. You can see our non shootout numbers are 600hp. That power graph shows about 24% less power than what the car made on a Dynojet dyno. You can see our Shootout graph shows 729.5hp. Our shootout graph actually reported a little less power than what the car made on the Dynojet but still falls in the same percentage difference of 22-27% that we saw on a different car we tested.

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(763) 316-5882