Steady State Dyno vs. DynoJet just some FYI

[steve shadows]

Steve's Homepage - Different dyno types

This is another good link I wanted to share with everyone regarding the differences in output you get as well as the ability to tune.

Again most shops that have been popularized by media and the common car culture use a dynojet. In Japan's most serious tuning shops, BMW north america as well as almost all australian shops a Steady State Capable dyno is used.

I am trying to educate people to this so that the head breaking and psychological effect of having a car tuned on a better dyno but recieving a "lower" number can be calmed.

The fact is a dynojet does not account for

1. Weight of the wheels or driveline
2. The actual load and drag (that increases as you accelerate in real life) on an inertial dyno the amount of drag that the engine has to fight against actually decreases
3. The moment of torque (a steady state dyno makes an explosive load up into torque much harder or impossible giving a more accurate number in the real world application of the output to the ground).
4. The lack of a true torque measurement - HP is Toruqe over RPM or TIME = a representation of work.
5. Dyna-Packs are will frequently read even lower than DynoJets as well - unsprung weight or the weight of the wheels, and rotating assembly actually make a huge difference in real output- more than most could possibly imagine

The advantage of the Inertia style dyno comes down to making customers happy and the reliability of comparing any given dyno number to any other dyno readout on the same type of dyno easier- because the given weight of the drum being used to test the acceleration rate is commonly the same as long as the intertia dyno is made by the same manufacturer.

This is why high end tuning shops often have a dyno dynamics to tune the car in every cell and to achieve the best tune and the Dyno Jet to print the best possible graph to show linear outputs under WOT so it can be easily compared to other cars from other shops that frequently have dynos from dyn-days- not from highly technical shops doing a full EMS overrun

I got these from the shop that is about to dyno my M Coupe. It is consistent with what I have been told elsewhere but certainly an interesting read:

20) My car makes 300 hp but your dyno says it makes 215. What is up? Our dyno is the most accurate measurement of torque at the wheels. More accurate than most. No "interpolation" or "estimation" or "inertia factors" are applied like they are on other competitors' lesser machines. What this means is that this is the actual torque being applied at the tire. Typically, a 300hp all wheel drive car will measure in around 210-215 on our dyno. This is normal.

21) I went to a Mustang dyno and they said theirs reads low, but you say yours reads low. Is this just some trick used by tuners? The Dyno Dynamics is known throughout the industry as being the "heartbreaker" dyno - because it breaks the heart of every man that thinks he has 500 hp when he really has 350. The Dyno Dynamics reads lower than the Mustang. It reads WAY lower than a Dynojet. It reads WAY lower than a Dynapack (which actually reads too high on tip-in). The closest in numbers (at low HP) is the mustang, but using the above example, the same 300hp car was dyno'd back to back on a Dyno Dynamics 450 LowBoy (what we have) and a Mustang AWD500E (what some other guys have), and that 300hp rated car consistently read 223 on the Dyno Dynam ics and 249 on the Mustang. One hour apart, exact same car, same town, same altitude, etc.

22) Why dont you just make your numbers look high to be the same as some others? Dyno correction is not a fixed amount. In other words, adding 30% at xx RPM and xx power does not translate. i.e. Using the above example, a car that makes 225 is about 1.3 to get 300. A 900hp car on this dyno is NOT making 1200hp ! Dyno numbers should be used for relative back to back comparison, and nothing else.

23) How do I compare my dyno results to others with similar setups? For Subaru owners, there are enough internet resources to compare, but essentially, Dyno Dynamics and Dynapack are the only 'consistent' numbers, and Dynapack reads very high, Dyno Dynamics very low. We can help you seek out other similar results. A great resource listing a slew of Dyno Dynamics HP baselines is available in the Gallery section at the KTR Performance Dyno Gallery Web Site. It should be noted that KTR uses atmospheric correction, which we do not use on our dyno plots.

24) How do I compare my pulls to Mustang Dyno, or a Dynojet, or a Dynapack? Every dyno is different. If you want dynojet or mustang-ish #s you have to multiply by 1.18 or so, 1.25+ for DynaPack. But remember, this is just ballpark, as it is not linear.