Cosworth's "Big Step"

From the desk of Mark Skewis

Cosworth has opened a new dynamometer facility at its Northamptonshire base. Engineering MD Nick Hayes heralds the move as a “big step” for the engine specialist, which supplies three Grand Prix teams. Three new transient dyno cells have been custom-built, rather than Cosworth opting for an off-the-shelf solution. It will significantly boost its F1 capacity, which has, until now, relied on the use of Ford’s Detroit facilities.

it's a start

What are acceleration tests and inertia "correction"?
When an engine is accelerating, the torque difference observed during the test is not simply a function of the inertia of the engine/dynamometer combination. The power of the engine actually changes, due to the effects of wall flow and spray flow of the fuel, as it travels down the port to the cylinder. The engine power is also affected by the temperature of the gases in the intake port, the combustion chamber, and the exhaust pipe. These are very different when the engine is accelerating, as opposed to when the engine is running at constant speed. There have been several SAE Papers written about this phenomenon, and the difference is substantial. You cannot simply calculate these factors away with an inertia correction factor.

In fact, the primary reason for running both steady state and acceleration tests is to be able to discern the differences between these effects. If you run an engine test at 100 rpm a second, and then again at 300 rpm a second, you will find an average torque reduction at each test point. This can be easily referred to as the torque required for 100 rpm a second acceleration. A typical number for a small block Chevrolet engine would be 3.5 lb-ft of torque for 100 rpm/sec acceleration. (This number would be for an engine on a SF-901 dynamometer). It is important to note, that this number is a function of the inertia of the engine, plus the inertia of the dyno. SuperFlow dynos have the lowest inertia of all the current dynos on the market and consequently, the dynamometer inertia has the least effect on the total test.

Some competitors measure the rate of speed change between each data point, and then multiply it by an adjustment constant for the engine and dynamometer inertia. There is nothing inherently wrong with this as long as you understand that there is no real-world basis for the result. As acceleration rates increase above the 300 rpm a second rate, as they frequently do in high performance applications, you will find that simply correcting for inertia does not calculate the steady state answer, and in fact gives a substantially different answer, as indicated in the SAE Papers. So, if the answer is not correct for acceleration, and it is not the same as steady state, what is the point in making this calculation? The answer seems to be that it simplifies the explanations you must provide, if your control system does not provide a smooth rate of acceleration, or you are trying to obtain this acceleration by manually controlling the dynamometer.

It appears that this feature does not provide any clear advantage in obtaining new or more accurate information during a test. Unfortunately, people are frequently confused between smoothed data and accurate data. If you are under rapid acceleration and your engine has occasional misses, do you want that smoothed out of your test data?

Scott, who wonders if John will be bringing legal action against Cosworth....

Scott, who wonders if John will be bringing legal action against Cosworth....

now THATS funny chit

nick, who thinks John should sue everyone that says, "high tech"

....I guess it can be measured after all. No kidding. An engine is a mechanical and electrical device.....output can always be measured. An engine isn't a magical device with non measureable power.

And this is why serious discussions on here turn into needless name calling and arguing about garbage not even on the subject. Grow up

...So they have a transient response dyno. So what?

Are you telling the truth, this time?

Unless you build race cars and engines for a living then most of what is thrown around about transient response is just words. To those very few who do this type of stuff for a living, undersatnd what transient response means. How to break it down into terms that would mean something to the average guy. Probably can't be explained to his satifaction.

Unless you build race cars and engines for a living then most of what is thrown around about transient response is just words. To those very few who do this type of stuff for a living, undersatnd what transient response means. How to break it down into terms that would mean something to the average guy. Probably can't be explained to his satifaction. Since I deal with these type of things on a daily basis. I understand what it all means, and how we quantify it with how we test our engines and exhaust systems. This is not just some simple math equation, this is cutting edge dynamics, which is over most peoples heads. I posted this in reply to Scott's attack on what he calls my koolaide! Snake oil or whatever.

There are simply to many variables that happen inside a race engine to attach some kind of label to. Phenomenons occur that have no explanation i.e. transient response or transient. The main purpose of the post was to enlighten all of you to the fact that what I talk about isn't just hype. It is real world dynamics. The fact that Cosworth has even come out and said they have built special transient dyno's is giving away a lot of info. Just mentioning the transient dyno will bring a whole new approach to how they desing and build their F1 engines and how others will follow. And eventually it trickels down to you the consumer who gets the benefits of it all.

Here John is holding himself up (againe) as an elite high priest of TR Mojo.

Unless you build race cars and engines for a living then most of what is thrown around about transient response is just words. To those very few who do this type of stuff for a living, undersatnd what transient response means. How to break it down into terms that would mean something to the average guy. Probably can't be explained to his satifaction. Since I deal with these type of things on a daily basis. I understand what it all means, and how we quantify it with how we test our engines and exhaust systems. This is not just some simple math equation, this is cutting edge dynamics, which is over most peoples heads. I posted this in reply to Scott's attack on what he calls my koolaide! Snake oil or whatever.

There are simply to many variables that happen inside a race engine to attach some kind of label to. Phenomenons occur that have no explanation i.e. transient response or transient. The main purpose of the post was to enlighten all of you to the fact that what I talk about isn't just hype. It is real world dynamics. The fact that Cosworth has even come out and said they have built special transient dyno's is giving away a lot of info. Just mentioning the transient dyno will bring a whole new approach to how they desing and build their F1 engines and how others will follow. And eventually it trickels down to you the consumer who gets the benefits of it all.

Even Hytech with all their resources and experience have been left in the dust scratching their *** and wondering how they got here.