| I regret to say that our dyno session with the second vehicle did not come to fruition.... we didn't receive the car until around 4 in the afternoon on friday and the dyno session is postponed until Monday. I was a bit too optimistic when I said I would have a nice Christmas present for the community; presenting the first of intercooler efficiency data. There were a couple of good questions brought up in the post put up thursday. One being what equation was being used to determine efficiency and the other suggesting a steady-state test process. 1st, the efficiency equation:
IE = (Tin-Tout)/(Tin-Tamb) Tin is the charge air temp before the IC
Tout is the charge air temp after the IC
Tamb is the ambient air temp The efficiency of the IC using this equation relates the IC's ability to bring the inlet charge air temp back down to the ambient air temperature. The efficiency value represents the relationship between the total temperature drop of the charge air to the difference between the inlet charge temp and the ambient air temp. Now to the suggestion for a steady-state test process: Steady state testing will require the construction of a test rig that can produce the massflow, pressure, and temperature like those which are seen in the actual in-car application as well as provide a metered flow of temperature controlled ambient airflow. While this is certainly possible to do, it is not an inexpensive or timely project to take on. Steady state testing would be the most ideal method of testing the efficiency of these devices. I really wish we had the time to build a rig to do it this way, however, I also see it unnecessary to do so; we can acquire the intercooler performance data with the units installed on a vehicle. In this configuration we are able to put the ICs into a simulated "real world" condition - we simulate the conditions the vehicle experiences when it is actually being driven on the road as closely as possible. I use the words "as closely as possible" for good reasons:
- the dynojet 248 only simulates about 75% of the actual load the car will feel when it is propelling itself down the road.
- we cannot simulate the ambient air velocity dynamic that the intercoolers experience when the car is being driven on the road. However, for sake of comparative testing, so long as all of the simulated conditions are the same when testing two different intercooling systems, the data that is collected in the tests will be of apples to apples. I could make the same argument to steady state testing; steady state testing requires that a system be set into action and only at such time when all variables have reached an equilibrium is a measurement of performance taken. While I do not discount the validity of this type of testing, one can debate the difference between a steady state test vs the actual dynamics the intercoolers experience in their real-world application. I must emphasize that the suggestion of a steady-state test would boil and reduce out all other variables - it really IS the ideal test procedure to use.... afterall, we are trying to determine intercooler efficiency which has nothing to do with a car, an engine, or a dyno, etc etc etc.. Thing is, we simply are not going to build such a rig to perform this kind of testing. The best we can do is a back to back test where all we are changing is the intercoolers. Interestingly enough, the efficiency equation we are using provides exactly the information we are seeking - we just aren't obtaining the data from a steady-state test. We are obtaining performance data of the intercoolers based on as close to a real-world scenario as we can affordably produce. During the dyno pulls with the FMIC in place I made a pull in which I started in the lower RPM in 3rd gear, ran it out at WOT to around 7000, shifted to 4th, WOT up to around 7K again, and then to 5th gear up to around 180MPH. The result of this clearly showed the effect of heatsoak - each consecutive upshift resulted in a higher intercooler outlet temperature while the intercooler inlet temperature remained the same. This test process, if it were to be continued without pause, would actually approach as close to a steady state condition as possible; we should eventually see a point where the intercooler discharge temperature no longer increased. With all of that said, I am open to suggestions here. What other test processes can be employed using the existing equipment on hand? Are there any additional mathematical analyses to use that will shed more light on the subject? I will be processing the data we have from these tests over the next few days and want to do the best possible in presenting the information. We are seeking to actively engage the community on this project. We will openly share the dyno runfiles in both standard .drf format as well as in delimited numerical format for those who would like to crunch the numbers themselves. We are also open to any suggestions on how this testing can be further refined so please do not be shy! :) Thanks!
Enthusiasts soon understand each other. --W. Irving.
Are you an enthusiast? If you are out to describe the truth, leave elegance to the
tailor.
Albert Einstein
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