Welcome to Cryofuzion!

The spray bar story...
by: C.J. Evers, Cryofuzion engineer & VP

9/19/03

This will be the first in a series of technical discussions we will be posting on the Cryofuzion web site. (Cryo 101, if you will.) I hope you enjoy this section of our page and find it to be both fun and informative. I appreciate your comments and feedback. If you would like to discuss any of the topics I mention in Cryo 101, please feel free to email me.

If you don't care to read the entire article, a quick synopsis is outlined in the following bullet points, with the complete discussion below.

	CO2 works as a fire extinguisher and displaces oxygen. Engines use this oxygen, combined with fuel, to make power.
	Ingesting even a small amount of CO2 into the air intake will slow your car down.
	It is nearly impossible to use an intercooler spray bar without ingesting residual gases from the intercooler spray.
	Nitrous oxide, when sprayed across an intercooler, can cause motor damage.
	Intercooler spray bars can work effectively if used during non critical conditions.

Background

I had been building intercooler spray bars since 1995 when clients, friends and myself used them for nitrous oxide applications on turbocharged vehicles. Often, these cars were using nitrous oxide in conjunction with rpm activated "window" controllers to assist in larger turbocharger spool up. I knew it worked at the time. Our quarter mile times were dropping with the use of the spray bars. However, the spray bars were always perceived as more of a gimmick and subsequently faded in popularity. It was assumed at the time that the primary gains were coming from the actual ingestion of the nitrous into the motor. This idea along with rising nitrous costs led to the demise of most of the spray bars I had fabricated. There was a lapse, during which I built very few spray bars that lasted around 3 years. Still interested, I then built a couple sets of bars for what would later become some rather high profile cars.

Brian Fox, of Fox Marketing, was handling the publicity for these cars and was in communication with a major corporation which produced nitrous oxide related products. He found that they were developing an intercooler spray bar to distribute on a large scale and were in the testing stages. Brian, Steven Fults (president of the Stedebani Enterprise Co., Inc.) and I were contracted shortly afterwards to do the testing for this spray bar, and ended up spending two days doing various dyno testing.

The Test

The car we used was a turbocharged 1995 Honda Civic with a large front mounted intercooler, belonging to Don Kiernan, of Modified Motorsports. The car, though turbocharged was reasonably mild, and I knew it to be a car that had been repeatable on the dyno in the past. We agreed it would make a good test bed for the testing we had in mind. At the time we were using a new Mustang chassis dynamometer. In addition, this series of tests incorporated a large, high velocity centrifugal blower to ensure adequate airflow across the intercooler and radiator. An anemometer showed nearly 90 mph of airflow across the front of the car during testing. This would help to avoid any heat soak related issues with the intercooler, thereby improving the accuracy of our tests.

Our spraybar samples arrived and were installed. The construction was of good quality and the installation was straightforward. With the preparation of the car now complete, we set out to begin testing and came upon some amazing results.

During our first series of tests using nitrous oxide, the intercooler spray bar added an additional 53 peak horsepower to the wheels! We were stunned. For a car with an initial base run of close to 250 peak horsepower, this represented a gain of almost 25%! Bear in mind, this is on a car with an already highly efficient intercooler with a 90 mph wind coming across it. If you use a standard rough calculation of 1% gain in horsepower for every ten degrees of lowered air intake temperature, this would equate to a 240+ degree Fahrenheit drop in air charge temperature. Though very, very unlikely, this isn't impossible. Skeptical, we continued our testing.

We did a couple more base runs to get the cars temperature to a stable point and had some good repeated results. With no spray bar activity, the car was averaging 255 peak hp at full operating temperature and was repeating these results within two horsepower per pass. Knowing that carbon dioxide has similar cryogenic cooling properties as nitrous oxide, we decided to try it. We knew CO2 was far less expensive and would make a viable alternative to N2O spray.

Again, our results were surprising. The horsepower dropped. We did a couple more base runs and verified our base numbers, again using no spray bar at all. We discussed the differences between the two gases and theorized that the residual gases during each test were being drawn in through the cars air intake. So, we decided to level the playing field.

We quickly rigged up a long snorkel and punched a small hole in the wall adjacent to the dyno. We ran the air inlet of the turbocharger to this pipe. (the pipe had a 4" dia and was around 10 feet long with a large conical K&N air filter on the end). This way, the only air the engine would ingest was the clean, cool air from the next room. We reran our baseline tests and arrived at roughly the same results. We then tried both the N2O and then the CO2 sprayed through the same bar in a series of follow up tests. All conditions being the same, the horsepower gain was almost identical. (Within one hp of each other.) When sprayed onto the intercooler, both gases netted a 9 hp gain to the wheels. This is much closer to the gain we expected to see. Using the same equation I mentioned earlier, this represented a drop in air charge temperature of approximately 40 degrees Fahrenheit.

Intrigued with our new data, we wondered how adversely CO2 can effect a motor in its operation. We reinstalled the air intake system on the Civic and reran our baseline test, again with no intercooler spray. Then, we opened the valve of a 50 lb. bottle of CO2 in the same room as the dyno for about 15 seconds immediately prior to a pull on the dyno. (roughly 12 feet away from the vehicle being tested). The horsepower again dropped. (By a total of 4 peak horsepower.)

The Conclusion

We now know that it is almost impossible to use an intercooler spray bar without some residual gases being drawn into the intake. We also know that CO2 displaces oxygen. Therefore, we can determine that even a very small amount of CO2 entering the air intake will decrease power output. This one of the theories used in producing Cryofuzion's system of Cheetah Jets.

Some racers who are unknowingly using these intercooler spray bars with CO2 have also installed hobbs switches. This means they are using a boost activated switch to turn the CO2 spray off and on. (When the boost pressure rises, the CO2 spray comes on.) This is perhaps the worst idea for a spray bar I had encountered. The power robbing effects of the CO2 will be maximized at full throttle conditions, which is when the switches are activating the spray bars. If CO2 is to be used on an intercooler, it should at least be done while at an idle when peak power isn't a concern.

We concluded that nitrous oxide, when sprayed onto the intercooler can net some impressive results. However, a larger portion of the gain seen while employing this method comes from the residual N2O being drawn into the intake and subsequently used within the combustion chamber. N2O's oxidizing capabilities assist in combustion, creating horsepower. This is a double edged sword. The problem with using nitrous oxide in this manner is that it is unmetered. In other words, there can be no way to correct the air/fuel ratio or ignition timing of the car when the nitrous oxide is added. This will almost certainly lead to eventual motor damage.

Both nitrous oxide and carbon dioxide when sprayed onto the intercooler can be effective if used during non-crucial times. They could be used effectively any time engine power output is not important. For example, while staging during a drag race to prevent heat soak. Or, pre-launch. However, using either one during a full power run, or during spirited driving of any kind can lead to disaster. Or, at least the loss of a race ... but isn't that almost as devastating?

Undeniable Proof

Below are the dyno sheets affiliated with the test I described above. You can view each dyno sheet by clicking on any image below. (Please be patient if you do not have broadband access. These picture files aren't small.) Each dyno image contains the information from both a test run and a base run. So, the five dyno sheets below represent ten dyno runs.

(Click on an image above to see the full sized dyno sheet.)