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Old 05-30-2009, 02:41 AM   #22
Scooby Specialist
Member#: 4498
Join Date: Feb 2001
Chapter/Region: NWIC
Location: Portland, Oregon
WRX H6-3.0 Turbo


Originally Posted by Vaus View Post
Cool test, but I never quite understand the point of such testing. A lot of, if not most, parts do in fact require additional tuning to realize the gains/benefits. Without adjusting the tune to better suite the part, you may not be showing the true potential of the part. I realize this makes it more difficult to do a direct comparison as there are many variables in the tune, but its the only real way to show what a part can do.

IMO, a better approach would be to lay down a good, maximized tune with the stock manifold and do 3-4 runs to show consistency. Then switch to the cosworth manifold and re-tune the car to the same degree of aggressiveness and do another 3-4 pulls. If you can see clear, repeatable gains in such a comparison, and the tuning was done by an unbiased party, you can be pretty sure the gains are a result of the added part.

-- Ed

Actually, the higher boost setup was as you described at least in terms of the technique. Take a look at the data I posted. The boost and AFRS were nearly the same, certainly within the run to run variance. Both setups were at equivalent aggressiveness, at least based on the variables available.

As you can certainly appreciate, I fully understand the notion of 'tuning' to match the capabilities of the part. In the case of this test, the higher boost runs didn't 'need' tuning to match the boost, timing, AVCS, and AFR settings. The runs were nearly identical in terms of pressure in the manifold. I could have ran more boost, but I also could have ran more boost with the stock manifold. The timing was pretty high, and at the point that adding more timing didn't add significant power. There were some subtle differences in tuning with the cosworth manifold, but I would need more time to really understand and demonstrate them. It is possible there are more gains to be had that I did not discover. I would welcome other tuners to post their test results and techniques.

I would consider this tune to be 'Aggressive', per the mention of this above. While I could get more power with a bit more boost, I wouldn't consider that a better test. If I truly matched those variables I would expect the results to be the same. With a larger turbocharger I suspect this might not be true.

If this were a test of two different turbochargers, with different compressor maps and different efficiencies, I would expect some significant tuning work in order to do a good comparison. Indeed I have done many of those tests and posted the results over the last few years.

The value of this particular approach seems self evident at least in my mind. Given the lack of need to change tuning settings in the higher boost setup, it is evident that the overall flow of the system was not significantly different. ( of course this is a MAF based seutp, so that would not have to be true ). Furthermore given the pressure in the intake manifold, there was not a significant difference in the available charge for combustion.

I am of course always willing to try a new approach, but I’m not sure if I would do this particular test differently.


Jeff Sponaugle
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Last edited by sponaugle; 05-30-2009 at 03:00 AM.
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