Removal of the stock airbox lid on 2002 Z06 worth 15.8HP and 11.4lb/Ft Tq

[J-Rod]

I have posted this elsewhere, but thought I would post it here also.

I went with the CF Southwest group to MTI for Dyno day. This is the third time to the Dyno for me. The first time was at 1100 miles. The second time was at around 4000-4500 miles. Today, the car was at ~6700 miles.

In both previous pull, the car dyno'd within 1-2 HP, with two pulls per trip. This time the only change was to remove the factory cover from the airbox. I left the frame in place (including the center section). I used two tie wraps in place of the factory metal straps.

After my two pulls on the dyno I walked over to Jayson @ MTI and he said. The car made a strong pull. I asked him what it came in at. He said 372. I said that wasn't bad for an uncorrected number. He replied that that was the corrected number. I was more than a little suprised.

The two runs were 372.7/363.5 372.8/362.0 HP/TQ

Folks had complained before my run that the correction factor was off, because their cars were dyno'ing too low. The folks who I heard from before me were claiming to be low by about 5HP. Jayson checked his weather station before my run, and it appeared to be right on.

We pulled up my last dyno pull, and layed it over the one from this time. Across the board the open airbox pull was ahead. The two runs we looked at were 356.9/352.1 vs 372.7/363.5 My correction factor in both runs was .95. Weather conditions were almost identical.

My uncorrected number for the two pulls were 388.9/377.6 and 389.8/379.5. My uncorrected numbers on my previous two trips to the dyno were ~374 for the first trip and ~377 for the second one.

 

[QUIKAG]

I saw your post about this before. I don't see how that big of a jump is possible as the '02 airbox is not nearly as bad as earlier years. I would think it's more of a function of the difference in day, calibration of the dyno, etc. Now, opening up the airbox will net some hp and tq, but not that much....IMO

 

[J-Rod]

Lots of folks saw it, and their dyno runs were right on. As for the comparison. The two dyno runs I compared for a before and after were the same correction factor .95 the tempearate was within 3 degrees on each day, and the humidity was within .3. So, I don't know that any of those was a factor. Now, the only thing I do believe is that the fact that the hood is open during the dyno proabably helps the numbers some.

I think this is why the Vararam and other make HP. They pull cool air from outside the car. Their is no heating of the intake charge on my car during my two pulls, as the hood was open. I suspect this is about the same gain I would see with a Vararam. But the car might be a tad bit quicker at the drag strip.

I think unless you isolate the stock airbox from the engine compartment you will be sucking some hot air initially until the air coming into the grills pushes the hot air out of the way and you are breathing cool air.