Philip had been running a RacingBeat muffler, in deference to his neighbors when he was garaging the car. I wanted to see if it made any difference power wise running without the muffler. Being in the ITA class, the car has a straight though header/exhaust, no CAT. Car has a MegaSquirt ECU/Tune, and runs on 100 octane.
On Sunday we ran track configuration 1, clockwise, 3.1 miles in length; the longest configuration.
I pretty much went faster on each lap, starting at 2:34 and ending up at 2:27:031 by the end of the 2nd Practice. For the 2nd Practice I removed the muffler. It probably weighs around 20 lbs. (btw. that 2:27 time would have qualified me in 18th out of 22 car in the IT/SSC/SSB Touring Car race. I was only doing the Time Trial Practice; no races for me. The fastest Spec Miata in the field was 11 seconds faster then me! But he was 3 seconds faster then the next Miata.)
For the third and last Practice I put the muffler back on. By now I was definitely feeling more comfortable with the car, keeping my foot down in more places, getting into the next gear sooner and getting into 5th gear in a couple of places (4.77 rear end). At 4PM it was pretty much the warmest it had been all day, but not hot. I figured I had probably dropped my time another 2 seconds.
So I was very surprised when I got my times. I was about 2.5 seconds SLOWER each lap for my string of four hot laps and my fastest last lap was still a good 2 seconds slower then my fast lap without the muffler. Losing the muffler definitely seemed faster.
But, I didn't have a turn down and melted the rear bumper. That fellow that was in the fastest Miata had the tiniest bit of a turn-down at the end of his exhaust, ending just past the rear A arm, and he wasn't suffering from any heat damage.
I HAD a turn-down made for Karen's Miata, but it got cannibalized to attach her Supertrapp muffler to her car.
So now I'm looking for a replacement RED rear NA bumper!


