The visit is done. It was, of course, a rather enlightening experience.

The 1.8 car decided it didn't want to play. (The other guy owns both it and the other 1.6, so it really WAS the car that decided this one....must not have spoken nice enough to it in the days leading up to the visit....)

Tests run on a Mustang dyno. The guys running it have only had it for a couple of months, so they're still getting used to it.

Garage/open building. About 90 degrees, 50 percent humidity. Total time on dyno - 2.5 hours. They were nice and rounded us to 2 hours.

AFR measured by a wide-band O2 sensor hooked to a Motec box, then plugged into the computer. Attached to end of tailpipe.

All pulls done in 4th gear, 1:1 ratio in a Miata.

Pull #1 yielded 131 horsepower. YEE HAW!

Then the guys changed the multiplier factor in the software, and we ended up with another pull yielding 96.9 HP/82.1 ft-lb at 6750 RPM. More realistic, I suppose....dangit. Of course, with 131 HP I'd have a hard time explaining why I haven't won every single time I've touched a track....

Did that baseline with my car, a known quantity. ('91 Miata, straightpipe plus resonator for exhaust, open air filter slapped on end of airflow sensor, 900 miles (10 or so races) on untouched Mazda crate motor, installed last winter). Note the RPMs - they cut the run off a bit short on that one.

Switched to the other 1.6 - pulled 93-ish HP (don't have his stats). Decided to swap airflow boxes - found tape covering half the opening, upstream of the airflow sensor. Whoops. Fixed tape, different airflow sensor: 97-ish HP. Much better.

Note: tape across half of intake loses 4 HP.

(This car is also a 1.6 - has a 300-mile motor with about 4 races on it. The motor came from a well-respected builder. VERY well respected. OK, VERY VERY well.....you get the idea. )

Swapped through the three meters (two spare, plus the two on each car), noting AF measurements for each. All ratios ended up within half a point of each other. I know mine ended up at 12.6 at the top end of my best run.

Pulled that car to swap injectors, and put mine on to try different meters.

After selecting the "best" meter for mine (turned out to be the one I was running), we threw on a meter from an RX-7 for kicks. Immediate 5.7 HP gain, zero torque gain. The torque peaked MUCH later with the 7 airflow meter, and the car was generally sluggish at all but high RPMs.

One final pull on mine, we bumped the timing up to 18 degrees. Gained 0.6 HP, 0.7 ft-lb. - ending at 100.6 HP at 7250 and 84.8 ft-lb at 5500. As mentioned before, AFR worked its way down to 12.6 right before the fun-limiter kicked in.

Meanwhile, the other car was getting fresh injectors. Put it back on, and gained a couple tenths in each area, but still pretty much even (within .5 on each) with my car.

THEN the guys running the dyno asked each other who had input the weather correction information....and neither had.

SO, after they plugged in the temperature and humidity levels, the other car picked up about 4 HP and about 4 ft-lb. Not a huge deal - we were able to make some adjustments and confirm some things we already suspected. At least they didn't figure that out and do it in the middle without telling us.

Overall, it was a good trip. There are claims floating around the SM site of an exhaust that adds 4 hp and 7 ft-lb, but there's no mention of what that's compared to. If we can get some research done and figure out what that exhaust is, we might pop for another visit in the near future; otherwise, I think we're done at the dyno for the year.

Comments?? Even though we've already gone, I'm still very interested in learning what we might have done wrong or can do better next time....

Jarrod