Thanks to Todd at 2NRWerks, I picked up a Taitec GT Lightweight exhaust two weeks ago and I wanted to report results back to the group. The sound at idle is perfect, a nice low rumble. There is a resonance with the cabin acoustics at 2000 RPM that some of the others have reported that makes the exhaust sound louder at 2000 RPM than other speed ranges. The wife noticed this, but didn’t complain (she was used to our M3). I find it best to avoid cruising at 2000 RPM. For instance, driving on a 45 mph road, it is best to leave it in 3rd gear and cruise at 2800 rpm instead of shifting to 4th gear.
Better idle sound and weight savings are the real reasons I wanted this exhaust. On a bathroom scale, the exhaust weighed 18 lbs, while the stock exhaust weighed 44 pounds; saving 26 pounds.
I used an Escort G-Timer to get a crude estimate of any horsepower gains. There are several ways to infer horsepower gains from the G-timer, but because run-to-run variability is very high due to variations in the launch, the data must be looked at carefully. The before runs obviously carried 26 extra weight (plus a little extra fuel) more than the after runs, but they were done in the morning 10 degrees cooler. In every measure (zero-to-any speed, peak horsepower….) the Taitec exhaust had better performance. Looking at the raw data it was best to look at differences between speed bands, rather than absolute values, to avoid launch variation. It was also best to look at speed bands that didn’t involve a shift. For instance, I made three before runs where the time it took to go from 70 to 80 mph was 1.50, 1.55, and 1.53 seconds. The two after runs resulted in 1.45 and 1.42 seconds.
Based on calculation, it would take 11.6 extra horsepower to achieve this added acceleration. The lower weight would account for roughly 1.6 extra horsepower, but this would be more than cancelled out by the 10 degree increase in ambient temperature which would have reduced the horsepower by 2.26 horsepower. Therefore, based on back-to-back runs and corrections for all the variables I could measure, I believe the Taitec GT Lightweight exhaust produces roughly 12 extra horsepower to an otherwise stock 1991 engine, plus the added benefit of better sound and 26 pounds less weight.
The peak horsepower point increased slightly from 44 mph to 45 mph road speed based on pure measurement of the G-timer and this would be due to the better breathing.
Bob
Better idle sound and weight savings are the real reasons I wanted this exhaust. On a bathroom scale, the exhaust weighed 18 lbs, while the stock exhaust weighed 44 pounds; saving 26 pounds.
I used an Escort G-Timer to get a crude estimate of any horsepower gains. There are several ways to infer horsepower gains from the G-timer, but because run-to-run variability is very high due to variations in the launch, the data must be looked at carefully. The before runs obviously carried 26 extra weight (plus a little extra fuel) more than the after runs, but they were done in the morning 10 degrees cooler. In every measure (zero-to-any speed, peak horsepower….) the Taitec exhaust had better performance. Looking at the raw data it was best to look at differences between speed bands, rather than absolute values, to avoid launch variation. It was also best to look at speed bands that didn’t involve a shift. For instance, I made three before runs where the time it took to go from 70 to 80 mph was 1.50, 1.55, and 1.53 seconds. The two after runs resulted in 1.45 and 1.42 seconds.
Based on calculation, it would take 11.6 extra horsepower to achieve this added acceleration. The lower weight would account for roughly 1.6 extra horsepower, but this would be more than cancelled out by the 10 degree increase in ambient temperature which would have reduced the horsepower by 2.26 horsepower. Therefore, based on back-to-back runs and corrections for all the variables I could measure, I believe the Taitec GT Lightweight exhaust produces roughly 12 extra horsepower to an otherwise stock 1991 engine, plus the added benefit of better sound and 26 pounds less weight.
The peak horsepower point increased slightly from 44 mph to 45 mph road speed based on pure measurement of the G-timer and this would be due to the better breathing.
Bob
