This is a project that dates back 4-5 years at this point, but I’ve never really put all of it together in one place until recently.
ITB Fabrication and Install on a 2001 Saturn SL2
I’ve posted some notes on ITB tuning in the past also. Follow the link below for that information.
Some notes on this build follow:
Road Dyno measurements indicated nearly 140 wheel horsepower on the NA engine prior to installation of the ITBs
Road Dyno Results
During the 12,000 miles of running with the individual throttles I never road dyno’d the car (most of these miles were during winter when the roads were slick so conditions never worked out when I had time).
The car didn’t “flatten out” (torque) as badly on the top end with the ITBs and I increased the fuel cut to 7500 RPM during that time (generally shifting around 7000). Infer what you will about that (given the previous Road Dyno plot).
Cams would have been absolutely huge on this build with the inlet and exhaust systems as they were. This was definitely the largest bottleneck in the system.
The car was the most fun from a 15-20 MPH roll in 2nd gear where you’d have to “pedal it” right past 60 MPH (remember the new rev limit) … and it would still chase traction at various points in 3rd with a Quaife ATB on dry pavement with 195/60/14 Dunlop SP40s (certainly there are stickier and wider tires, just to give a point of reference tho).
Power at any RPM above 3,000 was there “now” with the ITBs. Imagine the push a turbo car gives you, but not quite as hard, happening seemingly before you crack the throttle.
-David