Some friends in town have a chassis dyno in their shop.
It’s a dyno jet. They’re on there 2nd one.
The first one was the intertia style that had the heavy large diameter rollers.
Probably around 15 years ago they had a 69 Charger on it.
Flat top 440, SD intake, Demon 850, ootb RPM heads, 1-7/8” headers, MP 509 cam, 10” converter, 3.91’s.
Ran fine, felt pretty hot driving it around.
Made around 285hp to the wheels. The guy was all upset.
Took it to the track and it went 11’s.
I’ve seen a lot of that kind of thing that really make me scratch my head.
The new Dyno Jet they have has smaller rollers and uses an eddy current type of absorber instead of inertia....... so you can actually load the motor prior to making a “pull”, along with being able to set the accel rate.
I haven’t seen that one in action yet.
The 224 smaller drum is still inertia, the 224xlc is inertia and eddy current. I have the xlc now , I use to have a 248 , the large drum version. The stack has to be matched to the machines drum weight, if you use someone elses stack(dyno computer module), you'll get whacked readings. The 248 actually had loading via the modulation of the air brakes(locomotive brake shoes), if the brakes were acting up or setup wrong, it caused low readings, mine would flutter the air solenoid, it stopped when I fixed the cable shielding.Dynojets are calibrated on the inertia weight so that no matter where you dyno a car, if the same correction is used the number spit out should be pretty close to the same anywhere on a given car strappped down in a consistent manner on any dynojet. I keep notes on cars I dyno that I know are coming back.
Strapping the car down incorrectly will put a dent in the power. The less angle on the straps the better, but some people put angle in to load the tries up if the knurling is worn on the drums. I opted to build my own deck for the dyno, a longer version so that trucks and longer cars would still have less steep angle from the rear strap points.
