The modern chassis dyno cell, like this Wheel to Wheel Powertrain (W2W) four-wheel-drive Mustang dyno cell, is designed to provide repeatable testing for every type of vehicle up to big horsepower race cars.
'While you might consider buying testing time on a vehicle chassis dyno an expensive luxury, we hope you'll at least read this article to consider the possibilities. If anything, what we experienced in creating this story wasn't what we expected, but the safety, durability, and performance unleashed would have definitely been more painful to discover and resolve without time on the chassis rolls. To learn the most we could possibly learn, we partnered with the pros at Wheel to Wheel Powertrain (W2W), in Madison Heights, Michigan, as we ran a vehicle through its paces on the company's four-wheel-drive Mustang chassis dyno.
The Setup
So we dug up a pretty common vehicle for Car Craft: a barely streetable, cool-to-look-at-and-see-driving, somewhat-fast-at-the-dragstrip and seemingly ready to go faster with a little tuning street/strip machine. This '71 Buick Skylark GS Stage 1 killer is replete with a Dyer's 6-71 wheezer adding to the street cred of this 468ci all-Buford ride. Owner Mike Kunkle bought the car mostly complete about a decade ago and has been tuning on it ever since with the idea of getting into the 10-second club in the quarter-mile.
Since vehicles spew serious amounts of exhaust during the wide-open-throttle (WOT) testing, W2W uses an evacuation exhaust system that consists of large fans sucking air through these oversized metal hoses and out through the roof.
He has always felt the engine made enough power to go 10s but has never had the engine or vehicle on a dyno. Previous runs at the dragstrip have resulted in tire-smoking elapsed times in the 12s, with trap speeds in the 108-mph range, and after the dyno tune, the car went 11.55 at 114 mph.
The issues this car was faced with were not unusual on the street, making it a good starting point for going to the chassis dyno. The goal was to find out if there were any simple fixes/upgrades that would result in "found" power and improve the chances of a more impressive e.t. Some unexpected finds helped minimize the chances of burning the car to the ground and inadvertently breaking parts, so we'll add that in hindsight-and you should, too-when you test at the chassis dyno.
The process of mounting a vehicle onto a chassis dyno differs based on whether the dyno is installed in the floor or above ground (as the W2W dyno is). On an above-ground dyno, the vehicle is pulled onto a lift, as it being performed here, and raised up to the dyno floor.
The Experience
If you haven't seen a chassis dyno in action, here's the deal. There is a lot of setup time, the actual testing is brief but exciting, and the resulting power numbers are usually numbing-but not in a good way. Invariably, enthusiasts think their vehicles make much more power at the wheels than they really do. In fact, as far as we're concerned, there should be a special private room in which to share the power numbers for the first time-as this is usually gut-wrenching.
The testing with this Buick wasn't unusual in any of those respects. W2W dyno operator Rich Gala drove the vehicle onto the chassis dyno and positioned it so the rear wheels were over one set of the dyno rollers (this is a four-wheel-drive dyno, so in this case, only one set of rollers was used). Large straps were used to lock the vehicle down onto these rollers, and powerful fans directed at the radiator and under the vehicle kept everything cool during the runs.
The W2W dyno can record air/fuel ratio O2 sensor data during a run, but this vehicle did not have an O2 sensor bung in the headers. To assist in the tuning, Denny Dera from the W2W fab shop installed a bung in the passenger header. This would prove to be valuable later on.
The Buick was backed onto the dyno until the powered tires were on the rolls-the power-absorbing steel drums the tires ride on. This vehicle only has the rear wheels powered, so the front rolls were not used. A four-wheel-drive vehicle would have all its tires on rolls and is much more difficult to strap down, as it actually floats on the rolls during the testing. | 
W2W chassis dyno operator Rich Gala is skilled at strapping vehicles to the dyno. The positioning of the tie-down straps and the tension on them is critical to keep the vehicle in place during the testing. Various recording connections are also hooked up at this point, like engine rpm, manifold vacuum/boost, O2 exhaust gas, and others that the dyno records along with power output for future reference in problem and power research. |
Since vehicles are designed to shed heat via the air rushing through the radiator and under the vehicle, a chassis dyno needs to have a dramatic amount of air pushed through the radiator and under the vehicle. The W2W dyno uses a series of these high-volume and high-pressure squirrel fans and has a large fan pulling air throughout the entire dyno cell. | |