Testing Chassis Dyno - Car Craft Magazine

As Gala put it, "I always make a baseline run without looking at anything as long as the timing is safe, then immediately check that the throttle blades are opening 100 percent. I've had some great finds. On a recent 450hp vehicle test, we gained 30 hp by getting the throttle fully open. I usually find single-digit horsepower with this one check." In this case, Kunkle had addressed the issue the previous year, and the throttle blades were opening 100 percent.

As Gala put it, "I always make a baseline run without looking at anything as long as the t

The Findings
Check out the photos and sidebars to see how the testing went and what you can learn from our pain. Without a doubt, the chassis dyno testing discoveries were more than just horsepower-the car is much safer and consistent. Now, the car should be able to make some laps at the dragstrip with the focus being on getting the car to hook at the line and using all the power it is making.

With the vehicle strapped down, Gala "drives" it on the dyno to get everything up to temperature and then makes a few baseline runs to generate initial horsepower and torque results.

With the vehicle strapped down, Gala "drives" it on the dyno to get everything up to tempe

Kunkle is planning a new engine to produce the 600 rear-wheel horsepower W2W says he'll need to run in the 10s. He's a believer in chassis dynos and looks forward to coming back to the dyno rolls with his new engine installed to debug it before heading out to the dragstrip.

Chassis Dyno Testing Results

OK, so this is the brutal part. Just about every enthusiast believes his vehicle makes more power than it really does. Before going to the dyno, prepare yourself for the reality and try to focus on just making solid improvements in power, reliability, and durability.

OK, so this is the brutal part. Just about every enthusiast believes his vehicle makes mor

The chassis dyno is a brutally honest piece of equipment, but it tells you much more than just power output. If a vehicle is unsafe or unreliable, the dyno will expose it. We ran into multiple issues that needed to be resolved, and the vehicle is better for having corrected them. They are listed along with the power improvements because of their value to the overall performance of the vehicle.

TEST STEP	RESULTS	DIFFERENCE
Performed baseline testing	320 hp	n/a
Checked throttle travel at WOT	320 hp	0 hp, but peace of mind
Checked timing	326 hp	+6 hp, set to 35 BTDC
Tuned carb setup	326 hp	0 hp, but smoother idle
Fixed vacuum/pressure leaks	350 hp	+25 hp, blown-out gasket
Fixed underhood oil leak	350 hp	0 hp, minimized fire hazard
Fixed leaking transmission pan	350 hp	0 hp, durability improvement
Fixed slipping blower-belt tensioner	350 hp	0 hp, improved reliability
Repaired blown transmission	370 hp	+20 hp, replaced torque converter
Increased boost with Dyer's pulleys	390 hp	+20 hp, 1.5 pounds of boost
Horsepower results from testing	390 hp	+70 hp

Gala used a timing light to determine both the initial and final ignition timing. The Buick had 32 degrees of timing advance in it, which seemed conservative. So a few runs were made with 3 degrees more timing advance in them, which resulted in what appeared to be a 6hp gain.
Gala used a timing light to determine both the initial and final ignition timing. The Buic
The W2W team (now including General Manager Kurt Urban) thought there was a problem with the carburetors because the engine was cycling on idle speed. But on further investigation, a serious vacuum leak was discovered between the blower and intake manifold. The vehicle was removed from the chassis dyno to be tested again another day.
The W2W team (now including General Manager Kurt Urban) thought there was a problem with t
They found a blown-out intake gasket was so gone (see gasket closeup), it's hard to believe the engine ran at all. Kunkle also found a wide spray of fuel and oil on the firewall. A new gasket was installed and the blower case was torqued down onto the one-off intake manifold.
They found a blown-out intake gasket was so gone (see gasket closeup), it's hard to believ

During one of the later power runs, when the engine was making good power and Gala was legging it up the rpm band, the engine bay gave off a large flash of fire and a plume of smoke. Gala immediately shut down the car and looked under the hood. After some time inspecting the vehicle, he discovered the dipstick tube was not installed securely, which dumped hot oil out of the engine oil pan onto the headers at high rpm. Ace W2W machinist Bill Blair whittled up a stainless tube that press-fit into the block and held the dipstick at the proper height. Problem solved with a minimum of damage and fright.
During one of the later power runs, when the engine was making good power and Gala was leg
As the testing progressed, the W2W team kept noticing the boost for the engine was only in the 9-psi range at peak rpm. They felt the engine should be seeing at least 10 psi or more, so they ordered a set of slightly overdriven pulleys from Dyer's Blowers in Summit, Illinois. The crank pulley needed to be redrilled to fit this application, but otherwise, the pulleys bolted on and netted a little boost in overall power. The final analysis was that the 6-71 blower either needed to be spun much harder or an 8-71 blower needed to be called in to service the big-block Buick to more horsepower. But that will be a project for another day. We learned a lot, the car is much more consistent, and it made a little more horsepower along the way.
As the testing progressed, the W2W team kept noticing the boost for the engine was only in

After each major discovery, which included the intake-gasket leak, blown transmission, and leaking dipstick, the vehicle was removed from the chassis dyno, repaired, and brought back. Was this frustrating? Are you kidding? Yes, it sucked, but it was more educational than going to the dragstrip-and everyone is confident the car would've burned to the ground without this dyno day.
After each major discovery, which included the intake-gasket leak, blown transmission, and