911 Dyno testing

jacko241 · 08-26-2005, 02:08 AM

Those of you that have run your cars on a chassis dyno, how did you tie it down? When I ran mine they used nylon ratchet straps around the rear control arms, but we had to cut testing short because I am running headers, (no heater boxes) and the straps melted where they touched the pipes. Luckily we caught it before we had a disaster! Any ideas would be appreciated.

TimT · 08-26-2005, 05:27 AM

We run the straps through the car. In one door out the other, behind the seats. And use blankets or padding where the strap bears on the door jamb.

Also chock both front wheels

ValveFloat · ValveFloat's Garage

Quote:

We run the straps through the car. In one door out the other, behind the seats.

Seriously?

I guess that would work well, but it is kind of funny.

I typically go around the banana arm, and sometimes have to get creative from there to keep the strap away from the exhaust.

I recommend to people that will be dynoing often get those little tie-down loops that go on the shock bolt, those make it really easy.

jacko241 · 08-26-2005, 06:36 AM

Bingo! Joe, that was my next question! I felt like those would be the best way to go. I really couldn't do the thru the doors thing if i wanted to, because mine is an ultra wide RSR clone with 14" rear flares. Where can I buy those loops that go on the shock mount?

sewell94 · 08-26-2005, 06:41 AM

It depends on how the dyno is set up. Mine dyno is on ramps in the air , so i can run it to the tow hooks in the back and then strap it from underneath in the front. My buddy's dyno which is inground, they run the strap though the car behind the seats, first tme i seen it i was like holy ****, no way. But 911's that have made over 750 stapped like that, has definately changed my mind. On big hp cars i run a strap though the car just for some extra insurance

ValveFloat · ValveFloat's Garage

Quote:

Where can I buy those loops that go on the shock mount?

Autometrics has them, but they maybe available elsewhere.
http://www.autometricsmotorsports.com/products/911/index.htm#0-Accessories%20&%20Misc.:
Way at the bottom.

emcon5 · emcon5's Garage

They strapped mine to the tranny crossmember.

Tom

jacko241 · 08-26-2005, 08:44 AM

ok, thanks Joe!

TimT · 08-26-2005, 09:58 AM

The method of securing the car has alot to do with the physical restraints of the dyno itself, and of the car. A single roller dyno, that is accessed via ramps makes it really easy to tie a car down by its shock mounts/trailing arms.

However, our dyno is a dual roller eddy current dyno, which is mounted in the floor. When a car is placed on the dyno, there is very little clearance between the rear roller of the dyno, and the undercarraige of the car. We tried using shock mount tie downs, etc. but were not comfortable with the geometry of the straps, and wanted to keep the nylon away from potentially red hot exhaust components.

Going through the car is convenient and secure. We have dynoed a twin turbo supercup car we built at over 700hp-700ft/lbs torque
and a 935 clone that is equally as powerful. We will continue to run the straps through the car.