Chris White

I had a nice 930 on the dyno (tuning the Electromotive set up) on Friday.
We had it set up and the basic tuning was dialed in so it was time for some power testing. The dyno operator really wanted to keep it in 4th gear (4 speed) and that you get us to over 190 wheel speed…
As the car is building up to peak speed and the power is coming on nicely there is a bright flash and a loud noise….kind of freaked me out, I have never really ‘blown up’ an engine on the chassis dyno…

I ran out of the control room to see what the damage was….greeted by a loud hissing noise as the car coasted down (it takes quite a while for the rollers to stop when you were at 190+). The car owner was looking pretty concerned, so was the dyno owner (and I suppose I was too!).

At the right rear there was a lot of glass on the ground…a fluorescent bulb had fallen. Odd. Looked around some more and found a valve stem! The valve stem had separated from the wheel at 190 and shot up into the light fixture exploding the bulb. Pretty freaky.

No damage to the car, we installed a new valve stem and went back to work…

caster951

Did you have to replace anyone's underwear before continuing? Wow.

dillon410021

wow, thats crazy. Were you all laughing once you figured out what happened?

JohnKoaWood

BWAAAHAAAAHAAAA....

Did the owner shat on himself? I bet he was grinning ear to ear seeing the numbers, and then BANG...

I once upon a time in a previous life witnessed a T700-GE700 turbine engine (1200 or so shaft HP) detonate a compressor disk on a load cell (turbine engine dyno) it embedded a piece of a blade 1.5 inches into the window of the control booth...PUCKER

It is hindsight that makes these types of failures funny, in the moment... not so funny...

fast951

Whoever strapped the car on the dyno did a good job. I know of a newer Corvette, forced induction and lots of power that came off the dyno and took out all sort of things along the way. A ugly picture.

Chris, how close were my values?

ehall

I just shat, and it wasn't my car!

2bridges

yikes!,That should be a great lesson learned for the owner -> invest in solid valve stems......

150mph up I consider them required safety equipment. Land speed sanctioning bodies require solid stems for all classes over 130mph I believe

ehall

I agree. Hollow stems just can't support a full pour of a quality cabernet! Weak *** crystal is...weak.

EVOMMM

i want to know what kind of vlve did he have on the wheel all rubber or the metal capped ones
and next Ques. which is best
but my *** did twich on that story as it happened to me on my 88 M3 but my results were more costly

xsboost90

sounds like he had the rubber stockers- im running the solid bolt in type on my car after seeing quite a few break and cause flats along the road and track.

CarbonRevo

I'm glad tha hollow spokes on my S2 require the special valve stems. I'll look into solid ones for the turbo. What a scary thing!

los423

Essentially you tuned an automatic valve stem remover.. Maybe an overly expensive and elaborate one, but effective none the less..

V2Rocket

my grandfather worked his whole life in a petroleum company testing different oils on standard american V8s to see how they stood up to constant high-rev running and how they wore

more than once a mopar or chevy or something launched a piston or rod and they would ricochet around the basically bomb-shelter room

badcoupe

wow! I had a 383 lt1 Z-28 I built for guy break a strap on the dyno at Kenny Brown, Luckily the car didn't take off too bad as it was early in the pull. Mr Brown chucked the strap across the shop while cussing profusely, I think he was as worried about damaging the car as I was. Great to hear it wasn't a bad ordeal, I hate having owners present when doing that kind of work.

gt37vgt

good lesson I'd never given valve stems much thought ...but they are doing 80% of road speed in an 16" circle could be doing up to 8000 rpm ...
this raises the question do you guys usually get the tire guy to balance your wheels at a higher speed for a track car ??
as the standard here is just 40 and 60mph..