Automotive Dyno Issues?

[Dahgu]

I have seen a couple posts around PriusChat in regards to the behavior of our transmission in "Neutral". Today, I am having some Nokian WRG2s put on and am a little worried about the balancing process and them burning up the ole Prius.

How do we handle any situations where they put the Prius on to a Dyno and spin up the front tires? I assume the rears are no issue whatsoever.

[patsparks]

Do they balance your tyres on the car? Most places balance tyres off the car and if they use the old style on car dynamic balancer they only spin one wheel at a time. I doubt on car balancing will be any good on a front wheel drive car.
The only type of dyno I have seen that spins the wheels is a brake dyno and they turn at low speeds anyway. Normal dynos the car spins the rollers.

[bwilson4web]

Hi,

<div class='quotetop'>QUOTE(Dahgu @ Oct 19 2007, 11:03 AM) [snapback]527765[/snapback]</div>

I have seen a couple posts around PriusChat in regards to the behavior of our transmission in "Neutral". Today, I am having some Nokian WRG2s put on and am a little worried about the balancing process and them burning up the ole Prius.

How do we handle any situations where they put the Prius on to a Dyno and spin up the front tires? I assume the rears are no issue whatsoever.
[/b]

Your NHW20 model has a 10,000 rpm limit on MG1. If the ICE is off, they can spin the front wheels pretty dang fast before MG1 would even approach 10,000 rpm. But in normal operation, the ICE will come on at 42 mph to keep the MG1 rpm low.

I'd ask them if they can observe a 40 mph limit in the spin test and still do a good balance job. If not, I know Hobbit has reported speeds of 60 mph with the car in "N" and the ICE off and it didn't do any known damage. I've been up to just under 50 mph with my NHW11 but I used my brakes to slow down to 42 mph before putting the car back in gear. I hope your eyes don't glaze over but we're not sure if the rpm limit is mechanical (very unlikely) or electrical (leading hypothesis.)

When MG1 spins faster and faster, it generates a higher and higher AC voltage. Eventually, there will come an upper limit where MG1 can generate a voltage so high that the inverter electronics fails (the smoke escapes.) This potentially could be very ugly because the inverter electronics are between the battery and MG1. If the electronics fails 'open' (big blue spark with a non-conductive gap left behind,) it would be ugly but not so bad. If it fails in the "short from h*ll" mode, a lot of unmentionable things could happen to both the battery, fusible links and motors.

I'm conservative and would limit it to 40 mph and threaten a lawsuit at 50 mph. You are probably OK up to 60 mph but you are heading into the realm of 'forbidden experiments.'

Bob Wilson

[richard schumacher]

<div class='quotetop'>QUOTE(Dahgu @ Oct 19 2007, 11:03 AM) [snapback]527765[/snapback]</div>

How do we handle any situations where they put the Prius on to a Dyno and spin up the front tires?
[/b]

B!tch slap them, take the Prius down from the dyno, and go to a different tire shop.