HCH II-Specific Discussions Model Years 2006-2011

What's your lowest RPM at 70 mph?

Old 11-04-2006, 10:14 AM
Join Date: Jul 2006
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Default Re: What's your lowest RPM at 70 mph?

Give me a few days and I'll take the HCHII up and then down I-70 west of Denver. It's a very long, pretty steep hill. On the way down I'll be able to do 70 mph with gravity to help me out. I should be able to coast at 70 mph. If the tach doesn't go below 2k in that situation it never will.
Old 11-04-2006, 10:24 AM
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Location: Indianapolis
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Default Re: What's your lowest RPM at 70 mph?

another wiki article explains further

the drag equation article states : "Of particular importance is the vē dependence on velocity, meaning that fluid drag increases with the square of velocity"

The drag physics article states:Assuming a constant drag coefficient, drag will vary as the square of velocity. Thus, the resultant power needed to overcome this drag will vary as the cube of velocity.

So the drag increases as the square of velocity, but the power required to overcome that drag will increase as the cube of the velocity. The power required to overcome the force is what is relevant in our situation.
Old 11-04-2006, 04:52 PM
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Default Re: What's your lowest RPM at 70 mph?

Hey Nate - Do the I-70 hill in both Drive and Neutral. I've done all my testing in Drive as it is hard to coast in Neutral for 9 miles along an Interstate. I can't remember if Neutral runs lower revs than Drive (I know it doesn't shut the valves) but give us an update. Thanks.
Old 11-18-2006, 07:42 AM
Join Date: Jul 2006
Posts: 4
Default Re: What's your lowest RPM at 70 mph?

Ok. Did the test. The CVT definitely isn't infinitely variable. At some point (I think above about 55mph) it becomes tied to the vehicle speed.
On the way down the hill this is what happened: At 70 mph I took my foot off the accelerator. The mpg bar went all the way to 100, the charge bars went to full and my speed AND rpms kept increasing.
So I surmise that once I took my foot off the go pedal, the fuel injectors cut off and I was literally coasting and using no gas at all.
At one point I briefly bumped the transmission in to Neutral. The rpms dropped to 1000. The mpg bar fluctuated briefly before pegging at 100 again. I think that N in this situation used more gas than D. I think that in N the engine uses gas and keeps the rpms about 1000. I think D shuts off the fuel injections and therefore doesn't use any gas.
Old 11-18-2006, 10:05 AM
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Join Date: Jul 2006
Location: Monterery Bay area, Calif
Posts: 24
Default Re: What's your lowest RPM at 70 mph?

Nest time you try the downhill stretch, reset the trip meter to 0 and watch your MPG go to 150. 150 is the top limit it will read. You're porbably actually getting more than 150 at this point.
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