High speed driving

[gfh77665]

At what point does a 1.6 Fiesta become stressed driving at high speeds? I know all 4 cylinder engines will have higher RPM's than a V6 or V8, so at what sustained RPM does the 1.6 start to labor too hard? Has anyone driven a 1.6 at 90 or 100 mph for any extended period? Thanks all.

 

[scotman]

Fiesta was engineered for European roads. Given that it is properly maintained, I wouldn’t be afraid to drive it at 85 to 90 miles an hour all damn day. Speed control system is inoperable above 85. So, even on a freeway with little to no traffic the 1.6 is limited to something like 113 mph by the ecm.
Wide open freeway driving on relatively flat terrain doesn’t seem to overwork the 1.6. It just hum’s away.

 

[Handy Andy]

I don't usually have a road to drive that fast for any specific length of long time - so I can't tell you of the long-term effects or results because by the time you get to open roads around here - there's is the usual results of TXT-ing while driving idiots that start to plug up the lanes as they settle in for a longer drive commute and their Collision-avoidance system then backs down to about 80MPH in most vehicles.

• Why that is? Reasoning varies but usually it's the smoothness of the road - cracks in the pavement and other factors inclusive (Semis Busses - larger transports)
  • Ever try to type on a bus? Those shifts in pavement usually force you to brace against something and by doing so - tires you out faster than walking that same distance.
  • Other factors also include the ability of the Drivers to see...beyond...(I'll just leave it at that)

But to me the "buzz" the motor becomes to my ears turns into a painful ringing distortion - usually about 4K...so since the gearing between Auto and Manual "overdrive" ratios are different - the Auto side is usually quieter at higher speeds due to the "longer gear" ratios Autos have in Overdrive.

But you asked about "stress" - once on the road your main "drag" is the wind and terrain - the type of road considered smooth - you'd not have "stress" perse' - but torque to momentum acceleration starts to drop after the engines main torque band is exceeded - again, usually about 4.5K in RPM - once your there in top gear - you're already going way too fast to control the car in a usual sense. Then the stress issues then become more of control and steering.

So were you figuring roll over or braking or just torque to speed changes?

If it's acceleration, then the ball usually drops in N/A vehicles at about 65 to 70 MPH (in 5th Gear manuals that is going above 3.5K) but doesn't answer the question of which Gear you were thinking of using to attain that speed. Because, in say - 4th Gear, the upper limit of torque present to gain speed is different - speed is less but the torque to provide acceleration to raise the speed to the middle of 5th's working torque band is greater in range - ranges up about 4.5K)

ST models having a turbo boost gives you a longer - range - of RPM as a torque "band" to work with - can get you the 90MPH value easier and more quickly but still have limits on the torque band range versus throwing the turbos bearings out thru the tailpipe from the keep pushing the limit - figure of merit - approach. The - "Labor too hard" you mention.

So there are several ways to look at "stress" on the Fiesta - one of control, another of power - Torque considers Acceleration, even the mechanical and then there's the abilities of the driver

Because stress-factors on the car in lower gears, to the Frame, can be harder on the Engine mounts than say the car having already attained a cruising speed, it's harder to pinpoint a "value" to give you - so are you looking into something to work with, around RPM, or for power to weight ratios in Speed?

 

[gfh77665]

Thanks guys. I don't know if you ever travelled to rural west Texas, but it's hundreds and hundreds of miles of wide open space. Not surprisingly, highway speeds rise. Just for fun here is some trivia:

• King Ranch is the largest ranch in Texas and the US, at 1,289 square miles. It is bigger than the state of Rhode Island alone.
• The fastest road in the United States is in Texas and runs for 40 miles from Austin to San Antonio with a speed limit of 85 miles per hour.
• El Paso is closer to Denver at 637 miles than to Houston at 747 miles.
• El Paso, Texas is closer to the Pacific Ocean at San Diego California than it is to Texarkana Texas.

You get the idea. West Texans typically drive 80-90 mph. It just fits there, actually. I am totally sure there are any number of 1.6L Fiestas that endure this daily out there. (I am in the opposite corner of the state, east of Houston, one time zone, 800 miles and 10.5 hours away). I have no doubt the 1.6 can do it, but I am curious just how "wrung out" it would be loaded with passengers, luggage, and A/C on. Not scared at all, not overly concerned, just wanting to make an informed choice of my three vehicles to choose from. It would be good general information to know as an owner anyway. I appreciate the input!

 

[Handy Andy]

And one thing you didn't mention is that Austin to San Antonio it's mostly flat and hardly any curves. Flat out fun.

The Fiesta will take it on just fine but remember to keep the Oil changed, more like at every 5,000mi 3 or 6 months versus 10,000mi and 1 year - because of this type of driving is considered "severe" in some books, but "Normal" for many others.

In fact, I'd be looking into taking out the 5-speed and switching over to a 6-speed if you're into the manual clutch thing.

 

[gfh77665]

Thanks Andy, my 2017 has the DCT. I always do 5,000 mile oil changes, as described in the "oil weight" thread. I am not hesitant to drive it 80-90 mph, but I want to keep my Fiesta long term, getting every last inch out of it. Its has been and remains an amazing car. I'll try to keep it sub 3500 rpm when the high speed driving is necessary. Otherwise 75-80 is what I usually do on the interstates. I don't think that is much stress on it at all.

 

[Handy Andy]

The type of driving I work around in Light-to-Light sorts of driving - mostly mundane. So the "stress" factor you speak of I see different because of the drivers around me, being what they are - pay more attention to their phones than to the road.

It's when they get left behind at the light, do things get interesting - many just roar off and try to catch up - with others just flat out flooring the throttle to beat it to the next light - running over just about anything in their path...

This is all too familiar.​

To me, this behavior is the "New Normal" - so self-autonomous (driving) cars will ease that because of (some) drivers their "Social Media" addiction is pretty extreme - and the seasonal change to winter usually brings out their best colors.

Good to know you have a lot of highways (everything is bigger in Texas) so your issues with stresses on a vehicle have a similar root but are a lot different than those of us who live in the Rustbelt.

We're too busy trying to keep it together...
​

 

[Phil_F_NM]

Andy, you'd be right at home driving in Philadelphia with all the cell phone use by drivers out here.

 

[gfh77665]

My trip is complete. Kept speeds in the 80's, so I doubt the Fiesta stressed too much.