Top Cruising Speed

[Moneypenny]

Hello Forum...

Just looking for some opinions here. If you were presented with a beautifully smooth, perfectly graded and banked highway, with no other cars or law enforcement to worry about, what would be your highest comfortable cruising speed for sustained driving?

[sdg3205]

Hard to say. That has never happened. When that situation does temporarily - and very, very rarely present itself - I hit the gas. If it was the norm? Probably 120 kph/75mph. That's a nice cruising speed.

[Elvis]

160 kph is a great travelling speed, up to 180 it's ok, 200 is a bit unrelaxed

[Spittybug]

Really depends on car. With the Delorean, most will tell you that above say 75 they start to "float" a bit on the front end, giving a bit of an uneasy feeling. I think they are starting to airfoil and trying to lift off because of the flat bottom! When I still had my Infiniti G35S, that thing was a dream at any speed. On the long, wide, open parts of the Beltway in Houston in the middle of the night I could open it up for a few miles at a time. That car still had plenty of pedal even when doing 110+. Never felt loose at all.

[Michael]

That will depend on the drivetrain. Manuals will probably cruise a lot better around 85mph due to the taller final gear, where the 3 speed auto will want to cruise around 70mph. My auto on level ground spins around 3,100 RPM at 70mph where a manual will be much lower probably around 2,700 at the same speed. I personally have had mine at an (indicated) 120mph and no lie it was solid and stable. The suspension setup will not doubt have a lot to do with the higher speed characteristics as well. Remember stock D's are jacked up to the moon in the front...probably doesn't help when speeds get to triple digits.

I define "cruise" as a comfortable pace where you could drive it all day without stressing the engine, or make the interior noise unpleasant so Stage II and Stage I owners with the louder exhaust may feel more comfortable at the lower realms of the tach.

[Jonathan]

Really depends on car.

And the driver too.

A speed one guy might think is enjoyable might make another guy stressed out.

And depending on where you live and what the roads are like (not to mention what the laws are like too). In Ontario, we have a 50 over law that comes with a one week license suspension, one week minimum car impoundment, and up to a $10,000 fine. Not to mention what your insurance rates are going to be after that. Oh, don't forget that is 50 over in KILOMETERS PER HOUR. Which is closer to only 30 MPH. Most roads and rural highways here have 80 km/hr limits, and the major, divided highways are 100 km/hr limits. 50 over puts you at 130 km/hr and 150 km/hr respectively. That's only about 80 mph and 93 mph if you convert the units.

So, cruising speed? Probably closer to 60 mph day to day when just out for a drive. 75 mph when on the major highways. You can speed all you want here, you just don't want to get caught for one of the big numbers as it's now thrown into the "street racing" category. Not in the mood to see the DeLorean towed away from the side of the highway and going to court to deal with it, thanks.

Back to the car though...

Many cars might not be in ideal and perfectly maintained condition to make those higher speeds enjoyable. Flat spots on tires, various suspension components a little worn or weak, brake calipers sticking a little, door seals or panel fitment not great and making a lot of extra noise. Any of those can contribute to the cars not doing well at higher speeds. And the high front nose height they left the factory with as mentioned.

[mr_maxime]

I'm a bit more reckless, Id be in the 100+ mph assuming no speed limit or other cars.

[Moneypenny]

I really appreciate the input thus far. It's interesting to see the range of responses, and the attention to detail behind those responses.

I'll be getting 4115 in the next month or so, after a full go-over from DMC in Houston. It does have the Eibach suspension upgrade and a Stage II engine, and is a manual transmission car.

I'm thinking about some drives I'm likely to be making this summer. Parts of South Dakota, for example, have wide-open interstates with a posted limit of 80mph, and where traffic regularly travels at 90. If sustained speeds like that are uncomfortable or will cause undue strain on the car, then I want to plan my routes and/or trips differently. But if I can throw down 90mph for an entire tank of fuel with ease, that will be good to know.

Of course, I won't know how this car feels until I get it and drive it, but getting a sense from this community will help me manage my expectations. :-)

[81dmc]

With my car, the steering is remarkably annoying to control at high speeds.

[Moneypenny]

With my car, the steering is remarkably annoying to control at high speeds.

Do you have the Eibach kit, or is your suspension stock?

[81dmc]

Do you have the Eibach kit, or is your suspension stock?

I have Hervey's kit. Come to think of it, when it was stock, it was even more of a pain to control.

In the end, the steering is very tight, and any bump in the road can jerk the wheel.

[papanoel]

That will depend on the drivetrain. Manuals will probably cruise a lot better around 85mph due to the taller final gear, where the 3 speed auto will want to cruise around 70mph. My auto on level ground spins around 3,100 RPM at 70mph where a manual will be much lower probably around 2,700 at the same speed. I personally have had mine at an (indicated) 120mph and no lie it was solid and stable. The suspension setup will not doubt have a lot to do with the higher speed characteristics as well. Remember stock D's are jacked up to the moon in the front...probably doesn't help when speeds get to triple digits.

I define "cruise" as a comfortable pace where you could drive it all day without stressing the engine, or make the interior noise unpleasant so Stage II and Stage I owners with the louder exhaust may feel more comfortable at the lower realms of the tach.

yeah mine is defintley around 2500mph at 70 mph in 5th.

I get a little nervous anything over 70. mainly because i become ultra aware of the braking distance i would need should anything happen.
It also does feel a little floaty over 70. I have standard height springs with spax shocks set for softer ride.

[DMCVegas]

High-speed cruising for me was never a problem in Nevada. Far less worried about police than I was wandering wildlife and livestock.

But about 95 mph or so was about the limit of how fast I could go and be actually, truly comfortable.

I've done the sustained speeds of 115-120 mph on Yokohama AVS Intermediates with original suspension, and the car handled just fine. Especially with manual steering rather than power steering that doesn't move as easily. But it's damn nerve-wracking. Plenty of people have walked away from high speed crashes, or at least survived on some level. So that's always in the back of your mind reassuring you. But when you're going that fast on an uncontrolled road in just a normal car, you realize that that point that you're actually facing your own mortality. You're not just looking at the edge, but you're sticking your foot over it. You're testing the limits of your own life. It's a thrill for the first minute, maybe two. But then it just goes on and on. Between worrying about the cops just outright arresting you, or a stray cow killing you, it can wear you out.

The massive difference in speed makes dropping down to 80 feel slow, and 65 just feels like you're crawling along when you're still rushing by people. Afterwards, you feel just drained. Worse if you've got a car with bad steering, and you've had a prolonged death-grip. Then you just get sore arm and hand muscles.

The big problem with cars is Infrasound. The faster you go, the louder the low-frequency noises get amplified, and the worse the effect on you is.

http://www.kps.or.kr/jkps/downloadPdf.asp?articleuid=%7B40D87A9D-A082-4C16-9D98-49DD7F7C21DD%7D

[papanoel]

I really appreciate the input thus far. It's interesting to see the range of responses, and the attention to detail behind those responses.

I'll be getting 4115 in the next month or so, after a full go-over from DMC in Houston. It does have the Eibach suspension upgrade and a Stage II engine, and is a manual transmission car.

I'm thinking about some drives I'm likely to be making this summer. Parts of South Dakota, for example, have wide-open interstates with a posted limit of 80mph, and where traffic regularly travels at 90. If sustained speeds like that are uncomfortable or will cause undue strain on the car, then I want to plan my routes and/or trips differently. But if I can throw down 90mph for an entire tank of fuel with ease, that will be good to know.

Of course, I won't know how this car feels until I get it and drive it, but getting a sense from this community will help me manage my expectations. :-)

at end of day its what you're comfortable with. you won't know how you feel until you drive it. and be aware of braking distance.

Took me about 2 years to feel comfortable to get it to 88. and i did that at 4AM on the NJ Turnpike with no one around. But speed limits in NJ NY are 60 or 65 tops.

[Jonathan]

at end of day its what you're comfortable with. you won't know how you feel until you drive it. and be aware of braking distance.

Took me about 2 years to feel comfortable to get it to 88. and i did that at 4AM on the NJ Turnpike with no one around. But speed limits in NJ NY are 60 or 65 tops.

I have heard more than one person talk about how to drive in old cars and the comment is about how you need to "predict when to brake." Maybe not literally, but you do need to enter into intersections where you think it might turn red just as you get there, and slow down in advance. Between the old technology in most classic cars and people's nervousness driving their baby, the confidence you normally have in your day to day driver won't be quite the same while driving your D.

[Citizen]

On a trip a few years ago, coming back to Houston from a car show in Austin, the Texas club caravanned on US-290 (you can see a small part of it here (https://www.youtube.com/watch?v=0oM514THv-g)...credit to Crystal Mimms for the video).

We held 70 MPH most of the way, but easily hit and held 75 and 80 a number of times (based on if conditions permitted, of course). I was very comfortable at those speeds, and hardly knew the difference between 70 and 80.

Thomas

...

[Moneypenny]

On a trip a few years ago, coming back to Houston from a car show in Austin, the Texas club caravanned on US-290 (you can see a small part of it here (https://www.youtube.com/watch?v=0oM514THv-g)...credit to Crystal Mimms for the video).

We held 70 MPH most of the way, but easily hit and held 75 and 80 a number of times (based on if conditions permitted, of course). I was very comfortable at those speeds, and hardly knew the difference between 70 and 80.

Thomas

...

Missed shift at 3:04! :-)

Thanks for sharing that clip. The car sounds like it has a nice, throaty exhaust note and never sounded strained, even when you were running up on the other cars.

[Alan]

Truth be told, I have a hard time keeping below 65 or 70MPH. As Michael said, with the tall 5th, it just feels right to me in that range. I've had mine up to 85 or more (stock speedometer, possibly buried) and it felt a bit loose. I've only had mine since June and stored it for winter for a few months. So, with more familiarity and experience, I may feel more comfortable at higher speeds.

Eibach lowering kit, stock engine, 5 speed.

[David T]

If you are going to consistently drive over 85 you need to get the 170 MPH speedometer and make sure it is accurate. Consider that at high speeds your gas mileage is significantly reduced because of aerodynamic drag. You also need to increase the pressure in your tires to prevent bead roll-over when cornering. Do not go fast on old or worn tires.

[Moneypenny]

If you are going to consistently drive over 85 you need to get the 170 MPH speedometer and make sure it is accurate. Consider that at high speeds your gas mileage is significantly reduced because of aerodynamic drag. You also need to increase the pressure in your tires to prevent bead roll-over when cornering. Do not go fast on old or worn tires.

Good news; my brother informs me that he installed an Indiglo dash kit, which includes a 145mph speedo, so we're all set there.
Mileage is going to be better than my CTS-V no matter what speed I go.
Not a lot of cornering on South Dakota interstates. :-)

[David T]

Good news; my brother informs me that he installed an Indiglo dash kit, which includes a 145mph speedo, so we're all set there.
Mileage is going to be better than my CTS-V no matter what speed I go.
Not a lot of cornering on South Dakota interstates. :-)

You still need the higher pressures for lane change and exit ramps. Refer to L:12:01. It says for "High Speed", but doesn't specify what that is, 29 psi front and 34 psi rear.

[Mark D]

Wisconsin just passed a new law increasing freeway speeds from 65 to 70 mph so it's pretty common now to be moving at 75-80 mph to keep with the flow of traffic. My commute to work is 64 miles each way so I'm usually cruising just under 80 in my daily driver.

In the DeLorean I always feel safer going slightly faster than everyone on the road to reduce the risk of people lurking in my blind spot. I'm running eibach lowering springs with SPAX adjustable shocks, front LCA supports, all poly bushings, and a strut brace so the handling is greatly improved over stock. Prior to adding all the upgrade parts it would start to feel floaty above 75.

If I had to guess which upgrade helps the most I'd have to say the lowering springs are the biggest contributor to the improved ride. The suspension on my car was so high because of the tall springs I was basically at the end of travel before I'd top out the shock. Going over dips in the road felt like the tires were ready to leave the ground.

[David_NYS]

Between worrying about the cops just outright arresting you, or a stray cow killing you, it can wear you out.

+1

Had my old BWM Z3 somewhere above 120mph in Montana for a few minutes. After a while I became a little nerve racked thinking about wild animals that could potentially cross my path.

[dhaney]

Condition of the vehicle is biggest issue. My car was lowered using Grady's Springs and I was running a set of shocks recommended by the folks at Mid-sixties Delorean Club.

I also don't buy that there is a difference in automatic vs a manual. I've driven both for long stretches. They both can comfortably exceed the speed limit for long stretches of time. In fact I went from Dallas to Denver in one day once and averaged 88 mph in an automatic. So I didn't travel in time. I even had one extremely safe from the law area where I was well over 100mph for several miles.

A good condition car will smoke down the road same as any other car. I've never been in a floaty front end car. Though I don't recommend any Delorean in the snow... now that's a floaty front end!

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[dhaney]

Fastest I've ever been in my delorean and it was no different handling or ride than at 75... 119 mph according to the conversion tables...

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[Nicholas R]

I had my car up to 130mph a couple years ago on a limited access toll road (with a rolling road block for a legal road rally). If I had more space/time I would have tried to go higher, but there was a lot of speed up->slow down->speed up->slow down during the rally. I've got Eibach springs, LCA brackets, and a shock tower strut bar, and though the car handled fine, I'm not sure I'd say it was comfortable. At that speed, the front end of the car really starts to float like you're on a cloud. I'd say right around 100mph can still be comfortable though with the suspension/handling upgrades.

[Timebender]

If I had more spacetime.

If you converted your car into a time machine, that would no longer be an issue or thing to worry about not having....


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[jerzybondov]

I think it very much depends on the condition of your car. When I first got mine, 60mph was terrifying. The brakes sent you sideways, not backwards. Steering rack was shot, UJ loose, bushes rotted... Just trying to keep it in a straight line was a nightmare.

But five years and a full restoration later - running lowered front springs, SPAX, LCA reinforcements, full laser alignment etc - car felt pretty solid at 135mph on the autoroute in France (not sure it would have gone this fast before B28E engine swap, and it was downhill). Having said that, gearing and aerodynamics wise, car feels like it's in its sweet spot somewhere around 3400rpm in 5th - so about 90mph.