Top Cruising Speed

[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/downloadPd...9DD7F7C21DD%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...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...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. :-)