Highway Speed?
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Elder User
Joined: Jun 2008
Posts: 694
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From: Vashon, WA
Highway Speed?
I'm looking to get my first diesel. I'm pretty sure it'll be a '97 f250 or 350 ext cab longbed. My only question is how do they run on the highway? I do a fair amount of highway driving(mostly no load) and like to clip along not hang w the semis. The only way I'd buy one is with the manual tranny if that makes a difference.
Regardless of fuel mileage how fast can they cruise at without running out of power or causing engine damage due to RPM?
I know they had two gear options but I've searched and heard people say 75s about it and others saying they've run them over 120mph.
Regardless of fuel mileage how fast can they cruise at without running out of power or causing engine damage due to RPM?
I know they had two gear options but I've searched and heard people say 75s about it and others saying they've run them over 120mph.
Logistics Pro
Joined: Nov 2004
Posts: 3,550
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From: Lancaster County PA
Although I'll run 70-75 if I am trying to make time on a trip, I prefer to keep it right about 65. That keeps my rpms right at 2k and maximizes my highway mpg to a high of around 22 (empty, with a tail wind). The other, equally important to me, reason I keep it at 65 is that I am a lazy driver with a gamey right knee/leg. I can set the cruise and change position of my leg often on a long drive. Staying at 65 lets others pass me for the most part and I don't have to change lanes and get frustrated by cornholes that pass me on the right while I am waiting for safe clearance of the vehicle I just passed before returning to the right lane. That irritates the bejeesus out of me and I find I have a much more pleasurable drive at a leisurely ol' 65. And still make good time.
But, the PSD has plenty of power to easily cruise at speeds in excess of 80-85, if that's your thing (or you live in Montanta or other western plains states with high limits)
But, the PSD has plenty of power to easily cruise at speeds in excess of 80-85, if that's your thing (or you live in Montanta or other western plains states with high limits)
Logistics Pro
Joined: Jan 2005
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From: Brandon, MB
2 years ago, I went on a 7500 mile road trip with the PSD pulling my old camper. I don't think I ever went below 70. Average was 80. Was up to 90 for quite a few hours on I90. Mind you, I had 3.55's at the time. Nromally I cruise at 65ish same reasons as copedawg.
Post Fiend
Joined: Mar 2006
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From: Vacaville, Ca
Yep, the 3.55s will easily cruise at 80+ with the tack about 2300 rpm. My buddy has these and he gets 21mpg (97 F350 CC SRW 4X4)
The 4.10s cruise at 70 with the tack at 2500rpm. I have these witht the manual trans. I get 18 at this speed.
The 4.10s cruise at 70 with the tack at 2500rpm. I have these witht the manual trans. I get 18 at this speed.
Posting Guru
Joined: Nov 2007
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From: West Texas
These trucks are not race cars and were not meant for speed for extended times. They are heavy duty trucks.
If you are looking for fast, get a mustang.
Your stopping distance in one of these is going to be twice as much as a mustang. If not more and the handling at 80+ mph sucks compared to a mustang. Swerve to miss a deer and youre off the road most likely.
I keep mine at 65 too. It will do about 100 but it sure is a white knuckle kind of speed in it.
This is why I fixed my sons IDI so it will not go over 65.
If you are looking for fast, get a mustang.
Your stopping distance in one of these is going to be twice as much as a mustang. If not more and the handling at 80+ mph sucks compared to a mustang. Swerve to miss a deer and youre off the road most likely.
I keep mine at 65 too. It will do about 100 but it sure is a white knuckle kind of speed in it.
This is why I fixed my sons IDI so it will not go over 65.
Post Fiend
Joined: Mar 2006
Posts: 7,841
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From: Vacaville, Ca
Mine handles pretty darn good. I am not saying that it will outperform a mustang,LOL, but it holds its own. It is not as fragile as you make it sound,lol.
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Posting Guru
Joined: Nov 2007
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From: West Texas
My alignment and everything else underneath is just perfect and I do not feel safe going over 80. While there are times I would like to run over the little hybrids zipping in and out of traffic, when my family is in the truck it's not one of them. These things just aren't made for this. It's really setting yourself up for disaster going 80 or above in them.
We have 80mph speed limits all over the highways near here and I still go 65. Yes I do stay in the slow lane. Most of these roads are so hilly the big trucks are going 30 to 70 trying to get the hills and 65 works a lot better for me anyway for not continually passing them.
We have 80mph speed limits all over the highways near here and I still go 65. Yes I do stay in the slow lane. Most of these roads are so hilly the big trucks are going 30 to 70 trying to get the hills and 65 works a lot better for me anyway for not continually passing them.
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Post Fiend
Joined: Mar 2006
Posts: 7,841
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From: Vacaville, Ca
Personally I do not think any vehicle is safe at 80 or above. There is not much chance of saving it if something fails.
I have a Porsche that handles better than most cars on the road, but if something goes wrong at 80 I think a disaster will be tough to avoid.
I have a Porsche that handles better than most cars on the road, but if something goes wrong at 80 I think a disaster will be tough to avoid.
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Elder User
Joined: Jun 2008
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From: Vashon, WA
I appreciate all the input and not trying to sound rude but we've all heard the Capt. Saftey speech before.
Right now I live on Vashon island but do have to run up i90 to Ellensburg fairly often, also I plan on moving to Montana soon. All my hauling and heavy towing would be around town so that's not an issue but when I do have to drive on the highway it's long flat open road. When I'm on open strait highway with no other people I like to be able to sit around 85mph.
I plan to eventually put bigger tires on it, maybe 35s so would I be better off with the 4.10s since the tires would reduce this ratio some?
Right now I live on Vashon island but do have to run up i90 to Ellensburg fairly often, also I plan on moving to Montana soon. All my hauling and heavy towing would be around town so that's not an issue but when I do have to drive on the highway it's long flat open road. When I'm on open strait highway with no other people I like to be able to sit around 85mph.
I plan to eventually put bigger tires on it, maybe 35s so would I be better off with the 4.10s since the tires would reduce this ratio some?
Post Fiend
Joined: Mar 2006
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From: Vacaville, Ca
I would get 3.55's for that type of cruising. It is a big difference between 3.55 and 4.10's. Getting moving is a little easier with 4.10's with a load over 10,000lbs. The 3.55's can do it though.
Fleet Mechanic
Joined: Mar 2007
Posts: 1,808
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From: Meigs County Ohio
Is this porsche a Porsche 924? If so how did you get yours to run cause mine won't run worth a damn, stupid CIS injection.
Thread Starter
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Elder User
Joined: Jun 2008
Posts: 694
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From: Vashon, WA
How much does tire size affect the gear ratio? I plan to run 35s maybe bigger but I need to be able to use it as a truck so don't want it too high. I'm wondering if I should try to find one with 4.10s since the tires would make up the difference?
thanks
thanks
Post Fiend
Joined: Mar 2006
Posts: 7,841
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From: Vacaville, Ca
Cowboy, the Porsche is a Boxster.
F250, the 35's won't make that much of a difference. 38's would though.LOL
If you want to cruise at 80+ you will need 3.55's. Your motor will not last long spinning 3000 rpm all day long.
F250, the 35's won't make that much of a difference. 38's would though.LOL
If you want to cruise at 80+ you will need 3.55's. Your motor will not last long spinning 3000 rpm all day long.