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a quick question regarding 1.5 Diesel on modern highway

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ryanmiller

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Discussion starter · #1 ·
Is it Ok to drive 80mph for 3-4 hours straight? I know its revving out pretty high , and that MPG will suffer. , but I don't want to kill the thing.

what is the approx RPM at that speed?

Car in question is a 1980 1.5 4spd .

pix 4 possible clicks!

Image

My mechanic

Image

the caddy

Thanks !!
 
#2 ·
what is the transmission code? depending on the transmission and if everything is sorted properly it should have no problem cruising at 70-75 except on big hills. mine does but i have one of the tallest 4 speeds that were available. 80 is alot to ask tho and i don't really see why you even need to go that fast in a car with less than 50 hp.
 
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#3 ·
according to this, 1980 4-speed trucks came with a GC code trans. 3500rpm in 4th gear puts you around 61mph.

I recommend you leave 15 minutes early and cruise in the right lane at 70mph tops.
 
#4 ·
benjaminobscene said:
according to this, 1980 4-speed trucks came with a GC code trans. 3500rpm in 4th gear puts you around 61mph.

I recommend you leave 15 minutes early and cruise in the right lane at 70mph tops.
Click to expand...
x2

80 will be hard to sustain unless you have no wind and completely flat terrain. Even if you have a GP trans (which has a .70 4th), it's hard to get that little diesel to pull from 75+. I can't even imagine what a GC coupled with a diesel would be like...
 
Discussion starter · #5 ·
Just looked, trans code is GC.

Dang!

Reason behind wanting to go quicker , is just to keep pace with traffic. Didn't want to be "that guy" causing people to bottle up.

70mph I can live with, 80mph was preferred though.


Thanks!
 
#6 ·
just stay to the right and enjoy the drive. people are generally happy just to see a funky old volkwagen still on the road.

another important thing to consider with highway driving is your braking abilities. even at a slower pace, it's going to take quite bit of distance for your 30 year old truck to come to a stop. keep that in mind when driving behind another car. :)
 
#7 ·
Things like this make you realize how the advancement in automative technology has gone so far in just 20-30 years. I remember when I got my licence 16 years ago; 120 km/hr (75mph) was "speeding" lol.

Now i do 80mph with no sweat!

But as someone mentioned, if you stay in the right lane at 65-70 mph, you'll get more thumbs up at the fact that you're driving a 30 year old car than getting honked at/ middle fingers. :laugh:
 
#9 ·
My first car was an 80 Rabbit C 1.5D with a 4 speed and it made hundreds of trips from Sun Valley to Los Angeles 1000 Miles and 13-14 hours. Did just fine except for broken water pump bolts one time.
BUT it would not go much over 75 happily...

My experience is that with a 1.5 it will tell you where it is happy at higher speeds. It will sound like it is straining so back off to where it sounds better. You will definitely find a sweetspot

1.6s dont seem to care as much as 1.5s at higher speeds...

Yeah I know you dont want to be "that guy" but you are... Fact remains you are driving a car with a whopping 48HP. You cant make it do what it cant.... :)
 
#10 ·
I wouldn't even cruise at 70mph...keep it around 60-65.

Even my 1.9 with an FF transmission I'll only keep at 70mph for short amounts of time (30mins).

Arriving 15 minutes early isn't worth putting unnecessary wear and tear on my motor. ;) The 1.5's are so prone to failure as it is...

PS: I :heart: your Caddy!
 
#13 ·
jraney said:
Yeah I cruise 55-65mph down I-75 almost every day in the right lane with my 1.6 and have never had any problems, just a thumbs up from people from time to time.
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Haha I just bought a 79 1.5 4spd from north atlanta and cruised down i75 to turnpike all the way to west palm at 55-60

was a nice ride, took forever but still a good time. I still drive it at the same speeds down here in south florida but people are in a rush to go nowhere fast and you get the same dickheads every now and then who wanna ride your ass cut you off and/or throw their hands up. :facepalm:
 
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#14 ·
diesel so slow.....

my 1.5L cis struggles on hills and wind
but it does go to 90mph

the 1.7L cis i have no problem pegging the speedo 85mph and 4500rpm.

cd (coeficient of drag) will be your largest problem for increasing speed above 90mph

i would agree 55-70mph and just ride cool..keep an eye on your rear views and move out of the way
me? no i'll cruise 60mph all day long in the left lane no matter if the speedlimit is 75mph
f them


i read on the interwebs that in germany they test smog on diesels by revving the engine wide open throttle.
 
#16 ·
Never driven a 1.5

I thought the 4 speeds had same end gear as 5 speeds?

Some of the numbers in here sound terrible.

I got my first vw 4 years ago with acn tranny. No big deal and that darn 85 jetta gets good mileage, like 45+ all day long.

On my current truck and rabbit I tried some that are listed a bit better from the info i got online. like 2800 rpm @ 70 mph.

My rabbit has a turbo and doesn't give a crap about that speed on flat ground. I daily drive on freeway 2+ hours a day going 70-85. Don't even hear the engine screaming. I can do mild stretches of hills in fifth gear, long hard ones scream it in 4th gear at 60mph.
 
#19 ·
the sneakiest panda evar said:
only way your car is going to go 80 with a 1.5 and a 4 speed is if it was pushed out of a plane. i have a 1.6td with k24 and a 5 speed and my car hates doing 75 or more.
Click to expand...

:laugh: :thumbup: The AAZ when it was still turbo'd would do 90, with the AC on, but it was noisy and I'd hate to have to swerve or stop at that speed. Even with everything in good order.


70's leanin on any of em stock in my opinion.
Also the speedo's are frequently full of it.
 
#20 ·
Mine runs at 70-75 no big deal just did a trip to the poconos and back last Sunday. Even ran cool the whole time

Image


My old 1.6td would go very fast no problem I took it to 120 before but I can't say how accurate the speedo was but it was certainly atleast 100
 
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ryanmiller
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