Is 4k all day ok?

[pred]

I bought this car to do highway miles and today I did a short highway run of 120 miles running at about 80 mph. Seeing that is about 4000 rpm. So the question is. Is 4k all day ok? Seemed fine but I thing I need a better ratio rear for highway cruising. I intend to be doing 300 mile runs at that speed very soon. Any issues or concerns on running the car like that????
Peter.

[pdxmotorhead]

The ticket? LOL...

The M42/M44 are fine at 3500 to 4K, I find mine LIKE's 75 at 80 it starts using fuel.
I go from 34mpg at 75 to about 25 at 80.

Use good synthetic, I use the stuff from the dealer which is a Castrol manufactured full synthetic.

Good luck!

Dave

[pred]

Oh, Basically stock,
New tires, New suspension parts, newer rad and water pump all done before I bought car, 1997 Active 318ti.
Like I said, I ran it today at 80 MPH and hit 100 for a minute or two.
I want to start to use this one for my 300+ mile drive to pittsburgh which I currently use a Chevy Caprice wagon, 1995 with the LT1 in it,, I run at 85 with that beast and get about 20-22 MPG... I am hoping that this 5 speed 318ti will get 30 at 80 MPH.
So 4K all day is of no real concern with the 1.9 engine?
Thanks.
Peter

[pdxmotorhead]

Your not going to get 30 at 80 in the ti.. You'd need a higher ratio rear end to keep the revs at 3500. The DISA valve (Think 4 barrel) opens at ~4200 which really starts the car eating fuel.

Taller narrower tires help too, if you are just freeway commuting I'd get some tires about 1" taller and 1" narrower than the stock ones, that will help drop the RPM's a little. I use my GPS to check the speeds after this type of change. Set your tire pressure correctly so your tires don't get too hot helps on mileage too.

These cars run that speed on the EU highways and do fine, but they seldom run 300 miles straight, things over there are just not that far apart.

I find most engines run well at 50 to 60% of redline, above that it takes its toll.
I'd be comfortable running my ti at 3500 indefinitely, 4000 is more than I would run just because of power to heat load in the engine.

I'd definitely run watter wetter or blue ice in the cooling system. If you haven't I'd also read up on this forum about the hazards of cooling system failure and why at some point you just replace everything on E36 BMW's.

The car will take a LOT ,, I mean a LOT, it just depends on what life expectancy you want out of the engine. 4000 wont kill it, just wear it out more.. If it has high mileage I'd look at servicing the cam chain guides at some point.

Dave

[John Firestone]

Originally Posted by pred

So 4K all day is of no real concern with the 1.9 engine?

Once the engine is warmed up, I cruise at somewhat over 5000 rpm in fifth, traffic and speed restrictions permitting. It's an eager engine at that speed but a little thirsty -- I think around 12 liters/100km (19-20 U.S. mpg). I'll check the consumption next time I'm out.

[pdxmotorhead]

How far at a time? Remember hes talking about 300 miles not kilometers...
And hes planning on doing this a lot..

I WISH we could travel at 5000 in the US in fifth gear...

Dave

[pred]

That is the trouble,
I will run it at 4K and for stretches I will be near the 5K mark,
Early Wed the 4th at about 6am I was running with a few others down a length of highway and for a 4 to 5 min we were all doing 100 MPH, Now when I ran the Caprice at that speed it was nothing for that car,
I think I need to seriously consider a rear change. In reality I set the cruise at 75 and some days closer to 82.
Car has new tires, So I won't be changing them out any time soon, But I do pay attention to tire pressure.
So it seems like the engines will take 4K all day.
I have some engine wetter at the other house and will add it in a couple weeks when I make the 307 mile highway run.
PO used Mobil 1 oil as well, I guess I will be keeping that yup as well.
is there anything else I need to watch for?
Peter

[hotmilk400]

I never had a problem. if you keep it at 75mph, you should get very good gas millage. in my 5sp 98, i get about 33 - 35mpg going 75 on the highway for 120 miles. if you can get the extra MPG, you will be saving mucho money =]

should be nothing you need to worry about, i go back and forth from school to home. i put about 10k miles on that car in a few months doing that speed.

[cnaville210]

When I bought my Ti I drove it from Penn. to Texas at around 80 to 90mph on the speedo, never went below 80 through any of it other than some Arkansas construction, the car seems to enjoy driving at those speeds, and when driving in and around 90mph through a whole gas tank I averaged 32 highway mpg??? You guys are crazy to think it wont do that. On the highway an M3 engine should get close to 30!

[bmvw]

My experience is similar to cnaville, my best tank was averaging 80mph thru Nevada Arizona into Utah, uphill all the way, 2000 to 7000' altitude, hot day, with two people inside and all their ****. The tank was 420 miles, about 30mpg. Car usually gets 25 mpg the way I drive, 28 on open road.

[jimmypet]

Pred,
I just found a 2.79 diff from an ETA E30 so once I get it in I'll report about the driving change, but I expect it to put that right in the pocket at 80.

DISA closed, 3000 RPM ish with room to float above if desired.
You and I are in the exact same boat as we have discussed by PM.

If I keep it at 3800 RPM I have been getting 33-34, but I want that RPM to come down a bit. the car has nice torque for what it is rolling into the throttle between 3000 - 4000.
I'd like to make my cruise at the bottom of that range so that I can roll up to 3800 - 4000 for bursts.

I have to believe this will yield a mileage benefit that will pay for the diff in a year or so not to mention engine life.

I just don't believe this little engine will want to run hours at 4000 rpm and not see adverse wear,,, certainly lower MPG.

[jetblackbimmer]

If I'm cruising at 65, I am around 2800. I have an automatic. I can see 40 mpg if the road is flat at 75 mph. In my old manual, I could drive from LA to Phoenix on one tank and have some to drive around a bit before getting gas. In my automatic, I can drive from Berkeley/ San Francisco to LA with only one stop to fill up, it used to be two in my manual from LA to SF. I don't remember the RPM ranges for my old ClubSport.

What I have noticed in my automatic, if I take it up to 3800, it starts guzzling fuel. I do need to replace my valve cover gasket too though...

My basic advice, if you have an automatic keep it under 3200 when crusing and you will get optimal gas mileage. My last trip to LA, I did not care about time and I averaged 36 MPG after driving around Los Angeles for three days.