Cruising RPM's

[Hodee]

This is a bit of a repost but... I'm curious if anyone is comfortable running their stock/very good oil pressure, engine at 4000 rpm for 20 mins on the highway? And does ANYONE rev to redline at 5500 between shifts? What is the point at which, "Scotty, she can't take any more!", comes into play?

 

[Hillman]

One word or two words, or one hypenated word. Overdrive. You'll love it.

 

[alpine_64]

Think there are a few questions in here.

3.8-4k rpm is normal for a non od alpine on the highway. If the motor is in good condition its not an issue, especially for 20mins... But of course incurs more wear than if you have o/d and less rpm.

I used to run my car for 2 hours down freeway without od for years and im sure the wear was more on my ears than the motor.

All of that said my car now has od, 14x195x65 rear tyres and 3.89 diff so on the highway its a real cruiser .. Much more relaxed less wear and less stress.

As for shifting at 5500 or more. When having fun.. Yep in intermediate gears 2 and 3 i do it. However the majority of times around town i shift at 3-3800 as ots getting into the torque band and its not much more to gain in daily driving by revving it out.

Just my experience.. Ymmv

 

[Hodee]

Thanks for the replies but trying to not go the overdrive route. Hence,I am running 225/60/15 in the back and run about 74mph at 4000 rpm. ( GPS verified and fresh tach rebuild by Tom) Just curious how long I could cruise that way and be safe. It maintains 45 psi oil pressure and still pulls hard if I go further, so... should I? Just for grins?

 

[65beam]

My green series 4 was my everyday car for several years starting back in the 60's. I drove it 35 miles one way to work 5 to 6 days a week and on to Columbus in the evenings for classes for over 4 years. It made trips all over the east coast and Midwest while cranking close to 4000 rpm with a 3.89 rear and 13" tires. Have you ever noticed how many Alpines don't have and never had OD? Doug Jennings always told me the bearings were good for maybe 30K to 35K miles. It made it close to 50K before the rod bearing on #3 spun. The longest trip the wife and I have made in the series 5 took us 450 miles to Carlisle, Pa, then on to Philadelphia, down thru Delaware and on thru Virginia and back thru W. Va. in order to get back to Ohio. We sometimes drove 300 to 400 miles a day. What you are seeing with high RPM,s was normal for these cars unlike my company owned Malibu that turns 2100 at 65 mph. It seems that we now cringe at constant high RPM's at highway speeds. Remember that it's an old British car and if you maintain 45 lbs of oil pressure then continue to drive it for long periods of time and drive it like you stole it.

 

[George Coleman]

My stock Alpine V with 4.22 gear and std trans. at 60 mph the RPM was 4000, Now with a Toyota 5 speed and 3.89 gear on the high way 72 mph turning 3200 rpm all this with 13 inch tires. To me the Alpines like it when you keep the rpms under 4000 on the road.

 

[65beam]

George,
I switched the series 4 to a 3.70 gear and at 65 I'm turning around 3500 with 13"

 

[Hodee]

My green series 4 was my everyday car for several years starting back in the 60's. I drove it 35 miles one way to work 5 to 6 days a week and on to Columbus in the evenings for classes for over 4 years. It made trips all over the east coast and Midwest while cranking close to 4000 rpm with a 3.89 rear and 13" tires. Have you ever noticed how many Alpines don't have and never had OD? Doug Jennings always told me the bearings were good for maybe 30K to 35K miles. It made it close to 50K before the rod bearing on #3 spun. The longest trip the wife and I have made in the series 5 took us 450 miles to Carlisle, Pa, then on to Philadelphia, down thru Delaware and on thru Virginia and back thru W. Va. in order to get back to Ohio. We sometimes drove 300 to 400 miles a day. What you are seeing with high RPM,s was normal for these cars unlike my company owned Malibu that turns 2100 at 65 mph. It seems that we now cringe at constant high RPM's at highway speeds. Remember that it's an old British car and if you maintain 45 lbs of oil pressure then continue to drive it for long periods of time and drive it like you stole it.

Thanks Bob, we have long open roads in Texas that I like to cruise at a brisk pace. It is originally an Ohio car that Doug worked on a lot and runs really well.

 

[65beam]

Thanks Bob, we have long open roads in Texas that I like to cruise at a brisk pace. It is originally an Ohio car that Doug worked on a lot and runs really well.

Doug did bare metal body restorations of the green car and the blue car.

 

[mightyohm]

I had a valve seat erode very quickly on a long road trip from WA to CA. I was in overdrive most of the time but I imagine that the problem would have been much worse without the OD. I'd try to keep the RPMs down unless you have new seats.

 

[Tim R]

When we tour in Europe (with a Series IV Automatic and two Series Vs with overdrive) it is not unusual to be cruising with 4,500+ revs and 75-80mph consistently showing for long periods. Never had any serious problems beyond routine maintenance. This is a sports car, just get in it and give it some welly, that's what it was made for!

In this clip from a video we were setting the automatic Series IV up on a rolling road. At a computer calibrated 82mph she was doing about 5,250 revs. The speedo in the car was showing several mph more than this, the rev counter in the car was close.

Tim

 

[George Coleman]

George,
I switched the series 4 to a 3.70 gear and at 65 I'm turning around 3500 with 13"

I had a 3.70 but it got to loud took it out your right I think I am around 36 37 with the 3.89

 

[RootesRooter]

Are the 3.7's from the Netherlands all loud or is a 'roll the dice' situation?

 

[Bill Blue]

I don't recall anyone saying their's is quite, but a lot of comment about about being loud. I suppose there may be a few quite ones. Moley?

Bill

 

[65beam]

My 3.70 is quiet because it's an original Sunbeam part. I had three fastbacks that had the 3.70. The red Harrington has a set of 3.70 gears.

 

[mightyohm]

A little off topic, but my 4.22 rear end is fairly loud. Is there anyone that rebuilds these or how major of a DIY effort is it?

 

[Warren]

With all due respect its I'm for lowering RPM's at highway speeds just makes everything more enjoyable.

 

[65beam]

As one long time Alpine owner once said. "HIGH RPM'S KEEPS MY OIL PRESSURE UP". Since the Alpine oiling system isn't the best in the world to deliver a high volumn of oil you then need high pressure.

 

[Hodee]

All sounds good to me! My next outing I may push it to 4500 or beyond for a short bit. With a close eye on the OP gauge. 62,000 miles on the original engine numbers matching.

 

[alpine_64]

While oil pressure does correlate to rpm there is a base pressure needed for a healthy motor.

Alpines are sensitive to low oil psi and its a sign of issues if you require rpm to get decent readings. If ignored it will lead to failure. A tired motor will gain pressure with higher revs but the imminent failure will come sooner.

There has been some interesting contradiction in the thread. If high cruising rpm are neither an issue for car or occupant one would wonder why someone would change to a taller final drive?

Hodee, i stand by my original comments. A healthy rootes motor will spin along at 3800+ for hours on the freeway, but it will wear out oil, motor and occupants faster than at lower rpm.

As for o/d, half of alpines built had it new and most current owners now desire it or a 5 speed. Taller final drives, large rolling radius wheels help to real cruising on a freeway for car and driver.

Have fun for short bursts in the gears .. But why cruise at a constant higher rpm than you have to if you have other options?

You said 20min trips at freeway speeds... I consider that short and not such an issue. On a long constant freeway drive taller gearing is a bonus on every front.

Enjoy the car, be vigilant .. And if oil.pressure ever starts dropping.. The answer is not more rpm... Unless you want a fresh motor ;-)